8/18/2019 Egt End Sem 2014

1/3

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sgndPSTER'

SUB:

ELEMNTS

OF

cAS

TURBfiqB,

rlqD

SnnnbS'ffiR

EXAMINA'T'ION

(05

-05-20X4)

Marks:50

Time:

03l{rs.

(1)

Atlthe

questions

are

compulsory

iii

figrr"t

to the

right indicates

full

marks

i-3i

Arffi"

suitabd

data

with

justification

if

required

/"

=-{t7

ExPlain

with

figr-rre

Lucas

combustion

chamber

with

inlet

swirler

TNSTRUCTION:

Q.4

ztx

5o7o

reaction,

axial

flow

300

m/s.

The

Pressure

Determine

the

blade

and

m/s.

Condition

at

inlet

are

compressor

runs

at

a

mean

blade

speed

of

ratio

developed

by

the

machine

is

1 .:

"1,

,rrgf"

if

the

*"at'

flow

velocity

was

220

1

bar

and

300

K

Attempt

agy-JEg(from Q-3,4 and

5)

Air

at

l-

bar

.rrJ

288

K

enters

an

axial

flow

compressor

stage.

with

an

axial

velocity

160

mls.

There

,.1."

1.'o

inlet

guide

vanes.

The

rotor

stage

hasatipdiameterof50cmandahubdiameterof40cmandrotates

at

5000

RPM.

T

rre

"ir

enters

the

rotor

and

leaves

the

stator

in

the

axial

direction

with

no

change

in

velocitv

lt

t"aius'

The

blade

angle

at

exit

is

20o.

Assume

a

stage

pressure

ratio

1'5'

At

design

speed'

the

following

d'ata

apply

to

a

gas

turbine

set

a

separat"

po*"'

i;;;i;",

"heat

"*"tttttg"r'

reheater

and

hetween

two

stage

compresslon

-

Bit","rr"y

of

conipression

in

each

stage:

8oo/o

-^.

I;;;;;;;;-

efficiencv

of

compressor

turbine:

87?i'

i""tro"^p,ic

efficiency

of

power

turbine:

807o

;';;;"

ratio

in

each

"tug"

of

compression:

2

i;;;;r"ture

after

intercooling:

3oo

K

Calcgkate

,,

,1)

gonstruct

the

velocip

diagranr

at

mean

dia

for

this

stage'

-

H,M"9s

iiow

rate

/tg{

Ps6er required

-/t+Y6.eree

of

reaction'

--//

AsinglesidecentrifugalCompressorhastheinternaldiameterofeye15

cm.

The

"o*pr""*or?euv"rs

air

at

the

rate

of

9

kgls

with

a

pressure

ratio

of

4.4

to

1

at

2OOO0

rp*.

crre

axiat

velocity

is

15O

m/s

with

no

prewhirl.

Initial

condition

of

air

;;-p;-,re

1

bar

and

temperatute

20

0C

Assumirrg

aJiabatic

effici"rr"y

,1

'*0"/",

the

ratio

of

whirl

speed

to

tip

speed.

as

0.9s

""J""gr""ling

ali

other

losses,

calculate

the

rise

of totai

.temperature,

.,;;;;;,

tlp

aL*eter

and

external

diameter

of

eye'

emploYing

intercooler

Bii"&i""ttess

heat

exchange

r:

7 5o/o

8/18/2019 Egt End Sem 2014

2/3

Maximum

cycle

temPerature:

1000

K

Temperature

after

reheating:

100O

K

Air

mass

flow:

25

kg/s

Ambient

air

Pressure:

1 bar

Take calorific.

value

of

fuel as

42flJ

lkg

-.2

Find

the

go(

powe

r

o

u

tput13xefall

th

e

rmal

e

ffi

c

ie

ncyrdp

e

c

i fi

c

fu e

1

consumption.

Neglect

the

kinetic enerry

of

the

gases

ieaving

the

sYstem.

a"

Ar{

At}ernpt

4n3r

two

\-/'

*{ rterive

equation

for

maximum

Non-

dimensional

Mass

flow

rate.

16y'

prove

that

Mach

no.

at

maximum

entropy

point

is

1

and

at

maximum

\'/'

enthalpy

point

is

1/

{

y

in case

of

Rayleigh

Flow'

c|

Show

ihu-t

for

Normal

shock

the

product of

upstream

and

downstream

velocity

is equal

to square

of critical

velocity

of

flow.

