Compressors

141. The pressure ratio for an open cycle gas turbine compared to closed cycle gas turbine of same h.p. is

1. low
2. high
3. same
4. low/high depending on make and type
5. unpredictable.

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

1. ,2:l
2. 04:01
3. 61:01:00
4. 09:01
5. 12:01

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143. The pressure ratio of an ideal vaned compressor with increase in mass flow rate

1. increases
2. decreases
3. remains constant
4. first decreases and then increases
5. unpredictable.

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144. The ratio of isentropic work to Euler work is known as

1. pressure coefficient
2. work coefficient
3. polytropic reaction
4. slip factor
5. compressor efficiency.

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145. The ratio of isentropic work to euler’s work is known as

1. compressor efficiency
2. isentropic efficiency
3. Euler’s efficiency
4. pressure coefficient
5. pressure ratio.

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146. The ratio of outlet whirl velocity to blade velocity in case of centrifugal compressor is called

1. slip factor
2. velocity factor
3. velocity coefficient
4. blade effectiveness
5. none of the above.

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147. The ratio of specific weighf/h.p. of gas turbin and I.C engines may be typically of the order of

1. 01:01
2. 02:01
3. 04:01
4. 01:02
5. 01:06

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148. The ratio of the increase in pressure in rotor blades to total increase in pressure in the stage is called

1. pressure ratio
2. pressure coefficient
3. degree of reaction
4. slip factor
5. stage factor.

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149. The ratio of work doen per cycle to the swept volume in case of compressor is called

1. compression index
2. compression ratio
3. compressor efficiency
4. mean effective pressure
5. compressor effectiveness.

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150. The specific output per kg mass flow rate of a gas turbine (having fixed efficiencies of compressor and turine and fixed higher and lower temperature) with increase in pressure ratio will

1. increase first at fast rate and then slow
2. increase first at slow rate and then fast
3. decrease continuously
4. first increase, reach maximum and then decrease
5. none of the above.

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