This set of Hydraulic Machines test focuses on “Inward Radial Flow Reaction Turbines”.
1. Inward radial flow reaction turbine is a turbine in which water flows across the blades of runner______________
a) Radial direction
b) Radially inward
c) Radially outward
d) Axial direction
View Answer
Explanation: The name itself indicates that flow is in radial direction and flowing from outer periphery towards center.
2. Which of following is inward radial flow reaction turbine?
a) Pelton wheel
b) Francis turbine
c) Axial turbine
d) Kaplan turbine
View Answer
Explanation: Pelton is impulse a turbine, Kaplan is axial flow turbine and Francis is an inward flow reaction turbine.
3. In Inward radial flow reaction turbine which is not required?
a) Runner
b) Air tight casing
c) Guide vanes
d) Breaking jet
View Answer
Explanation: Here in inward flow reaction turbine, instead of jet water is passed into spiral casing directly and breaking jet is not used for its halt instead of it guide vanes are used.
4. The main difference between reaction turbine and inward radial flow reaction turbine is water flows___________
a) Radial direction
b) Radially inward
c) Radially outward
d) Axial direction
View Answer
Explanation: The name itself indicates the type of flow that is radial direction but the thing that is unknown is whether it is radially inward or outwards.
5. In Inward radial flow reaction turbine the ratio of tangential wheel at inlet to given velocity of jet is known as _______
a) Speed ratio
b) Flow ratio
c) Discharge
d) Radial discharge
View Answer
Explanation: Flow ratio is known as ratio of tangential wheel at inlet to given velocity of jet and it is scalar quantity.
6. In Inward radial flow reaction turbine the ratio of tangential velocity at inlet to the given velocity ____________
a) Speed ratio
b) Flow ratio
c) Discharge
d) Radial discharge
View Answer
Explanation: Speed ratio is ratio of tangential velocity at inlet to the given velocity and it is scalar quantity because it is ratio of two speeds.
7. The discharge through a reaction radial flow turbine is given by____________
a) P1*b1*Vf1
b) P2*b2*Vf2
c) P1*b2*Vf2
d) Both P1*b1*Vf1 & P2*b2*Vf2
View Answer
Explanation: Discharge of radial flow reaction turbine is product of perimeter of runner, thickness, whirl velocity, at inlet as well as outlet runner vanes.
Where, P1=perimeter of runner at inlet, P2=perimeter of runner at outlet, b=thickness and Vf=flow velocity
8. In Inward radial flow reaction turbine if thickness is considered then discharge is _________
a) (P1-n*t)*b1*Vf1
b) (P2-n*t)*b2*Vf2
c) (P1-n*t)*b2*Vf2
d) Both (P1-n*t)*b1*Vf1 & (P2-n*t)*b2*Vf2
View Answer
Explanation: Discharge of radial flow reaction turbine is product of perimeter of runner, thickness, whirl velocity, at inlet as well as outlet runner vanes. If n blades of thickness t is considered then discharge is (P1-n*t)*b1*Vf1.
Where, P1=perimeter of runner at inlet, P2=perimeter of runner at outlet, b=width, Vf=flow velocity, n=number of blades and t=thickness of blades
9. In Inward radial flow reaction turbine if angle made by absolute velocity with its tangent is 90 degrees and component of whirl is zero at outlet is _____________
a) Radial inlet discharge
b) Radial outlet discharge
c) Flow ratio
d) Speed ratio
View Answer
Explanation: If angle made by absolute velocity with its tangent is 90 degrees and component of whirl is zero at outlet in radial flow reaction then total velocity will be flow velocity.
10. In which of following turbine whirl component is zero?
a) Reaction turbine
b) Inward radial flow reaction turbine
c) Axial flow turbine
d) Impulse turbine
View Answer
Explanation: If angle made by absolute velocity with its tangent is 90 degrees and component of whirl is zero at outlet in radial flow reaction turbines then total velocity will be flow velocity.
11. Discharge in inward flow reaction turbine ____________
a) Increases
b) Decreases
c) Remains constant
d) Gradually decreases
View Answer
Explanation: Discharge in inward flow reaction turbine decreases because area decreases as fluid flows across spiral structure.
12. Speed control of Outward flow reaction turbine is _________
a) Easy
b) Moderate
c) Difficult
d) Very difficult
View Answer
Explanation: In an outward reaction turbine, we can only partly control the speed.
13. Centrifugal head in inward flow reaction turbine __________
a) Increases
b) Decreases
c) Remains constant
d) Gradually decreases
View Answer
Explanation: Because centrifugal head is proportional to difference of outlet blade velocity and inlet blade velocity.
Here, u2 < u1 so centrifugal head decreases.
14. Tendency of wheel to race is almost nil in ___________turbine.
a) Inward flow reaction turbine
b) Outward flow reaction turbine
c) Impulse turbine
d) Axial flow turbine
View Answer
Explanation: In an inward reaction flow turbine, wheel moves with the constant speed.
15. Inward flow reaction turbine is used in practical applications.
a) True
b) False
View Answer
Explanation: Inward flow reaction turbine is used in practical applications that is “Francis turbine”.
Sanfoundry Global Education & Learning Series – Hydraulic Machines.
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