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

这项研究的目的是寻找发展叶轮机械的指导原则，这些透平机械配备了针对极端运行条件下不稳定流动现象的主动和被动控制装置和机制。针对叶轮机械中的不稳定流动现象，本文重点研究了以下几个方面的问题：(1)泵诱导轮内的空化振荡；(2)极高压力超低比速泵的正斜率扬程特性；(3)超低扬程水轮机尾水管的涡塌非定常特性；(4)极端风流条件下风力机叶片的动态失速行为；(5)扩散泵内动静叶流相互作用引起的压力波动。由于这些不稳定的流动行为可能发生轴振动，因此，本文还提出了轴振动的稳定控制和滑动轴承在超高速轴旋转条件下的性能问题。这些研究是在每个单独的实验室进行的，结果从综合的角度进行了讨论。在此基础上，阐明了空化、失速、旋涡和叶排干扰等不稳定行为的流动机理，为透平机械的设计和运行提供了提前控制和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.