# Hydraulic Machines Questions and Answers – Main Parts of Radial flow Reaction Turbines

This set of Hydraulic Machines Multiple Choice Questions & Answers (MCQs) focuses on “Main Parts of Radial flow Reaction Turbines”.

1. Radial flow reaction turbines are those turbines in which water flows ____________
b) Axial direction
c) Tangential direction
d) All of the mentioned

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.

2. Main parts of radial flow reaction turbines are ______________
a) Casing
b) Guide mechanism
c) Draft tube
d) All of the mentioned

Explanation: The main parts in a radial turbine are tight casing to prevent spill of water, runner, guide vanes, guide mechanism to regulate flow and draft to increase inlet pressure.

3. Discharge through radial flow reaction turbine is ______________
a) P1*b1*Vf1
b) P2*b2*Vf2
c) P1*b2*Vf2
d) Both P1*b1*Vf1 & P2*b2*Vf2

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.

4. Radial flow reaction turbines contain spiral casing which area ____________
a) Remains constant
d) Suddenly decreases

Explanation: Area of spiral structure gradually decreases because as discharge decreases correspondingly area also decreases. So, runner will rotate with constant velocity.

5. ____________ consists of stationary circular wheel all around the runner of turbine
a) Casing
b) Guide mechanism
c) Runner
d) Drafting

Explanation: Guide vanes are placed around the runner to regulate the flow and to provide shock less entry at inlet to runner.
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6. The casing of radial flow reaction turbine is made of spiral shape, so that water may enter the runner__________
a) Variable acceleration
b) Constant acceleration
c) Variable velocity
d) Constant velocity

Explanation: Area of spiral structure gradually decreases because as discharge decreases correspondingly area also decreases. So, runner will rotate with constant velocity.

7. _____________ allow the water to strike the vanes fixed on runner without shock at inlet
a) Casing
b) Guide vanes
c) Runner
d) Draft tube

Explanation: Guide vanes are placed around the runner to regulate the flow and to provide shock less entry at inlet to runner.

a) Cast steel
b) Cast iron
c) Wrought iron
d) Steel

Explanation: Runner blades are made up of cast steel because they are less corrosive and highly durable.

9. The pressure at the exit of runner of reaction turbine is generally____________than atmospheric pressure
a) Greater
b) Lesser
c) Constant
d) Equal

Explanation: In general, the exit of runner has a low pressure compared to the atmospheric pressure.

10. ___________is a pipe of gradually increasing area used for discharging water from exit of the turbine to the tail race.
a) Casing
b) Guide mechanism
c) Draft tube
d) Runner

Explanation: Draft is a pipe of gradually increasing area, as water leaving runner has less pressure, draft tube will increase pressure energy of water by decreasing its velocity.

11. ____________and __________of radial flow reaction turbine are always full of water.
a) Casing and runner
b) Casing and penstocks
c) Runner and penstocks
d) Runner and draft tube

Explanation: Casing and runner are completely covered by water as it is a reaction turbine in which pressure energy is predominant.

12. ____________governs the flow of water entering the runner blades.
a) Casing
b) Guide vanes
c) Draft tube
d) Runner

Explanation: Guide vanes are placed around the runner to regulate the flow and to provide shock less entry at inlet to runner.

13. Spiral casing of reaction turbine will regulate the flow.
a) True
b) False

Explanation: Guide vanes are placed around the runner to regulate the flow and to provide shock less entry at inlet to runner.

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