Active Instability Control in Ducted Axial Fan Using c Progrmming
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Transcript of Active Instability Control in Ducted Axial Fan Using c Progrmming
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International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 6340(Print), ISSN 0976 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) IAEME
44
ACTIVE INSTABILITY CONTROL IN DUCTED AXIAL FAN USING
C PROGRMMING
Manikandapirapu P.K.1
Srinivasa G.R.2
Sudhakar K.G.3
Madhu D.4
1 Ph.D Candidate, Mechanical Department, Dayananda Sagar College of Engineering, Bangalore.2
Professor and Principal Investigator, Dayananda Sagar College of Engineering, Bangalore.3Professor, Mechanical Department, K L University, Vijayawada, AndraPradesh.
4Professor and Head, Mechanical Department, Government Engg. College, KRPET-571426.
ABSTRACT
Performance of axial fan is found to reduce drastically when instability is
encountered during its operation. Performance of an axial fan is severely impaired by
many factors mostly related to system instabilities due to rotating stall and surgephenomenon experienced during its operation. The present work involves developing the
active instability control in ducted axial fan from stall region to jump the unstall region in
10 seconds automatically by using c programming. Objective of the experiment is todevelop the algorithm and simulate the code from stall region flow parameters to stable
region flow parameter by using C Graphics and Programming through active control.
Keywords: C Graphics, Flow Chart, Stall Region, Stable Region, Active Control,
Pressure Measurements, Throttle position, Rotor speed.
1.0 INTRODUCTION
Mining fans and cooling tower fans normally employ axial blades and or required to work
under adverse environmental conditions. They have to operate in a narrow band of speed
and throttle positions in order to give best performance in terms of pressure rise, highefficiency and also stable condition. Since the range in which the fan has to operate under
stable condition is very narrow, clear knowledge has to be obtained about the whole rangeof operating conditions if the fan has to be operated using active adaptive control devices.
The performance of axial fan can be graphically represented as shown in figure 1.
INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING ANDTECHNOLOGY (IJMET)
ISSN 0976 6340 (Print)
ISSN 0976 6359 (Online)
Volume 3, Issue 3, Septmebr - December (2012), pp. 44-56
IAEME: www.iaeme.com/ijmet.htmlJournal Impact Factor (2012): 3.8071 (Calculated by GISI)
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IJMET
I A E M E
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International Journal of Me6340(Print), ISSN 0976 635
Fig.1 Gra
2.0 TEST FACILITY ANDExperimental setup, fab
conditions in an industrial du
Fig. 2 Ducted Axial F
A 2 HP Variable frequency
motor to derive variable sp
shown in figure 6.
Fig.4 Variable frequency Drive f
hanical Engineering and Technology (IJMET)(Online) Volume 3, Issue 3, Sep- Dec (2012) I
45
phical representation of Axial Fan performa
INSTRUMENTATIONricated to create stall conditions and to intr
cted axial fan is as shown in figure 2 to figure 5
an Rig Fig. 3 Side View of Ducted
3-phase induction electrical drive is coupled to
ed ranges. Schematic representation of ducte
or speed control Fig.5 Automatic Throttle c
ISSN 0976 EME
ce curve
oduce unstall
.
xial Fan Rig
the electrical
fan setup is
ntroller
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International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 6340(Print), ISSN 0976 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) IAEME
46
Fig. 6 Ducted Axial Fan - Schematic
The flow enters the test duct through a bell mouth entry of cubic profile. The bell
mouth performs two functions: it provides a smooth undisturbed flow into the duct and
also serves the purpose of metering the flow rate. The bell mouth is made of fiber
reinforced polyester with a smooth internal finish. The motor is positioned inside a 381
mm diameter x 457 mm length of fan casing. The aspect (L/D) ratio of the casing is 1.2.
The hub with blades, set at the required angle is mounted on the extended shaft of the
electric motor. The fan hub is made of two identical halves. The surface of the hub is
made spherical so that the blade root portion with the same contour could be seated
perfectly on this, thus avoiding any gap between these two mating parts. An outlet duct
identical in every way with that at inlet is used at the downstream of the fan. A flow
throttle is placed at the exit, having sufficient movement to present an exit area greater
than that of the duct.
3.0 ACTIVE INSTABILITY CONTROL ALGORITHM
Stall phenomenon experienced in ducted axial fans which is experimented and
analysed through simulation specifically with an aim to control the instability avoidanceprogramming with the help of an algorithm developed for the purpose. The main
objectives are to examine the stall signal characteristics as a function of variations in
pressure rise, velocity, sound level, rotor speed and throttle position. The algorithm is also
helpful in comprehending the following
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International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 6340(Print), ISSN 0976 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) IAEME
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Examination of the stable signal associated with pressure rise, velocity, soundlevel, rotor speed and throttle position.
