Chapter: Turbine
201.

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. Radially outward
202.

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. Pressure energy and Kinetic energy
203.

Centrifugal head in Outward flow reaction turbine                         

A. Increases
B. Decreases
C. Remains constant
D. Gradually decreases
Answer» A. Increases
204.

Discharge in outward flow reaction turbine                        

A. Increases
B. Decreases
C. Remains constant
D. Gradually decreases
Answer» A. Increases
205.

Speed control of Outward flow reaction turbine is                         

A. Easy
B. Moderate
C. Difficult
D. Very difficult
Answer» D. Very difficult
206.

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. Outward flow reaction turbine
207.

Outward flow reaction turbine will quite suitable for_                       

A. High head
B. Medium head
C. Low head
D. Static head
Answer» B. Medium head
208.

In outward flow reaction turbine tangential velocity at inlet is always_ than outlet velocity.

A. Equal
B. Less
C. More
D. Constant
Answer» B. Less
209.

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. Radial inlet discharge
210.

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. Radially inward
211.

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. Flow ratio
212.

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. Straight divergent tube
213.

The simple elbow draft tube is placed close to the_            

A. Head race
B. Tail race
C. Tank
D. Nozzle
Answer» B. Tail race
214.

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. Reaction turbine
215.

An example of reaction turbine is_              

A. Parsons turbine
B. Curtis turbine
C. Rateau turbine
D. Pelton wheel
Answer» A. Parsons turbine
216.

When we arrange turbine blades in multiple stages it is called                

A. Pressure change
B. Vane deviation
C. Compounding
D. Pressure ratio
Answer» C. Compounding
217.

Compounding is needed to                      

A. Increase Pressure
B. Decrease temperature
C. Change volume
D. Increase efficiency
Answer» D. Increase efficiency
218.

Which among the following is not a type of compounding?

A. Pressure
B. Temperature
C. Pressure velocity
D. Velocity
Answer» B. Temperature
219.

Newtons second law describes the transfer of energy through impulse turbines.

A. True
B. False
C. none
D. none
Answer» A. True
220.

Inner radial flow extracts energy from           

A. Turbine blades
B. Moving fluid
C. Pressure change
D. Temperature increase
Answer» B. Moving fluid
221.

Reaction turbines develop torque by reacting to the gas or fluids pressure or mass.

A. True
B. False
C. none
D. none
Answer» A. True
222.

What is the water flow direction in the runner in a Francis turbine?

A. Axial and then tangential
B. Tangential and then axial
C. Radial and then axial
D. Axial and then radial
Answer» C. Radial and then axial
223.

Which of the following is true in case of flow of water before it enters the runner of a Francis Turbine?

A. Available head is entirely converted to velocity head
B. Available head is entire converted to pressure head
C. Available head is neither converted to pressure head nor velocity head
D. Available head is partly converted to pressure head and partly to velocity head
Answer» D. Available head is partly converted to pressure head and partly to velocity head
224.

Why does the cross sectional area of the Spiral casing gradually decrease along the circumference of the Francis turbine from the entrance to the tip?

A. To ensure constant velocity of water during runner entry
B. To prevent loss of efficiency of the turbine due to impulsive forces caused by extra area
C. To prevent leakage from the turbine
D. To reduce material costs in order to make the turbine more economical
Answer» A. To ensure constant velocity of water during runner entry
225.

Which of the following profiles are used for guide vanes to ensure smooth flow without separation?

A. Rectangular
B. Bent Rectangular
C. Elliptical
D. Aerofoil
Answer» D. Aerofoil
226.

In which of the following type of runners the velocity of whirl at inlet is greater than the blade velocity?

A. Such a case is practically impossible
B. Slow Runner
C. Medium Runner
D. Fast Runner
Answer» B. Slow Runner
227.

Which of the following runner types will have the highest vane angle at inlet (β1 value)?

A. Slow Runner
B. Medium Runner
C. Fast Runner
D. Vane angle is defined only for Kaplan Turbines and not Francis turbines
Answer» C. Fast Runner
228.

In case of a Medium runner, tan (α1) CANNOT be given by (α1 = Guide vane angle at inlet)?

A. Vf1 / Vw1
B. Vr1 / Vw1
C. Vr1 / u1
D. Vw1 / u1
Answer» D. Vw1 / u1
229.

In the velocity diagrams for Francis turbine, which of the following velocity directions is along the blade curvature?

A. Vr1
B. Vw1
C. V1
D. u1
Answer» A. Vr1
230.

In the figure shown below,which of the following angles replace the question mark?

