SPPU Question Papers
Class: TE Mechanical (2015 Course)
Unit III: Reaction Water Turbines
March 2015
Q. 3 a) What is function draft
tube and mention various types. [4
marks]
Q. 3 b) Derive
the expression of specific speed of hydraulic turbines. [6 marks]
OR
Q. 4 a) Explain
with neat sketch governing mechanism of any one reaction turbine. [6 marks]
Q. 4 b) A Kaplan
turbine runner has outer diameter of 4.5 m and the diameter of the hub is 2 m.
It is required to develop 20.6 MW when running at l50 rpm, under a head of 2l m.
Assume hydraulic efficiency of 94% and overall efficiency of 88%. Determine the
runner vane angle at inlet and exit at the mean diameter of the vane. [4 marks]
May 2015
Q. 2 a) Describe
with a neat sketch the construction of Francis turbine. [5 marks]
Q. 2 b) A
Kaplan turbine has a runner diameter of 4 m and hub diameter of l.2 m.
Discharge through the turbine = 7000 LPS. The hydraulic & mechanical
efficiencies are 90% and 93% respectively. Assume no whirl at outlet. Find the
net head and power developed by the turbine. [5 marks]
Q. 3 a) What
is cavitation? How it can be prevented? [4
marks]
OR
Q. 4 b) Explain
different types of draft tubes used in reaction turbines. [4 marks]
December 2015
Q. 2 a) The
inner and outer diameters of the wheel are l.5 m and 2 m respectively. Water
flows outwards over the series of moving vanes attached to the wheel. The wheel
runs at 250 rpm. Water is discharged radially at the exit with a velocity of 5
m/s. Work done per kg of water is 250 Nm. The velocity of flow through the
runner is constant.
Determine: [6
marks]
i)
The angles of the moving vane tips
ii)
Guide vane angle at inlet
Q. 2 b) Compare
Francis Turbine and Kaplan Turbine. [4
marks]
March 2016
Q. 3 a) A
Kaplan turbine develops 12 MW power under the net head of 24 m. The water leaves the vane at an angle of 30° and
enters the runner of the turbine. The outer diameter of the runner is 3 m and
hub diameter is 1.3 m. The hydraulic and overall efficiency of the turbine are
90% and 85% respectively. The discharge is axial. Determine: [6 marks]
i)
Discharge through the turbine
ii) Velocity
of flow
iii) Speed
of the turbine
iv) Runner
vane angle at inlet
OR
Q.
4 a) The external and internal diameters of an inward flow
reaction turbines are 1.20 m and 0.6 m respectively. The head on the turbine is
22 m and velocity of flow through the runner is constant and equal to 2.5 m/s.
The guide blade angle is given as 10° and runner vanes are radial at inlet. If
the discharge is radial at outlet, determine: [6 marks]
i)
The speed of the turbine
ii)
The vane angle at outlet
iii) Hydraulic
efficiency
Q. 4 b) Compare
Francis Turbine and Kaplan Turbine. [4
marks]
May 2016
Q. 2 b) Following
data is available related to Francis turbine: Shaft power = l4990 kW, runner
speed = 275 rpm, net head = ll0 m, diameter at inlet = l.8 times diameter at
outlet, axial length of the blade at inlet = 0.l5 times diameter at inlet, flow
ratio = 0.2, hydraulic efficiency = 90%, Overall efficiency = 85%, velocity of
flow at inlet = velocity of flow at outlet
Determine: [6
marks]
i)
Inlet and Outlet diameters
ii)
Guide blade angles
iii)
Runner vane angles
Assume radial flow at
exit.
Q. 3 a) Discuss
main and operating characteristics curves for hydraulic turbine?
[4 marks]
OR
Q. 4 a) Define
angular momentum and explain how it is used to determine the torque and work
done in case of radial flow turbine runner. [4 marks]
December 2016
Q. 2 a) The
external & internal diameters of an inward flow reaction turbine are 2 m
& l m respectively. The head on the turbine is 60 m. The width of the vane
at inlet & outlet are same and equal to 0.25 m. The runner vanes are radial
at inlet & discharge is radial at outlet. The speed is 200 rpm and the
discharge is 6 m3/s. Determine: [6
marks]
i)
The vane angle at outlet and inlet of the runner
ii) The hydraulic efficiency
Q. 3 a) Define
the term: Degree of reaction and explain the meaning of pure reaction and 50%
reaction turbines. [4
marks]
Q. 3 b) A
Kaplan turbine develops l500 kW under a head of 6 m. The turbine is set 2.5 m
above the tailrace level. A vacuum gauge inserted at the turbine outlet records
a suction head of 3.2 m. If the turbine efficiency is 85%, what will be
efficiency of the draft tube having inlet diameter of 3 m. (Neglect losses in
draft tube). [6 marks]
March 2017
Q.