Establishing the functional relationship between performance curve of pressurerise and throttle position as a function of speed.
Examining the possibility of moving the stall region to unstall or stable region in10 seconds that too automatically. The active control phenomenon can be
graphically represented as shown in fig.7.
Fig.7 Graphical Representation of Active Control
3.1 ACTIVE INSTABILTY CONTROL PROGRAM FLOW CHART
The program developed for the purpose is schematised with the help of a flow
chart shown in fig.8.
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International Journal of Me6340(Print), ISSN 0976 635
Fi
3.2 ACTIVE INSTABILIT
The objective of thestable operating range of the
#include
#include
void main()
{
int Tp,Sp;
printf("Enter the Tp in cm
scanf("%d \n %d ", &Tp,
if(Tp==2&&Tp==3&&Tp{
if (Sp ==2400&&2700)
{
Tp=5;
Sp=3000;
printf("Tp is chang
hanical Engineering and Technology (IJMET)(Online) Volume 3, Issue 3, Sep- Dec (2012) I
48
.8 Flow Chart of the Algorithm
CONTROL PROGRAMMING USING C
eveloped algorithm written in C Language isaxial fan based on an active control technique.
and Sp in Rpm");
Sp);
==4)
d to %d and Sp is changed to %d",Tp,Sp);
ISSN 0976 EME
o extend the
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}
elseif
{
Tp=5;
printf("Tp is changed to %d",Tp);}
}
else if(Tp==5 && Tp ==6 && Tp==7)
{
if(Sp==2400 && 2700)
{
Sp=3000;
printf("Sp is changed to %d",Sp);
}
else
{
Printf(" No Changes in Tp and Sp");
}
}
}
3.3 PROGRAM OUTPUT
Case1
> Enter the Tp in cm and Sp in Rpm
>3
>2700
>Tp is changed to 5and Sp is changed to 3000
Case2
> Enter the Tp in cm and Sp in Rpm
>5
>3000>No Changes to Tp and Sp
Case3
> Enter the Tp in cm and Sp in Rpm
>5
>2400
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International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 6340(Print), ISSN 0976 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) IAEME
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> Sp is changed to 3000
Case4
> Enter the Tp in cm and Sp in Rpm
>3
>3600
> Tp is changed to 3000
3.4 ACTIVE INSTABILITY CONTROL PROGRAMING USING C GRAPHICS
#include
#include
#include
#include
#include
#include
voiddrawXY();
voiddraw_line();
void plotXY_1(float[],float[]);
voiddraw_graph(int);
void case3(float,float,float,float);
int main(void)
{
intch;
clrscr();
do {
clrscr();
printf(" \n Options \n");
printf(" 1 - Default \n");
printf(" 2 - Case 3 \n");
printf(" 3 - Exit \n");
printf("\n Enter choice \n");
scanf("%d",&ch);
switch(ch) {
case 1:draw_graph(ch); break;
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case 2:draw_graph(ch); break;
case 3:exit(0);break; default: printf(" Please enter correct option \n");break;
} }while(ch!=3);
return 0;
}
void case3(float x1,float y1,float x2,float y2){
int X1,X2,Y1,Y2;
X1=40+50*x1;
Y1=430-100*y1;
X2=40+50*x2;
Y2=430-100*y2;
sleep(3);
moveto(X1-3,Y1-3); outtext("*");
sleep(3);
moveto(X2-3,Y2-3);outtext("*");
sleep(5);
line(X1,Y1,X2,Y2);
}
voiddraw_graph(intch){
/* request auto detection */
intgdriver = DETECT, gmode, errorcode;
float X[]={1,2,3,4,5,6,7};
float Y2400[]={0.4,1.8,1.8,1.5,1.6,1.5,1.3};
float Y2700[]={1.3,2.0,2.2,1.9,2.0,1.9,1.8};
float Y3000[]={1.45,2.2,2.65,2.25,2.4,2.3,2.15};
float Y3300[]={1.55,2.55,2.95,2.65,2.9,2.62,2.4};float Y3600[]={1.93,2.85,3.3,2.75,2.85,2.7,2.5};
clrscr();
/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "C:\\TC\\BGI");
setcolor(getmaxcolor());
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52
drawXY();
if(ch!=1)
{
setlinestyle(DOTTED_LINE,1,1);
line(240,430,240,20);
setlinestyle(SOLID_LINE,1,1);
}
//plotXY(1,0.4);
setcolor(4);
plotXY_1(X,Y2400);
if(ch==2)
{
//sleep(10);
setcolor(getmaxcolor());
case3(2.2,1.8,4.3,2.4);
case3(3.3,2.3,5.2,3.0);
case3(3.5,1.6,6.5,2.8);
}
/* clean up */
getch();
closegraph();
}
void plotXY_1(float x[],float y[])
{
intX,Y,yi;
int i;float X1=40,Y1=430;
for(i=0;i
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Y=430-100*y[i];
moveto(X-3,Y-3);
outtext("*");
if(i!=0)
line(X1,Y1,X,Y);
X1=X;
Y1=Y;
}
}
voidplotXY(float x,float y)
{
int X,Y;
//y=y-90;
X=40+50*x;
Y=430-100*y;
moveto(X-3,Y-3);
outtext("*");
}
voiddrawXY()
{
// HEAD
moveto(100,20);
outtext("Presure Head versus Throttle Position");
//setlinestyle(DOTTED_LINE,1,1);
line(40, 20, 40, 430);
line(40, 430, 430,430);outtext("0");
}
3.5 PROGRAM INPUT AND OUTPUT USING C GRAPHICS
The input format for the program using c graphics is shown in fig.9, whereas the
output clearly indicating the location of the stall region is shown in fig.10.
