Hydraulic Machines MCQs - Outward Radial Flow Reaction Turbines Part-4

1. Speed control of Outward flow reaction turbine is _____________
a) Easy
b) Moderate
c) Difficult
d) Very difficult

Answer: d
Explanation: Speed control of Outward flow reaction turbine is very difficult

2. Tendency of wheel to race is predominant in____________turbine
a) Inward flow reaction turbine
b) Outward flow reaction turbine
c) Impulse turbine
d) Axial flow turbine

Answer: b
Explanation: Tendency of wheel to race is predominant in outward flow reaction turbine

3. Outward flow reaction turbine will quite suitable for_____________
a) High head
b) Medium head
c) Low head
d) Static head

Answer: b
Explanation: Since it is radial flow reaction turbine which is operated under medium head and medium discharge.

4.In outward flow reaction turbine tangential velocity at inlet is always__________than outlet velocity.
a) Equal
b) Less
c) More
d) Constant

Answer: b
Explanation: Though runner has same angular velocity, diameter of outer periphery is large when compared to inner diameter.

5. In outward radial flow reaction turbine if angle made by absolute velocity with its tangent is 90 degrees and component of whirl is zero at inlet is _______________
a) Radial inlet discharge
b) Radial outlet discharge
c) Flow ratio
d) Speed ratio

Answer: a
Explanation: if angle made by absolute velocity with its tangent is 90 degrees and component of whirl is zero at inlet in radial flow reaction then total velocity will be flow velocity.

6. In outward 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

Answer: d
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.

7. The main difference between reaction turbine and outward radial flow reaction turbine is water flows __________
a) Radial direction
b) Radially inward
c) Radially outward
d) Axial direction

Answer: b
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.

8. In 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

Answer: b
Explanation: Flow ratio is known as ratio of tangential wheel at inlet to given velocity of jet and it is scalar quantity.

9. Conical diffuser draft tube is also called_______
a) Straight divergent tube
b) Simple elbow tube
c) Thermal tube
d) Elbow tube with varying cross section

Answer: a
Explanation: Conical diffuser draft tube is one of the most commonly used drafts tubes in the Kaplan turbine. It works as an outlet at the Kaplan turbine. Conical diffuser draft tube is also called straight divergent tube.

10.Steam turbine converts energy into________
a) Electrical work
b) Mechanical work
c) Chemical work
d) Thermal work

Answer: b
Explanation: Turbine extracts energy and converts it into useful work. Turbine is a vortex related device. It means turbulence. Steam turbine converts energy into mechanical work by extracting thermal energy from pressurized steam.