Effects of Inlet Swirl on centrifugal pumps TDH

[billions]

Came across an interesting study and also read someone's response on a forum a long time ago. It states that by having counter swirl at the inlet (opposite of impeller) you can generate head as flow is increased.

I do not know enough about pumps yet so I found this study,

http://trace.tennessee.edu/cgi/viewcontent.cgi?article=1878&context=utk_gradthes

Is this legit? Anyone every applied this? drawbacks?

Cheers

 

[bimr]

The reference that you cite is for a compressor, not a pump.

The existence of inlet prerotation may have unforeseen consequences for the suction performance of the centrifugal pump. For that reason, prerotation should be avoided.

Link

For example:

"If a swirl in the opposite direction to the pump's direction of rotation increases, the head will increase at constant flow rate to the point where the vanes are overloaded (flow separation at the suction side of the vane, mechanical vibrations). The pump's efficiency will however drop faster than in the case of a swirl in the same direction of rotation. In the case of a swirl in the opposite direction, the resultant additional pump input power requirement may lead to drive overload."

KSB Link

 

[billions]

Makes sense, unforseen consequences/overloading = bad even though TDH might increase. Thanks!