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Study on Unstable Structure of Three-dimensional Vortices and its Oscillation induced by Cavitation Interaction

三维涡旋不稳定结构及其空化作用引起的振荡研究

基本信息

批准号：
17360081
负责人：
FURUKAWA Akinori
金额：
$ 9.92万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17360081/
关键词：
Cavitation Inducer Cavitation surge Inlet back flow Flow control Inlet obstacle plate Multi-cameras observation system Flow measurement 能動制御流体工学渦流れ回転流れ場流体機械

项目摘要

Cavitation instabilities such as rotating cavitation and cavitation surge are one of the most important problems to be solved for realization of small-sized high-speed turbopumps. It is important to understand complex vortex structures in the internal flow and the unsteady cavity behavior, both of which play dominant roles in the cavitation instabilities. In the present study, we focused on the cavitation surge in helical inducers, in which the complex vortical flow structures including strong inlet back flow appear.It is known that the cavitation surge is strongly associated with the inlet back flow and the installation of the obstacle plate upstream of inducer is effective for the suppression of the cavitation surge. In the present study, in FY2005, we measured the inlet flow of inducers with the different blade tip angle, and we investigated the effect of the inlet ring plate, which blocks the back flow near the tip region, on the inlet back flow as well as on the onset region of the cavitation surge. As a result, it was found that the angular momentum in the back flow is increased by installing the inlet plate, resulting in the increase of the static pressure near the tip region and the suppression of the cavitation surge. In FY2006, we carried out the numerical flow analysis of the inducer, which supported the previous experimental results. Next, we measured the inlet flow distortion due to the inlet baffle plate which blocks the back flow partially in the circumferential direction. And also we developed the multi-cameras observation system which enables us to observe the simultaneous cavity pattern from blade to blade. In FY2007, we clarified the suppression mechanism of the cavitaion surge by installing the above two kinds of obstacle plate through the flow measurement, the cavity observation and the numerical simulation.

旋转空化和空化振荡等空化不稳定性是实现涡轮泵小型化、高速化所要解决的重要问题之一。了解内部流动中的复杂涡结构和非定常空泡行为是很重要的，这两者在空化不稳定性中起着主导作用。针对螺旋诱导轮内出现的包含强烈进口回流的复杂旋涡流动结构的空蚀喘振现象进行了研究，发现空蚀喘振与进口回流有很强的关联，在诱导轮上游设置阻流板可以有效抑制空蚀喘振。在本研究中，在FY2005，我们测量了不同的叶片尖端角度的诱导轮的进口流量，我们调查的进口环板，它阻止了在顶部区域附近的回流，对进口回流的影响，以及对空泡喘振的起始区域。结果表明，进口板的安装增加了回流中的角动量，从而提高了叶尖附近的静压，抑制了空泡振荡。在2006财年，我们进行了诱导轮的数值流动分析，支持了以前的实验结果。接下来，我们测量了由于入口挡板在圆周方向上部分阻挡回流而导致的入口流畸变。同时，我们还开发了多摄像机观察系统，使我们能够观察到的同时，从叶片到叶片的空腔图案。在2007财年，我们通过流量测量、空泡观测和数值模拟，阐明了安装上述两种障碍板对空泡涌的抑制机理。