Thermal Engineering 26

Objective Questions and Answer: Thermal Engineering 26

Subject: Thermal Engineering 26

Part 26: Objective questions and answers of Thermal Engineering

Q1. Mechanical efficiency of gas turbines as compared to I.C engines is

a) Higher

b) Lower

c) Same

d) None of the above

Q2. The ratio of specific weight/h.p. Of gas turbine and I.C engines may be typically of the order of

a) 1:01

b) 2:01

c) 4:01

d) 1:06

Q3. The thermal efficiency of a gas turbine as compared to a diesel plant is

a) Same

b) More

c) Less

d) Depends on other factors

Q4. The air-fuel ratio in gas turbines is of the order of

a) 7:01

b) 15:01

c) 30:01:00

d) 50:01:00

Q5. The pressure ratio in gas turbines is of the order of

a) 2:01

b) 4:01

c) 61:01:00

d) 9:01

Q6. The hottest point in a gas turbine is

a) At the base

b) At the tip

c) In the center

d) Between ~ to i of the blade height

Q7. The following is true for an open cycle gas turbine having exhaust heat exchanger. Atmospheric air before entering the compressor is

a) Heated

b) Compressed air before entering the combustion chamber is heated

c) Bled gas from turbine is heated and readmitted for complete expansion

d) Exhaust gases drive the compressor

Q8. Gas turbine blades are given a rake

a) Equal to zero

b) In the direction of motion of blades

c) Opposite to the direction of motion of blades

d) Depending on the velocity

Q9. Efficiency of gas turbine is increased by

a) Reheating

b) Inter cooling

d) All of the above

Q10. Temperature of gases at end of compression as compared to exhaust gases in a gas turbine is

a) Higher

b) Lower

c) Equal

d) Can't be compared

Q11. The ideal efficiency of simple gas turbine cycle depends on

a) Pressure ratio

b) Maximum cycle temperature

c) Minimum cycle temperature

d) All of the above

Q12. The thermal efficiency of a simple gas turbine for a given turbine inlet temperature with increase in pressure ratio

a) Increases

b) Decreases

c) First increases and then decreases

d) First decreases and then increases

Q13. Gas turbines use following type of air compressor

a) Centrifugal type

b) Reciprocating type

c) Lobe type

d) Axial flow type

Q14. As the turbine inlet temperature increases, the thermal efficiency of gas turbine for the optimum pressure ratio

a) Increases

b) Decreases

c) Remains same

d) First increases and then decreases

Q15. There is a certain pressure ratio (optimum) for a gas turbine at which its thermal efficiency is maximum. With increase in turbine temperature, the value of pressure ratio for the peak efficiency would

a) Remain same

b) Decrease

c) Increase

d) Unpredictable

Q16. The material commonly used for air craft gas turbine is

a) Stainless steel

b) High alloy' steel

c) Duralumin

d) Timken, Haste and Inconel alloys

Q17. It is not possible to use closed gas turbine cycle in aeronautical engines because

a) It is inefficient

b) It is bulky

c) It requires cooling water for its operation

d) None of these

Q18. The combustion efficiency of a gas turbine using perfect combustion chamber is of the order of

a) 50%

b) 75%

c) 85%

d) 99%.

Q19. 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

Q20. For an irreversible gas turbine cycle, the efficiency and work ratio both depend on

a) Pressure ratio alone

b) Maximum cycle temperature alone

c) Minimum cycle temperature alone

d) Both pressure ratio and maximum cycle temperature

Part 26: Objective questions and answers of Thermal Engineering