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EXPERIMENTAL STUDY OF THE EFFECT OF SUBSONIC EXHAUST GAS DIFFUSERS ON THE TEST CELL WALL

AND TF39 COLD-FLOW MODEL ENGINE EXHAUST

NOZZLE PLUG AND CORE ENGINE COWL SURFACE PRESSURES

Delbert Taylor, Marvin Simmons, and Frank T. Loo

MO, Inc. ftopefly «tits. »Fon»

AEDC LIBRARY F4O6OO-81-C-DO04

April 1973

Approved for public release; distribution unlimited. I

ENGINE TEST FACILITY

ARNOLD ENGINEERING DEVELOPMENT CENTER

AIR FORCE SYSTEMS COMMAND

ARNOLD AIR FORCE STATION, TENNESSEE

mm When U. S. Government drawings specifications, or other rlata arc used for any purpose other than a definitely related Government procurement operation, the Government thereby incurs no responsibility nor any obligation whatsoever, and thi* fact that the Government may have formulated, furnished, or in any way supplied the said drawings, specifications, or other data, is not lo be regarded by implication or otherwise, or in any manner licensing the holder or any other person or corporation, or conveying any rights or permission to manufacture, use, or sell any patented invention that may in any way be related l hereto.

Qualified users may obtain copies of this report from the Defense Documentation Center.

Heferenr.es to named commercial products in this report are not lo be considered in any sense as an endorsement of the product by ihe United States Air Force or the Government.

AEDC-TR-73-13

EXPERIMENTAL STUDY OF THE EFFECT OF SUBSONIC

EXHAUST GAS DIFFUSERS ON THE TEST CELL WALL

AND TF39 COLD-FLOW MODEL ENGINE EXHAUST

NOZZLE PLUG AND CORE ENGINE COWL

SURFACE PRESSURES

Delbert Taylor, Marvin Simmons, and Frank T. Lee

ARO, Inc.

Approved for public release; distribution unlimited.

AEDC-TR-73-13

FOREWORD

The work reported herein was conducted at and was sponsored by Arnold Engineering Development Center, Air Force Systems Command, Arnold Air Force Station, Tennessee, under Program Element 64719F.

The results presented were obtained by ARO, Inc. (a subsidiary of Sverdrup &. Parcel and Associates, Inc. ), contract operator of the Arnold Engineering Development Center (AEDC), Air Force Systems Command (AFSC), Arnold Air Force Station, Tennessee. The work was conducted in the Engine Test Facility (ETF) under ARO Project No. RW5224 from July 1971 to June 1972, and the manuscript was submitted for publication on August 11, 1972.

This technical report has been reviewed and is approved.

EDWARD W. HANSON ROBERT O. DIETZ Captain, USAF Director of Technology Requirements Planning Division Directorate of Technology

ii

AEDC-TH-73-13

ABSTRACT

An experimental investigation was conducted to determine the effects of .exhaust gas collectors/subsonic diffusers on engine and test cell surface pressures during tests of high-bypass-ratio front-fan engines in ground test facilities. A one-tenth scale model of a TF39 turbofan engine installed in a one-tenth scale model of Propulsion Development Test Cell (J-l) was employed. Engine cowl and plug surface pressure data were recorded during model engine operation with cold air at five simulated power settings without exhaust collector, with exhaust collector, with exhaust collector equipped with a conventional subsonic diffuser, and with exhaust collector equipped with a segmented subsonic diffuser which separately diffused the fan and core engine exhaust jets. Stagnation pressure data were also recorded for the purpose of establishing the flow losses in the free-jet exhausts and in the diffusers. Data from all configurations were analyzed to determine the effect of exhaust jet collector/diffusers on engine and test cell surface pressures and to determine the efficiency of the diffusion process. Data from the full-scale TF39 engine in test cell J-l of the ETF (Ref. 1), from the TF39 model test conducted in a scale model of test cell J-l by Fluidyne (Ref. 2), and from this test compared favorably, thus indicating that the effect of the exhaust diffusers on test cell and engine surface pressures was negligibly small. '"Splitting" and separately diffusing the fan and core exhaust streams did not affect test cell or engine surface static pressures. The diffusers produced static pressure rise ratios as high as 1. 41 which corresponds to a decrease of approximately 28 percent in exhaust gas volume flow rate.

m

AEDC-TR-73-13

CONTENTS

Page

ABSTRACT iii NOMENCLATURE ix

I. INTRODUCTION 1 II. APPARATUS 2

III. PROCEDURE 8 IV. RESULTS AND DISCUSSION 8 V. SUMMARY OF RESULTS 14

REFERENCES 15

APPENDIXES

I. ILLUSTRATIONS

Figure

1. Test Cell Installation 19

2. 1/10th-Scale Model of the TF39 Engine 20

3. Simulated J-1 Exhaust Collector Details . . 21

4. Test Section with Simulated J- 1 Exhaust Collector Installed 22

5. Conventional Subsonic Diffuser Details 23

6. Test Section with Conventional Subsonic Diffuser Installed 24

7. Segmented Diffuser a. Design Details 25 b. View of Core Jet Diffuser with Radial Splitter

Plates Installed 26

8. Test Section with Segmented Diffuser Installed 27

9. Modifications Made to the Segmented Diffuser for Improving Diffuser Performance a. Sketch of Air Ejector in the Annular Diffuser .... 28 b. Top Annular Passage Sealed with Streamlined

Plug 29

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Figure Page

c. Splitter Plates with Knife-Edged Wedges 29 d. Segmented Diffuser with Four Splitter

Plates Removed 30 e. Segmented Diffuser with Only the Two Horizontal

Splitter Plates Installed 31

10. Model TF39 Exhaust Plug Static Pressure Tap Location . 32

11. Model TF39 Nacelle Static Pressure Tap Location ... 33

12. Test Section Instrumentation Stations 34

13. Pitot Tube Arrangement at Collector Inlet Plane a. Total Pressure Probe Arrangement, 10 Probes

on Equal Areas with One on Centerline 35 b. 15 Total Pressure Probe Arrangement 36

14. Total Pressure Survey Rake Showing Probe Location . . 37

15. Subsonic Diffuser Exit Pitot Tube Arrangement .... 38

16. Segmented Diffuser Exit Pitot Tube Arrangement a. Diffuser with Pitot Tubes in the Exit of

Each Passage 39 b. 13-Pitot Tube Rake Installed Vertically, Top

Passage Open 40

17. Total Pressure Rake Arrangement and Location for Measuring the Pylon Wake 41

18. Location of Pitot Tubes for Flow Check Outside Diffuser Inlet 42

19. Test Cell Surface Pressures a. For Ptr /Pp Ratio of 2.34 43

•-fe Lav b. For Pt„ /Pc Ratio of 2.04 44 lfe "-av c. For Pt, /PP Ratio of 1.60 45 lfe *-av d. For Pt /Pn_ Ratio of 1.47 46

"e tf '*-cav

20. Turbofan Engine Surface Pressures a. For Pt. /Pc Ratio of 2. 34 47 lfe "-av b. For Ptp /PP Ratio of 2. 20 48 xfe cav c. For Ptj /P„ Ratio of 2.04 49 ■•ff, cav

VI

AEDC-TR-73-13

Figure Page

d. For Ptf /Pc Ratio of 1.60 50 lfe *-av e. For Pt, /P„ Ratio of 1.47 51 lfe cav

21. Exhaust Jet Pressure Survey at Collector Inlet Plane a. For Pt, /P~ Ratio of 2.20 52 lfe cav b. Results from Full-Scale TF39 Test in Test Cell

J-lforPf, /Pc Ratio of 2. 23 53 Lfe Lav c. Model Study Results for Each Fan Nozzle

Pressure Ratio Tested 54

22. Total Pressure Survey in Pylon Wake, Collector Inlet Plane 55

23. Comparison of Collector Inlet Velocity Profile between Laser Velocimeter and Calculated Values a. For Pu /Pr_ Ratio of 2. 34 56

e t* '±c lfP cav b. For Pt, /P„ Ratio of 2. 05 57 Lfe Lav c. For Pt, /Pc Ratio of 1.63 58 lfe ^av d. For Pt, /P„ Ratio of 1.44 59 lfe cav e. For Pt /P0 Ratio of 2.18 60

'e ^fp cav

24. Total Pressure Survey Rake Showing Pitot Tube Locations and Measured Pressures a. For Pt, /Pn Ratio of 2.35 61 lfe cav b. For Ptf /Pn Ratio of 2.05 61 lfe cav c. For Pt, /P~ Ratio of 2.20 61 lfe *-av d. For Pt„ /Pn Ratio of 2. 27 62 Lfe Lav e. For P+J. /P„ Ratio of 2. 34 62 xfe cav f. For Pt, /Pn Ratio of 2. 20 62

"•fe cav

25. Collector-Conventional Diffuser Performance 63

26. Conventional Diffuser Exit Total Pressure Survey ... 64

27. Collector-Segmented Diffuser Performance 65

vu

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Figure Page

28. Total Pressure Profile at Segmented Diffuser Exit a. For Ptf /Pr Ratio of 2.33 66 lfe cav b. For Ptr /Pr Ratio of 2. 19 67

••fe cav c. For Ptj. /Pp Ratio of 2. 15 68 Lfe cav d. For Pt, /PP Ratio of 1.62 69 xfe Lav e. For Ptt /Pp Ratio of 1.48 70 Lfe *-av

