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MCQOPTIONS
This section includes 219 Mcqs, each offering curated multiple-choice questions to sharpen your Automobile Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
If compression is achieved by trapping a refrigerant vapour in an enclosed space, and then reducing its volume, then it is called: |
| A. | roto-dynamic type compressor |
| B. | open type compressor |
| C. | radial-flow type compressor |
| D. | positive-displacement type compressor |
| Answer» E. | |
| 52. |
In reciprocating air compressors, the clearance ratio is: |
| A. | clearance volume to swept volume of the cylinder |
| B. | swept volume to clearance volume of the cylinder |
| C. | clearance volume to total volume of the cylinder |
| D. | total volume to clearance volume of the cylinder |
| Answer» B. swept volume to clearance volume of the cylinder | |
| 53. |
Consider the following statements:The compression process in a centrifugal compressor is comparable with:1. Reversible and adiabatic2. Irreversible and adiabaticWhich of the above statements is/are correct? |
| A. | Both 1 and 2 |
| B. | Neither 1 nor 2 |
| C. | 1 only |
| D. | 2 only |
| Answer» E. | |
| 54. |
Intake filters are provided in compressors primarily to _____ from the suction air. |
| A. | remove dirt and moisture |
| B. | remove dirt and regulate the temperature |
| C. | remove dirt as well as reduce the pressure |
| D. | remove only dirt |
| Answer» E. | |
| 55. |
High positive incidence in an axial compressor bladed leads to |
| A. | suppression of separation of flow on the blade |
| B. | choking of the flow |
| C. | separation of flow on the suction side of the blade |
| D. | separation of flow on the pressure side of the blade |
| Answer» D. separation of flow on the pressure side of the blade | |
| 56. |
An ideal air compressor cycle (with clearance) on p-v diagram can be represented by ________ processes. |
| A. | One adiabatic, two isobaric, and one constant volume |
| B. | Two adiabatic and two isobaric |
| C. | Two adiabatic, one isobaric, and one constant volume |
| D. | One adiabatic, one isobaric, and two constant volume |
| Answer» C. Two adiabatic, one isobaric, and one constant volume | |
| 57. |
In gas turbines, the work input with intercooling is __________ the work input with no intercooling. |
| A. | less man |
| B. | more than |
| C. | Can't say |
| D. | None of these |
| Answer» B. more than | |
| 58. |
For maximum work, the reheating should be done to an intermediate pressure of (where p1 = Maximum pressure, and p2 = Minimum pressure) |
| A. | (p₁ - p₂)/2 |
| B. | (p₁ + p₂)/2 |
| C. | p₁/p₂ |
| D. | p₁ p₂ |
| Answer» E. | |
| 59. |
A compressor at high altitudes will require __________ power. |
| A. | same |
| B. | less |
| C. | more |
| D. | None of these |
| Answer» C. more | |
| 60. |
In reciprocating air compressors, isothermal efficiency is used for all sorts of calculations. |
| A. | Correct |
| B. | Incorrect |
| C. | Can't say |
| D. | None of these |
| Answer» B. Incorrect | |
| 61. |
In axial flow compressors, the flow of air is parallel to the axis of compressor. |
| A. | Correct |
| B. | Incorrect |
| C. | Can't say |
| D. | None of these |
| Answer» B. Incorrect | |
| 62. |
When the outlet angle from the rotor of a centrifugal compressor is more than 90°, then the blades are said to be |
| A. | forward curved |
| B. | backward curved |
| C. | radial |
| D. | none of these |
| Answer» B. backward curved | |
| 63. |
In a jet engine, the compression varies as the square of the speed. |
| A. | Correct |
| B. | Incorrect |
| C. | Can't say |
| D. | None of these |
| Answer» B. Incorrect | |
| 64. |
The volume of air delivered in a medium capacity air compressor per unit time is |
| A. | 0.1 to 1.2 m³/s |
| B. | 0.15 to 5 m³/s |
| C. | above 5 m³/s |
| D. | none of these |
| Answer» C. above 5 m³/s | |
| 65. |
A turbo-prop is preferred to turbo-jet because |
| A. | it has high propulsive efficiency at high speeds |
| B. | it can fly at super sonic speeds |
| C. | it can fly at high elevations |
| D. | it has high power for take off |
| Answer» E. | |
| 66. |
The free air delivery is the volume of air that can be delivered by a compressor freely. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 67. |
