281. 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

282. The weight per horse power ratio for gas. turbine as compared to I.C. engine and steam turbine is________________?
A. same
B. higher
C. lower
D. incomparable
E. unpredictable

283. The blades of gas turbine are made of_________________?
A. mild steel
B. stainless steel
C. carbon steel
D. high alloy seal
E. high nicked alloy (mnemonic)

284. Fighter bombers use following type of engine __________________?
A. turbo-jet
B. turbo-propeller
C. rocket
D. ram-jet ,
E. pulsojet

285. The following property is most important for material used for gas turbine blade___________________?
A. toughness
B. fatigue
C. creep
D. corrosion resistance
E. bulk modulus

286. The specific output per kg mass flow rate of a gas turbine (having fixed efficiencies of compressor and taurine and fixed higher and lower temperature) with increase in pressure ratio will___________________?
A. increase first at fast rate and then slow
B. increase first at slow rate and then fast
C. decrease continuously
D. first increase, reach maximum and then decrease
E. none of the above

287. The effective power of gas turbines is increased by adding the following in compressor__________________?
A. ammonia and water vapor
B. carbon dioxide
C. nitrogen
D. hydrogen
E. none of the above

288. Air-fuel ratio in a jet engine will be of the order of__________________?
A. 10: 1
B. 15: 1
C. 20 : 1
D. 60 : 1
E. 100 :

289. In jet engines the compression ratio__________________?
A. varies as square root of the speed
B. Varies linearly to the speed
C. varies as square of the speed
D. varies as cube of the speed
E. is constant irrespective of variation in speed

290. High air-fuel ratio is used in gas turbines______________________?
A. to increase the output
B. to increase the efficiency
C. to save fuel
D. to reduce the exit temperature
E. none of the above

NOTE
IF YOU THINK ANY OF THE MCQ ABOVE IS WRONG.
PLEASE COMMENT WITH CORRECT ANSWER AND ITS DETAIL EXPLANATION IN COMMENT BOX.
THANK YOU

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