29. Total Pressure Survey at the Exit of the Segmented Diffuser a. For Pt, /P„ Ratio of 2. 33 71 Lfe cav b. For Pt, /Pc_ Ratio of 2.07 71

tfe ^av c. For Pt. /Pp Ratio of 1.62 71

••fg cav d. For Ptj /Pr Ratio of 1.50 72 H. av le e. For Ptf /Pr Ratio of 2.20 72

••fg cav

30. Total Pressure Survey at the Exit of the Segmented Diffuser with Sharp Leading Edge Splitter Plates

a. For Pt, /Pc Ratio of 2. 34 73 Lfe *-av b. For Pt. /Pc Ratio of 2.02 73

fe av

c. For Pt /Pn_ Ratio of 1.64 73 'e

lla cav d. For Ptf /Pp Ratio of 1.50 74 lfe Gav e. For Ptj /P„ Ratio of 2. 20 74

fp uav

31. Total Pressure Survey at the Exit of the Segmented Diffuser with Four Splitter Plates Removed a. For Pt. /Pp Ratio of 2. 33 75 Lfe cav b. For Pt. /Pc Ratio of 2. 04 75

'tf av e c. For Pt, /Pc Ratio of 1.66 75 xfe '-av d. For Pt, /Pc Ratio of 1.50 76 Lfe '-av e. For Pt, /Pp Ratio of 2.20 76

'fg cav

32. Total Pressure Survey at the Exit of the Segmented Diffuser with Only the Horizontal Splitter Plates a. For Ptf /Pp Ratio of 2. 36 77

tfe cav

vui

AEOC-TR-73-13

Figure Page

b. For P+, /P„ Ratio of 2.05 77 ^fg cav

c. For Ptf /Pc Ratio of 1.65 77 Lfe '-av d. For Ptf /Pn Ratio of 1.50 78 lfe cav e. For Ptx. /Pc Ratio of 2.20 78 ufe *-av

33. Diffuser Inlet Duct Wall Pressure 79

II. TABLE

I. Test Cell Pressure Comparison per Fan Nozzle Exit Pressure Ratio 80

NOMENCLATURE

A Area, in.2

B Bias limit

«£ Centerline

CPR Pressure coefficients, -^ ~ 1 s Fti " Fl

■pi

-pi D Diameter, in.

F Impulse, lbf

L Length, in.

P Static pressure, psia

Pt Total pressure, psia

R Radius, in.

S Precision error index

Tt Total temperature, °F

t Statistical distribution function

u Uncertainty

IX

AEDCTR-73-13

SUBSCRIPTS

av Average

C Core

c Test cell

CO Collector

d Diffuser

e Exit

ex Exhaust

f Fan

I Air inlet

i Inlet

j Jet

n Nozzle

r Rake

w Wall

1,2, etc. Station locations

AEDC-TR-73-13

SECTION I INTRODUCTION

Large thrust high-bypass-ratio subsonic turbofans place stringent requirements on ground test facilities for two reasons:

1. The airflow which must be supplied to the engine inlet, and

2. The large volume flow of exhaust gases which must be removed from the test cell.

The very large airflow required by these turbofan engines exceeds the continuous air supply capability of existing ground test facilities when the engines are tested in the direct-connect mode. To alleviate this problem somewhat, it has been proposed that the fan and core engine exhaust jets be diffused separately. This facilitates redirecting the fan jet to the engine inlet. For a bypass ratio of 8:1, this would result in an approximate 80-percent reduction in the continuous airflow required of the test facility air supply system. At the same time, the core engine exhaust diffuser converts some of the exhaust jet kinetic energy to static pressure, thus reducing the volume flow which the facility exhausters must handle.

In a free-jet installation of a large thrust, high-bypass turbofan engine, separate diffusion is also needed, but for a somewhat different reason. Free-jet testing in a large wind tunnel requires that the core engine exhaust j.et be scavenged so that the process air in the closed- loop wind tunnel does not become contaminated with exhaust products. Pressure recovery is needed not only to reduce the scavenge system exhauster capacity required but also to reduce the power requirements for the main wind tunnel compressors.

For either the direct-connect or the free-jet mode of testing at subsonic or transonic exhaust gas velocities, the proposed use of exhaust gas collectors/diffusers has raised questions concerning their influence on the test cell ambient and engine external surface pressures (cowling, boattails, etc.). Splitting the exhaust jets at the diffuser inlet may affect diffuser inlet flow to the extent that pressures on the engine and test cell surfaces are also affected; in which case extensive static pressure surveys would be required to permit one to analyze the effects on measured thrust.

AEDC-TR-73-13

An extensive literature search produced a limited amount of experimental performance data from tests of vaned or segmented diffusers of both the two-dimensional and axisymmetrical designs; none of the diffuser configurations reported were comparable with that required for separately diffusing the fan and core engine jets nor were the magnitudes of the diffuser inlet velocities and flow distortions.

Therefore, a study of concentric exhaust diffusers was initiated for the purpose of determining:

1. The magnitude of the effects of exhaust gas collectors/diffusers on test cell and engine surface pressures, and

2. The efficiency of the energy conversion which might be attained.

A one-tenth scale model of a TF39 turbofan engine was mounted in a one-tenth scale model of Propulsion Development Test Cell (J-l). The engine/test cell unit was installed in Propulsion Research Cell (R-2A- 3) where the test program was conducted.

SECTION II APPARATUS

2.1 TEST CELL SECTION

The test cell section was fabricated from,two sections of nominal 20-in. -diam pipe (Fig. 1, Appendix I). The front section of the test cell was 39 in. long and was flanged to the aft section, which was 43. 75 in. long giving an overall test cell length of 82. 75 in., a scale model of AEDC test cell J-l. The upstream end was sealed by a flat plate which supported the 10-in. -diam air inlet connection to the engine fan section. The model TF39 was installed in the center of the aft section with the engine pylon secured to the test cell wall. The aft section contained two 6- by 15-in. rectangular observation windows and instrumentation access ports. The downstream end of the cell was connected to a 24-in. -diam exhaust duct, which links the test cell to the plant exhaust machines. Provisions were made at this point for installation of the diffuser configurations to be investigated.

AEDC-TR-73-13

2.2 ENGINE MODEL

Shown in Fig. 2 is a sectional view of the l/10th-scale model of the TF39 engine. FluiDyne Engineering Corporation fabricated the model according to specifications supplied by Lockheed Aircraft Cor- poration and General Electric Corporation and conducted the static performance testing of the model engine. These results as well as de- tailed and assembly drawings of the model are presented in Ref. 2.

The model was installed inside and concentric with the aft test cell section. The 10-in. -diam air inlet duct was adapted to the engine fan nozzle inlet thus providing support for the model and direct connection to the plant air supply. The engine pylon was secured to the top of the test cell by a rectangular bracket that was utilized to align the model on the centerline of the test cell.

2.3 EXHAUST COLLECTOR

The exhaust collector (Fig. 3) is essentially a 1/10th-scale model of the exhaust collector with diffuser used in the full-scale test of the TF39 turbofan engine in the J-l test cell. The collector was comprised of a truncated conical inlet section, 3. 12 in. long, with a 30- deg converging angle and a 9. 6-in. -diam cylindrical duct having a length-to-diameter ratio (L/D) of 0. 5. Attached to the collector was the 14-in. -diam cylindrical section, which simulated the J-l diffuser.

The exhaust collector (Fig. 4) was installed on, and concentric with, the centerline of the 24-in. exhaust duct. The collector inlet plane was positioned 5. 5 in. downstream of the model exhaust plug.

2.4 CONVENTIONAL SUBSONIC DIFFUSER

The conventional subsonic diffuser (Fig. 5) was comprised of the 1/10th-scale model of the J-l exhaust collector equipped with a truncated conical diffuser having an exit-to-entrance area ratio of 4 and a cone angle of 10 deg. Installation of the diffuser (Fig. 6) was similar to that of the exhaust collector with the spacing between the model exhaust plug and the diffuser inlet plane maintained at 5. 5 in.

AEDC-TR-73-13

2.5 SEGMENTED DIFFUSER

The segmented diffuser (Fig. 7a) consisted of two truncated conical diffusers: the core jet diffuser and the fan jet annular segmented diffuser.

The core jet diffuser was designed to capture and diffuse the high energy flow of the core engine exhaust. The entrance section was cylindrical with a diameter of 3. 5 in. and a length-to-diameter ratio (L./D) of 2. 75. The diverging section had a 10-deg cone angle with an area ratio of 4. 0.

The fan jet annular segmented diffuser, designed to separately diffuse the fan exhaust gas, was installed concentric with the core jet diffuser and positioned so that the diffusers terminated in the same plane. The diverging conical section had a cone angle of 25 deg with an annular entrance area of 62.86 in.2. The inlet to the fan jet diffuser was geo- metrically similar to the exhaust collector; however, the capture duct diameter was increased 0. 2 in. to compensate for the area loss caused by the capture duct of the core jet diffuser.

Ten radial splitter plates were installed in the annular passage to divide it into 10 diffusers of equal dimensions having effective conical diffusion angles of approximately 8 deg and area ratios of 4. The splitter plates were 0. 25-in. -thick steel plates, 19. 9 in. long and were welded to the outside surface of the core jet diffuser. The assembly (Fig. 7b) fits inside the collector-fan diffuser. The plates were installed in the annular passage with the leading edge 2. 2 in. downstream of the junction of the collector and the fan diffuser to compensate for the flow area blockage by the plates. The total flow area at the entrance of the plates was 70.20 in.2.

