Inlet Flow And Aspects Of Cavitation In Centrifugal Impellers
This paper describes the relationships of inlet velocity distribution, incipient cavitation and suction performance of centrifugal pumps. It also discusses, in particular, the aspects of cavitation as related to inlet reverse flow (internal recirculation). There are many ways of improving the suction performance of centrifugal pumps. Enlarging the inlet diameter or inlet angle are two of the most commonly used methods. However, this may increase the capacity at which inlet reverse flow begins. Inlet reverse flow normally starts to occur at about half of the shock-free inlet capacity, and this has no relation to the best efficiency flow. Pump total head begins to drop only during advanced cavitation, especially at partial flow operation. When the impeller is designed with a large inlet angle to improve suction performance, there is a possibility of increasing the capacity where inlet reverse flow occurs, which may even be at the best efficiency point. There are still other ways of improving suction performance without increasing the capacity at which inlet reverse flow occurs, e.g. reducing the number of blades, sharpening inlet edges, etc., and these are also referred to in this paper.
Oshima, Masao (1982). Inlet Flow And Aspects Of Cavitation In Centrifugal Impellers. Texas A&M University. Turbomachinery Laboratories. Available electronically from