Compressors, Gas Dynamics and Gas Turbines MCQs Archives

111. The overall isothermal efficiency of the compressor is defined as the ratio of

work required to compress the air isothermally to the actual work required to compress the air for the same pressure ratio

isothermal power to the shaft power or B.P. of the motor or engine required to drive the compressor

volume of free air delivery per stroke to the swept volume of the piston

isentropic power to th

✅ The correct answer is option B.

112. The compression ratio for the compressor is always __________ unity.

equal to

less than

more than

✅ The correct answer is option C.

113. In a single stage, single acting reciprocating air compressor, without clearance volume, the workdone is minimum during

isothermal compression

isentropic compression

polytropic compression

none of these

✅ The correct answer is option A.

114. Which of the following bladings will give maximum pressure rise in a centrifugal compressor, assuming the same overall dimensions, blade inlet angle and rotational speeds ?

Forward curved blades

Backward curved blades

Radial blades

all of these

✅ The correct answer is option A.

115. In a two stage reciprocating compressor with intercooler, the amount of work saved with incomplete intercooling is __________ that in case of complete intercooling.

less than

more than

✅ The correct answer is option A.

116. In n1 and n2 are the indices of compression for the first and second stage of compression, then the ratio of workdone on the first and second stages (W1/W2) with perfect intercoooing is given by

✅ The correct answer is option B.

117. If the flow of air through the compressor is parallel to its axis, then the compressor is

reciprocating compressor

centrifugal compressor

axial flow compressor

turbo-compressor

✅ The correct answer is option C.

118. The assumption made in two stage compression with intercooler is that

there is no pressure drop in the intercooler

the compression in both the cylinders is polytropic

the suction and delivery of air takes place at constant pressure

all of the above

✅ The correct answer is option D.

119. The free air delivery is the volume of air that can be delivered by a compressor freely.

TRUE

FALSE

✅ The correct answer is option B.

120. The minimum work required for a three stage reciprocating air compressor is __________ the work required for each stage.

equal to

double

three times

six times

✅ The correct answer is option C.