Installation of the segmented diffuser (Fig. 8) was identical to the installation of the J-l exhaust collector-conventional subsonic diffuser with the inlet 5.5 in. downstream of the model TF39 exhaust plug.

To compensate for the low energy wake in the fan jet which result- ed from the pylon blockage and boundary layer, a high energy air jet was installed (Fig. 9a) at the inlet to the segmented fan diffuser section behind the pylon to accelerate this flow; then the air jet was removed, and a streamlined plug (Fig. 9b) was inserted in this diffuser section. The plug sealed the inlet to this diffuser segment and extended forward to guide the low energy flow into the adjacent segments.

AEDC TR-73-13

To improve the performance of the diffuser, the leading edges of the 1/4-in. -thick splitter plates were modified by adding wedges which were 2 in. in axial length and had sharp leading edges (Fig. 9c).

The segmented diffuser was further modified to improve the performance by removing four of the splitter plates, forming six segments (Fig. 9d), and by removing all the splitter plates except the two on the horizontal centerline (Fig. 9e).

2.6 INSTRUMENTATION

2.6.1 Data Conditioning and Recording

All pressure and temperature data obtained during this test were recorded on a computer-controlled digital acquisition system. This system has the capability of obtaining 100 high speed channels of data at a scan rate of 14, 500 channels/ sec and an additional 448 channels of data at a scan rate of 200 channels/sec and of automatically controlling the stepping of 30 scanner valves of that 360 channels of pressure data can be obtained with 30 transducers. The computer automatically controlled and recorded millivolt calibrations of all temperature channels, resistance calibration of all pressure channels, and in-place calibration of pertinent pressure channels.

Operation was conducted in an on-line mode; the ETF computer was used to record all the data and to provide in real time selected parameters for use in evaluating the validity of the test conditions.

The computer in all cases was utilized during testing to obtain im- portant test parameters for a display on a cathode-ray tube. Data dis- played in this manner was updated every 2 sec permitting monitoring of up to 20 parameters of data during operation.

2.6.2 Instrument Calibration

Calibrations of all instrument parameters before and after each test period were conducted as required. These included millivolt calibrations of all temperature parameters and resistance calibrations of all pressure parameters. The results of these calibrations were reviewed and discrepancies corrected before each test.

AEDCTR-73-13

2.6.3 Test Data Measurement Uncertainty

For simplicity and comparison of data, uncertainty is used to ex- press a reasonable limit for error. Uncertainty is calculated as follows (Ref. 3):

where

U = ±(B + t0.95 S)

B is the bias limit

S is the precision error index

t is the 95th percentile point for the two. tailed student "t" distribution (The t value is a function of the number of degrees of freedom, used in calculating S. The t is arbitrarily selected to equal 2 for samples sized from 30 to infinity.)

Although uncertainty is not a statistical confidence interval, it is an arbitrary subsitute which is probably best interpreted as the largest error we might expect. Under any reasonable assumption for the distribution of bias, the coverage of U is greater than 95 percent (Ref. 3).

In these data, the uncertainty for an average of four measurements of pressure is

U = i(B + tS) = 0.020 psi

where

B = 0. 0116 psi

tS = 0. 0084 psi

t = 2

Range of pressure data = 3 to 15 psia

This level of uncertainty reflects the characteristics of the transducers, electrical systems, data recording systems, and data process- ing systems. It does not consider the physical condition of the taps or the flow conditions existing in the region of the taps.

2.6.4 Pressure Sensing Locations

The model exhaust plug and nacelle surface static pressure probe locations are shown in Figs. 10 and 11, respectively. The fan nozzle

AEDC-TR-73-13

exit, core engine air supply venturi, and core engine nozzle pitot tube locations are shown in Fig. 2.

Axial stations and circumferential locations of test cell static pressure probes are shown in Fig. 12.

Four pitot tubes positioned on equal areas were installed in the 10- in. air supply duct at station 5 for measuring air inlet total pressure (Fig. 12). Inlet air temperature was sensed by a copper-constantan thermocouple installed at station 5.

Station 20 was at the plane of the inlet of the collector-diffuser configurations (5. 5 in. from the engine exhaust plug). During testing without a diffuser (test cell only), pitot tubes were installed for measuring the total pressure profile at the collector-diffuser inlet plane (Figs. 13a and b).

A pressure survey rake (Fig. 14) containing 39 pitot tubes for docu- menting the pressure profile of the model TF39 fan jet was used at station 20 (diffuser inlet plane) and at a position 6. 65 in. downstream of the fan nozzle exit.

Stations 26 and 30 represent the location conventional and the segmented diffuser exits, respectively. Diffuser exit pitot tube arrange- ments are shown in Figs. 15, 16a, and 16b.

A rake was installed behind the pylon of the model TF39 to measure the total pressure profile across (horizontally) the wake of the pylon. The rake contained seven pitot tubes and was centered on the vertical centerline 3. 8 in. downstream of the model exhaust plug exit and at 3.45 in. above the centerline of the model (Fig. 17).

Six pitot tubes, three at the 90-deg and three at the 180-deg circumferential locations looking downstream, were installed between the test cell wall and the subsonic diffuser inlet (Fig. 18) to document impact pressures in this area.

A laser doppler velocimeter was used on four tests for determining the gas velocity at the plane of the collector inlet to avoid perturbating the flow with standard pressure measuring instrumentation. The prin- ciple of operation of the velocimeter is explained in Refs. 4 and 5.

AEDC TR-73-13

SECTION III PROCEDURE

The test cell exhaust plant isolation valves were opened, and the plant exhausters were employed to evacuate the test installation. The desired test cell ambient pressure was established, and an altitude instrumentation check was taken. The air supply plant isolation valves were opened to initiate airflow to the model engine. Steady-state conditions were established, and test data were recorded.

The five test conditions at which each configuration was evaluated are presented in the following:

-av

2. 34

2.02

1.62

1.48

2.20

c psia

3.28

3.28

3.28

3.28

6.30

ti' psia

7. 85

6.85

5.50

4.98

14. 13

100 to 110

SECTION IV RESULTS AND DISCUSSION

4.1 EFFECT OF EXHAUST COLLECTOR-DIFFUSER ON TEST CELL PRESSURE

The effect of the exhaust configurations tested on test cell pressure is shown in Figs. 19a through d. These graphs depict the averages of a number of pressures located circumferentially at each of several stations divided by the average of all the test cell pressures measured. Individual values of test cell pressure are tabulated in Table I (Appen- dix II). The trends of the nondimensionalized average test cell pressures are similar and compare with those presented in Fig. 38 of Refs. 1 and 2, The exhaust collector apparently caused a slight depression in the curve at the downstream end of the test cell; however, the addi- tion of diffusers caused little if any additional change except at the fan

/

AEDC-TR-73-13

nozzle pressure ratio of 1.57 where the conventional subsonic diffuser apparently caused a random variation in pressure which is of questionable validity since it produced no effect at the other fan nozzle pressure ratios.

The test cell wall pressure tap located at station 20 (Fig. 19) which is at the inlet plane of the exhaust collector consistently recorded the largest value of test cell pressure except at the fan nozzle pressure ratio of 1. 57. The large value of pressure is probably the result of the tap being located in the impact zone of the test cell vortex, indicated in Fig. 8.

4.2 EFFECT OF EXHAUST COLLECTOR DIFFUSERS ON ENGINE SURFACE PRESSURES

Engine surface pressures, nondimensionalized by the average test cell pressure, are presented in Figs. 20a through e for all configurations tested. These graphs also present results from the full-scale test in J-l test cell and/or from the scale model study reported in Refs. 1 and 2. The method of connecting the test points was taken from Ref. 2 so that the trends could be compared directly. The vari- ations in fan and core engine nozzle pressure ratios among runs caused the variation in the axial location of the curve peaks; however, there is no apparent effect of the exhaust collector-diffusers on engine surface pressures. The full-scale engine core nozzle pressure ratio was varied during developmental testing in J-l, and the effect of this variation is noticeable in these comparison curves of tail-pipe plug surface pressures (see Figs. 20a through e).

4.3 ENGINE EXHAUST FLOW FIELD SURVEYS

During tests of the full-scale engine in J-l test cell, a total pressure rake was installed on the vertical centerline of the exhaust jet at the plane of the inlet to the exhaust collector. The rake extended from the test cell floor to a point a short distance above the engine centerline. The results of the pressure survey conducted during full-scale engine test without the exhaust collector and during these model studies are presented in Figs. 21b and 21a and c, respectively. The peak pressure in the flow field of the full-scale engine occurred at a radius of 3. 0 ft which shows that the high energy core of the fan jet followed the surface of the core engine cowl as expected. The wake behind the core engine nozzle plug is located above the engine centerline and has a

AEDCTR-73-13

discrete velocity decrement. The model engine plug wake was also located above the engine centerline. The effect of the fan jet converging on the core jet is discussed in Ref. 2. Test results (Ref. 2) taken with the core jet only and with both the core jet and fan jet flowing showed that the core nozzle plug surface pressures are larger when both jets are flowing. This was attributed to the convergence of the fan jet on the core jet, which can also explain the plug wake position: the very large engine mounting pylon that bisects the fan jet from a plane inside the fan nozzle to the core nozzle exit plane generates a very large wake plus boundary layers on both sides of the pylon. Thus, there is an arc of some 30 to 45 deg on each side of the vertical centerline of the engine at the core nozzle exit plane which is essentially the pylon wake flow and is, therefore, at a low level of kinetic energy (Fig. 22). The remaining fan flow field exerts a larger force as it converges on the core jet than does the pylon wake, and therefore, a radial force imbalance exists in the combined jet flow field downstream of the core nozzle which results in moving the core jet toward the pylon.