-r/

A{

Give

proper

representation

of

Fanno

line,

Rayliegh

line and

normal

\/

shock

on

the

same

h-s

diagram

for a

particular

value

of

Impulse

.

function,

Stagnation

enthalpy

and

mass

flux

density'

./

/'

Q/8

Tfuttempt

anY

two

\rr

{

A convergent--divergent

nozzle

is

provided

with

a

pipe

of

constant

\-/

'

cross-seciion

at

its

exit;

the exit

d.iameter

of

the

nozzle

and

that

of

the

pipe

is

lggrrl

The

mean

coefficient

of friction

for

the

pipe is 0.0025.

Bt';-t*:tt.

':iics$'r-li::

a-nd

te'lperature

of

air

at

tlre

raz'21'e

enliY

are

L2btar

and

600K.

The

flow

is isentropic

in

the

nozzle

atrd

uCiiLatic

in

the

pipe. The

mach

number

at

the

entry

and

exit

of the

pipe are

2 and

1.0

TesPectivelY.

Determine

:

y'.T,he

length

of

the

PiPe,

J

b(Oiameter

of the

nozzle

throat,

and

\,/

(;{Yressure

and

temperature

at

the

pipe

exit'

Depict

the

physics

of

the

problem

by

line diagram

and

h-s

plane'

Aiso,

e

entry

to the

piPe

exit.

{

ei,

enters

a

combustion

chamber

at

Mr

=

2.5,

Pt.

-

2 bar

and

Tr

:

288

K.

A

normal

shock

occurs

at

the

end

of

the

combustionrchamber;

the

statr{pressure

before

the

shogk

is 4

bar. Determinry*(Mach

number,

AV/stitrc

piessure

etC

C/static

temperatr.rre

at

the

exit

of

the

L/ornbustion

cha.nber.

rrrhYt

are

these

values

in

the

absence

of

shock?

Calcuiate

the

lreat

suppiied

and

its

maximum

vaiue

in

the

two

casc'";

Depict

the

physics of

the

problem

by

line

diagram

and

h-s

plane'

AIso

show

the

vlriations

occur

in

static

pressr-lre

and

stagnation

pressure

throughout

the

length.

J

t{

t\

.

'1

,(

"?

*'gt

8/18/2019 Egt End Sem 2014

3/3

-

c)

In

a

compressed

air

system

variable

area

convergent

nozzle

is

employed

to

limit

the

maximum

mass

flow rate.

Following

two

cases

are

considered:

1) A

frictionless

duct

of 15

cm diameter

is

fitted

with

the

variable

areanozzle

at its

exit.

Air

enters

the

duct at Mr

=

O.2O,

pi:4bar,

Tr

=

4O0K.

Calculate

the flow

rate

and

the

nozzle

exit

area for

maximum

flow

rate.

2l

Heat

is supplied

to

the

air

raising

the stagnation

temperature

of

air in

the duct

to twice

its

value

at entry.

Recaicuiate

the

new

value

of.

nozzle

throat

area

for

the

same

value

of

the

maximum

flow

rate.

lsentropic

Flow Table

M

P/Po

T/To

A/A*

0.2 0.973

0.992

2.964

1.0

0.528

0.833

1.0

2

0.128

0.555

1.687

2.5

0.0585

0.444

2.637

2.99

0.0276

0.3587

4.2

Ravleish

Flow

Table

Fanno

Flow Table

M

To/To*

T/T*

P/P*

Po/Po*

g*la

-

o.2

0.1r3s

0.2066

2.273

'

't.235

0,091

0.3

0.3468

0.409

2.131

{.{98

0,192

1.6

0.884

0.702

o.523

1.176

1.340

1.7

0.859

0.654

0.475

1.240

1.375

2

0,794

0.529

0.363

1.503

1.455

2.5

0.710

0.378 o.245

2,222

1.538

Normal

Shock

Table

Mx

My

Tv/Tx

Pv/Px

PovlPox

1.6

0.668

1.388

2.824

0.895

1,7

a

6a,l

1.458

3.205

0.856

2

o.577

1.687

4.5

o.721

2.5

0.513 2.137

7.125

0.499

M

*

vnl*

-

T/T*

-'

"

PlP"

-

Po/Po*

4fL.rr/D

0.2

0.218

1.1905

5.455

2.963

14.533

1.0

1.0

{.0

1.0

1.0

o.0

2. 1.633

0.667

0.408

1.687

0.305

2,5

1.826

0.533

0.292

2,637

0.432

-B**q

''.,,