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International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 6340(Print), ISSN 0976 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) IAEME
54
Fig.9 Input Details
Fig.10 Active Instabilty Control Output
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4.0 CONCLUSIONIn this paper, an attempt has been made to develop the active instability
avoidance control in ducted axial fan from stall region to jump the stable region in 10
seconds automatically by using c graphics and programming. This methodology also
helps to completely avoid the stall region in ducted axial fan. Further, this work can be
extended by working on real time simulation of active instability control in ducted axial
fan. The results so far discussed, indicate that active instability control in ducted axial fan
using c programming is very promising.
ACKNOWLEDGEMENT
The authors gratefully thank AICTE (rps) Grant. for the financial support of present
work.
NOMENCLATURE = Whirl velocity in m/s
= Pressure ratio
N = Tip speed of the blades in rpm
p= Pressure rise across the fan in N/m2
d = Diameter of the blade in m
air = Density of air in kg/m3
Lp = Sound Pressure Level in db
REFERENCES
[1] Day I J (1993),Active Suppression of Rotating Stall and Surge in Axial
Compressors, ASME Journal of Turbo machinery, vol 115, P 40-47.
[2] Patrick B Lawlees (1999),Active Control of Rotating Stall in a Low SpeedCentrifugal Compressors, Journal of Propulsion and Power, vol 15, No 1, P 38-44.
[3]C A Poensgen (1996) ,Rotating Stall in a Single-Stage Axial Compressor, Journal of
Turbomachinery, vol.118, P 189-196.[4] J D Paduano (1996), Modeling for Control of Rotating stall in High Speed
Multistage Axial Compressor ASME Journal of Turbo machinery, vol 118, P 1-10.
[5] Chang Sik Kang (2005),Unsteady Pressure Measurements around Rotor of an Axial
Flow Fan Under Stable and Unstable Operating Conditions, JSME InternationalJournal, Series B, vol 48, No 1, P 56-64.
[6] A H Epstein (1989),Active Suppression of Aerodynamic instabilities in turbo
machines, Journal of Propulsion, vol 5, No 2, P 204-211.[7] Bram de Jager (1993),Rotating stall and surge control: A survey, IEEE Proceedings
of 34th Conference on Decision and control.
[8] S Ramamurthy (1975),Design, Testing and Analysis of Axial Flow Fan, M EThesis, Mechanical Engineering Dept, Indian Institute of Science.
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[9] S L Dixon (1998), Fluid Mechanics and Thermodynamics of Turbo machinery, 5th
edition, Pergamon, Oxford Press.[10] William W Peng (2008), Fundamentals of Turbo machinery, John Wiley & sons.Inc.
AUTHORS
Manikandapirapu P.K. received his B.E degree from Mepco Schlenk
Engineering college, M.Tech from P.S.G College of Technology, AnnaUniversity,and now is pursuing Ph.D degree in Dayananda Sagar College
of Engineering, Bangalore under VTU University. His Research interest
include: Turbomachinery, fluid mechanics, Heat transfer and CFD.
Srinivasa G.R. received his Ph.D degree from Indian Institute of Science,
Bangalore. He is currently working as a professor in mechanical
engineering department, Dayananda Sagar College of Engineering,Bangalore. His Research interest include: Turbomachinery,
Aerodynamics, Fluid Mechanics, Gas turbines and Heat transfer.
Sudhakar K.G received his Ph.D degree from Indian Institute of Science,
Bangalore. He is currently working as a Professor in Mechanical
Engineering department, Koneru Lakshmiah University,Vijayawada,
Andrapradesh. His Research interest include: Surface Engineering,Metallurgy, Composite Materials, MEMS and Foundry Technology.
Madhu D received his Ph.D degree from Indian Institute of Technology
(New Delhi). He is currently working as a Professor and Head in
Government Engineering college, KRPET-571426, Karnataka. HisResearch interest include: Refrigeration and Air Conditioning, Advanced
Heat Transfer Studies, Multi phase flow and IC Engines.