Difference between a Centrifugal pump and Fan Pump

Can anyone explain what is the difference between a centrifugal pump and fan Pump ? For me It looks the same except for very minor variations.

Thanks!!

Prabhakaran R

Reply to
rprabhakaran
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In a centrifugal pump the flow is radial (usually from the center of the impeller to the outside edge). In a fan pump the flow is axial (parallel to the shaft).

The physics are also different. Centrifugal pumps rely on centripidal acceleration to create a radial pressure gradient across the impeller; this radial outflow is collected by the pump volute and directed into a single flow. Fan pumps blades have airfoil cross-sections and use the pressure difference across their blades to create an axial pressure differnce.

You can also mix the two types and have both axial and radial flow in the same pump.

Tom.

Reply to
Tom Sanderson

one more difference is there the compression ratio ( of fluid for which it is used) is more in compressors (more than 2.7) for fans it is less than that and blowers and in between these.

Reply to
jas_nitj

Good point, but it's the *pressure* ratio that's different, not necessarily the compression ration.

The compression ratio of most liquid pumps is effectively 1 (no compression), even though the pressure ratio can be in the thousands.

Tom.

Reply to
Tom Sanderson

ya that's true but tell me on what parameters do we select the type of compressor(axial or centrifugal)

jas

Reply to
jas

It depends on a lot of things. A sufficiently good design can meet most requirements with either a centrifugal or axial compressor. Very generally for gases, you use axial for high flow rates (large diameters) and low pressure ratios (< ~40) and centrifugal for lower flow rates and high pressure ratios.

For liquids you almost always use centrifugal unless your primary requirement is high flow/low pressure ratio (i.e. propulsion).

There's a lot of overlap...you may choose axial vs. centrifugal based on form factor, for example, even if this isn't the optimal design from a performance perspective.

Things to consider would be:

-fluid to be moved

-desired flow rate

-operating flow rate range

-prime mover (RPM & torque characteristics)

-form factor

-pressure ratio

-cost

Tom.

Reply to
Tom Sanderson

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