Synthetic Study on Unstable Flow Phenomena in Turbomachineries under Extreme Operating Conditions and the Flow Control and Advance Detection

本研究项目的目的是寻找开发涡轮机械的指导原则，涡轮机械配备了极端工况下不稳定流动现象的主动和被动控制装置和机构。作为涡轮机械中的不稳定流动现象，本研究重点关注以下几个方面：(1)泵诱导器内的空化诱导振荡；(2)超低比速特高压泵的正斜率水头特性；(3)超低水头水轮机尾水管由于旋涡坍缩而产生的非定常特性；(4)极端风量条件下风力机叶片的动态失速特性；(5)扩压泵内由于转子/定子流动相互作用而产生的压力波动。由于轴振动可能会出现这些不稳定的流动行为，因此除了上述问题外，还研究了轴振动的稳定控制以及轴在超高速旋转条件下滑动轴承的性能。这些研究是在每个单独的实验室进行的，结果从合成的角度进行了讨论。阐明了空化、失速、旋涡和叶排相互作用等不稳定行为的流动机理，为叶轮机械的设计和运行提供了控制和提前检测不稳定行为的有用信息。

The purpose of this research project is to find the guiding principles for developing turbomachineries, which are equipped with active and passive control devices and mechanisms for unstable flow phenomena under extreme operating conditions. As unstable flow phenomena in turbomachineries, the following subjects were focused in this research ; (1) the cavitation induced oscillation in pump-inducers, (2) the positive slope head characterisitics of ultra-low specific speed pump with extremely high pressure, (3) the unsteady characteristics, due to the vortex collapse, of the draft tube for ultra-low head hydro turbine, (4) the dynamic stall behavior of wind turbine blade under the extreme wind flow conditions and (5) Pressure fluctuations, due to the rotor/stator flow interaction, in diffuser pumps.. As these unstable flow behaviors might occur the shaft vibration, in addition of the above, the subject on the stable control of shaft vibration and the performance of sliding bearings under ultra-high speed shaft rotating conditions was also picked up. These researches ware carried out in each individual laboratory and the results were discussed together from the synthetic standpoint. Then, the flow mechanisms of unstable behaviors due to cavitation, stall, swirling vortex and blade-rows interaction were clarified and the useful information for the design and operation of turbomachineries to control and detect the unstable behaviors in advance.