Mechanical Engineering Quiz

For a six compression of air set, the minimum work conditions are:

• Pressure rise per stage will be equal

• work done in succesive stages will be geometrical progression

• cylinder volumes will be same

• temperature rise in the cylinders will be the same

Stalling of the blades of axial flow compressor is:

• An unsteady periodic and reversal of flow

• The reduction in lift force at higher angle of incidence

• The fixed mass flow rates irrespective of pressure ratio

• All of the above

In a four stage compressor system, the first and third stage pressures are 1 and 9 kg/cm2 respectively. What is the fourth stage delivery pressure?

• 9 kg/cm2

• 81 kg/cm2

• 27 kg/cm2

• 243 kg/cm2

In case of axial flow compressors for minimum fluid friction and blade tip clearance losses, the blades of an axial flow compressor are designed for _______.

• 80% reaction

• 85% reaction

• 60% reaction

• 53% reaction

Which of the following is a displacement compressor?

• Reciprocating air compressor

• Vane blower

• Centrifugal blower

• Axial flow compressors

Which of the following give the optimum intermediate pressure in case of two stage compression?

• P2 = P1 + P3/2

• P2 = P1 + P1 + P3/2

• P2 = ඥP1P3

• P2 = P1 + ටP12+P32

In air compressor performance curve a surge line represents what?

• Limit of compressor efficiency

• Limit of compressor discharge

• Limit of stable operation

• Lower critical speed of shaft

Which of the following is a positive displacement rotary compressor?

• Roots blower

• Centrifugal compressor

• Axial flow compressor

• None of the above

In an axial flow compressor, the pressure rise takes place in:

• fixed blades only

• Moving blades only

• Both fixed and moving blades

• None of the above

An axial flow compressor is suitable for:

• High volume flow rates with small pressure rise

• Low volume flow rates with high pressure rise

• High volume flow rates with high pressure rise

• Low volume flow rates with low pressure rise