Pressure and velocity surveys were conducted in the exhaust jet at the plane of the collector inlet prior to its installation. The results are presented in Figs. 23a through e. Velocity profiles determined from pressure measurements are along the vertical centerline below the center of the jet; those determined by the velocimeter are along the horizontal centerline from beyond the center toward the left when viewing the engine from the jet collector. The calculated velocities were de- rived from the measured stagnation pressures and temperatures and the average test cell static pressure and thus are of questionable ac- curacy; however, the velocity profiles determined by the two methods compare favorably as do the profiles determined by the velocimeter during tests of different exhaust hardware configurations at comparable values of fan nozzle pressure ratios, thus indicating that the exhaust collector-diffusers tested exerted a negligible influence on the velocity of the exhaust jet near the collector inlet.

The laser velocimeter was used to indicate the exhaust gas velocity along the horizontal centerline of the jet near the plane of the collector inlet during tests with the various collector-diffusers installed in order to get an immediate indication of any appreciable level of disturbance caused by these configurations without additional disturbances caused by conventional instrumentation hardware in the stream.

10

AEOC-TR-73-13

The pressure surveys recorded from tests with the circular rake (Figs. 24a through f) show the radial and circumferential gradients in the fan flow field at the plane of the collector inlet and at a plane approximately midway between the exit planes of the fan and core nozzles. The pressure surveys recorded during tests with the rake located in the pylon wake at a station 3. 45 in. above the engine centerline and 3.8 in. aft of the core engine plug (Fig. 22) indicate the extent and the energy level of the wake at the inlet to the collector-diffusers.

4.4 COLLECTOR-DIFFUSER PERFORMANCE

The static pressure rise ratio of the exhaust collector and the exhaust collector-conventional diffuser are presented in Fig. 25 as a function of the fan nozzle pressure ratio. In order to determine the pres-

/ Pe " Pcav \ sure coefficient [ CpR = T> = j of the collector-diffuser, the

V tdI- cav/ x lav

average value of the ratio of stagnation-to-static pressures upstream of the collector was determined from a one-dimensional application of the conservation analysis as follows.

The average values of P+ , /P0 at the diffuser inlet was calcu- ° Ld.- / Lav Lav lated by a one-dimensional application of the momentum analysis, the assumption of an ideal fluid, and the assumption that the static pressure at the diffuser inlet equals the average value of the test cell pressure.

F«»i - Pcav [A,», " <Atj * Ac )] ♦ F,n + FCp

where

© Pc Lav

Af. = Af^ t ^T") for B— < 0.528 lj ln\AtJ Ptf

and

AC- = Ar I * for TT"^ < 0.528 CJ Cn \AcJ ptCn

11

AEDC TR-73-13

The results of these evaluations were used to estimate the ideal value of the pressure coefficient (Cpp =1.0) which is also presented in Fig. 25. Test results indicate that the pressure coefficient of the collector-conventional diffuser exceeds 0. 62 which is quite satisfac- tory for this configuration with the relatively large value of average inlet velocity and the extremely poor velocity distributions. It is probable that the minimum area of the diffuser system should be made more nearly equal to the sum of the engine nozzle areas in order to prevent the distribution of the kinetic energy in the exhaust jets over such a large area. Obviously, the length of the minimum area section is much too short to effect a uniform velocity profile at the diffuser inlet. Total pressure surveys at the diffuser exit (Fig. 26) show that there remains only a small average velocity head to recover, which also indicates that the diffuser area is too large. Note also that the total pressure profile measured by the vertical rake reflects only a very slight depression at the top of the diffuser where the effect of the pylon wake, were it not thoroughly mixed, should be quite noticeable.

The segmented diffuser which split the fan and core flows did not affect the upstream flow field; however, it performed so poorly (Fig. 27) that a number of modifications were incorporated in an effort to effect a reasonably acceptable pressure recovery. The poor performance was attributed to the concentric ducts which limit the amount of mixing and thus momentum transfer through the constant area annulus. The pressure surveys conducted at the exit of the diffuser (Figs. 28a through e) show that the top segment limited pressure recovery. Therefore, an air jet with an impulse of 12 to 16 lbf was installed in the annulus behind the pylon to impart energy to the flow. The results of a test of this configuration indicated that a large quantity of air would be required to effect the level of performance desired. There- fore, this method was abandoned, and the top segment was plugged at the inlet by a streamlined wooden plug designed to guide the flow from this area into adjacent segments. Pressure survey rakes were installed at the exit of each segment (Figs. 29a through e). The diffuser performance with the segment plugged approached that of the diffuser with the air jet augmentation.

The diffuser splitter plates were equipped with sharp leading edges which further improved its performance (Figs. 30a through e). The performance of the diffuser with four of the splitter plates removed showed slight improvement (Figs. 31a through e); therefore, the plug and all the splitter plates except those located on the horizontal centerline were removed resulting in slightly improved performance at the

12

AEDC-TR-73-13

larger values of fan nozzle pressure ratios (Figs. 32a through e). All diffuser exit pressure surveys show a circumferential variation of stagnation pressure; therefore, an additional length of cylindrical ducts upstream of the concentric diffusers could be expected to produce further improvements in the diffuser performance by providing for further smoothing of the velocity profile at the inlet to the diffuser segments.

The circumferential variation in the wall static pressure near the exit plane of the 9. 8-in. -diam cylindrical duct (Fig. 33) permits a de- termination of the maximum static pressure rise through some individual diffuser segments. The segment at 30 deg produced a static pressure rise ratio of 1. 152, whereas those at 180 and 210 deg produced ratios of 1.502 and 1.495, respectively. The area-weighted pressure ratio (Pt /Pe ) on the 180-deg radial line at the inlet to the annular uav ^av ö

fan collector was 1. 78 for this test point. The flow was assumed to at- tain some circumferential velocity, as it moved through the constant area annulus to the inlets of the diffuser segments, due to the circumferential variation in total pressure in the exhaust jet. Therefore, the total pressure and thus the pressure ratio (P* /Pr ) at the inlet to r c lav Lav the 180-deg diffuser segment may have been somewhat smaller in value than the 1. 78 measured at the collector inlet. At the engine operating point corresponding to a fan nozzle pressure ratio of P^. /Pc = 2. 34,

the wall static pressure ratio Pw/Pc at 180 deg was 0. 876. Since

subsonic flow in a constant area channel cannot accelerate beyond the velocity of sound, it can be assumed that the maximum pressure ratio at the station of this wall static pressure tap is P^. /Pw = 1. 89; thus

the minimum value of the total pressure decrease in the constant area annulus between the collector inlet and the static pressure tap location (1/4 in. upstream of the junction between the cylindrical duct and the truncated diffuser) is

ndi . 1.78- 1.89(0.876) . 1.78- 1.656 . 1J co 1.78 1.78

or approximately 7 percent. The decrease in total pressure may have been greater which would have made the flow subsonic at the plane of the static tap; however, if the flow was sonic, then the maximum recovery in the 180-deg diffuser segment could be determined only by measuring the wall static pressure at the inlet to the truncated section just downstream of the junction of the cylindrical duct and the truncated diffuser duct. This analysis leads to the belief that the slight increase

13

AEDC-TR-73-13

in rise ratio resulting from the removal of splitter plates was the effect of mixing of the low energy pylon wake and adjacent higher energy air in the diffuser.

SECTION V SUMMARY OF RESULTS

The results of this study of exhaust gas collectors-diffusers may be summarized as follows:

1. The diffusers tested caused no discernible effect on flow parameters in the test cell except for one configuration at one specific test point.

2. The collector-conventional subsonic diffuser produced a maximum rise ratio (test cell to exhaust duct) of 1. 4 which corresponds to a decrease in exhaust gas volume flow > 28 percent.

3. The collector-segmented diffuser produced a maximum rise ratio of 1.3.

4. The performance of individual diffuser passages in the segmented diffuser indicates that the diffuser design was adequate (CPP =0. 64), since the mini-

mum energy conversion exceeded that normally used in performance designs of systems with highly non- uniform velocity profiles, and that lengthening the cylindrical duct inlet to the diffuser would improve its overall efficiency.

5. This experiment should be extended to document, in detail, the experimental performance of diffuser configurations having a smaller cylindrical duct diameter and utilizing long, shallow angle converging sections upstream of the cylindrical duct.

14

AEDCTR-73-13

REFERENCES

1. Kimzey, W. F. and Rakowski, W. J. "Preparatory Studies for for Qualification Testing of the TF39 Turbofan Engine in the Propulsion Engine Test Cell (J-l). " AEDC-TR-69-85 (AD855621L), July 1969.

2. Aircraft Engine Group. "Aerodynamic Model Test Report (Engine), 1/10-Scale Model Exhaust System Static Performance, TF39 Engine for C-5A Aircraft. " GE No. 6DT006A03, February 14, 1968.

