Hydraulic Machines Interview Questions and Answers for freshers 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
Answer: c
Clarification: 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
Answer: b
Clarification: 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
Answer: d
Clarification: 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 _____________ 5. Discharge in outward flow reaction turbine ____________ 6. Speed control of Outward flow reaction turbine is _____________ 7. Tendency of wheel to race is predominant in____________turbine 8. Outward flow reaction turbine will quite suitable for_____________ 9. In outward flow reaction turbine tangential velocity at inlet is always__________than outlet velocity. 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) Increases
b) Decreases
c) Remains constant
d) Gradually decreases
Answer: a
Clarification: Because centrifugal head is proportional to difference of outlet blade velocity and inlet blade velocity .
Here, u1
a) Increases
b) Decreases
c) Remains constant
d) Gradually decreases
Answer: a
Clarification: Discharge in outward flow reaction turbine increase because area increases to keep velocity constant.
a) Easy
b) Moderate
c) Difficult
d) Very difficult
Answer: d
Clarification: None.
a) Inward flow reaction turbine
b) Outward flow reaction turbine
c) Impulse turbine
d) Axial flow turbine
Answer: b
Clarification: None.
a) High head
b) Medium head
c) Low head
d) Static head
Answer: b
Clarification: Since it is radial flow reaction turbine which is operated under medium head and medium discharge.
a) Equal
b) Less
c) More
d) Constant
Answer: b
Clarification: Though runner has same angular velocity, diameter of outer periphery is large when compared to inner diameter.
a) Radial inlet discharge
b) Radial outlet discharge
c) Flow ratio
d) Speed ratio
Answer: a
Clarification: 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
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
Answer: d
Clarification: 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 .
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
Answer: b
Clarification: 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
Answer: b
Clarification: 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
Answer: a
Clarification: 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
Answer: b
Clarification: 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
Answer: b
Clarification: 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
Answer: a
Clarification: 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
Answer: a
Clarification: 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
Answer: d
Clarification: 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
Answer: b
Clarification: 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
Answer: d
Clarification: 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
Answer: a
Clarification: 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
Answer: c
Clarification: 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
Answer: d
Clarification: 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
Answer: b
Clarification: 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
Answer: a
Clarification: 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
Answer: b
Clarification: 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
Answer: a
Clarification: 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.