Hydraulic Machines Questions and Answers – Outward Radial Flow Reaction Turbines – 1

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This set of Hydraulic Machines Multiple Choice Questions & Answers (MCQs) focuses on “Outward Radial Flow Reaction Turbines – 1”.

1. In an outward flow reaction turbine, water from casing enters guiding wheel.
a) True
b) False
View Answer

Answer: a
Explanation: Water enters the stationary guide wheel from the casing of the turbine in the outward radial flow reaction turbine.

2. The water from penstocks enters the _____ which is spiral in shape which the area of cross section of casing goes on decreasing gradually
a) guide wheel
b) draft tube
c) casing
d) runner
View Answer

Answer: c
Explanation: The water from penstocks enters the casing which is spiral in shape in which the area of cross section of casing decreases gradually.

3. If the water flows from inwards to outwards, the turbine is known as _____________
a) Tangential flow turbine
b) Turbulent low inward flow
c) Inward flow turbine
d) Outward flow turbine
View Answer

Answer: d
Explanation: If the water in the runner flows from inwards to outwards, then such type of turbine is said to be outward radial flow turbine.
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4. In general, reaction turbines consist of which types of energies?
a) kinetic energy and potential energy
b) potential energy and pressure energy
c) kinetic energy and pressure energy
d) gravitational energy and potential energy
View Answer

Answer: c
Explanation: Reaction turbine is a kind of turbine in which the water at inlet of the turbine possesses both kinetic energy and pressure energy.

5. ___________ is a circular wheel on which a series of smooth, radial curved vanes are fixed.
a) Guide wheel
b) Runner
c) Casing
d) Draft tube
View Answer

Answer: b
Explanation: The radial curved vanes are so shaped that water enters and leaves the runner without shock .It is a circular type wheel on which a series of smooth, radial curved vanes are fixed.

6. In outward radial flow reaction turbines, tangential velocity at inlet is less than that of the outlet.
a) False
b) True
View Answer

Answer: b
Explanation: In outward radial flow reaction turbines, tangential velocity at inlet is less than that of the outlet as the inlet of the runner is the inner diameter.

7. In an outward 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

Answer: b
Explanation: Flow ratio is known as ratio of tangential wheel at inlet to given velocity of jet and it is scalar quantity.
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8. In an outward radial flow reaction turbine the ratio of tangential velocity at inlet to the given velocity is ______
a) Speed ratio
b) Flow ratio
c) Discharge
d) Radial discharge
View Answer

Answer: a
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.

9. Discharge in an outward flow reaction turbine ____________
a) Increases
b) Decreases
c) Remains constant
d) Gradually decreases
View Answer

Answer: a
Explanation: Discharge in an outward flow reaction turbine increases because area increases as fluid flows across spiral structure in the turbine.
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10. An outward radial reaction turbine has ______
a) u1 < u2
b) u1 > u2
c) u1 = u2
d) u2 = u1 = 0
View Answer

Answer: a
Explanation: For an outward flow reaction turbine, tangential velocity at inlet should be less than the tangential velocity at outlet.

11. An outward flow reaction turbine, ________
a) D1 > D2
b) D1 < D2
c) D1 = D2
d) D1 = D2 = 0
View Answer

Answer: b
Explanation: In an outward flow reaction turbine, to maintain flow of water, the inlet diameter should be less than outlet diameter.

12. ___________is ratio of pressure energy change inside runner to total energy change inside runner
a) Degree of reaction
b) Speed ratio
c) Flow ratio
d) Hydraulic efficiency
View Answer

Answer: a
Explanation: This is just a formula and it is scalar quantity because it is ratio of two changes of energies.

13. Degree of reaction for impulse turbine
a) 0
b) 1
c) 2
d) 3
View Answer

Answer: a
Explanation: For pelton turbine u1=u2 and Vr1=Vr2 by substituting these values in degree of reaction we get it as 0.

14. The formula for degree of reaction for hydraulic turbines is __________
a) 1- (V1*V1-V2*V2)/(V1*V1-V2*V2)*(u1*u1-u2*u2)*(Vr2*Vr2-Vr1*Vr1)
b) (V1*V1-V2*V2)/ (V1*V1-V2*V2)*(u1*u1-u2*u2)*(Vr2*Vr2-Vr1*Vr1)
c) 1+ (V1*V1-V2*V2)/ (V1*V1-V2*V2)*(u1*u1-u2*u2)*(Vr2*Vr2-Vr1*Vr1)
d) 1- (V2*V2-V1*V1)/ (V1*V1-V2*V2)*(u1*u1-u2*u2)*(Vr2*Vr2-Vr1*Vr1)
View Answer

Answer: a
Explanation: This is obtained by substituting mathematical terms in actual expression of degree of reaction.
Where, V=jet velocity, Vr=relative velocity, u=blade velocity

15. Degree of reaction for reaction turbine is _____________
a) 1- cot x /2(cot x –cot y)
b) 1+ cot x /2(cot x –cot y)
c) 1- cot x /2(cot x +cot y)
d) 1+ cot x /2(cot x +cot y)
View Answer

Answer: a
Explanation: Because for reaction turbine Vw2=0 and V2=Vf2, there is also no much change in velocity of flow implies that Vf1=Vf2 by substituting these values, we get it.

