Performance Analysis of Rotor Tip Shapes in Hover …...Helicopter Rotor Tip Shapes in Hover Rotor...

Westland Helicopters is an AgustaWestland Company

Helicopter Rotor Tip Shapes in Hover

Department of EngineeringRotor Systems, AerodynamicsUniversity of Liverpool

Performance Analysis of Rotor Tip Shapes in Hover Using Computational Fluid Dynamics

Presented at the Burn 7-8 April 2006

by

Alan Brocklehurst and George Barakos

Rotor Systems, Aerodynamics




INTRODUCTION

Validation – UH-60A


Conclusions and Future Goals

Aims and Objectives

Comparison with Model TR Tests

Comparison Vortex Wake Trajectories

Tip Shapes - Vortex Wake Trajectories

Tip Shapes - Hover Performance

Loading and Downwash




AIMS AND OBJECTIVES

CFD starts from the conservation laws, and needs only Geometry Definition and Boundary (Flight) Conditions


Progress towards a high fidelity method for rotor designcapable of resolving subtle differences in tip shape

‘Work-in-progress’ towards PhD – Overlaps with WHL GoalsCurrent studies use Euler methods in Hover for economy





0.965R

CFD – Validation - UH-60A Model Tail Rotor Tests (Lorber)




CFD – Validation - UH-60A Model Tail Rotor Tests (Lorber)


11.47o collective pitch, M tip =0.628, inviscid, 240-block grid, 4.5M grid points

Radial positionAxial position




Comparison of CFD with Model Tail Rotor Tests from 1980/4


Rectangular Blade, NACA0012, 0,8,16 deg Twist, 0 deg Twist Considered Here




Comparison of Euler CFD Predictionswith Model Rotor Test Data from 1980


Comparison with Model Rotor Thrust - Pitch Measurements Twisted Blades Test (1980), Mtip=0.492 (Vt=550 ft/s, 3000rpm)

0.0000

0.0500

0.1000

0.1500

0.2000

0.2500

0.3000

0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00

Impressed Pitch Referenced to Rotor Centre (deg)

Bla

de

Load

ing C

oef

fici

ent, C

T/s

Twist=0 Mtip=.492

Twist=8 Mtip=.492

Twist=16 Mtip=.492

Twist=0 Euler Fr Mtip=0.492

CFD predictions with zero coning,corrected for pitch-flap coupling

Comparison with Model Rotor Thrust - Pitch MeasurementsTwisted Blades Tests (1980), Mtip=0.263 (Vt=293ft/s,1600rpm)

0.0000

0.0500

0.1000

0.1500

0.2000

0.2500

0.3000

0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00

Impressed Pitch Referenced to Rotor Centre (deg)

Bla

de

Load

ing C

oef

fici

ent, C

T/s

Twist=0 Mtip=.263

Twist=8 Mtip=.263

Twist=16 Mtip=.263

Twist=0 Euler Fr Mtip=0.263

CFD predictions with coning, corrected for pitch-flap coupling

Rectangular Blade, NACA0012, Zero Twist





Comparison of Euler CFD Predictions with Model Tail Rotor Tests from 1984

Comparison with Model Tail Rotor Thrust - Pitch MeasurementsTests 1980, Mtip=.263, and 'Fin-Blockage' Tests (No Fin)1984, Mtip=0.361

0.0000

0.0500

0.1000

0.1500

0.2000

0.2500

0.3000

0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00

Impressed Pitch (degrees)

Bla

de L

oadi

ng

Coef

ficie

nt,

CT/

s

Test (1980) Mtip=.263

Test (1984) Mtip=.361

CFD Euler Mtip=.263

CFD Euler Mtip=0.492

Zero Twist

All predictions corrected for pitch-flap coupling

Comparison with Model Tail Rotor Thrust - Power Measurements'Fin-Blockage' Tests (No Fin) 1984, Mtip=0.3610

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.014

0.016

0.018

0.000 0.010 0.020 0.030 0.040 0.050 0.060

Rotor Thrust Coefficient, CT

Roto

r Torq

ue

Coef

fici

ent, C

Q

Twist=0 Mtip=.361 1984

Twist=0 CFD Euler M=0.263

Twist=0 CFD Euler M=0.492

Mom Theory CDo=.018, ki=1.4

Rectangular Blade, NACA0012, Zero Twist





Comparison of CFD and Model Tail Rotor Vortex Wake Trajectories

Vertical Sections at 0 degrees wake age

Model Rotor Flow Visualisation





Comparison – Model Tail Rotor – Vortex Wake Trajectories (1)Comparison of CFD and Experiment

