A. centrifugal compressors deliver prac-tically constant pressure over a considerable range of capacities
B. Axial flow compressors have a sub-stantially constant delivery at variable pressures
C. centrifugal compressors have a wider stable operating range than axial flow compressors
D. axial flow compressors are bigger in diameter compared to centrifugal type
E. axial flow compressors apt to be longer as compared to centrifugal type
Compressors, Gas Turbines and Jet Engines
Compressors, Gas Turbines and Jet Engines
A. gas turbine uses low air-fuel ratio to economise on fuel
B. gas turhine uses high air-fuel ratio to reduce outgoing temperature
C. gas turbine uses low air-fuel ratio to develop the high thrust required
D. all of the above
E. none of the above
A. large gas turbines employ axial flow compressors
B. axial flow compressors are more stable than centrifugal type compressors but not as efficient
C. axial flow compressors have high capacity and efficiency
D. axial flow compressors have instability region of operation
E. centrifugal compressors are used mainly on low flow pressure ratio gas turbines
A. gas turbine requires lot of cooling water
B. gas turbine is capable of rapid start up and loading
C. gas turbines have flat efficiency at part loads
D. gas turbines have high standby losses and require lot of maintenance
E. gas turbines can be used to generate power only
A. large gas turbines use radial inflow turbines
B. gas turbines have their blades similar to steam turbine
C. gas .turbine’s blade will appear as impulse section at the hub and as a reaction section at tip
D. gas turbines use both air and liquid cooling
E. all of the above are correct.
A. pulsojet requires no ambient air for propulsion
B. ramjet-engine has no turbine
C. turbine drives compressor in a burbojet
D. bypass turbo-jet engine increases the thrust without adversely affecting, the propulsive efficiency and fuel economy
E. propeller is an indirect reaction device
A. closed cycle gas turbine is an I.C engine
B. gas turbine uses same working fluid over and over again
C. air-fuel ratio in a gas turbine is 100 : 1
D. ideal efficiency of closed cycle gas turbine plant is more than carnot cycle efficiency
E. thrust in turbo-jet is produced by nozzle exit gases
A. gas turbine is a self-starting unit
B. gas turbine does not require huge quantity of water like steam plant
C. exhaust losses in gas turbine are high due to large mass flow rate
D. overall efficiency of gas turbine plant is lower than that of a reciprocating engine
E. gas turbine can be easily started and stopped and thus is best suited for peaking demands
A. atmosphere
B. back to the compressor
C. discharge nozzle
D. vacuum
E. none of the above
A. Vi=V0B
B. Vt>V0
C. U,<V0
D. V,= U0
E. Vri=Vm
