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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、空化喘振等空化不稳定性是实现小型高速涡轮泵需要解决的重要问题之一。了解内部流动中复杂的旋涡结构和非定常空泡行为是非常重要的，这两者在空化不稳定性中都起着主导作用。本文主要研究了螺旋桨叶轮内的空化喘振现象，发现螺旋桨叶轮内存在着包括强回流在内的复杂的涡流结构，空化喘振与进口回流有很强的相关性，在诱导器上游设置障碍板是抑制空化喘振的有效措施。在本研究中，我们在2005财年测量了不同叶尖角的引进器的进口流量，并研究了进口环板对进口回流的影响，以及对空化喘振起始区的影响。结果表明，加装进气板后，回流角动量增大，导致叶尖附近静压增大，空化浪涌得到抑制。在2006财年，我们进行了诱导器的数值流动分析，支持了前面的实验结果。接下来，我们测量了由于进气挡板在圆周方向上阻挡了部分回流而引起的进气变形。并开发了多摄像机观测系统，可以同时观测叶片间的空泡图案。2007财年，我们通过流量测量、空泡观测和数值模拟，通过安装上述两种障碍板，阐明了空泡涌浪的抑制机理。