Steam and Gas Turbines Multiple Choice Questions on “Free and Forced Vortex”.
1. In vortex region flow rotates perpendicular to the axis line.
a) True
b) False
Answer: b
Clarification: 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
Answer: a
Clarification: 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
Answer: b
Clarification: 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
Answer: a
Clarification: 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
Answer: c
Clarification: Steam lines and Path lines are closed in stationary vortex where as in moving vortex it carries momentum and energy.
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
Answer: a
Clarification: 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
Answer: b
Clarification: 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
Answer: b
Clarification: 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.
9. In forced vortex the total head _______ with radius.
a) radius is not related to head in forced vortex
b) decreases
c) increases
d) none of the mentioned
Answer: c
Clarification: In forced vortex total head increases with radius from the head equation.
10. For forced vortex external torque is to be supplied continuously.
a) True
b) False
Answer: a
Clarification: To maintain forced vortex external energy is to be supplied constantly and hence external torque is to be supplied constantly.