Cavitation Control in Turbomachinery by J-Groove.

汽蚀是叶轮机械中的一大障碍，给用户和设计人员带来了许多麻烦。因此，许多研究人员试图通过降低泵的吸力高度、减小进水管损失或安装诱导器和增压泵等常规的最低压力区加压方法来克服或抑制这一异常现象。然而，由于汽蚀是一种物理现象，不可能完全抑制汽蚀的爆发本身，但人们认为在一定程度上可以在内部抑制汽蚀的爆发。本项目的研究人员提出了在叶轮机械的壳体壁上沿主流压力梯度方向安装一种名为J槽的浅槽，作为对各种异常流动现象的对策。从以往的相关研究中已经证实，J型槽具有抑制各种异常…的功能通过控制主流的角动量来实现更多的旋转流动现象，以及通过将高压流体带到低压区来增加低压区的压力的更重要的作用。因此，如果后一种提高低压的功能能够应用于汽蚀的控制，就有可能抑制叶轮机械中的汽蚀。本研究的目的是利用J型槽来控制和抑制叶轮机械中的汽蚀现象。研究结果表明，采用合理的结构可以显著改善带诱导轮的涡轮泵的吸气性能。此外，采用J型槽几乎可以抑制诱导器内发生的旋转空化和空化浪涌。在全流量范围内，采用J型槽可以在不降低泵效率的前提下，改善闭式叶轮和半开式叶轮离心泵的吸入性能。较少

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