Compressors, Gas Turbines and Jet Engines – Set 03

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Q1. In a closed cycle gas turbine, the air is compressed

(A) Isothermally
(B) Polytropically
(C) Isentropically
(D) None of these

Q2. When air is to be compressed at a high pressure, then it is advantageous to use

(A) Single stage compression
(B) Multistage compression without intercooling
(C) Multistage compression with intercooling
(D) None of these

Q3. 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

Q4. The maximum combustion pressure in gas turbine as compared to I.C. engine is

(A) More
(B) Less
(C) Same
(D) Depends on other factors

Q5. In multistage compressor, the isothermal compression is achieved by

(A) Employing inter-cooler
(B) By constantly cooling the cylinder
(C) By running compressor at very slow speed
(D) By insulating the cylinder

Q6. Reciprocating air compressor is best suited for

(A) Large quantity of air at high pressure
(B) Small quantity of air at high pressure
(C) Small quantity of air at low pressure
(D) Large quantity of air at low pressure

Q7. The gas in cooling chamber of a closed cycle gas turbine is cooled at

(A) Constant volume
(B) Constant temperature
(C) Constant pressure
(D) None of these

Q8. The compressor capacity is defined as 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

Q9. 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

Q10. Gas turbines use following type of air compressor

(A) Centrifugal type
(B) Reciprocating type
(C) Lobe type
(D) Axial flow type

Q11. The area of actual indicator diagram on an air compressor as compared to area of ideal indicator diagram is

(A) Less
(B) More
(C) Same
(D) More/less depending on compressor capacity

Q12. Pick up the wrong statement

(A) Pulse-jet requires no ambient air for propulsion
(B) Ramjet engine has no turbine
(C) Turbine drives compressor in a Turbojet
(D) Bypass turbojet engine increases the thrust without adversely affecting, the propulsive efficiency and fuel economy

Q13. 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

Q14. Reheating in a multistage expansion gas turbine __ compressor work.

(A) Has no effect on
(B) Decreases
(C) Increases
(D) None of these

Q15. Separators in compressor installations are located

(A) Before inter-cooler
(B) After inter-cooler