3. Abernethy, R. B., Colbert, D. L. , and Powell, B. D. "ICRPG Handbook for Estimating the Uncertainty in Measurements Made with Liquid-Propellant Rocket Engine Systems. " Per- formance Standardization Group, CPIA No. 180, April 30, 1969.

4. Shipp, J. I., Hines, R. H., and Dunnill, N. A. "Development of a Laser Velocimeter System. " AEDC-TR-67- 175 (AD821534), October 1967.

5. Lennert, A. E., Brayton, D. B., Crosswy, F. L. , et al. "Summary Report of the Development of a Laser Velocimeter to be used in AEDC Wind Tunnels. " AEDC-TR-70-101 (AD871321), July 1970.

15

AEDC-TR-73-13

APPENDIXES I. ILLUSTRATIONS

II. TABLE

17

-Test Cell

\o

Flow

-Front Cell Section

-TF39 Engine Model

-Aft Test Cell Section

To Exhausters

24-in. -diam Exhaust Duct

Spacer

Fig. 1 Test Cell Installation

o o H 3) •il (f)

CO

Fan Passage

to O

> m D O H X

CO

All Dimensions in Inches Note: See Ref. 1 for Model Design Details

Fig. 2 1/10th-Scale Model of the TF39 Engine

to

3.

9.6 Di am

*

-16.4-

-7.92*1

30 deg

1

18.4

14 Olai

Mounting Flange

All Dimensions in Inches

Fig. 3 Simulated J-1 Exhaust Collector Details

o o I H 3D

U

U

> m O

-10-in. -diam Air Inlet Duct


To Exhausters

Simulated J-l Exhaust Nozzle


Fig. 4 Test Section with Simulated J-1 Exhaust Collector Installed

Mounting Flange

7.92

All Dimensions In Incbes

Fig. 5 Conventional Subsonic Diffuser Details

> m D o

o o


CO I

to

TO Exhausters

All Dimensions in Inches -10-in. -diam Air Inlet Duct

Collector Conventional Subsonic Diffuser

Fig. 6 Test Section with Conventional Subsonic Diffuser Installed

to

-Fan Jet Annular Segmented Diffuser

?ore Jet Diffuser Radial Splitter Plate (10 Plates Installed)

Mounting Flange


a. Design Details Fig. 7 Segmented Diffuser

> m U o ■H 3D i -J U i

u

•Radial Splitter Plate (Typical of 10)

o

Truncated Conical Section


b. View of Core Jet Diffuser with Radial Splitter Plates Installed Fig. 7 Concluded

to


To Exhausters

-10-in. -diam Air Inlet Duct

Segmented Diffuser

Probable Vortex Formations Generated by the Fan Jet-Ambient Air Mixing Action —


Fig. 8 Test Section with Segmented Diffuser Installed > m a o

Flow

K> 00

I Fan Jet Annular Diffuser

Splitter Plate

> m a o

-j

Core Jet Diffuser

a. Sketch of Air Ejector in the Annular Diffuser Fig. 9 Modifications Made to the Segmented Diffuser for Improving Diffuser Performance

AEDC-TR-73-13

Exhaust Flow

Wedge (Typ.)

Streamlined Plug Plate Seal on Passage Exit

Top View

b. Top Annular Passage Sealed with Streamlined Plug

Wedge (Typ.)

Fan Jet

Core. Jet

1 I n 01

Knife Edged Wedge

0.25 -Splitter Plate


Plan View

c. Splitter Plates with Knife-Edged Wedges Fig. 9 Continued

29

o

Splitter Plate (Typ.)

Streamlined Plug

72 deg (Typ.)

o o

w

Fan Jet Diffuser

Fan Jet Diffuser Outer Casing Removed for Clarity

d. Segmented Diffuser with Four Splitter Plates Removed Fig. 9 Continued

Fan Jet Diffuser

<JJ


Fan Jet Diffuser Outer Casing Removed for Clarity

Core Jet Diffuser


e. Segmented Diffuser with Only the Two Horizontal Splitter Plates Installed Fig. 9 Concluded

> m b O ■H 30 i -J u

23 Tap Numbers

•22

Tap Engine No. Station

13 30.15 14 29.55 15 29.05 16 28.45 17 27.80 18 27.05 19 26.35 20 25.55 21 25.05 22 24.70 23 24.60

Static Pressure Tap Location on Engine

Nacelle

Taps Rotated for Clarity Radial Location of Taps 330 deg

> m □

Fig. 10 Model TF39 Exhaust Plug Static Pressure Tap Location

Pressure Taps Rotated 180 deg for Clarity

Tap Engine No. Station

33 23.85 34 22.85 35 21.85 36 20.95 37 20.05 38 19.15 39 18.00 40 17.30 41 16.25 42 15.30 43 14.40 44 13.55 45 13.05 46 12.50

Static Pressure Tap Locations on Engine

Nacelle

Fig. 11 Model TF39 Nacelle Static Pressure Tap Location o

30

w u


Station Number—»- (?)

Flow

Conventional Diffuser Plane (See Fig. 15)-

Segmented Diffuser Exit Plane (See Fig. 16)-

© <3> ®

To Exhausters

E-i • w. o ~

■ Jo.?

f-^45deg (Typ.) [~-45 deg (Typ.) r-45deg (Typ.) <r Exhaust Static X *V "X \Pressure IP™

-lO-in.-diam Air Inlet Duct

Station 5 F

Station 15

-Test Cell (Pc) Static Pressure Stations

Station 16 Station 17

24'

> m O O H 3)

Station 18 Station 24

Fig. 12 Test Section Instrumentation Stations

AEDC TR-73-13

-Test Cell Wall

Station 20

a. Total Pressure Probe Arrangement, 10 Probes on Equal Areas with One on Centerline Fig. 13 Pitot Tube Arrangement at Collector Inlet Plane

35

AEDC-TR-73-13

Station 20

b. 15 Total Pressure Probe Arrangement Fig. 13 Concluded

36

AEDC-TR-73-13

Fan Exit OD 9.518

Nacelle OD 6.741

0.5-in. Support Ring

Fig. 14 Total Pressure Survey Rake Showing Probe Location

37

AEDC-TR-73-13

Diffuser Exit Static Pressure

8.74

13 Pitot Tube Diffuser Exit Rake Probes Are on Equal Areas

-Subsonic Diffuser Exit

Station 30

Fig. 15 Subsonic Diffuser Exit Pilot Tuba Arrangement

38

AEDC-TR-73-13

^e"1

Diffuser Exit Pitot Tube <Ptde)(Typ)

Fan Jet Diffuser ore Jet Diffuser

Diffuser Exit Static Pressure <Pde"2>


Station 26

a. Diffuser with Pitot Tubes in the Exit of Each Passage Fig. 16 Segmented Diffuser Exit Pitot Tube Arrangement

39

AEDC-TR-73-13

-Fan Jet Diffuser Diffuser Exit Static Pressure

Core Jet Diffuser


R - 6.0

R = 8.6 Diffuser Exit Pitot Tube (Typ.)

Station 26

b. 13-Pitot Tube Rake Installed Vertically, Top Passage Open Fig. 16 Concluded

40

Flow

Aft Test Cell Section

All Dimensions in Inches Rake Location

I 1.5

h— l.o -»

p. 5—|-« •»

1.5

l.o-»-

— 0.5

H 1 1 H

I I I H h

Pitot Tube Arrangement

Fig. 17 Total Pressure Rake Arrangement.and Location for Measuring the Pylon Wake

> m a r> ■H 3)

AEDC-TR-73-13

Diffuser Inlet

R - 6.70

Pitot Tubes (Typ.) Located in Collector- Dlffuser Inlet Plane

-Test Cell Wall

Fig. 18 Location of Pitot Tubes for Flow Check Outside Diffuser Inlet

42

Irr

Station

a Q»

1.05

> ^ 1.00

0.95

fr—fr—.

Sym /'

9 a

-av

• 2.34 No Exhaust Hardware a 2.38 Exhaust Collector A 2.355 Conventional Diffuser o 2.33 Segmented Diffuser 2.35 Ref. 2.

> m a o

a. For Ptf /PCaw Ratio of 2.34 Fig. 19 Test Cell Surface Pressures

■si

s u

a

u

irr j—i ,

■ ■ i

D O

•vl

u Station 15 16 17 18 20

1.05 —

> 1.00

0.95 —

!-—i—% Sym tfe/Pcav • 2.365 No Exhaust Hardware n 2.025 Exhaust Collector A 2.049 Conventional Diffuser O 2.04 Segmented Diffuser 2.05 Ref. 2

b. For Ptfe/Pc,„ Ra^o of 2.04 Fig. 19 Continued

n irr LLL

D Station 15 16 17 18 20

4».

1.05

> Cd

> a ü

10. 1.00 8 I ft--' 8

Q

O

0.95

Sym

• a o A o

PA 1M/1 -av

1.625 1.632 1.75 1.57 1.623 1.60

No Exhaust Hardware Exhaust Collector No Exhaust Hardware Conventional Diffuser Segmented Diffuser Ref. 2

c. For P tf/Pca,, Ratio of 1.60

Fig. 19 Continued

> m a o H 30

V 01

n n a a

w

u Station

w •"»

15 16 17 18 20

1.05

> g 1^00

• 0.95 D

O

o

*-—I— "I i ° \A cav

1.445 1.4738 1.476 1.488 1.484 1.46

Exhaust Collector No Exhaust Hardware Conventional Diffuser Segmented Diffuser Ref. 2

ü

d. For Ptf<t/Pca Ratio of 1.47

Fig. 19 Concluded

B?

