# Mechanical Engineering - Compressors, Gas Dynamics and Gas Turbines

Exercise : Compressors, Gas Dynamics and Gas Turbines - Section 1
41.
An aftercooler is used to
remove impurities from air
reduce volume of air
cause moisture and oil vapour to drop out
cool the air
Explanation:
No answer description is available. Let's discuss.

42.
High air-fuel ratio in gas turbines
increases power output
improves thermal efficiency
reduces exhaust temperature
Explanation:
No answer description is available. Let's discuss.

43.
The ratio of the volume of free air delivery per stroke to the swept volume of the piston, is known as
compressor efficiency
volumetric efficiency
isothermal efficiency
mechanical efficiency
Explanation:
No answer description is available. Let's discuss.

44.
If p1, is the pressure of air entering the L.P. cylinder and p2 is the pressure of air leaving the L.P. cylinder (or intercooler pressure), then the ratio of cylinder diameters for a single acting, two stage reciprocating air compressor with complete intercooling is given by (where D1 = Dia. of L.P. cylinder, and D2 = Dia. of H.P. cylinder)
D1/D2 = p1p2
D1/D2 = p1/p2
D1/D2 = p2/p1
none of these