The function of guide vanes in a reaction turbine is to
Allow the water to enter the runner without shock
Allow the water to flow over them, without forming eddies
Allow the required quantity of water to enter the turbine
All of the above
Correct Answer :
D. All of the above
Related Questions
Axial flow pump is started with its delivery valve
Kept fully closed
Kept fully open
Irrespective of any position
Kept 50% open
The flow rate in gear pump
Increases with increase in pressure
Decreases with increase in pressure
More or less remains constant with increase in pressure
Unpredictable
Discharge (Q) of a centrifugal pump is given by (where D = Diameter of impeller at inlet, b = Width of impeller at inlet, and Vf = Velocity of flow at inlet)
Q = π.D.Vf
Q = π.b.Vf
Q = π.D.bf.V
Q = D.b.Vf
A jet of water is striking at the centre of a curved vane moving with a uniform velocity in the direction of jet. For the maximum efficiency, the vane velocity is ________ of the jet velocity
One-half
One-third
Two-third
Three-fourth
The function of guide vanes in a reaction turbine is to
Allow the water to enter the runner without shock
Allow the water to flow over them, without forming eddies
Allow the required quantity of water to enter the turbine
All of the above
If a pump is handling water and is discharging a certain flow Q at a constant total dynamic head requiring a definite B.H.P., the same pump when handling a liquid of specific gravity 0.75 and viscosity nearly same as of water, the horse power required will be
Same
0.75 B.H.P.
B.H.P./0.75
1.5 B.H.P.
By fitting an air vessel to the reciprocating pump, there is always a saving of work done and subsequently saving of power. The saving in case of a double acting reciprocating pump is
39.2 %
48.8 %
84.8 %
88.4 %
The width of the bucket for a Pelton wheel is generally ________ the diameter of jet.
Double
Three times
Four times
Five times
Impulse turbine is generally fitted
At the level of tail race
Little above the tail race
Slightly below the tail race
About 2.5 m above the tail race to avoid cavitations.
Francis, Kaplan and propeller turbines fall under the category of
Impulse turbines
Reaction turbines
Axial flow turbines
Mixed flow turbines
A hydraulic accumulator normally consists of
Two cylinders, two rams and a storage device
A cylinder and a ram
Two coaxial rams and two cylinders
A cylinder, a piston, storage tank and control valve
Low specific speed of a pump implies it is
Centrifugal pump
Mixed flow pump
Axial flow pump
None of the above
If the ratios of all the corresponding linear dimensions are equal, then the model and the prototype are said to have
Geometric similarity
Kinematic similarity
Dynamic similarity
None of these
In a centrifugal pump, the liquid enters the pump
At the top
At the bottom
At the canter
From sides
In a reciprocating pump, air vessels are used to
Smoothen the flow
Reduce suction head
Increase delivery head
Reduce acceleration head
The overall efficiency for a Pelton wheel lies between
0.50 to 0.65
0.65 to 0.75
0.75 to 0.85
0.85 to 0.90
Which of the following statement is correct?
The centrifugal pump is suitable for large discharge and smaller heads.
The centrifugal pump requires less floor area and simple foundation as compared to reciprocating pump.
The efficiency of centrifugal pump is less as compared to reciprocating pump.
All of the above
The discharge through a reaction turbine with increase in unit speed
Increases
Decreases
Remain unaffected
First increases and then decreases
The optimum value of vane exit angle for a centrifugal pump impeller is
10-15°
20-25°
30-40°
50-60°
The ratio of actual work available at the turbine to the energy imparted to the wheel is known as ________ efficiency.
Hydraulic
Mechanical
Overall
None of these
Which of the following turbine is preferred for a specific speed of 60 to 300 r.p.m.?
Pelton wheel
Francis turbine
Kaplan turbine
None of these
In a single casing, multistage pump running at constant speed, the capacity rating is to be slightly lowered. It can be done by
Designing new impeller
Trimming the impeller size to the required size by machining
Not possible
Some other alterations in the impeller
In a Kaplan turbine runner, the numbers of blades are generally between
2 to 4
4 to 8
8 to 16
16 to 24
A ship with jet propulsion draws water through inlet orifices at right angles to the direction of its motion. The propelling force of the jet is (where a = Area of the jet, Vr = Relative velocity of the jet and ship = V + v, v = Velocity of the ship, and V = Velocity of the jet issuing from the ship)
waVr /g × (Vr + v)
waVr /g × (Vr - v)
waVr /g × (Vr + v)²
waVr /g × (Vr - v)²
For 450 m head of water, _________ shall be used.
Pelton wheel
Kaplan turbine
Francis turbine
None of these
Motion of a liquid in a volute casing of a centrifugal pump is an example of
Rotational flow
Radial
Forced spiral vortex flow
Spiral vortex flow
Braking jet in an impulse turbine is used
To break the jet of water
To bring the runner to rest in a short time
To change the direction of runner
None of these
Which of the following statement is correct?
In an impulse turbine, the water impinges on the buckets with pressure energy.
In a reaction turbine, the water glides over the moving vanes with kinetic energy.
In an impulse turbine, the pressure of the flowing water remains unchanged and is equal to atmospheric pressure.
In a reaction turbine, the pressure of the flowing water increases after gliding over the vanes.
The maximum efficiency of jet propulsion of a ship with inlet orifices at right angles to the direction of motion of ship, is
40 %
50 %
60 %
80 %
Casting of a centrifugal pump is designed so as to minimize
Friction loss
Cavitations
Static head
Loss of kinetic energy