Vortex Locations - Vertical Displacement

-0.600

-0.500

-0.400

-0.300

-0.200

-0.100

0.000

0 30 60 90 120 150 180 210 240 270 300 330 360

Vortex Age (deg of azimuth)

Ver

t D

ispla

cem

ent, z

v/R

(re

l to tip

)

Test (WHL, 1980), 5 degrees pitch




CFD TRB-0100 5 deg CT=.00598

CFD TRB-0100 8 deg CT=.01190

CFD TRB-0100 10 deg CT=.01723

CFD TRB-0100 15deg CT=.03401

Kocurek and Tangler CT=.00598 (5 deg)


Kocurek and Tangler CT=.01723 (10deg)


TRB-0100 Rectangular Blade, Zero Twist, Mtip=0.263






Vortex Locations - Contraction

0.000

0.050

0.100

0.150

0.200

0.250

0 30 60 90 120 150 180 210 240 270 300 330 360

Vortex Age (deg of azimuth)

Contr

action (1-

xv/R

)





CFD TRB-0100 5 deg CT=.00598

CFD TRB-0100 8 deg CT=.01190

CFD TRB-0100 10 deg CT=.01723

CFD TRB-0100 15 deg CT=0.03401











Vortex Locations - Trajectory

-0.600

-0.500

-0.400

-0.300

-0.200

-0.100

0.000

0.000 0.100 0.200 0.300 0.400 0.500 0.600 0.700 0.800 0.900 1.000

Radial Location, xv/R (shifted)

Ver

t D

ispla

cem

ent, z

v/R

(re

l to tip

)

Test (1980), 5 degrees pitch




CFD TRB-0100 5 deg CT=.00598

CFD TRB-0100 8 deg CT=.01190

CFD TRB-0100 10 deg CT=.01723

CFD TRB-0100 15 deg CT=.03401






5 deg

10 deg

8 deg

15 deg




Tip Shapes – CFD Performance Analysis – Mtip=0.6


Thrust, Power, Pitch and and Figure of Merit

Vortex Wake Comparisons

Blade Loading and Downwash Distribution

Different Tip Shapes and Anhedral

TRB-004 Rectangular Tip, 20 deg Anhedral,10 deg Pitch – Iso-surfaces of Vorticity Magnitude




Tip Shapes – CFD Performance Analysis


TRB-000 Rectangular Tip, Datum Blade TRB-001 Kuchemann (1/4c wide) Tip

TRB-002 Kuchemann (1/2c wide) TipTRB-004 Rectangular Tip, 20 deg Anhedral

Euler Hover using HMB (no coning)

Mtip=0.6 Pitch=10 deg

Root 33%R

Root 33%R

Root 33%R

Root 33%R

Tip100%R

Tip100%R

Tip100%R

Tip100%R






TRB-000 Rectangular Tip Datum Blade

TRB-001 Kuchemann Tip(1/4c wide)

TRB-002 Kuchemann Tip(1/2c wide)

TRB-004 Rectangular Tip20 deg Anhedral

Euler Hover using HMB

All Tips at 14 deg Pitch (no coning)

Mtip=0.6






Effect of Tip Shape on Rotor PerformanceThrust vs Pitch - Hover - HMB Euler - Mtip=0.6

0.00

0.01

0.02

0.03

0.04

0.05

0.0 5.0 10.0 15.0 20.0 25.0 30.0

Blade Pitch Angle (deg)

Roto

r Thru

st C

oef

fici

ent, C

T

TRB-000 (Rectangular)

TRB-001 (.25c Kuchemann)


TRB-004 (Rectangular + Anhedral)






Effect of Tip Shape on Rotor PerformanceTorque vs Thrust - Hover - HMB Euler - Mtip=0.6

0.0000

0.0010

0.0020

0.0030

0.0040

0.0050

0.0060

0.000 0.005 0.010 0.015 0.020 0.025 0.030 0.035 0.040 0.045 0.050


Roto

r Torq

ue Coef

ficien

t, C

Q



TRB-002 (.5c Kuchmann)


Induced, ki= 1.3

14deg

6deg

8deg

10deg

12deg

3deg4deg

15deg

16deg

5deg

2deg






Effect of Tip Shape on Rotor PerformanceTorque vs Thrust1.5 - Hover - HMB Euler - Mtip=0.6

0.0000

0.0005

0.0010

0.0015

0.0020

0.0025

0.0030

0.0035

0.0040

0.0045

0.0050

0.0000 0.0010 0.0020 0.0030 0.0040 0.0050

(Rotor Thrust Coefficient)1.5, CT1.5

Ro

tor

To

rqu

e C

oef

fici

ent,

CQ

T R B -000 (R ectangu la r)

T R B -001 (.25c K uchem ann)

T R B -002 (.5c K uchemann )