16. A turbine is a ________
a) Rotary mechanical device
b) Static pressure drop device
c) Electrical device
d) Static temperature device
View Answer

Answer: a
Explanation: Turbine is a vortex related device. It means turbulence. Turbine is a rotary mechanical device. The energy generated from the turbine can be used to generate electrical power. It is used in jet engines.

17. Turbine converts _________
a) Work to energy
b) Energy to work
c) Work to Electricity
d) Work to pressure
View Answer

Answer: b
Explanation: Turbine extracts energy and converts it into useful work. Turbine is a vortex related device. It means turbulence. Turbine is a rotary mechanical device. The energy generated from the turbine can be used to generate electrical power. It is used in jet engines.

18. Turbine extracts energy from________
a) Reaction ratio
b) Pressure ratio
c) Fluid flow
d) Volumetric ratio
View Answer

Answer: c
Explanation: Turbine extracts energy from fluid flow and converts it into useful work. Turbine is a vortex related device. It means turbulence. Turbine is a rotary mechanical device. The energy generated from the turbine can be used to generate electrical power. It is used in jet engines.

19. Inward flow reaction turbine enter through ______
a) Outer periphery
b) Blades
c) Inner periphery
d) Pressure angle
View Answer

Answer: a
Explanation: Inward flow flow reaction turbine enter through outer periphery of the turbine. It provides a force at the outer curvature of the blades to provide an inward flow.

20. A turbine is a ________
a) Turbomachinery
b) Pressure drag
c) Aerodynamics
d) Automobiles
View Answer

Answer: a
Explanation: A turbine is a turbomachinery. Turbine extracts energy from fluid flow and converts it into useful work. Turbine is a vortex related device. It means turbulence. Turbine is a rotary mechanical device.

21. Centrifugal flow is imparted when the__________
a) Reaction flow is negative
b) Reaction flow is positive
c) Efficiency is 100 percent
d) Reaction rate is negligible
View Answer

Answer: c
Explanation: Centrifugal flow is imparted when the reaction flow is negative in its direction. This happens when the centrifugal head loses its relative velocity with the flow of water.

22. Where is the turbine not used?
a) Solar power
b) Windmill
c) Water wheels
d) Gas plant
View Answer

Answer: a
Explanation: Turbine is not used in solar power plants. The source of energy in solar power plants is the sunlight. It falls on the solar plates during the day, which stores the energy and converts them into useful work.

23. In an inward flow reaction turbine the discharge _______
a) Increases
b) Decreases
c) Same
d) Independent
View Answer

Answer: b
Explanation: In an inward flow reaction turbine the discharge of fluid decreases. Thus, making it different from an outward flow reaction turbine.

24. A working fluid contains kinetic energy only.
a) True
b) False
View Answer

Answer: b
Explanation: A working fluid contains kinetic energy and potential energy. The fluid that flows and hits the turbine blades coverts kinetic energy into useful work. The flow can be either compressible or incompressible.

25. In impulse turbines with moving blades, there is no _________ in blades of the turbine.
a) Pressure change
b) Same pressure
c) Volumetric change
d) Pressure independent
View Answer

Answer: a
Explanation: In impulse turbines, there is no pressure change in blades of the turbine. There is no pressure change that is developed in fluid or gas in the turbine blades. The turbine blades are in moving condition.

26. In impulse turbines with stationary blades, there is_________ in blades of the turbine.
a) Pressure change
b) Same pressure
c) Volumetric change
d) Pressure independent
View Answer

Answer: a
Explanation: In impulse turbines, there is pressure change in blades of the turbine. There is pressure change that is developed in fluid or gas in the turbine blades. The turbine blades are in stationary condition.

27. In an outward flow reaction turbine the discharge _______
a) Increases
b) Decreases
c) Same
d) Independent
View Answer

Answer: a
Explanation: In an outward flow reaction turbine the discharge of fluid increases. Thus, making it different from an inward flow reaction turbine.

28. Before reaching the turbine, the acceleration of the fluid takes place through the__________
a) Vane angle
b) Nozzle
c) Pump
d) Pipe
View Answer

Answer: b
Explanation: Before the fluid reaches the turbine, the pressure head is converted into its velocity head by accelerating the fluid with a nozzle. Nozzle increases the velocity and decreases the pressure.

29. The Pelton wheel extracts energy from________
a) Vane angle
b) Moving fluid
c) Increase in temperature
d) Heat rejection
View Answer

Answer: b
Explanation: The Pelton wheel extracts energy from moving of fluid. When the fluid flows through the Pelton wheel, a kinetic energy is developed. This kinetic energy is extracted from the moving fluid.

30. Pelton wheel is a Reaction type water turbine.
a) True
b) False
View Answer

Answer: b
Explanation: The statement is false. The Pelton wheel is not a reaction type water turbine. It is an impulse type water turbine. The Pelton wheel extracts energy from moving of fluid. When the fluid flows through the Pelton wheel, a kinetic energy is developed.

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