Effect of raised blade on cavitation performance of centrifugal pumps
A method was proposed to improve the cavitation performance of centrifugal pumps by arran-ging a raised structure on the blade working surface.Based on the RNG k-e turbulence model and Kubota cavitation model,the three-dimensional unsteady cavitation flow was numerically simulated,and the cavitation development under the initial blade profile and raised blade profile was analyzed in detail.The simulation results show that the head of the raised blade profile is slightly lower than that of the initial smooth blade profile before cavitation occurres.When the cavitation number is reduced to lower than 0.43,the head of the raised blade is higher than that of the initial blade,the head with 2 mm raised diameter is the highest.The raised structure delays the occurrence of cavitation and shows a good inhibition effect on cavitation phenomenon.In the stage of cavitation development,the raised structure of the blade working surface increases the area and surface roughness of the blade working surface,which changes the internal flow channel structure of the impeller,forms a relatively high-pres-sure area and high turbulent kinetic energy near the wall.The pressure gradient increases,and the area of the low-pressure area at the impeller inlet reduces,which effectively reduces the cavitation volume,and inhibits the occurrence and development of cavitation.At different stages of cavitation development,the raised structure at different positions on the working face has no significant impact on cavitation development.
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