This set of Steam and Gas Turbines Multiple Choice Questions & Answers (MCQs) focuses on “Cascade Principle”.

1. Arrangement of blades in an order to represent the blade ring in Turbo machinery is called as cascade.
a) True
b) False

a) decreases
b) increases
c) does not effect
d) none

Explanation: Cascades are introduced to improve the efficiency.

3. When steam is passed through the cascade the direction of air __________
a) reverse
b) remains the same
c) turned
d) cascade is nowhere related to direction

Explanation: When steam is passed through cascade its direction is reversed.

4. Across the turbine cascade static pressure _________
a) drops
b) increases
c) remains same
d) none of the mentioned

Explanation: Across the turbine cascade the static pressure drops.

5. Due to the formation of boundary layers on blades friction losses _________
a) remains the same
b) decreases
c) increases
d) none of the mentioned

Explanation: Due to the formation of boundary layers frictional losses increase due to viscous forces.

6. In compressor cascade when internal pressure is lost ____________
a) axial force is gained
b) axial force is reduced
c) efficiency reduces
d) none of the mentioned

Explanation: In compressor cascade when internal pressure is lost axial force is developed.

7. Drag force is parallel to lift force.
a) True
b) False

Explanation: Drag force is always perpendicular to lift force.

8. Due to viscosity lift force is __________
a) increased
b) decreased
c) remains constant
d) none

Explanation: Due to viscosity lift force is decreased.

9. Due to turbine cascade the drag ________ the lift.
a) increases
b) decreases
c) does not change
d) none of the mentioned

Explanation: Due to turbine cascade drag contributes some useful work which increases the lift.

10. Due to compressor cascade, the static pressure is __________
a) reduced
b) does not change
c) increased
d) none of the mentioned

Explanation: Due to compressor cascade viscous force decreased and hence static pressure is also decreased.

Sanfoundry Global Education & Learning Series – Steam and Gas Turbines.

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