3 a) A
Francis
turbine working under head of 30 m has a wheel diameter of l.2 m at the
entrance and 0.6 m at the exit. The vane angle at entrance is 90ยบ and the guide
blade angle is l5ยบ. The water at exit leaves the vane without any tangential
velocity and velocity of flow in the runner is constant. Neglecting the effect
of draft tube and losses in the guide and runner passage, determine the speed
of the wheel in RPM and vane angle at exit. [6 marks]
Q. 3 b) What is draft tube? What are its advantages?
[4 marks]
Q. 4 a) A conical draft tube having inlet and outlet
diameters l.2 m and l.8 m discharges water at outlet with velocity of 3 m/s.
The total length of the draft tube is 7.2 m and l.44 m of the length of the
draft tube is immersed in water. If the atmospheric pressure head is l0.3 m of
water and loss of head due to friction in the draft tube is equal to 0.2 times
velocity head at outlet of the tube, determine: [6 marks]
i) Pressure head at inlet
ii) Efficiency of the draft tube
May 2017 (2012
Pattern)
Q. 2 b) The external and internal diameters of an inward
flow reaction turbine are l00 cm and 50 cm respectively. The head available is 45
m and velocity of the flow through the runner 3.5 m/s and it is constant. The guide
vane angle at inlet is l0o and runner vanes are radial are inlet. Assuming the discharge
at the outlet of the runner is radial, Determine:-
i) Speed
of the turbine
ii) Power
developed
iii) Hydraulic
Efficiency. [6
marks]
Q.
3 a) Explain the necessity of
draft tube in reaction turbines? [2
marks]
August 2017 (2015 Pattern – Insem.)
Q.
5 a) Compare Francis turbine
& Kaplan turbine. [4
marks]
Q. 5 b) Design a Francis turbine runner with the following
data: Net Head = 68 m; Speed = 750 RPM, Power output = 330 kW; Hydraulic efficiency
= 94%; Overall Efficiency = 85%; Flow ratio = 0.l5; Ratio of breadth to diameter
= 0.l; Inner diameter of the runner is half of outer diameter of the runner. 6%
of circumferential area of the runner is occupied by the thickness of the vanes.
Assume velocity of flow remains constant and flow is radial at exit. [6 marks]
OR
Q. 6 a) In an inward flow reaction turbine the head on the
turbine is 32 m. The external and internal diameters are l.44 m and 0.72 m. The
velocity of flow through the runner is constant and equal to 3 m/s. The guide blade
angle is l0 degree and the runner vanes are radial at inlet. If the discharge at
outlet is radial. Determine: [6
marks]
i) The speed of the turbine
i ) The vane angle at outlet of the runner
and
iii) Hydraulic efficiency.
Q.
6 b) What is the significance
of specific speed? Derive the relation for the same. [4 marks]
December 2017 (2012 Pattern)
Q.
1 a) What is degree of reaction?
Explain its significance. [4
marks]
OR
Q.
2 a) What is draft tube? Define
efficiency of draft tube. [4
marks]
December 2017 (2015 Pattern)
Q. 3 b) A Kaplan turbine runner has outer diameter of 4.5
m and the diameter of the hub is 2 m. It is required to develop 20.6 MW when running
at l50 rpm, under a head of 2l m. Assuming hydraulic efficiency of 94% and overall
efficiency of 88%, determine the runner vane angle at inlet and exit at the mean
diameter of the vane. [6
marks]
OR
Q. 4 b) Particulars of the reaction turbine are given below:
Head of the turbine is l80 m, Inlet diameter is 4.25
m, Outlet diameter is 2.75 m, Inlet vane angle is l20 deg., Velocity of flow at
outlet is l6 m/s, hydraulic efficiency is 92%, width of wheel is same at inlet and
outlet, discharge is radial at outlet. Calculate the speed of the turbine. [6 marks]
May 2018
Q. 2 b) A Kaplan turbine develops 24647.6 kW power at an
average head of 39 m. Assuming the speed ratio of 2, flow ratio 0.6, the
diameter of boss equal to 0.35 times the diameter of the runner and an overall
efficiency 90%, calculate the diameter, speed and specific speed of the runner.