4)

3 tn in 4)

01 u

u s

01 c

•H fid c H

1.3

1.2

0.8

120 140 160 180 200 220 240 260 Station Number, in. Full Scale

280 300 320

For Pt# /P. Ratio of 2.34 8. . w. rtfa,rCt

Fig. 20 Turbofan Engine Surface Pressures

> m O O I H 3) i

u L0

00

«?

01 u 3 m

01 u A

3 03

01 s

w

1.3

1.2

1.1

1.0

0.9

0.8

o.r

\

\ \ \ \ \ \ 8 \ \ \ \ \ < \

> — *^L • *N _ <5 JfimSr

\ / * \ / 1 V / / \r7

iA \ \\ A /7

^zs V *<*^yo i o

Svm tfe/

1 cav

O 2.182 No Diffuser Hardware A 2.255 Exhaust Collector + Conventional Diffuser

— V 2.1

- 2.2 88 3

Ex ha Full

ust C -Seal

oiiec e TF3

tor + 9/J-l

Segmented Diffuser Test Results

> m o o

u

120 140 160 180 200 220 240 260 Station Number, In. Full Scale

280 300 320

b. For Pt# /Pe.„ Ratio of 2.20 Fig. 20 Continued

> a

o a.

& (0 m 4)

£ 41 O a

<M ft 3

09

ai c M c W

1.3

1.2

1.1

1.0 -

0.9

0.8

0.7

//

1 \\

\

•^ ^'" <*

« \

'u \^-- •y • ^ if ,\A ^-<t n*^ jfjT 9 — »—|—c !-*♦ *~v

€K

^'^J

,p*f / Sym Ie/ pc cav

O 2.098 No Diffuser Hardware D 2.025 J-l Exhaust Collector A 2.049 Exhaust Collector + Conventional Diffus O 2.040 Exhaust Collector + Segmented Diffuser 2.083 Ref. 1

er , .

120 140 160 180 200 220 240

Station Number, in. Full Scale 260 280 300

C. For P,fe/Peav Ratio of 2.04 Fig. 20 Continued

> m o o

to

u

a o

1.2

>1.1 eg

u ft

1.0 —

o

<ti u a <n n

« o •2 0.9 9

CO

V s

c w 0.8

0.7

w<±

o A A A

V*

A ™ ^ * &

*~& A ^^^~ ""* -A--A- A A """d—f-'A <r&

A

Sym Ptfe/PCav

O 1.625 No Diffuser Hardware O 1.632 J-l Exhaust Collector A 1.575 Exhaust Collector + Conventional Diffus O 1.623 Exhaust Collector + Segmented Diffuser 1.688 Full-Scale TF39/J-1 Test Results

er

w

120 140 160 180 200 220 240

Station Number, in. Full Scale 260 280 300

d. For P., /P. Ratio of 1.60 Fig. 20 Continued

<J\

> a

V u 3

V V a

<M u 3

CO

<o c

to c H

1.3

1.2

1.1

1.0 -

0.9

0.8

0.7

HP

^' #> -zr-

f\ --^% s**j£

r o ^/5^ - c. -B—Q—■

O 1.445 No Diffuser Hardware a 1.474 J-l Exhaust Collector A 1.488 Exhaust Collector + Conventional Diffus O 1.484 Exhaust Collector + Segmented Diffuser 1.507 Full-Scale TF39/J-1 Test Results

i er

120 140 160 180 200 220 240

Station Number, In. Full Scale

e. For Ptf /PCaw Ratio of 1.47

Fig. 20 Concluded

260 280 300

o

CO

AEDC-TR-73-13

s. > V 'av

a. For Pt# /P- Ratio of 2.20 i e B v

Fig. 21 Exhaust Jet Pressure Survey at Collector Inlet Plane

52

2.25

2.00

1.75 > as

1.50

1.25

1.0 -20 10 I 20 I 30

Engine Radius, In.

b. Results from Full-Scale TF39 Test in Test Cell J-1 for Pu /P. Ratio of 2.23 Fig. 21 Continued

> m O o

i H a u u

2.50

2.25

2.00

ft"

■o

1.75

1.50

1.25

1.00

D O

-J u

2 3

Radius, R, in.

c. Model Study Results for Each Fan Nozzle Pressure Ratio Tested

Fig. 21 Concluded

m Vt

> et

•a « a> at N H

■H 3 rH (0 cd an a a>

CO

a> d B-K ■H P a O CD KM

cd

£

1.2 ■

1

1.1 } f \

^E—! fc= ~\ |

1 1.0

Sj

> 2.34 3 2.04 ^ 1.62 > 1.49 > 2.19

"i

0.9

c c /

N ote: See Prob

Fig. e Loc

17 fo ation

r < i

0.8

Open symbol: No Air Jet Operating Closed Symbol: Air Jet Operating

1 1 1 1 1 1 1 -2.0 -1.5 -1.0 -0.5 <£ 0.5 1.0 1.5 2.0

Probe Location, Distance from Vertical Centerline of the Engine Pylon, in.

Fig. 22 Total Pressure Survey in Pylon Wake, Collector Inlet Plane

> m o o

1400

1200

1000

u

■ 800

2 600

400

200

Sym

O Velocity Calculated fron Presau (No Diffuser Hardware)

re Measure

lie With:

Installed

mentB

baser Velocimeter velocity Prof

• Exhaust Collector Installed A Conventional Subsonic Diffuser 0 Segmented Diffuser Installed

1 ptfe/

pca, - 2-34

PCav - 3.267 psla

1 1

D n

-7 -6 -5 -4 -3 -2-1 0 1

Jet Radius, R, at Exhaust Collector Inlet Plane, in.

a. For Ptf /Peav Ratio of 2.34

Fig. 23 Comparison of Collector Inlet Velocity Profile between Laser Velocimeter and Calculated Values

1400

1200

1000

u m 800

8 600

>

400

200

Pt„ /Pc - 2.05 t*e/ »v

O Velocity Calculated from Pressure Measurements (No Diffuser Hardware)

Laser Veloclmeter Velocity Profile With:

• Exhaust Collector Installed A Conventional Subsonic Diffuser Installed O Segmented Diffuser Installed

I L -6 -5 -4 -3 -2 -1

Jet Radius, R, at Exhaust Collector Inlet Plane, in. o

b. For P., /Pc.„ Ratio of 2.05 «=av

Fig. 23 Continued

1400

1200

1000

ü m BOO

00 01 >

600

400

200

Sym

A O

Velocity Calculated from Pressure Measurements (No Diffuser Hardware)


No Diffuser Hardware Exhaust Collector Installed Conventional Subsonic Diffuser Installed Segmented Diffuser Installed

o o

-6 -5 -4 -3 -2 -1 0 Jet Radius, R, in. at Exhaust Collector Inlet Plane, in.

c. For Ptf /PCaw Ratio of 1.63

Fig. 23 Continued

en

o «i CD

01

1400

1200

1000

800

600

400

200

Sym

_ O Velocity Calculated fron Pressure Measurements. (Ho Diffuser Hardware)


□ No Diffuser Hardware • Exhaust Collector Installed

" A Conventional Subsonic Diffuser Installed O Segmented Diffuser Installed

-6 -5 -4 -3 -2 -1 0

Jet Radius, R, in. at Exhaust Collector Inlet Plane, in.

d. For Ptfa/Pcaw Ratio °f 1-4* Fig. 23 Continued

> m o o 2D ■

V U

ON o

u 41 0)

0)

1400

1200

1000

800

600

400

200

D

CO

O Velocity Calculated from Pressure Measurements (No Diffuser Hardware)

Laser Velocimeter Velocity Profile With:

A Conventional Subsonic Diffuser Installed O Segmented Diffuser Installed

-7 -6 -S -4 -3 -2 -1 0 Jet Radius, R, in. at Exhaust Collector Inlet Plane, in.

e. For Ptf /P. Ratio of 2.18 Fig. 23 Concluded

AEDCTR-73-13

Rake Location • Plane of Exhaust Collector Inlet

•Jr-Fan Exit OD 9.518 „ „,„„ ij 1 /—hctocel le 00 & 741

Rake Location - Plane of Exhaust Collector Inlet

Fan Exit OD ». 5» —*—.Nacelle 0D6\ 741

For Ptfe/P,

View Looking Upstream p,,^ . 2.35

PM)Pe-1.087

Ratio of 2.35 b

Rake Location - Plane of Exhaust Collector Inlet

View Looking upstream

PCV-3.Z7»

•3.4896

Pt,e/Pc-2.05

PM/Pe-1.067

For Ptf /PCav Ratio of 2.05

Engine Pylon—"ir~Fan BtHOP^-SB celleOD 6.741

All Dimensions In Inches

View Looking Upstream

c. For Ptf /PCav Ratio of 2.20

Fig. 24 Total Pressure Survey Rake Showing Pitot Tube Locations and Measured Pressures

61

AEDC-TR-73-13

Rake Location - 6.65-in. Downstream of Fan Exit

Engine Pylon »Jr-Fan Exit OD 9. SIB

Rake Location - 6.65-in. Dwmslreim of Fan Exit

Engine Pylon—-{pFan Ex« 009.5» • i —,—"icelle OD 6.741

View Looking Upstream View Looking Upstream

d. For Ptfe/Peav Ratio of 2.27

Ptf( -6.679

PcjV'3.2716

Pa «3.585

PM/PC

e. For Ptf /P. Ratio of 2.34

Rake Location - 6.65-ln. Downstream of Fan Exit

Engine Pylon——{pFan Exit 009.518 le OD 6.741

All Dimensions In Inches

View Looking Upstream

f. For Ptfe/Pc8v Ratio of 2.20 Fig. 24 Concluded

62

AEDC-TR-73-13

1.6

1.5

> et

ü

K (1)

2.4

Pt fe/Pc av

Fig. 25 Collector-Conventional Diffuser Performance

63

ft

1.18

1.16

1.14

1.12

1.10

1.08

1.06

1.04

1.02

1.00 h-

0.08

1 Subsonic

1 1 1 1 Diffuser Exit Total

1 Rake

Je Tcav

Syi i Ver Hoi 0 izontal Rake

0 270 deg

90 -| deg 1 180

deg

> m □ a

w

6 4 2 (£ 2 4 6

Probe Radial Distance, R, from Centerline of Diffuser, in.

