The optimum value of vane exit angle for a centrifugal pump impeller is
10-15°
20-25°
30-40°
50-60°
Correct Answer :
B. 20-25°
Related Questions
The specific speed of turbine is defined as the speed of a unit
Of such a size that it delivers unit discharge at unit head
Of such a size that it delivers unit discharge at unit power
Of such a size that it requires unit power per unit head
Of such a size that it produces unit horse power with unit head
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
Head developed by a centrifugal pump depends on
Impeller diameter
Speed
Fluid density
Both (A) and (B) above
High specific speed of turbine implies it is
Propeller turbine
Francis turbine
Impulse turbine
None of the above
The speed of a turbine runner is
Directly proportional to H1/2
Inversely proportional to H1/2
Directly proportional to H3/2
Inversely proportional to H3/2
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
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
For starting an axial flow pump, its delivery valve should be
Closed
Open
Depends on starting condition and flow desired
Could be either open or closed
According to fan laws, for fans having constant wheel diameter, the pressure varies
Directly as fan speed
Square of fan speed
Cube of fan speed
Square root of fan speed
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
The discharge through a turbine is
Directly proportional to H1/2
Inversely proportional to H1/2
Directly proportional to H3/2
Inversely proportional to H3/2
The efficiency of a Pelton wheel working under constant head ________ with the increase in power.
Remain same
Increases
Decreases
None of these
Which of the following pump is preferred for flood control and irrigation applications?
Centrifugal pump
Axial flow pump
Mixed flow pump
Reciprocating pump
In a centrifugal pump casing, the flow of water leaving the
Radial
Axial
Centrifugal
Vortex
Which of the following pump is generally used to pump highly viscous fluid?
Centrifugal pump
Reciprocating pump
Air lift pump
Screw pump
A hydraulic ram is a device used to
Store the energy of water
Increase the pressure of water
To lift water from deep wells
To lift small quantity of water to a greater height when a large quantity of water is available at a smaller height
Kinematic similarity is said to exist between the model and the prototype, if both of them
Have identical velocities
Are equal in size and shape
Are identical in shape, but differ only in size
Have identical forces
In axial flow fans and turbines, fluid enters and leaves as follows
Radially, axially
Axially, radially
Axially, axially
Radially, radially
Medium specific speed of turbine implies it is
Propeller turbine
Francis turbine
Impulse turbine
Any one of the above
Maximum impulse will be developed in hydraulic ram when
Waste valve closes suddenly
Supply pipe is long
Supply pipe is short
Ram chamber is large
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 would discharge
Same quantity of liquid
0.75 Q
Q/0.75
1.5 Q
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
Dynamic similarity is said to exist between the model and the prototype, if both of them
Have identical velocities
Are equal in size and shape
Are identical in shape, but differ only in size
None of the above
Guide angle as per the aerofoil theory of Kaplan turbine blade design is defined as the angle between
Lift and resultant force
Drag and resultant force
Lift and tangential force
Lift and drag
When a piping system is made up primarily of friction head and very little of vertical lift, then pump characteristics should be
Horizontal
Nearly horizontal
Steep
First rise and then fall
For centrifugal pump impeller, the maximum value of the vane exit angle is
10° to 15°
15° to 20°
20° to 25°
25° to 30°
The cavitation in a hydraulic machine
Causes noise and vibration of various parts
Reduces the discharge of a turbine
Causes sudden drop in power output and efficiency
All of the above
According to fan laws, at constant speed and capacity, the pressure and power vary
Directly as the air or gas density
Inversely as square root of density
Inversely as density
As square of density
Which of the following pump is successfully used for lifting water from deep wells?
Centrifugal pump
Reciprocating pump
Jet pump
Air lift pump
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