[6 marks]
Q. 3 a) An outward flow reaction turbine has internal and
external diameters of runner as 0.6 m and l.2 m respectively. The guide blade angle
is l5° and velocity of flow through runner is constant and equal to 4 m/sec. If
the speed of the turbine 200 rpm, head on the turbine is l0 m and discharge at outlet
is radial, determine: [7
marks]
i) Runner vane angle at inlet and outlet
ii) Work done by water on runner
iii) Hydraulic efficiency
OR
Q. 4 b) Two inward flow turbine runners having same diameter
of 0.50 m have the same efficiency, and work under same head. Both the turbines
have same velocity of flow of 5.6 m/sec. If one of the runner 'A' runs at 525 RPM
and has an inlet blade angle of 65° and the other runner 'B' has inlet blade angle
of ll0°, what should be the speed of the runner 'B'? Both the turbines discharge
radially at outlet. [6
marks]
August 2018
Q. 5 a) A reaction (Francis) turbine runs at 450 rpm under
head of l20 m. Its diameter at inlet is l20 cm and flow area is 0.4 m2.
The angles made by the absolute and relative velocities at inlet are 20° and 60°
respectively with the tangential velocity. Determine:
i) Volume
flow rate
ii) Hydraulic
Power developed
iii) Hydraulic
efficiency. Assume no whirl at outlet. [6
marks]
Q.
5 b) What do you mean by Degree
of Reaction? Explain with significance. [4
marks]
OR
Q. 6 a) A Kaplan turbine developing 3250 kW under a head
of 6 m has a draft tube with inlet diameter 2.8 m and is placed l.5 m above the
tailrace level. If the vacuum gauge connected at inlet of draft tube reads 5 m of
water, determine the efficiency of turbine. Assume draft tube efficiency as 76%
and take atmospheric pressure l0.3 m of water. [6
marks]
Q.
6 b) Explain causes and remedies
for Cavitation in Reaction water Turbine. [4
marks]
December 2018
Q. 3 a) A turbine was originally installed at the tail water
level. If it is now proposed to place it above the tail water level without any
decrease in head on the turbine, how this can be achieved? [4 marks]
Q. 3 b) Find the main dimensions and blade angles for an
inward flow reaction turbine to the following data:
Velocity of flow through runner is constant; Speed
= 950 rpm; Head on the turbine = 105 m; Output = 800 kW; Guide blade angle at inlet
= 18ยบ; Inner diameter = 0.6 times of Outer diameter; Hydraulic efficiency = 88%;
Overall efficiency = 80%; Breadth at inlet = 0.10 times the inlet diameter; 6% of
the circumferential area of the runner is blocked by vane thickness; the turbine
discharges radially at outlet. [6
marks]
OR
Q. 4 a) What do you mean by characteristic curves of a turbine?
Why these are important? [4
marks]
Q. 4 b) A propeller turbine runner has an external diameter
of 5 m and the diameter at hub is 2 m. The turbine has to develop a shaft power
of 29430 kW under a head of 25 m at a speed of 160 rpm. If the hydraulic efficiency
is 95% and the overall efficiency is 85%, determine the runner vane angles at inlet
and outlet at mean diameter and at extreme edge of the runner. Assume that the turbine
discharges without whirl at outlet. [6
marks]
May 2019
Q. 2 a) For the Francis turbine, following data is
available: shaft power = 130 Kw, Net Head = 9 m, Speed = 120 RPM, Overall
Efficiency = 75%, Hydraulic efficiency = 90%, Velocity of flow at inlet = 1.15√H, Maximum
absolute velocity at inlet = 3.45√H. Assume
radial discharge at exit. Find:
i) Guide blade angle and moving vane
angle at inlet
ii) Diameter of runner at inlet. [6
marks]
Q.
3 a) Explain the necessity
of draft tube in reaction turbines. [4
marks]
Q. 3 b) A Kaplan turbine operates at a discharge of 77 m3/s.
The runner diameter and hub diameter are 4.2 m and 1.5 m respectively. Taking the
speed ratio of 2.1, determine:
i) The net head,
ii) The power developed and
iii) The specific speed. Assume the mechanical and
hydraulic efficiency of 88% and 92% respectively and no whirl at outlet. [6 marks]
OR
Q.
4 a) Define: [4 marks]
i) Mechanical efficiency
ii) Run away speed
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