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Home » Engineering » Mechanical Engineering » Aptitude Test - 16
1.The blade friction in the impulse turbine reduces the velocity of steam by ____ while it passes over the blades.
A. 10 to 15%
B. 15 to 20%
C. 20 to 30%
D. 10 to 15%
2.The effect of bleeding is that
A. it increases the thermodynamic efficiency of the turbine
B. boiler is supplied with hot water
C. it decreases the power developed by the turbine
D. it increases the thermodynamic efficiency of the turbine
3.The expansion of steam, as it flows over the blades in reaction turbine, represents
A. isothermal process
B. isentropic process
C. throttling process
D. isothermal process
4.The efficiency of an impulse turbine is maximum when (where Vb = Blade speed, V = Absolute velocity of steam entering the blade, and ? = Nozzle angle)
A. Vb = 0.5 V cos ?
B. Vb = V cos ?
C. Vb = 0.5 V2 cos ?
D. Vb = 0.5 V cos ?
5.The velocity of whirl at outlet for an axial discharge turbine is
A. minimum
B. maximum
C. zero
D. minimum
6.In impulse turbines, when friction is neglected, the relative velocity of steam at outlet tip of the blade is ____ the relative velocity of steam at inlet tip of the blade.
A. equal to
B. less than
C. greater than
D. equal to
7.The friction present between the steam and the nozzle surfaces reduces the heat drop by
A. 10 to 15 percent
B. 15 to 25 percent
C. 25 to 40 percent
D. 10 to 15 percent
8.An impulse turbine as compared to a reaction turbine, for a given power has ___row of blades.
A. equal
B. less
C. more
D. equal
9.Degree of reaction is defined as the ratio of
A. heat drop in fixed blades to the heat drop in moving blades
B. heat drop in moving blades to the heat drop in fixed blades
C. heat drop in moving blades to the heat drop in fixed blades plus heat drop in moving blades
D. heat drop in fixed blades to the heat drop in moving blades
10.The expansion of steam in a nozzle follows
A. Carnot cycle
B. Rankine cycle
C. Joule cycle
D. Carnot cycle
11.A cycle consisting of one constant pressure, one constant volume and two isentropic processes is known as
A. Carnot cycle
B. Stirling cycle
C. Otto cycle
D. Carnot cycle
12.The efficiency and work ratio of a simple gas turbine cycle are
A. low
B. very low
C. high
D. low
13.The amount of heat required to raise the temperature of the unit mass of gas through one degree at constant volume, is called
A. specific heat at constant volume
B. specific heat at constant pressure
C. kilo Joule
D. specific heat at constant volume
14.An adiabatic process is one in which
A. no heat enters or leaves the gas
B. the temperature of the gas changes
C. the change in internal energy is equal to the mechanical workdone
D. no heat enters or leaves the gas
15.Which of the following is the lightest and most volatile liquid fuel?
A. Gasoline
B. Kerosene
C. Fuel oil
D. Gasoline
16.The processes occurring in open system which permit the transfer of mass to and from the system, are known as
A. flow processes
B. non-flow processes
C. adiabatic processes
D. flow processes
17.Which of the following has the minimum atomic mass?
A. Oxygen
B. Sulphur
C. Nitrogen
D. Oxygen
18.Workdone in a free expansion process is
A. zero
B. minimum
C. maximum
D. zero
19.The pressure exerted by an ideal gas is ____ of the kinetic energy of all the molecules contained in a unit volume of gas.
A. one-half
B. one-third
C. two-third
D. one-half
20.The compression ratio for petrol engines is
A. 3 to 6
B. 5 to 8
C. 15 to 20
D. 3 to 6
21.The efficiency of Diesel cycle approaches to Otto cycle efficiency when
A. cut-off is increased
B. cut-off is decreased
C. cut-off is zero
D. cut-off is increased
22.The entropy ___ in an irreversible cyclic process.
A. remains constant
B. decreases
C. increases
D. remains constant
23.The atomic mass of oxygen is
A. 12
B. 14
C. 16
D. 12
24.The ratio of specific heat at constant pressure (cp) and specific heat at constant volume (cv) is
A. equal to one
B. less than one
C. greater than one
D. equal to one
25.Carbonisation of coal consists of
A. drying and crushing the coal to a fine powder
B. moulding the finely ground coal under pressure with or without a binding material
C. heating the wood with a limited supply of air to temperature not less than 280�C
D. drying and crushing the coal to a fine powder
26.The efficiency of Stirling cycle is __________ Carnot cycle.
A. greater than
B. less than
C. equal to
D. greater than
27.If the value of n = 0 in the equation pvn = C, then the process is called
A. constant volume process
B. adiabatic process
C. constant pressure process
D. constant volume process
28.The value of specific heat at constant pressure (cp) is ___ that of at constant volume (cv).
A. less than
B. equal to
C. more than
D. less than
29.Which of the following is correct?
A. Absolute pressure = Gauge pressure + Atmospheric pressure
B. Gauge pressure = Absolute pressure + Atmospheric pressure
C. Atmospheric pressure = Absolute pressure + Gauge pressure
D. Absolute pressure = Gauge pressure + Atmospheric pressure
30.Which of the following statement is incorrect?
A. The liquid fuels consist of hydrocarbons.
B. The liquid fuels have higher calorific value than solid fuels.
C. The solid fuels have higher calorific value than liquid fuels.
D. The liquid fuels consist of hydrocarbons.
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