Which place in hydraulic turbine is most susceptible for cavitations?
Inlet of draft rube
Blade inlet
Guide blade
Penstock
Correct Answer :
A. Inlet of draft rube
Related Questions
Which of the following pump is successfully used for lifting water to the boilers?
Centrifugal pump
Reciprocating pump
Jet pump
Airlift pump
The unit discharge through the turbine is
Q/√H
Q/H
Q/H3/2
Q/H²
The runaway speed of a hydraulic turbine is the speed
At full load
At which there will be no damage to the runner
Corresponding to maximum overload permissible
At which the turbine will run freely without load
Saving of work done and power by fitting an air vessel to double acting reciprocating pump is of the order of
39.2 %
49.2 %
68.8 %
84.8 %
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
The maximum number of jets generally employed in impulse turbine without jet interference is
4
6
8
12
A Pelton wheel working under a constant head and discharge, has maximum efficiency when the speed ratio is
0.26
0.36
0.46
0.56
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
The speed of an imaginary turbine, identical with the given turbine, which will develop a unit power under a unit head, is known as
Normal speed
Unit speed
Specific speed
None of these
The cavitation in reaction turbines is avoided, to a great extent by
Installing the turbine below the tail race level
Using stainless steel runner of the turbine
Providing highly polished blades to the runner
All of the above
According to fan laws, for the fans having constant wheel diameters, the power demand varies
Directly as fan speed
Square of fan speed
Cube of fan speed
Square root of fan speed
Discharge of a centrifugal pump is
Directly proportional to diameter of its impeller
Inversely proportional to diameter of its impeller
Directly proportional to (diameter)² of its impeller
Inversely proportional to (diameter)² of its impeller
Discharge of a centrifugal pump is (where N = Speed of the pump impeller)
Directly proportional to N
Inversely proportional to N
Directly proportional to N²
Inversely proportional to N²
The gross or total head of the turbine is the ________ of the water levels at the head race and tail race.
Sum
Difference
Product
None of these
In reaction turbine, draft tube is used
To transport water downstream without eddies
To convert the kinetic energy to flow energy by a gradual expansion of the flow cross-section
For safety of turbine
To increase flow rate
Pressure intensifier increases the pressure in proportion to
Ratio of diameters
Square of ratio of diameters
Inverse ratio of diameters
Square of inverse ratio of diameters
In impulse Turbine, energy available at the inlet is in the form of
Potential Energy
Strain Energy
Kinetic energy
None of these
The Fourneyron turbine is _________ reaction turbine.
An axial flow
An inward flow
An outward flow
A mixed flow
Saving of work done and power by fitting an air vessel to single acting reciprocating pump is of the order of
39.2 %
49.2 %
68.8 %
84.8 %
The Thomson's turbine is __________ reaction turbine.
An axial flow
An inward flow
An outward flow
A mixed flow
The force exerted (in Newton) by a jet of water impinging normally on a fixed plate is (where w = Specific weight of water in N/m3, a = Crosssectional area of jet in m², and V = Velocity of jet in m/s)
waV / 2g
waV / g
waV² / 2g
waV² / g
A centrifugal pump will start delivering liquid only when the pressure rise in the impeller is equal to the
Kinetic head
Velocity head
Manometric head
Static head
The force exerted by a jet of water (in a direction normal to flow) impinging on a fixed plate inclined at an angle θ with the jet is
waV/2g × sinθ
waV/g × sinθ
waV²/2g × sin2θ
waV²/g × sinθ
The depth of the bucket for a Pelton wheel is generally ________ the diameter of jet.
Equal to
1.2 times
1.8 times
Double
By fitting an air vessel to the reciprocating pump, there is always a saving of work done and subsequently saving of power. This saving in case of a single acting reciprocating pump is
39.2 %
48.8 %
84.8 %
88.4 %
The speed ratio in case of Francis turbine varies from
0.15 to 0.3
0.4 to 0.5
0.6 to 0.9
1 to 1.5
Power required to drive a centrifugal pump is directly proportional to ________ of its impeller.
Diameter
Square of diameter
Cube of diameter
Fourth power of diameter
The centrifugal pump preferred for a specific speed between 80 to 160 r.p.m. is
Slow speed with radial flow at outlet
Medium speed with radial flow at outlet
High speed with radial flow at outlet
High speed with mixed flow at outlet
The force exerted by a jet of water impinging normally on a plate which due to the impact of jet, moves in the direction of jet with a velocity v is
[wa (V - v)]/2g
[wa (V - v)]/g
[wa (V - v)²]/2g
[wa (V - v²)]/g
The hydraulic efficiency of an impulse turbine is maximum when velocity of wheel is _______ of the jet velocity,
One-fourth
One-half
Three-fourth
Double