# Steam and Gas Turbines Questions and Answers – Free and Forced Vortex

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

1. In vortex region flow rotates perpendicular to the axis line.
a) True
b) False

Explanation: In vortex region fluid rotates on an axis line.

2. Viscous friction in the fluid causes the flow to become vortex.
a) True
b) False

Explanation: In the absence of forces viscous friction causes the flow to become vortex.

3. In vortex fluid flow velocity is ______________ to the distance from the axis line.
a) directly proportional
b) inversely proportional
c) not related
d) none of the mentioned

Explanation: In vortex fluid velocity is more near to the axis and decreases as the distance from the axis line increases. Hence Fluid flow velocity is inversely proportional to the distance from the axis line.

4. Vorticity is _______ in the core region.
a) very high
b) very low
c) zero
d) none of the mentioned

Explanation: In the core region fluid rotates with high velocity and hence vorticity is high in the core region.

5. Steam lines and Path lines are _______ in stationary vortex.
a) high
b) less
c) closed
d) none of the mentioned

Explanation: Steam lines and Path lines are closed in stationary vortex where as in moving vortex it carries momentum and energy.
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6. In a fluid with constant density Vortex flow pressure is proportional to ________
a) square of the distance from axis
b) distance from the axis
c) cube of the distance from the axis
d) none of the mentioned

Explanation: In a vortex flow with constant fluid density its fluid pressure is inversely proportional to the square of the distance from the axis line.

7. In forced vortex all fluid particles rotate with the ________________
a) constant velocity
b) constant angular velocity
c) variable angular velocity
d) none of the mentioned

Explanation: In forced vortex all fluid vortex rotates with constant angular velocity.

8. Solid body rotation is another name for ________
a) free vortex
b) forced vortex
c) free & forced vortex
d) none of the mentioned

Explanation: Solid body rotation is another name for forced vortex as all fluid particles in forced vortex rotate with same angular velocity like a solid rotation.

b) decreases
c) increases
d) none of the mentioned

10. For forced vortex external torque is to be supplied continuously.
a) True
b) False

Explanation: To maintain forced vortex external energy is to be supplied constantly and hence external torque is to be supplied constantly.

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