A. Guide vane angle at inlet
B. Blade angle at inlet
C. Vane angle at inlet
D. Blade angle at outlet
Answer» A. Guide vane angle at inlet
231.

In the figure shown below, which of the following type of runners has the blade curvature as shown in the above figure (The arrow denotes direction of blade motion)?

A. Information insufficient to determine
B. Slow Runner
C. Medium Runner
D. Fast Runner
Answer» B. Slow Runner
232.

Francis turbine is typically used for which of the following values of available heads?

A. 300 m
B. 100 m
C. 30 m
D. 5 m
Answer» B. 100 m
233.

Water flow velocity is given 10 m/s. The runner diameter is 3 m and the width of the wheel is 25 cm. Find the mass of water (kg) flowing across the runner per second.

A. 7500π
B. 50π
C. 300π
D. RPM of the turbine needs to be given
Answer» A. 7500π
234.

Work done per second by a Francis turbine can be given by ρAVf (Vw1u1 + Vw2u2).

A. True
B. False
C. none
D. none
Answer» B. False
235.

Which of the following terms is considered to be zero while deriving the equation for work done per second for Francis Turbine?

A. Vr1
B. Vw2
C. Vf2
D. Vr2
Answer» B. Vw2
236.

Power developed by Francis turbine are calculated for a certain set of conditions. Now, the inlet whirl velocity is doubled, the blade velocity at inlet is doubled and the flow velocity is quartered. The power developed:

A. Is 4 times the original value
B. Is 2 times the original value
C. Is ½ times the original value
D. Is same as the original value
Answer» D. Is same as the original value
237.

Volume flow rate of water in a Francis turbine runner is 25 m3/s. The flow velocity, whirl velocity and blade velocity are 11 m/s, 10 m/s and 5 m/s respectively, all values given at runner inlet. Find the power developed by the turbine.

A. 25 kW
B. 1.25 MW
C. 1.25 kW
D. 25 MW
Answer» B. 1.25 MW
238.

The flow rate of the water flow in a Francis turbine is increased by 50% keeping all the other parameters same. The work done by the turbine changes by?

A. 50% increase
B. 25% increase
C. 100% increase
D. 150% increase
Answer» A. 50% increase
239.

A student performs an experiment with a Francis turbine. He accidently set the RPM of Francis turbine to 1400 rpm instead of 700 rpm. He reported the power to be 1 MW. His teacher asks him to perform the same experiment using the correct RPM. The student performs the same experiment again, but this time the erroneously doubled the flow velocity. What does the student report the power to be?

A. 0.5 MW
B. 0.25 MW
C. 2 MW
D. 1 MW
Answer» D. 1 MW
240.

The available head of a Francis Turbine is 100 m. Velocity of the flow at the runner inlet is 15 m/s. Find the flow ratio.

A. 0.33
B. 0.45
C. 0.67
D. 0.89
Answer» A. 0.33
241.

How does the flow ratio (ψ) of a Francis turbine vary with available head (H)?

A. ψ α H
B. ψ α 1/H
C. ψ α sqrt (H)
D. ψ α 1/(sqrt (H))
Answer» D. ψ α 1/(sqrt (H))
242.

What is the typical value for flow ratio in a Francis turbine?

A. 0.05 – 0.1
B. 0.15 – 0.30
C. 0.35 – 0.45
D. 0.50 – 0.60
Answer» B. 0.15 – 0.30
243.

The available head of a Francis Turbine is 120 m. The blade velocity is given 35 m/s. Find the speed ratio of the turbine.

A. 0.56
B. 0.61
C. 0.71
D. 0.81
Answer» C. 0.71
244.

The speed ratio (φ) varies directly with which of the following parameters?

A. Vw1
B. V1
C. N (RPM)
D. H (Available head)
Answer» C. N (RPM)
245.

The typical value range of speed ratio for a Francis turbine is:

A. 0.3 – 0.6
B. 0.5 – 0.6
C. 0.1 – 0.4
D. 0.6 – 0.9
Answer» D. 0.6 – 0.9
246.

Which of the following efficiencies for Francis Turbine is described as the ratio between the power produced by runner to the power supplied by water at the inlet?

A. Hydraulic efficiency
B. Volumetric efficiency
C. Mechanical efficiency
D. Overall efficiency
Answer» A. Hydraulic efficiency
247.

Which of the following efficiencies for Francis Turbine is described as the ratio between total quantity of water over runner blades to total quantity of water supplied to turbine?

