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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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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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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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


>5

>3000>No Changes to Tp and Sp

Case3


>5

>2400


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> Sp is changed to 3000

Case4


>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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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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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.

Active Instability Control in Ducted Axial Fan Using c Progrmming

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