We were discussing the pumps and
basic pumping system, total
head developed by the centrifugal pump, parts
of centrifugal pump and their function, work done by the centrifugal pump
on water and heads and efficiencies of a centrifugal pump in our previous
post.
Today we will find out the expression for minimum
starting speed of a centrifugal pump. Before deriving the expression for
minimum starting speed of a centrifugal pump, we must understand that why we
need to find out the expression for minimum starting speed of a centrifugal
pump.
Expression for minimum starting speed of a centrifugal pump
Centrifugal pump will discharge the water only if
the pressure rise in the pump is more than or equal to the manometric head. If
the pressure rise in the pump is less than the manometric head, centrifugal
pump will not deliver the water.
While pump impeller will be rotating and water,
which will be in contact with pump impeller, will also be rotating and such
condition is also termed as forced vortex.
In case of forced vortex, the centrifugal head or
head developed due to pressure rise in the pump impeller will be given by
following equation as mentioned here.
Centrifugal pump will start deliver the water only
if
Therefore above equation derived here provides the
expression of minimum speed for starting a centrifugal pump.
Do you have any suggestions? Please write in comment
box.
Further we will find out, in our next post, Head and
efficiency of centrifugal pump.
Reference:
Fluid mechanics, By R. K. Bansal
Image courtesy: Google
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