A. Hydraulic efficiency
B. Volumetric efficiency
C. Mechanical efficiency
D. Overall efficiency
Answer» B. Volumetric efficiency
248.

Which of the following efficiencies for Francis Turbine is defined as the ratio between the power available at the shaft of the turbine to the power produced by the runner?

A. Hydraulic efficiency
B. Volumetric efficiency
C. Mechanical efficiency
D. Overall efficiency
Answer» C. Mechanical efficiency
249.

Which of the following efficiencies for Francis Turbine is defined as the ratio between the power available at the shaft to the power supplied by water at the inlet?

A. Hydraulic efficiency
B. Volumetric efficiency
C. Mechanical efficiency
D. Overall efficiency
Answer» D. Overall efficiency
250.

The whirl velocity at inlet of Francis turbine is given to be 20 m/s. The blade velocity is given as 35 m/s. What is the hydraulic efficiency for a head of 100 m?

A. 80%
B. 90%
C. 70%
D. 98%
Answer» C. 70%
251.

The desired hydraulic efficiency of a turbine is 80% at a whirl velocity of 20 m/s and a head of 100 m. What should be the blade velocity of the turbine at inlet in m/s?

A. 40
B. 60
C. 80
D. 25
Answer» A. 40
252.

The input water power of the Francis turbine is 1.25 times the runner power. What would be the hydraulic efficiency of the turbine (in %)?

A. 60
B. 70
C. 80
D. 90
Answer» C. 80
253.

The volume flow rate into a Francis turbine is Q m3/s. 0.25Q m3/s volume of water do not flow over the runner blades. What is the mechanical efficiency of the turbine (in %)?

A. 65
B. 75
C. 80
D. Mechanical efficiency cannot be found out from the given information
Answer» D. Mechanical efficiency cannot be found out from the given information
254.

The volumetric efficiency of a Francis turbine is given to be 90%. If the volume flow rate through the turbine is 25 m3/s. What is the flow rate of water over the runner blades (in m3/s)?

A. 20
B. 25
C. 22.5
D. 21.5
Answer» C. 22.5
255.

The volumetric efficiency of a given turbine is 80%. If volume flow rate of water in given to be 30 m3/s, find the volume of water (m3) NOT flowing over the runner blades per second?

A. 5
B. 6
C. 10
D. 12
Answer» B. 6
256.

The power available at the shaft of a Francis turbine is 1 MW. The volume flow rate of water in 25 m3/s, whirl velocity at inlet is 10 m/s and blade velocity is 5 m/s. Find the mechanical efficiency (in %)?

A. 65
B. 75
C. 80
D. 90
Answer» C. 80
257.

The whirl velocity at inlet is 15 m/s and blade velocity is 10 m/s. The volume flow rate of water in 20 m3/s. Find the power output available at the shaft if the mechanical efficiency is 95% (in MW)?

A. 2.85
B. 3.075
C. 6.55
D. 0.285
Answer» A. 2.85
258.

The power output of the shaft is 5 MW. The volume flow rate of water in 10 m3/s at an available head of 60 m. Find the overall efficiency of the turbine in % (g = 10 m/s2)?

A. 80
B. 82.5
C. 83.3
D. 85
Answer» C. 83.3
259.

The volume flow rate of water in 10 m3/s at an available head of 60 m (g = 10 m/s3). Find the shaft power (in MW) if the overall efficiency of the turbine is 90%.

A. 54
B. 5.4
C. 540
D. 0.54
Answer» B. 5.4
260.

The hydraulic efficiency of a Francis turbine is 90%, the mechanical efficiency is 95% and the volumetric efficiency is assumed to be 100%. Fine the overall efficiency (in %)?

A. 80
B. 85.5
C. 87.5
D. 83.3
Answer» B. 85.5
261.

In a Kaplan turbine, what is the direction of water flow?

A. Axial and then axial
B. Radial and then axial
C. Tangential and then axial
D. Tangential and then radial
Answer» A. Axial and then axial
262.

For which of the following values of available heads may Kaplan turbine be used?

A. 250 m
B. 100 m
C. 80 m
D. 50 m
Answer» D. 50 m
263.

In this type of low head turbine, the guide vanes are fixed to the hub of the turbine and are not adjustable. What is this type of turbine called?

A. Francis turbine
B. Kaplan Turbine
C. Propeller Turbine
D. Pelton turbine
Answer» A. Francis turbine
264.

The velocity of flow through a Kaplan turbine is 10 m/s. The outer diameter of the runner is 4 m and the hub diameter is 2 m. Find the volume flow rate of the turbine in m3/s?

