Propulsion efficiency of the following order-is obtained in practice _______________?

Related Mcqs:

1. In jet propulsion power unit, the inlet duct of diverging shape is used in order to _______________ ?

   A. collect more air
   B. convert kinetic energy of air into pres-sure energy
   C. provide robust structure
   D. beautify the shape
   E. none of the above

2. The maximum propulsion efficiency of a turbojet is attained at around following speed __________________?

   A. 550 km/hr
   B. 1050km/hr
   C. 1700 km/hr
   D. 2400km /hr
   E. 4000 km/hr

3. In gas turbines^ high thermal efficiency is obtained in_________________?

   A. closed cycle
   B. open cycle
   C. both of the above
   D. closed/open depending on other con-siderations
   E. unpredictable

4. There is a certain pressure ratio (optimum) for a gas turbine at which its thermal efficiency is maximum. With increase in turbine temperature, the value of pressure ratio for the peak efficiency would__________________?

   A. remain same
   B. decrease
   C. increase
   D. unpredictable
   E. none of the above

5. Volumetric efficiency of air compressors is of the order of________________?

   A. 20-30%
   B. 40-50%
   C. 60-70%
   D. 70-90%
   E. 90-100%

6. The combustion efficiency of a gas turbine using perfect combustion chamber is of the order of________________?

   A. 50%
   B. 75%
   C. 85%
   D. 90%
   E. 99%

7. Volumetric efficiency of a compressor with clearance volume ________________?

   A. increases with increase in compression ratio
   B. decreases with increase in compression ratio
   C. in not dependent upon compression ratio
   D. may increase/decrease depending on compressor capacity
   E. unpredictable

8. The thermodynamic efficiency of rotary compressor is based on_______________?

   A. isothermal compression
   B. adiabatic compression
   C. isentropic compression
   D. polytropic compression
   E. none of the above

9. For an irreversible gas turbine cycle, the efficiency and work ratio both depend on___________________?

   A. pressure ratio alone
   B. maximum cycle temperature alone
   C. minimum cycle temperature alone
   D. both pressure ratio and maximum cycle temperature
   E. none of the above

10. Propulsive efficiency is defined as ratio of___________________?

    A. thrust power and fuel energy
    B. engine output and propulsive power
    C. propulsive power and fuel input
    D. thrust power and propulsive power
    E. none of the above