Steam and Gas Turbines Multiple Choice Questions on “The Diffuser and Prewhirl”.
1. Gas turbine diffuser _________ the production of energy.
a) increases
b) decreases
c) remains constant
d) none of the mentioned
Answer: b
Clarification: Gas turbine diffuser increases the production of energy.
2. Gas turbine diffusers ________ the speed of the flow.
a) increases
b) reduces
c) remains constant
d) none of the mentioned
Answer: a
Clarification: Gas turbine diffuser increases the speed of the flow.
3. Movement speed of motor shaft is _________ when diffuser is used.
a) decreased
b) increased
c) remains constant
d) none of the mentioned
Answer: b
Clarification: Motor shaft speed is increased when diffuser is used. When diffuser is used it converts the pressure energy of the gas into rotation of motor shaft and diffuses the working fluid.
4. In automobiles diffuser _________ the down force.
a) decrease
b) minimizes
c) increases
d) none of the mentioned
Answer: c
Clarification: In automobiles diffuser allow the air to escape from outside and as a result down force increases.
5. In jet engines diffusers are used __________
a) At low speeds
b) At Supersonic speeds
c) Not related to speed at all
d) None of the mentioned
Answer: b
Clarification: Diffuser allows extra air to escape and as a result aerodynamic properties increases and hence diffuser is used in jet engine when operated at supersonic speeds.
6. Diffuser is installed after turbine where air passes the turbine first then passes through diffuser.
a) True
b) False
Answer: b
Clarification: Diffuser is installed between vanes and turbine where air after passing through the diffuser enters the vanes.
7. In centrifugal compressor diffuser is used in a channel ________ the vanes.
a) before
b) after
c) between
d) none of the mentioned
Answer: c
Clarification: In a centrifugal compressor diffuser is used in a channel between vanes.
8. Diffusers are also used in underwater breathing systems.
a) True
b) False
Answer: a
Clarification: Diffusers are used in under water breathing systems so that bubble formation is reduced.
9. Diffuser ___________ velocity air.
a) depends o the situation
b) slows
c) increases
d) none of the mentioned
Answer: c
Clarification: Diffuser is used in compressor section and slows down the high velocity air and increases the pressure.
10. Diffuser changes the ______________ to longitudinal direction.
a) parallel flow
b) radial direction
c) perpendicular flow
d) none of the mentioned
Answer: b
Clarification: Diffuser changes the radial air flow direction into longitudinal direction.