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Home » Engineering » Mechanical Engineering » Aptitude Test - 14
1.The difference of supersaturated temperature and saturation temperature at that pressure is called
A. degree of supersaturation
B. degree of superheat
C. degree of undercooling
D. degree of supersaturation
2.The ratio of the useful heat drop to the isentropic heat drop is called
A. condenser efficiency
B. nozzle efficiency
C. boiler efficiency
D. condenser efficiency
3.The efficiency of steam turbines may be improved by
A. reheating of steam
B. regenerative feed heating
C. binary vapour plant
D. reheating of steam
4.In a reaction turbine, when steam flows through the fixed blades,
A. pressure increases while velocity decreases
B. pressure decreases while velocity increases
C. pressure and velocity both decreases
D. pressure increases while velocity decreases
5.A single stage impulse turbine with a diameter of 1.2 m runs at 3000 r.p.m. If the blade speed ratio is 0.42, then the inlet velocity of steam will be
A. 79 m/s
B. 188 m/s
C. 450 m/s
D. 79 m/s
6.The flow of steam is super-sonic
A. at the entrance to the nozzle
B. at the throat of the nozzle
C. in the convergent portion of the nozzle
D. at the entrance to the nozzle
7.De-Laval turbine is a
A. simple impulse turbine
B. simple reaction turbine
C. impulse-reaction turbine
D. simple impulse turbine
8.The impulse turbine rotor efficiency will have a maximum value of 0.5 cos2 ?, where ? is the nozzle exit flow angle, if the
A. blades are equiangular
B. blade velocity coefficient is unity
C. blades are equiangular and frictionless
D. blades are equiangular
9.When the cross-section of a nozzle increases continuously from entrance to exit, it is called a
A. divergent nozzle
B. convergent nozzle
C. convergent-divergent nozzle
D. divergent nozzle
10.Rateau turbine is
A. simple reaction turbine
B. velocity compounded turbine
C. pressure compounded turbine
D. simple reaction turbine
11.Curtis turbine is a
A. simple reaction turbine
B. velocity compounded turbine
C. pressure compounded turbine
D. simple reaction turbine
12.The velocity of steam at throat of the nozzle is ____ the velocity of sound.
A. equal to
B. less than
C. more than
D. equal to
13.The critical pressure ratio for initially dry saturated steam is
A. 0.546
B. 0.577
C. 0.582
D. 0.546
14.The critical pressure ratio for gases is
A. 0.528
B. 0.546
C. 0.577
D. 0.528
15.The efficiency of a pressure-velocity compounded impulse turbine is _____ as compared to pressure compounded impulse turbine.
A. same
B. less
C. more
D. same
16.The effect of supersaturation is that the
A. mass of the steam discharged increases
B. entropy and specific volume of the steam increases
C. exit velocity of steam reduces
D. mass of the steam discharged increases
17.The effect of friction on the flow of steam through a nozzle is to
A. decrease the mass flow rate and to increase the wetness of steam
B. increase the mass flow rate and to increase the exit temperature
C. decrease the mass flow rate and to decrease the wetness of steam
D. decrease the mass flow rate and to increase the wetness of steam
18.The ratio of the isentropic heat drop to the heat supplied, is called
A. reheat factor
B. stage efficiency
C. internal efficiency
D. reheat factor
19.The purpose of governing in steam turbines is to
A. maintain the speed of the turbine
B. reduce the effective heat drop
C. reheat the steam and improve its quality
D. maintain the speed of the turbine
20.De-Laval turbines are mostly used
A. where low speeds are required
B. for small power purposes and low speeds
C. for large power purposes
D. where low speeds are required
21.The reheat factor depends upon
A. initial pressure and superheat
B. exit pressure
C. turbine stage efficiency
D. initial pressure and superheat
22.In an impulse turbine
A. the steam is expanded in nozzles only and there is a pressure drop and heat drop
B. the steam is expanded both in fixed and moving blades continuously
C. the steam is expanded in moving blades only
D. the steam is expanded in nozzles only and there is a pressure drop and heat drop
23.A nozzle is said to be a divergent nozzle
A. when the cross-section of the nozzle increases continuously from entrance to exit
B. when the cross-section of the nozzle decreases continuously from entrance to exit
C. when the cross-section of the nozzle first decreases from entrance to throat and then increases from its throat to exit
D. when the cross-section of the nozzle increases continuously from entrance to exit
24.The compounding of turbines is done in order to
A. reduce speed of rotor
B. improve efficiency
C. reduce exit losses
D. reduce speed of rotor
25.The pressure of steam __________ while flowing through a nozzle.
A. increases
B. decreases
C. remains constant
D. increases
26.The process of maintaining the speed of the turbine constant for various load conditions, is known as
A. bleeding
B. reheating
C. governing
D. bleeding
27.Reheating of steam in a turbine
A. increases the workdone through the turbine
B. increases the efficiency of the turbine
C. reduces wear on the blades
D. increases the workdone through the turbine
28.Which of the following statement is correct for steam turbines as compared to reciprocating steam engines?
A. A steam turbine develops higher speeds
B. The efficiency of steam turbine is higher
C. The steam consumption is less
D. A steam turbine develops higher speeds
29.The density of supersaturated steam is about ______ that of the ordinary saturated vapour at the corresponding pressure.
A. same as
B. 2 times
C. 4 times
D. same as
30.The ratio of the workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam is called
A. blading efficiency
B. nozzle efficiency
C. stage efficiency
D. blading efficiency
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