Cavitation Control in Turbomachinery by J-Groove.

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Cavitation occurring in turbomachinery is one of the great obstacles, and it has made users and designers to suffer many troubles. Therefore, many researchers have been tried to overcome or suppress the abnormal phenomenon by use of the conventional methods of raising pressure in a minimum pressure region such as making suction height of a pump low, reducing loss of the inlet pipe or installing an inducer and a booster pump as positive methods. However, because cavitation is a physical phenomenon, it is impossible to completely restrain outbreak itself of cavitation, but it is thought that to some extent it can be suppressed internally.The investigators of this project have proposed shallow grooves, which is named "J-Groove", mounted on a casing wall of turbomachinery in the pressure gradient direction of mainstream as a countermeasure of various abnormal flow phenomena. From the previous related studies, it has been verified that J-Groove has the function of suppressing various abnorm … More al flow phenomena with rotation by controlling the angular momentum of mainstream, as well as one more important function of increasing the pressure in a low pressure region by carrying the high pressure fluid to the low pressure region. Thus, if the latter function of increasing low pressure can be applicable to the control of cavitation, suppression of the cavitation occurring in turbomachinery can be possible.The purpose of present study is to control and suppress cavitation occurring in turbomachinery by use of J-Groove.The research results showed that the suction performance of turbopump with inducer can be improved considerably by application of J-Groove with proper configuration. Moreover, rotating cavitation and cavitation surge occurring in the inducer can be almost suppressed by adopting J-Groove. Improvement of suction performance in centrifugal pumps with both closed impeller and semi-open impeller can be possible by use of J-Groove without decreasing pump efficiency in the range of whole flowrate. Less