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Home » Engineering » Aptitude Test - 126
Hassan
1.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
2.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
3.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
4.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
5.The diagram efficiency is the ratio of
A. workdone on the blades to the energy supplied to the blades
B. workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam
C. energy supplied to the blades per kg of steam to the total energy supplied per stage per kg of steam
D. workdone on the blades to the energy supplied to the blades
6.Blading efficiency is also known as
A. stage efficiency
B. diagram efficiency
C. nozzle efficiency
D. stage efficiency
7.In order to reduce the rotor speed of an impulse turbine, the method employed is
A. velocity compounding
B. pressure compounding
C. pressure-velocity compounding
D. velocity compounding
8.The nozzle efficiency is the ratio of
A. workdone on the blades to the energy supplied to the blades
B. workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam
C. energy supplied to the blades per kg of steam to the total energy supplied per stage per kg of steam
D. workdone on the blades to the energy supplied to the blades
9.The friction in the nozzle ____ exit velocity of steam.
A. has no effect on
B. decreases
C. increases
D. has no effect on
10.In a reaction turbine
A. the steam is allowed to expand in the nozzle, where it gives a high velocity before it enters the moving blades
B. the expansion of steam takes place partly in the fixed blades and partly in the moving blades
C. the steam is expanded from a high pressure to a condenser pressure in one or more nozzles
D. the steam is allowed to expand in the nozzle, where it gives a high velocity before it enters the moving blades
11.A stage, in reaction turbine, is represented by
A. number of casing
B. number of entries of steam
C. number of exits of steam
D. number of casing
12.When the nozzle operates with the maximum mass flow, the nozzle is said to be
A. choked
B. underdamping
C. overdamping
D. choked
13.In a velocity compounded impulse turbine, when steam flows through the second row of moving blades,
A. velocity increases
B. velocity decreases
C. velocity remains constant
D. velocity increases
14.A steam nozzle converts
A. heat energy of steam into kinetic energy
B. kinetic energy into heat energy of steam
C. heat energy of steam into potential energy
D. heat energy of steam into kinetic energy
15.The maximum discharge of steam through a convergent-divergent nozzle depends upon
A. area of nozzle at throat
B. initial pressure and volume of steam
C. final pressure ofsteam leaving the nozzle
D. area of nozzle at throat
16.Steam turbines may be classified according to
A. direction of steam flow
B. number of stages
C. mode of steam action
D. direction of steam flow
17.The process of draining steam from the turbine, at certain points during its expansion and using this steam for heating the feed water in feed water heaters and then supplying it to the boiler is known as
A. regenerative heating
B. reheating of steam
C. bleeding
D. regenerative heating
18.In a 50% reaction turbine stage, tangential component of absolute velocity at rotor inlet is 537 m/s and the blade velocity is 454 m/s. The power output in kW of steam will be
A. 260 kW
B. 282 kW
C. 296 kW
D. 260 kW
19.In an impulse turbine, steam expands
A. wholly in blades
B. wholly in nozzle
C. partly in the nozzle and partly in blades
D. wholly in blades
20.In a nozzle, the effect of supersaturation is to
A. decrease dryness fraction of steam
B. decrease specific volume of steam
C. increase the entropy
D. decrease dryness fraction of steam
21.Which of the following statement is correct?
A. The efficiency of steam turbines is greater than steam engines.
B. A flywheel is a must for steam turbine.
C. The turbine blades do not change the direction of steam issuing from the nozzle
D. The efficiency of steam turbines is greater than steam engines.
22.If the critical pressure ratio for steam is 0.546, then the steam is initially
A. wet steam
B. dry saturated steam
C. superheated steam
D. wet steam
23.The maximum efficiency of a De-Laval turbine is (where ? = Nozzle angle)
A. sin2 ?
B. cos2 ?
C. tan2 ?
D. sin2 ?
24.The pressure compounded impulse turbine as compared to velocity compounded turbine require ______ number of stages.
A. same
B. less
C. more
D. same
25.In a reaction turbine when the degree of reaction is zero, then there is
A. no heat drop in moving blades
B. no heat drop in fixed blades
C. maximum heat drop in moving blades
D. no heat drop in moving blades
26.The effect of friction in the nozzle _____ dryness fraction of steam.
A. has no effect on
B. decreases
C. increases
D. has no effect on
27.In an ideal impulse turbine, the
A. absolute velocity at the inlet of moving blade is equal to that at the outlet
B. relative velocity at the inlet of the moving blade is equal to that at the outlet
C. axial velocity at inlet is equal to that at the outlet
D. absolute velocity at the inlet of moving blade is equal to that at the outlet
28.In a reaction turbine, when steam flows through the moving 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
29.The critical pressure ratio is given by (where p1 = Initial pressure of steam, and p2 = Pressure of steam at throat or critical pressure)
A. p1 p2
B. p1/p2
C. p2/p1
D. p1 p2
30.A steam turbine, in which a part of the steam after partial expansion, is used for process heating and the remaining steam is further expanded for power generation, is known as
A. back pressure turbine
B. pass out turbine
C. low pressure turbine
D. back pressure turbine
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