In a centrifugal compressor, the ratio of the __________ to the blade velocity is called slip factor. |
| A. | inlet whirl velocity |
| B. | outlet whirl velocity |
| C. | inlet velocity of flow |
| D. | outlet velocity of flow |
| Answer» E. | |
| 68. |
A regenerator in a gas turbine improves thermal efficiency. |
| A. | Correct |
| B. | Incorrect |
| C. | Can't say |
| D. | None of these |
| Answer» B. Incorrect | |
| 69. |
In a single stage, single acting reciprocating air compressor, without clearance, the workdone on the air during isentropic compression is __________ the heat required to raise the temperature of air from T1 to T2 at a constant pressure. |
| A. | equal to |
| B. | less than |
| C. | greater than |
| D. | None of these |
| Answer» B. less than | |
| 70. |
In air compressors, free air delivery means the |
| A. | actual volume of the air delivered by the compressor when reduced to normal temperature and pressure conditions |
| B. | volume of air delivered by the compressor |
| C. | volume of air sucked by the compressor during its suction stroke |
| D. | none of the above |
| Answer» B. volume of air delivered by the compressor | |
| 71. |
The velocity of air entering in a rocket is __________ as compared to an aircraft. |
| A. | zero |
| B. | less |
| C. | more |
| D. | same |
| Answer» B. less | |
| 72. |
In a single stage, single acting reciprocating air compressor without clearance volume, the workdone is maximum during |
| A. | isothermal compression |
| B. | isentropic compression |
| C. | polytropic compression |
| D. | none of these |
| Answer» C. polytropic compression | |
| 73. |
The compression ratio for the compressor is always __________ unity. |
| A. | equal to |
| B. | less than |
| C. | more than |
| D. | None of these |
| Answer» D. None of these | |
| 74. |
Workdone by an air compressor __________ upon the way in which the air is compressed. |
| A. | depends |
| B. | does not depend |
| C. | Can't say |
| D. | None of these |
| Answer» B. does not depend | |
| 75. |
For minimum work in multi-stage compression, the workdone on all stages should be equal. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» B. No | |
| 76. |
Air motors work on the cycle which is the reverse of the reciprocating air compressor cycle. |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» B. Disagree | |
| 77. |
Reheating in a gas turbine |
| A. | increases the thermal efficiency |
| B. | increases the compressor work |
| C. | increases the turbine work |
| D. | decreases the thermal efficiency |
| Answer» B. increases the compressor work | |
| 78. |
In a single acting reciprocating air compressor, without clearance, the compression of air may be |
| A. | isothermal |
| B. | polytropic |
| C. | isentropic |
| D. | any one of these |
| Answer» E. | |
| 79. |
In open cycle turbo-jet engines used in military aircraft, reheating the exhaust gas from the turbine by burning, more fuel is used to increase the |
| A. | thrust and range of aircraft |
| B. | efficiency of the engine |
| C. | both (a) and (b) |
| D. | none of these |
| Answer» B. efficiency of the engine | |
| 80. |
In a closed cycle gas turbine, the air is compressed |
| A. | isothermally |
| B. | polytropically |
| C. | isentropically |
| D. | none of these |
| Answer» D. none of these | |
| 81. |
If the flow of air through the compressor is perpendicular to its axis, then it is a |
| A. | reciprocating compressor |
| B. | centrifugal compressor |
| C. | axial flow compressor |
| D. | turbo compressor |
| Answer» C. axial flow compressor | |
| 82. |
The overall isothermal efficiency of the compressor is defined as the ratio of |
| A. | work required to compress the air isothermally to the actual work required to compress the air for the same pressure ratio |
| B. | isothermal power to the shaft power or B.P. of the motor or engine required to drive the compressor |
| C. | volume of free air delivery per stroke to the swept volume of the piston |
| D. | isentropic power to the power required to drive the compressor |
| Answer» C. volume of free air delivery per stroke to the swept volume of the piston | |
| 83. |
If the clearance ratio for a reciprocating air compressor is 'K', then its volumetric efficiency is given by |
