Compressors, Gas Dynamics and Gas Turbines Questions

• Only rocket engines can be propelled to space because
• The increase in pressure in a roots blower is entirely due to back flow of air.
• A rocket works with maximum overall efficiency when air-craft velocity is __________ the jet velocity.
• The degree of reaction in an axial flow compressor is defined as the ratio of static enthalpy rise in the
• The compression ratio in a gas turbine is
• The volume of air delivered by the compressor is called
• The compressed air may be used
• The ratio of workdone per cycle to the stroke volume of the compressor is known as
• Which of the following statement is correct?
• The clearance volume in the compressor is kept minimum because it effects on volumetric efficiency.
• When the temperature of air leaving the intercooler, in a two stage compression with intercooler, is __________ the original atmospheric air temperature, then the intercooling is known as perfect or complete intercooling.
• The increase in pressure in a vane blower takes place first due to compression and then due to back flow of air.
• Intercooling in multi-stage compressors is done
• The stagnation pressure rise in a centrifugal compressor takes place
• The type of rotary compressor used in aeroplanes, is of
• In a centrifugal compressor, an increase in speed at a given pressure ratio causes
• The total heat rejected in a reciprocating air compressor is equal to the sum of the heat rejected during polytropic compression per kg of air and heat rejected in the intercooler per kg of air.
• High air-fuel ratio in gas turbines
• 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)
• In a four stage compressor, if the pressure at the first and third stage are 1 bar and 16 bar, then the delivery pressure at the fourth stage will be