Fig. 26 Conventional Diffuser Exit Total Pressure Survey

> U a

M ft

ON

1.4

1.3

1.2

1.1

1.0

o a V o

o

Diffuser Only With Air Jet in Top Compartment With Top Compartment Sealed With Knife-Edged Splitter Plates With Four Splitter Plates Removed With Only the Two Horizontal

Plates Remaining

1 i 1 1 1 1

Splitter

1 1.4 1 .6 1 .8 2 .0

/'

2 .2

av

2.4 2.6 2 .8

Fig. 27 Collector-Segmented Diffuser Performance o

3)

u>

u

01

1.3

1.2

1.1

1.0

0.9

0.8

0.7

^Cav'2-33

1 1 1 1 Sym

■ _■

O D

Diffuser Only Air Jet Operating

VD"

\

0 d« H

5g

9 180 deg

Rai e Ins talle d Ver tical ly al Difi user Exit (See Fig. 16)

Core Jet Diffuser Wall


L_ 1

10

o o H 3D

i) CO

u

6 4 2 £ 2 4 6

Probe Location, Distance from Centerline of Diffuser, in.

a. For Ptf /PCaw Ratio of 2.33 Fig. 28 Total Pressure Profile at Segmented Diffuser Exit

10

-J

01 •u a

1.3

1.2

1.1

1.0

0.9

0.8

0.7

pt, /pc " 2.19 Lfe/ *-av i i I I 1 1 1 1

Sym

D Air Jet Operal ting

■^

0

0 di 2g 1 i "fi

>^ l"*" 180 deg

Rak 1

e Ins talle d Ver tlcal ly at Dlff user Exit (See Fig. 16)

i Core Jet Diffuser

Wall

Core Jet Diffuser

Vail

1 1 10 6 4 2 £ 2 4

Probe Location, Distance from Centerline of Diffuser, In.

b. For Ptfe/Peai, Ratio of 2.19 Fig. 28 Continued

10 > m a a

0J

00

ID ■ö

p.

1.3

1.2

1.1

1.0

0.9

0.8

0.6

ptfe/pcav - 2.15

1 1 1 Sym

u uiirus □ Air Je

er uniy t Operatin g

) deg "" -O" f 1 -fl

180 deg

Rak e Ins talle d Ver tical ly at Dlff user Exit (See Fig. 16)



10 6 4 2 g 2 4 6 Probe Location, Distance from Centerline of Diffuser, in.

c. For Ptf /PCaw Ratio of 2.15

Fig. 28 Continued

o o

10

ON

0)

0.

1.3

1.2

1.1

1.0

0.9

0.8

0.7

Ptfe/pcav" 16S

Sym 1 1

~ O D

Ulf Air

tuser Jet

uniy Dpera ting

4 ̂ ̂ N V ■ a \ N,

0 di e \

\ deg-

Rak e Ins talle i Ver tical Ly at Diff iser Exit (See Fig. 16)

Cc Di

re Je ffuse Wall

t r

Core Jet Diffuser

Wall

| |

10 6 4 2^246

Probe Location, Distance from Centerline of Diffuser, in.

d. For Ptf /PCav Ratio of 1.62

Fig. 28 Continued

10 > m □ o

tj

o

(V

Pi

1.3

**J* cav 1.486

1 .2

Sym - n

1 1

Diffuser Only Air Jet Operal D ing

1.1 nr =3 O"

^ V 1.0

"^ s. 0 d« 9- f ) a 180 deg

0.9

Ral e Ins tall« d Vex tical ly at Dlfl user Exit (See Fig. 16)

0.8 Cc Dl

re Je ffuse Wall

t r

Core Jet Diffuser

Wall

0.7 1

10

D O

3)

to

6 4 2 g 2 4 6 Probe Location, Distance from Centerline of Diffuser, in.

10

e. For Pu /P- Ratio of 1.48 ig a v

Fig. 28 Concluded

AEDC-TR-73-13

Core Jet Diffuser Core Jet Diffuser

Wf> 270°

\/Pc„ ■*■»

■3.2287 180° *- Splitter Plate

Looking Upstream

P^PCv-1-M Kc« •3.2243

180» *— Splitter Plate

Looking Upstream

a. For P„ /P- Ratio of 2.33 "a'

'No Data Available

■ Fan Jet Diffuser

b. For Pu /P. „ Ratio of 2.07

Core Jet Diffuser

\l^„ -1.624 ^fcw-l-l«

'ClY '3.3165 Igpo *- Splitter Plate

Looking Upstream

c. For Ptfe/PCatf Ratio of 1.62

Fig. 29 Total Pressure Survey at the Exit of the Segmented Diffuser

71

AEDC-TR-73-13

Cora Jet Diffuser

P24rt»Cav-1.112

PCav ■ 3.2591

*No Data Available

ISP '-Splitter Plates

Looking Upstream

d. For Ptf /P. Ratio of 1.50 lU

re Jet Diffuser

■Vf.*-1-286

Pcav"»!« lwp '-Splitter Plate

Looking Upstream

e. For Ptfe/Pcav Ratio of 2.20 Fig. 29 Concluded

72

AEDC-TR-73-13

lore Jet Diffuser ore Jet Dill user

90 270°

P24/PC» ■ 1.3»

Pcw-3.tf99 ^gfu Splitter Plate

Looting Upstream

\/Pc„-l.« PZ^/PCJV • i. is

PCa¥-3.Z971 18rf>"- Splitter Plate

Looking Upstream

a. For Pt, /P,..., Ratio of 2.34 »♦e b. For Pt4 /Pc„„ Ratio of 2.02

-Fan Jet Diffuser Core Jet Diffuser

'No Data Available

P24'Pcw ■ 1 24

Pcw-3.30M

{& <- Splitter Plat*

Looking Upstream

c. For Ptf /PCav Ratio of 1.64

Fig. 30 Total Pressure Survey at the Exit of the Segmented Diffuser with

Sharp Leading Edge Splitter Plates

73

AEDC-TR-73-13

fan Jet Diffuser

P24/Pca„ -1.115

Pc,,-3.292

d. For P«

lij<P«- Splitter Plate

Looking Upstream

/Pc.v Ratio of 1.50

"No Dab Available

Core Jet Diffuser

P24/Pcav

PCav-6.3304 180o L Splitter Plate

Looking Upstream

e. For Ptf /PCav Ratio of 2.20

Fig. 30 Concluded

74

AEDC-TH-73-13

- Fan Jet Diffuser Core Jet Dlfluser Fan Jet Diffuser „i r core Jet Diffuser

90° zr&

P^Pc» ■ 1-315

Pcw-3.285 ltf>

looking Upstream

Splitter Plata Pj4ft?cav ■ 1254

Pc„-3.2843 180° *-sP,mw' Plat*

Looking Upstream

a. For Pt, /P. Ratio of 2.33 b. For P„ /P. Ratio of 2.04

'No Data Available

py^v-1-«6

PZ4/PC.V ■ 1.165 Splitter Plate

Pcw ■ 3.2562 Looking Upstream

c. For Pt^/Pc... Ratio of 1.66 tfe'- «av

Fig. 31 Total Pressure Survey at the Exit of the Segmented Diffuser with Four Splitter Plates Removed

75

AEDC-TR-73-13

- Fan Jet Diffuser Cor» Jet Diffuser

Pc^,-3.2534 180°

Looking Upstream

Splitter Plate

'No Data Available

d. For Ptfa/Pcatf Ratio of 1.50 -Fan Jet Diffuser

Core Jet Diffuser

P24/Peev ■ 1.3ffl3

Pc,,-6.325 IMP Looking upstream

Splitter Plate

e. For Ptf /PCav Ratio of 2.20

Fig. 31 Concluded

76

AEDC-TR-73-13

■ Fan Jet Offluser rf> r Core Jet Oilf user Fan jet Diffuser tf> r Core Jet Diffuser

h,e/Pc,¥-M65

Puf?c„ -1.317 ISO4

Looking Upstream Pcw - 3.2873 180°

Looking Upstream

a. For Pt,/PCav Ratio of 2.36 b. For Ptfe/Peatf Ratio of 2.05 *V -Fan Jet Diffuser ^ _ core Jet Diffuser

'No Data Aval labte

Pza/Pc* -1.159

Pc^-3.2852 180°

Looking Upstream

c. For Pt1 /PC(|v Ratio of 1.65

Fig. 32 Total Pressure Survey at the Exit of the Segmented Diffuser with Only the Horizontal Splitter Plates

