intro propulsion lect 3

7/29/2019 Intro Propulsion Lect 3

1/22

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3


2/22

Prof. Bhaskar Roy, Prof. A M Pradeep, Department of Aerospace, IIT Bombay2

Lect-3

Thrust=m(V -V )e a


3/22


Lect-3

Simple Gas Turbine based Turbojet Engine


4/22


Lect-3

Mechan ism o f Cr eat ion o f Th r us t


5/22


Lect-3

The net thrust F due to change in momentum isIntake Ram drag

F = Ve - Va + Ae.(Pe- Pa)

Gross Momentum Pressure

Thrust Thrust

m m

The propulsive efficiency p can be defined as the ratio of the useful

propulsive energy or thrust power (F.Va) to the sum of that energy

and the unused kinetic energy of the jet ,

The latter is the kinetic energy relative to earth.

2

e am (V - V )

.2

a ap 2

e aa e a

e

a

em.V .( V - V ) 2 = =

V(V - V ) 1+m V .(V -V ) + V2

propulsive efficiency


6/22


Lect-3

When Ve>> Va i.e. a very large acceleration and,

so with even with low mass flow,Thrust produced, F = very high- , but

propulsive efficiency, p= low , typical jet

engine, which produces compact thrusters

When, Ve= Va the propulsive efficiency is 100%,but Thrust, F 0; - has given rise to turbofans,

where large part of the thrust is produced withhigh mass flow, low air acceleration and highpropulsive efficiency, and only a small part ofthrust is produced with high jet effect.


7/22Prof. Bhaskar Roy, Prof. A M Pradeep, Department of Aerospace, IIT Bombay7

Lect-3

The graph captures theutility zones of various

kinds of propulsivedevices. At low subsonic speedspropellers are the better

thrusting devices. At medium speeds (highsubsonic) turbofans arethe better thrusters At high (supersonic)speeds, there is noalternative but to go forpure jet engines



Lect-3

A sing le spoo l byp ass t u r bo j e t eng in e



Lect-3

A t w in - sp o o l Tu r b o -p ro p e n g in e



Lect-3

A bypass t w in spoo l gas t u r b ine eng ine



Lect-3

A h igh byp ass tw in spoo l Tu r bo fan eng ine



Lect-3

A n Ul t r a -h i g h b yp a ss t w in sp o o l g ea red t u r b o f a n


13/22Prof. Bhaskar Roy, Prof. A M Pradeep, Department of Aerospace, IIT Bombay

13

Lect-3

A t h r ee-spoo l t u r bo fan by pass eng ine



14

Lect-3

Tw o sp o ol t u r b o sh af t en g i n e ( f o r p r o p el ler )



15

Lect-3

Tw in sp oo l p ow er p lan t w i t h i n t e r - co ol in g



16

Lect-3

Thr ee spoo l gea red con t ra - r o t a t i ng a f t p r op - fans



17

Lect-3

Tw o-spoo l h igh bypass a f t - f an t u r bo fan



18

Lect-3

Fron ta l

v iew o f ag ear ed t w ospoo l v e ryh igh bypasst u r b o f a neng ine


19/22


Lect-3

A co n t r a- r o t at i n g t w i n r o t o r a f t f a n p r o p - f an t est


20/22


Lect-3

Co n t r a - r o t a t i n g t w i n r o t o r a f t - p r o p - f an f l i gh t t e st


21/22


Lect-3

A ir c ra f t Eng ine deve lopm en t ove r t he

years have p roceeded t ow ards m ak ingt h e m m o r e co m p act ( l ig h t - w ei gh t , sm al lsi zed , m easu r e d in Th r u st / w e ig h t r a t i o )and h igh ly fu e l e f f i ci en t .

Recen t research and deve lopm ent s focuson t he fo l low ing i ssues :1 ) Ene rgy Aud i t & search f o r new fue l s2 ) Chem ica l Po l l u t i on Aud i t3 ) No ise Aud i t4 ) I n f r a- r ed sig n at u r e au d i t ( f or m i l i t a r y

a i r c ra f t )


22/22

Prof Bhaskar Roy Prof A M Pradeep Department of Aerospace IIT Bombay22

Lect-3

Space v eh ic le

be ing l i f t ed by arock e t eng ine

intro propulsion lect 3

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