A. 95
B. 75
C. 85
D. 105
Answer» A. 95
265.

The velocity of the flow at the inlet of Kaplan turbine is V. In an experimental setup, what could be the possible value of the velocity of the flow at the outlet of Kaplan turbine?

A. V
B. 0.8V
C. 1.2V
D. 2V
Answer» B. 0.8V
266.

Which of the following turbines will have the lowest number of blades in it?

A. Pelton turbine
B. Steam turbine
C. Francis turbine
D. Kaplan turbine
Answer» D. Kaplan turbine
267.

The velocity of the flow through the Kaplan turbine is 25 m/s. The available head of the turbine is 60 m. Find the flow ratio of the turbine (take g = 10 m/s2).

A. 0.65
B. 0.72
C. 0.69
D. 0.75
Answer» B. 0.72
268.

A Kaplan turbine requires a speed ratio of 2. The available head of the turbine is 5 m. What should be the blade velocity of the turbine such that a speed ratio of 2 is maintained (take g = 10 m/s2)?

A. 75.75 m/s
B. 63.25 m/s
C. 23.35 m/s
D. 50.00 m/s
Answer» B. 63.25 m/s
269.

The flow ratio of a Kaplan turbine is given as 0.7. The available head is 30 m. The outer diameter of the runner is 3.5 m and the hub diameter is 2 m. Find the volume of water flowing through the turbine per second (m3/s)?

A. 90
B. 111
C. 125
D. 168
Answer» B. 111
270.

In which of the following type of runners in a Kaplan turbine the velocity of whirl at inlet is smaller than the blade velocity?

A. Such a case is practically impossible
B. Slow Runner
C. Medium Runner
D. Fast Runner
Answer» D. Fast Runner
271.

In the outlet velocity triangle of a Kaplan turbine, β2 = 30o. Vf2 = 5 m/s. What is the relative velocity of the flow at outlet?

A. 10 m/s
B. 5.77 m/s
C. 8.66 m/s
D. 2.88 m/s
Answer» A. 10 m/s
272.

In the inlet velocity triangle of a Kaplan turbine, α1 = 45o. The velocity of flow at inlet = 10 m/s. Find the whirl velocity of water at the inlet of Kaplan turbine?

A. 5 m/s
B. 10 m/s
C. 12.5 m/s
D. 15 m/s
Answer» B. 10 m/s
273.

The whirl velocity of water at the inlet of the Kaplan turbine is 15 m/s. The velocity of water at inlet of the turbine is 20 m/s. Find the guide vane angle at inlet (In degrees).

A. 53.13
B. 36.86
C. 45
D. 41.41
Answer» D. 41.41
274.

The relative velocity of water at the inlet of the Kaplan turbine is 7 m/s. β1 = 75o. The whirl velocity of the water at inlet is 10 m/s. Find the blade velocity of the turbine?

A. 26.124 m/s
B. 40 m/s
C. 36.124 m/s
D. 60 m/s
Answer» C. 36.124 m/s
275.

For the figure given below, find the missing terms in the order of (1), (2), (3) and (4).

A. Vr1, α1, β1, Vw1
B. Vw1, β1, α1, Vr1
C. Vw1, α1, β1, Vr1
D. Vr1, β1, α1, Vw1
Answer» C. Vw1, α1, β1, Vr1
276.

Kaplan turbine works on               

A. Electrical energy
B. Hydro energy
C. Thermal energy
D. Chemical energy
Answer» C. Thermal energy
277.

Kaplan turbine is an reaction turbine

A. Inward flow
B. Outward flow
C. Radial
D. Axial
Answer» A. Inward flow
278.

The Kaplan Turbine is an evolution of                

A. Francis turbine
B. Pelton wheel
C. Parsons turbine
D. Curtis turbine
Answer» A. Francis turbine
279.

What is the dimension of thermal efficiency of a Kaplan turbine?