T R B -004 (R ectangu la r + Anhedra l)

Induced, k i= 1 .3

6deg

8deg

10deg

12deg

4deg

2deg

TRB-000 ki=1.397TRB-001 ki=1.370TRB-002 ki=1.400TRB-004 ki=1.336






Effect of Tip Shape on Rotor Performance Blade 'Profile' Drag - Hover - HMB Euler - Mtip=0.6

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.00 0.01 0.02 0.03 0.04 0.05


Inte

gra

ted B

lade

Dra

g C

oef

fici

ent, C

de





14deg

6deg

8deg 10deg 12deg

3deg

4deg

15deg

16deg

17deg

5deg

2deg

TRB-000 ki=1.397TRB-001 ki=1.370TRB-002 ki=1.400TRB-004 ki=1.336






Effect of Tip Shape on Rotor PerformanceFigure of Merit - Hover - HMB Euler - Mtip=0.6

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0.65

0.70

0.75

0.80

0.000 0.005 0.010 0.015 0.020 0.025 0.030 0.035 0.040 0.045 0.050


Fig

ure

of M

erit, F

oM TRB-000 (Rectangular)

TRB-000 (+CDsf=.008)


TRB-001 (+CDsf=.008)


TRB-002 (+CDsf=.008)


TRB-004 (+CDsf=.008)

Induced, ki= 1.3

with constant CD= 0.01

14deg

6deg

8deg

10deg12deg

2deg

4deg

14deg6deg

8deg 10deg 12deg

2deg

4deg17deg16deg15deg

17deg16deg15deg

3deg

5deg

3deg

5deg

TRB-000

TRB-002

TRB-004

(20deg anhedral)

Inviscid, Euler

Euler + CDsf=.008

TRB-001






Effect of Tip Shape on Rotor Performance'Thrust/Power' Ratio - CT/CQ - Hover - HMB Euler - Mtip=0.6

5.00

10.00

15.00

20.00

0.0 5.0 10.0 15.0 20.0

Blade Pitch Angle (deg)

'Thru

st/P

ow

er' R

atio

, CT/C

Qe





If desired, multiply CT/CQ by 0.82065to get lb/hpfor this rotor




Effect of Tip Shapes on Vortex Wake Trajectories

Euler HoverMtip=0.64 Tip shapescompared


Radius

Z

0 2 4 6 8-6

-4

-2

0

2TRB-000Mtip=0.6

ZeroTwist,ZeroConing10degpitch

VorticityContoursSectionthroughbladerefaxis

V2age=90deg

V3age=180deg

V4age=270deg

V1age=360deg

V1age=0deg

S2

S3

S4




CFD- Tip Shapes – Wake Trajectories (1a)


Comparison of Computed Vortex Wake Vertical Displacements in Hover Blade Pitch Angle=10 degrees, Mtip=0.6

-0.500

-0.450

-0.400

-0.350

-0.300

-0.250

-0.200

-0.150

-0.100

-0.050

0.000

0 50 100 150 200 250 300 350 400

Vortex Age (degrees)

Ver

t D

ispla

cem

ent, z

v/R

TRB-000 (Rectangular, datum)



TRB-004 (Rectangular+Anhedral)




CFD- Tip Shapes – Wake Trajectories (1b)


Comparison of Computed Vortex Wake Vertical Displacements in Hover Blade Pitch Angle=10 degrees, Mtip=0.6

-0.120

-0.100

-0.080

-0.060

-0.040

-0.020

0.000

0 20 40 60 80 100 120


Vert Displace

men

t, zv/R








CFD- Tip Shapes – Wake Trajectories (2a)


Comparison of Computed Vortex Wake Contraction in Hover Blade Pitch Angle=10 degrees, Mtip=0.6

0.0000

0.0500

0.1000

0.1500

0.2000

0.2500

0 50 100 150 200 250 300 350 400


Contr

action (1-

xv/R

)




TRB-004(Rectangular+Anhedral)




CFD- Tip Shapes – Wake Trajectories (2b)


C o m p a r i s o n o f C o m p u t e d V o r t e x W a k e C o n t r a c t i o n i n H o v e rB l a d e P i t c h A n g l e = 1 0 d e g r e e s , M t i p = 0 . 6

0 . 0 0 0 0

0 . 0 2 0 0

0 . 0 4 0 0

0 . 0 6 0 0

0 . 0 8 0 0

0 . 1 0 0 0

0 . 1 2 0 0

0 . 1 4 0 0

0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 1 1 0 1 2 0

V o r t e x A g e ( d e g r e e s )

Co

ntr

acti

on

(1-

xv/R

)

T R B - 0 0 0 ( R e c t a n g u l a r , d a t u m )