77

AEDC TR-73-13

- Fan Jtl Diffuser tf> r Co„ W DWuwr

Pz^Peav ■ 1-121

P(w -3-2667 VHP

Looking Upstream 'No Data Aval lable

For P, /Pclv Ratio of 1.50

Cora Jet Diffuser

PZ^Pc», " 1-315 IMP

Looking Upstream

e. For Pt,e/Pcav Ratio of 2.20 Fig. 32 Concluded

78

1.20

1.15

1.10

% 1.05

ft* 1.00

0.95

0.90

0.85

Sym

Diffuser with Knife Edges on Splitters

-av Pex/P° av

2.36 2.05 1.65 1.497

1.30 1.25 1.16 1.11

180°

Open Symbols:

Closed Symbols:

f

All Splitter Plates With Knife Edges

Two Splitter Plates

I—J I yl AJ 30 180 210 30

Static Tap Location, deg

Fig. 33 Diffuser Inlet Duct Wall Pressure

180 210 o

3J I

*J W t

—k

CO

AEDC-TR-73-13

TABLE I TEST CELL PRESSURE COMPARISON PER FAN NOZZLE EXIT PRESSURE RATIO

Circumferential Location. deg

Test Sta

(Looking Downstream) Ptfe Configuration :o 45 90 135 180 225 270 31S Pc cav

No Exhaust IS 3.265 3.271 3.277 Hardware 16 3.263 3.259 2.340 Pc = 3.267 17 3.249 3.240 3.263 3. 255

IS 3.252 3.258 ...

Model J-l 15 3.223 3.206 3.229 3.246 Exhaust Collector 16 3.199 3.213 3.210 3.224 2.380 P. = 3.233 17 3. 197 3.205 3.216 3.211

18 3. 186 3.163 ...

Exhaus: Collector 15 3.328 3.303 3.315 3. 296 with Conventional 16 3.307 3.319 3.303 3.314 2.355 Subsonic Diffuser 17 3.282 3.293 3.271 3.287 Pc = 3. 299 cav 18 3. 296 3.275

Exhaust Collector 15 3.308 3.315 3.319 3.287 1 wit.i Segmented 16 3. 309 3.277 3. 290 3.303 2.332

Diffuser 17 3.279 3.283 3.277 3.305 Pc = 3.296 cav 18 3.266 ... 3.268 ...

No Exhaust 15 3.372 3.375 3.381 Hardware 16 3. 367 3.370 1.445 Pc = S.376 17 3. 352 3.359 3.380 3.368

18 3.362 3.369 ...

ModelJ-l 15 3. 289 3.296 3.294 3. 284 Exhaust Collector 16 3.2B1 3.287 3.278 3.284 1.474 Pc =3.293 17 3.267 3.272 3.277 3.295

18 3. 266 ... 3.277 ...

Exhaust Collector 15 3.369 3.389 3.3B6 3.401 with Conventional 16 3.400 3.376 3.358 3.362 1.488 Subsonic Diffuser 17 3.346 3. 353 3.309 3.347 Pe = 3. 3667

<-av 18 3.347 ... 3.386 ...

Exhaust Collector 15 3.311 3.306 3.286 3.297 with Segmented 16 3.312 3.305 3.299 3.315 1.484 Diffuser 17 3.291 3. 292 3.320 3.319 Pc = 3. 3017

^av IB 3.299 3.302

No Exhaust 15 3.285 3.263 3.236 Hardware 16 3.269 3.276 2.098 Pc = 3. 285 17 3.268 3.258 3.287 3.269

18 3.273 3.272

.Model J-l 15 3.287 3.298 3.278 3.317 Exhaust Collector 16 3.322 3.291 3.266 3.304 2.025 Pc = 3. 309 17 3.263 3.281 3.308 3.312

18 3.249 3.306

80

TABLE I (Concluded)

AEDC-TR-73-13

Circumferential Location, leg P'fe p

cav

Test Sta

(Looking Downstream)

Configuration 10 45 90 135 180 225 270 315

Exhaust Collector 15 3.320 3.345 3.315 3.307 with Conventional 16 3.287 3.318 3.278 3.319 2.049 Subsonic Diffuser 17 3.268 3.307 3.261 3.293 Pc = 3. 297 18 3.285 --- 3.253 ...

Exhaust Collector 15 3.291 3.306 3.316 3.316 with Segmented 16 3.306 3.313 3.280 3.323 2.040 Diffuser 17 3.267 3.302 3.323 3.333 P_ =3.306

Sav IB 3.255 ... 3.279 ...

No Exhaust 15 3.307 3.300 3.303 Hardware 16 3.295 3.303 1.625 Pc = 3. 303 17 3.283 3.2B6 3.299 3.296

18 3.288 3.292 ...

Model J-l 15 3. 2S7 3.292 3.277 3.277 Exhaust Collector 16 3.281 3.270 3.264 3.290 1.632 PCav ■ 3. 2B96 17

IB 3.256 3. 278

3.270 3.280 3.269

3.280

Exhaust Collector 15 3.415 3.432 3.451 3.457 with Conventional 16 3.496 3.572 3.604 3.543 1.575 Subsonic Diffuser 17 3.593 3.523 3.388 3.387 P. = 3. 4B035

. cav 18 3.389 ... 3.475 ...

Exhaust Collector 15 3.341 3.315 3.311 3.324 with Segmented 16 3.332 3.318 3.314 3.335 1.623 Diffuser 17 3.322 3.321 3. 335 3.332 P. = 3. 3249 Cav IB 3.328 ... 3.320 ...

No Exhaust 15 6.325 6.300 6.300 Hardware IG 6.314 6.269 2.182 Pc ■= 6. 295 17 G.284 3.251 6.290 6.290

18 6.309 6. 308

ModeL J-l 15 Exhaust Collector 16

17 18

XO DATA

'■ Exhaust Collector 15 6.300 6.282 6.269 6.246 with Conventional 16 6.270 6.313 6.343 6.361 2.254 Subsonic Diffuser 17 6.345 6.342 6.275 6.340 Pc =6.295 '■av IB 6.230 6.210 ...

i Exhaust Collector 15 6. 338 6.418 6.331 6.315 with Segmentec 16 6.308 6.317 6.288 6.378 2.188 Diffuser 17 6.287 6.363 6.258 6.312 Pr = 6. 3261 IB 6.290 6.240 cav

81

UNCLASSIFIED Security Classification

DOCUMENT CONTROL DATA -R&D (Security claailtlcation ot ttlta. body ot abatract and rndaatno annotation muxt be antarad whan the overall report la ctosatttad)

I ORIGINATING ACTIVITY (Corporata author)

Arnold Engineering Development Center Arnold Air Force Station, Tennessee 37389

2a. REPORT SECURITY CLASSIFICATION

UNCLASSIFIED 2b. GROUP

N/A 3 REPORT TITLE

EXPERIMENTAL STUDY OF THE EFFECT OF SUBSONIC EXHAUST GAS DIFFUSERS ON THE TEST CELL WALL AND TF39 COLD-FLOW MODEL ENGINE EXHAUST NOZZLE PLUG AND CORE ENGINE COWL SURFACE PRESSURES

4 DESCRIPTIVE NOTES (Type ol report and inclusive date*)

July 1971 to July 1972—Final Report 5 AUTHORISE (Fltal nama, mlddla initial, laut name)

Delbert Taylor, Marvin Simmons, and Frank T. Lee, ARO, Inc.

I REPORT OATE

April 1973 7». TOTAL NO OP PASES

91 76. NO OP REFS

Ja. CONTRACT OR GRANT NO

b. PROJECT NO

9a. ORIGINATOR'S REPORT NUMBER!*)

AEDC-TR-73-13

e. Program Element 64719F 9b. OTHER REPORT NO(S) (Any other number* that may b* aa.tfjn»d this report)

ARO-ETF-TR-72-130 10 DISTRIBUTION STATEMENT

Approved for public release; distribution unlimited.

II SUPPLEMENTARY NOTES

Available in DDC

12. SPONSORING MILITARY ACTIVITY

Arnold Engineering Development Center (XON) Arnold Air Force Station, Tennessee,

13 ABSTRACT An experimental investigation was conducted to determine the ef-

fects of exhaust gas collectors/subsonic diffusers on engine and test cell surface pressures during tests of high-bypass-ratio .front-fan engines in ground test facilities. A one-tenth scale model of a TF39 turboian engine installed in a one-tenth scale model of Propulsion Development Test Cell (J-l) was employed. Engine cowl and plug surface pressure data were recorded during model engine operation with cold air at five simulated power settings without exhaust collector, with exhaust collector, with exhaust collector equipped with a conventional subsonic diffuser, and with exhaust collector equipped with a segmented subsonic diffuser which separately diffused the fan and core engine exhaust jets. Stagnation pressure data were also recorded for the purpose of establishing the flow losses in the free-jet exhausts and in the diffusers. Data from all configurations were analyzed to determine the effect of exhaust jet collector/diffusers on engine and test .cell surface pressures and to determine the efficiency of the diffusion process.

DD FORM I NOV.8» 1473 UNCLASSIFIED

Security Classification


KSV WORD«

exhaust gases

diffusers

cold flow

nozzle inserts

pressure distribution

accumulators

subsonic flow

scale model

turbofan engine


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