This set of Hydraulic Machines Interview Questions and Answers for freshers focuses on “Outward Radial Flow Reaction Turbines – 2”.
1. The outward radial flow reaction turbine is a turbine in which direction of water flow is ___________
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 center towards outer periphery.
2. Outward flow reaction turbine is used in practical applications
a) True
b) False
View Answer
Explanation: There are several limitations of outward flow reaction turbine hence it is used in practical applications.
3. The energy available at inlet for outward reaction flow turbine is ____________
a) Potential
b) Kinetic energy
c) Pressure energy
d) Pressure energy and Kinetic energy
View Answer
Explanation: Since it is reaction turbine energy available at inlet consists of both pressure energy and kinetic energy.
4. Centrifugal head in Outward 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, u1<u2 so centrifugal head increases.
5. Discharge in outward flow reaction turbine ____________
a) Increases
b) Decreases
c) Remains constant
d) Gradually decreases
View Answer
Explanation: Discharge in outward flow reaction turbine increase because area increases to keep velocity constant.
6. Speed control of Outward flow reaction turbine is _____________
a) Easy
b) Moderate
c) Difficult
d) Very difficult
View Answer
Explanation: None.
7. 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
View Answer
Explanation: None.
8. Outward flow reaction turbine will quite suitable for_____________
a) High head
b) Medium head
c) Low head
d) Static head
View Answer
Explanation: Since it is radial flow reaction turbine which is operated under medium head and medium discharge.
9. In outward flow reaction turbine tangential velocity at inlet is always__________than outlet velocity.
a) Equal
b) Less
c) More
d) Constant
View Answer
Explanation: Though runner has same angular velocity, diameter of outer periphery is large when compared to inner diameter.
10. 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
View Answer
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.
11. 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
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.
12. 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
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.
13. 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
View Answer
Explanation: Flow ratio is known as ratio of tangential wheel at inlet to given velocity of jet and it is scalar quantity.
14. 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
View Answer
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.
15. Steam turbine converts energy into________
a) Electrical work
b) Mechanical work
c) Chemical work
d) Thermal work
View Answer
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.
16. Most common application of steam turbine is _______
a) Motor
b) Generator
c) Pump
d) Filter
View Answer
Explanation: Since the turbine generates rotary motion, it is best suited for the use of electrical generator. It is used to drive an electrical generator. Now a days, the maximum usage for generation of electricity is done by using an electrical generator.
17. Conical diffuser draft tube consists of conical diffuser with angles of______
a) 10 degrees
b) 20 degrees
c) 30 degrees
d) 40 degrees
View Answer
Explanation: Conical diffuser draft tube is one of the most commonly used drafts tubes in the Kaplan turbine. Conical diffuser draft tube consists of conical diffuser with angles less than or equal to 10 degrees.
18. What is the purpose of a conical diffuser?
a) To prevent flow separation
b) To avoid Pressure drag
c) To prevent rejection of heat
d) To increase efficiency
View Answer
Explanation: Conical diffuser draft tube is one of the most commonly used drafts tubes in the Kaplan turbine. It is called so because it consists of a conical diffuser. The main function of the diffuser is to prevent flow separation.
19. What is the efficiency of conical diffuser draft tube?
a) 30
b) 50
c) 70
d) 90
View Answer
Explanation: Conical diffuser draft tube is one of the most commonly used drafts tubes in the Kaplan turbine. It is called so because it consists of a conical diffuser. The main function of the diffuser is to prevent flow separation. The efficiency of conical diffuser draft tube is 90 percent.
20. The simple elbow draft tube is placed close to the_______
a) Head race
b) Tail race
c) Tank
d) Nozzle
View Answer
Explanation: The simple elbow draft tube is placed close to the tail race. It consists of an extended elbow type tube. It is mainly used in the Kaplan turbine. It is placed close to the tail race of the turbine.
21. Turbine that consists of moving nozzles and with fixed nozzles is called as__________
a) Impulse turbine
b) Curtis turbine
c) Rateau turbine
d) Reaction turbine
View Answer
Explanation: A turbine that consists of moving nozzles which are alternating with the fixed nozzles is called as a reaction turbine. When the steam hits the nozzle, the pressure is decreased and the temperature is increased.
22. An example of reaction turbine is________
a) Parsons turbine
b) Curtis turbine
c) Rateau turbine
d) Pelton wheel
View Answer
Explanation: A turbine that consists of moving nozzles which are alternating with the fixed nozzles is called as a reaction turbine. When the steam hits the nozzle, the pressure is decreased and the temperature is increased. It is also called as Parson’s turbine.
23. When we arrange turbine blades in multiple stages it is called ________
a) Pressure change
b) Vane deviation
c) Compounding
d) Pressure ratio
View Answer
Explanation: When we arrange turbine blades in multiple stages it is called as compounding. Compounding plays an essential role in turbines. It has various plus points.
24. Compounding is needed to ___________
a) Increase Pressure
b) Decrease temperature
c) Change volume
d) Increase efficiency
View Answer
Explanation: Compounding is needed to improve efficiencies at low speeds. When we arrange turbine blades in multiple stages it is called as compounding. Compounding plays an essential role in turbines.
25. Which among the following is not a type of compounding?
a) Pressure
b) Temperature
c) Pressure velocity
d) Velocity
View Answer
Explanation: Temperature is not a type of compounding. The three important types of compounding are pressure compounding, velocity compounding and pressure- velocity compounding.
26. Newtons second law describes the transfer of energy through impulse turbines.
a) True
b) False
View Answer
Explanation: Before the fluid reaches the turbine, the pressure head is converted into its velocity head by accelerating the fluid with a nozzle. Thus, Newtons second law describes the transfer of energy through impulse turbines.
27. Inner radial flow extracts energy from _____
a) Turbine blades
b) Moving fluid
c) Pressure change
d) Temperature increase
View Answer
Explanation: Inner radial flow extracts energy from moving fluid of a turbine. It also helps in determine the efficiency of the turbine blades.
28. Reaction turbines develop torque by reacting to the gas or fluids pressure or mass.
a) True
b) False
View Answer
Explanation: Reaction turbines develop torque by reacting to the gas or fluids pressure or mass. The pressure or the gas of a fluid changes during this as it contains the working fluid acts on the turbine stages.
Sanfoundry Global Education & Learning Series – Hydraulic Machines.
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