T R B - 0 0 1 ( . 2 5 c K u c h e m a n n )

T R B - 0 0 2 ( . 5 c K u c h e m a n n )

T R B - 0 0 4( R e c t a n g u l a r + A n h e d r a l )T e s t 1 0 d e g




CFD- Tip Shapes – Wake Trajectories (3)


Comparison of Computed Vortex Wake Trajectories in Hover Blade Pitch Angle=10degrees, Mtip=0.6

-0.20

-0.15

-0.10

-0.05

0.000.70 0.75 0.80 0.85 0.90 0.95 1.00

Horizontal Location, xv/R

Vert Displacement, zv/R

Test (Mtip=.263)





Euler CFD , no coning

90 deg age




CFD - Tip Shapes (000, 001, 002) – Visualisation


Radial Location

Z/R

0.85 0.9 0.95 1-0.15

-0.1

-0.05

0

TRB-002 (1/2cwideKuchemannTip), Mtip=0.6, Pitch=10degVorticesat 10degreesbehindblade

Radial Location

Z/R

0.85 0.9 0.95 1-0.15

-0.1

-0.05

0

TRB-001 (1/4cwide KuchemannTip), Mtip=0.6, Pitch=10degVorticesat 10degbehindblade

Radial Location

Z/R

0.85 0.9 0.95 1-0.15

-0.1

-0.05

0

TRB-000 (Rectangular, Datum) Mtip=0.6 Pitch=10degVorticesat 10 degreesbehindblade




CFD - Tip Shapes (000, 004) – Visualisation - Anhedral


RadialLocation

Z/R

0.85 0.9 0.95 1-0.15

-0.1

-0.05

0

TRB-000 (Rectangular, Datum) Mtip=0.6 Pitch=10degVorticesat 10 degreesbehindblade

Radial Location

Z/R

0.85 0.9 0.95 1

-0.15

-0.1

-0.05

0

TRB-004 (Rectangular+ Anhedral), Mtip=0.6, Pitch=10degVorticesat 10degbehindthe blade




CFD - Tip Shapes - Wake Trajectories – Anhedral (1)


Comparison of Computed Vortex Displacements Near Blade Tip in Hover Effect of Anhedral - Blade Pitch Angle=10deg, Mtip=0.6

-0.10

-0.08

-0.06

-0.04

-0.02

0.00

0.02

-15 -10 -5 0 5 10 15 20

Azimuth Angle Relative to Blade Ref Axis (degrees)

Ver

tica

l Dis

pla

cem

ent, z

v/R

TRB-000 (Rectangular,Datum)

TRB-000 Geometry


TRB-004 Geometry

L.E.

T.E.





CFD - Tip Shapes - Wake Trajectories – Anhedral (2)Comparison of Computed Vortex Contraction Near Blade Tip in Hover

Effect of Anhedral - Blade Pitch Angle=10deg, Mtip=0.6

-0.02

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

-15 -10 -5 0 5 10 15 20

Azimuth Angle Relative to Blade Ref Axis (degrees)

Rad

ial D

ispla

cem

ent, (1-

xv/R

)

TRB-000 (Rectangular, Datum)

TRB-000 Geometry


TRB-004 Geometry




CFD Analysis – Loading Distribution


TRB-000 Mtip=0.6 10 deg PitchCT=.0199 Ct/s=0.100

Pressure Distribution in Tip RegionThrust Distribution

0

0.1

0.2

0.3

0.4

0.5

0.6

0.25 0.35 0.45 0.55 0.65 0.75 0.85 0.95

Radial Location, r/R

Load

ing, C

z*x2

TRB-000 Mtip=0.6 10deg

Moment Distribution

-0.12

-0.1

-0.08

-0.06

-0.04

-0.02

0

0.02

0.04

0.25 0.35 0.45 0.55 0.65 0.75 0.85 0.95

Radial Location, r/R

Aer

odyn

amic

Mom

ent C

oef

fici

ent, C

m.x

2

TRB-000 Mtip=0.6 10deg




CFD Analysis - Tip Shapes – Downwash


TRB-000 Mtip=0.6 10 deg PitchCT=.0199 Ct/s=0.100

Downwash DistributionIn a horizontal plane0.25c below the rotor




CONCLUSIONS AND FUTURE GOALS

CFD method has been validated against UH-60A dataand by comparison to model tail rotor measurements


Vortex Wake – Euler - better than expected – N-S?

Progress to Navier-Stokes for even more realistic rotor (tip) design evaluations

CFD has been used to determine the effect of tip shape on rotor performance (induced power) in hover

Investigate effect of tip shape on loading and downwash

Performance Analysis of Rotor Tip Shapes in Hover …...Helicopter Rotor Tip Shapes in Hover Rotor...

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