| A. | 1 - k + k (p₁/p₂)1/n |
| B. | 1 + k - k (p₂/p₁)1/n |
| C. | 1 - k + k (p₁/p₂) n- 1/n |
| D. | 1 + k - k (p₂/p₁) n-1/n |
| Answer» C. 1 - k + k (p₁/p₂) n- 1/n | |
| 84. |
When air is to be compressed at a high pressure, then it is advantageous to use |
| A. | single stage compression |
| B. | multi-stage compression without intercooling |
| C. | multi-stage compression with intercooling |
| D. | none of these |
| Answer» D. none of these | |
| 85. |
If the flow of air through the compressor is parallel to its axis, then the compressor is |
| A. | reciprocating compressor |
| B. | centrifugal compressor |
| C. | axial flow compressor |
| D. | turbo-compressor |
| Answer» D. turbo-compressor | |
| 86. |
The pressure of air at the beginning of the compression stroke is __________ the atmospheric pressure. |
| A. | equal to |
| B. | less than |
| C. | more than |
| D. | None of these |
| Answer» C. more than | |
| 87. |
The overall thermal efficiency of an ideal gas turbine plant is (where r = Pressure ratio) |
| A. | rγ - 1 |
| B. | 1 - rγ - 1 |
| C. | 1 - (1/r) ɣ-1/ɣ |
| D. | 1 - (1/r) ɣ/ɣ-1 |
| Answer» D. 1 - (1/r) ɣ/ɣ-1 | |
| 88. |
Reheating in a multi-stage expansion gas turbine __________ compressor work. |
| A. | has no effect on |
| B. | decreases |
| C. | increases |
| D. | None of these |
| Answer» C. increases | |
| 89. |
The pressure ratio in a centrifugal compressor can be increased by increasing the tip speed and lowering the inlet temperature. |
| A. | Correct |
| B. | Incorrect |
| C. | Can't say |
| D. | None of these |
| Answer» B. Incorrect | |
| 90. |
A jet engine has |
| A. | no propeller |
| B. | propeller in front |
| C. | propeller at back |
| D. | propeller on the top |
| Answer» B. propeller in front | |
| 91. |
With the decrease in compression ratio, the volumetric efficiency |
| A. | does not change |
| B. | increases |
| C. | decreases |
| D. | None of these |
| Answer» C. decreases | |
| 92. |
The assumption made in two stage compression with intercooler is that |
| A. | there is no pressure drop in the intercooler |
| B. | the compression in both the cylinders is polytropic |
| C. | the suction and delivery of air takes place at constant pressure |
| D. | all of the above |
| Answer» E. | |
| 93. |
Which of the following statement is correct as regard to centrifugal compressors? |
| A. | The flow of air is parallel to the axis of the compressor. |
| B. | The static pressure of air in the impeller increases in order to provide centripetal force on the air. |
| C. | The impeller rotates at high speeds. |
| D. | The maximum efficiency is higher than multi-stage axial flow compressors. |
| Answer» C. The impeller rotates at high speeds. | |
| 94. |
If p1 is the pressure of air entering the L.P, cylinder and p3 is the pressure of air leaving the H.P. cylinder, then the ratio of cylinder diameters for a single acting, two stage reciprocating compressor with complete intercooling is given by |
| A. | D1/D2 = (p1p3)1/2 |
| B. | D1/D2 = (p1/p3)1/4 |
| C. | D1/D2 = (p1p3)1/4 |
| D. | D1/D2 = (p3/p1)1/4 |
| Answer» E. | |
| 95. |
The efficiency of roots blower __________ with the increase in pressure ratio. |
| A. | decreases |
| B. | increases |
| C. | does not change |
| D. | None of these |
| Answer» B. increases | |
| 96. |
For perfect intercooling in a two stage compressor, |
| A. | p₂/p₁ = p₃/p₂ |
| B. | p₁/p₃ = p₂/p₁ |
| C. | p₁ = p₃ |
| D. | p₁ = p₂p₃ |
| Answer» B. p₁/p₃ = p₂/p₁ | |
| 97. |
Volumetric efficiency of a compressor decreases with __________ in compression ratio. |
| A. | decrease |
| B. | increase |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 98. |
In a centrifugal compressor, the flow of air is __________ to the axis of compressor. |
| A. | parallel |
| B. | perpendicular |
| C. | inclined |
| D. | none of these |
| Answer» C. inclined | |
| 99. |
Euler's equation can be used for |
| A. | radial flow compressors |
| B. | axial flow compressors |
| C. | pumps |
| D. | all of these |
| Answer» E. | |
| 100. |
In a double acting compressor, the air is compressed |
| A. | in one cylinder |
| B. | in two cylinders |
| C. | in a single cylinder on both sides of the piston |
| D. | in two cylinders on both sides of the piston |
| Answer» D. in two cylinders on both sides of the piston | |