A. kg
B. m
C. kg/m
D. Dimensionless
Answer» D. Dimensionless
280.

A Kaplan turbine is used in                

A. Turbomachinery
B. Pressure drag
C. Aerodynamics
D. Automobiles
Answer» A. Turbomachinery
281.

The head of the Kaplan ranges from             

A. 100 to 200 m
B. 250 to 300 m
C. 10 to 70 m
D. 0 m
Answer» C. 10 to 70 m
282.

Nozzles in the Kaplan turbine move due to impact of                

A. Water
B. Steam
C. Blade
D. Another nozzle
Answer» B. Steam
283.

The power output of Kaplan turbine ranges from                   

A. 5 to 200 MW
B. 1000 to 2000 MW
C. 2000 to 3000 MW
D. 5000 and above
Answer» A. 5 to 200 MW
284.

Kaplan turbines rotates at a rate

A. Increasing
B. Decreasing
C. Constant
D. Increasing and then decreasing
Answer» C. Constant
285.

What type of turbine is Kaplan?

A. Impulse
B. Reaction
C. Energy
D. Hydro
Answer» B. Reaction
286.

Kaplan turbine is needed to improve                

A. Increase Pressure
B. Decrease temperature
C. Change volume
D. Increase efficiency
Answer» D. Increase efficiency
287.

Kaplan turbine is an type turbine

A. Pressure
B. Inward flow
C. Outward flow
D. Velocity
Answer» B. Inward flow
288.

The turbine does not have to be at the lowest point of water flow as long as the water in the draft tube is full.

A. True
B. False
C. none
D. none
Answer» A. True
289.

The outlet of the Kaplan turbine is through               

A. Vane Blades
B. Moving pipeline
C. Draft tube
D. Pump
Answer» C. Draft tube
290.

Kaplan turbine is most commonly used in propeller turbines.

A. True
B. False
C. none
D. none
Answer» A. True
291.

For a Kaplan turbine, the whirl velocity at inlet of the turbine is given to be 18 m/s. The blade velocity is given as 25 m/s. What is the hydraulic efficiency for a head of 50 m. Take g = 10 m/s2?

A. 80%
B. 90%
C. 70%
D. 98%
Answer» B. 90%
292.

Which of the following efficiencies for Kaplan Turbine is described as the ratio between the power produced by runner to the power supplied by water at the inlet?

A. Hydraulic efficiency
B. Volumetric efficiency
C. Mechanical efficiency
D. Overall efficiency
Answer» A. Hydraulic efficiency
293.

The desired hydraulic efficiency of a Kaplan turbine is 98% at a whirl velocity of 20 m/s and a head of 60 m. What should be the blade velocity of the turbine at inlet in m/s? Take g = 10 m/s2.

A. 40
B. 60
C. 80
D. 30
Answer» D. 30
294.

It is given that the input water power of the Kaplan turbine is 1.10 times the runner power. What would be the hydraulic efficiency of the turbine (in %)?

A. 60.61
B. 70.71
C. 80.81
D. 90.91
Answer» D. 90.91
295.

Which of the following efficiencies for Kaplan Turbine is described as the ratio between total quantity of water over runner blades to total quantity of water supplied to turbine?

A. Hydraulic efficiency
B. Volumetric efficiency
C. Mechanical efficiency
D. Overall efficiency
Answer» B. Volumetric efficiency
296.

The volume flow rate into a Kaplan turbine is Q m3/s. 0.10Q m3/s volume of water do not flow over the runner blades. What further information is required to find the volumetric efficiency (numerical value) of the Kaplan turbine?

A. The numerical value of Q
B. The available head of the turbine
C. The RPM or the blade velocity of the turbine
D. No further information is required
Answer» D. No further information is required
297.

A student reports the volumetric efficiency of a Kaplan turbine to be 95%. If he measures the volume flow rate through the turbine is 40 m3/s. What is the flow rate of water over the runner blades (in m3/s)?

A. 38
B. 40
C. 42.11
D. 45
Answer» A. 38
298.

95*40 = 38 m3/s. 358. In a Kaplan turbine experiment, the volumetric efficiency of a given turbine is 91%. If volume flow rate of water in given to be 35 m3/s, find the volume of water (m3) NOT flowing over the runner blades per second?

A. 4.05
B. 3.15
C. 3.30
D. 2.55
Answer» B. 3.15
299.

Which of the following efficiencies for Kaplan Turbine is defined as the ratio between the power available at the shaft of the turbine to the power produced by the runner?

A. Hydraulic efficiency
B. Volumetric efficiency
C. Mechanical efficiency
D. Overall efficiency
Answer» C. Mechanical efficiency
300.

The power available at the shaft of a Kaplan turbine is 0.75 MW. The volume flow rate of water in 15 m3/s, whirl velocity at inlet is 12 m/s and blade velocity is 5 m/s. Find the mechanical efficiency (in %)?

A. 66.66
B. 75.00
C. 83.33
D. 91.33
Answer» C. 83.33
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