宫川和芳教授简介
宫川和芳先生1983年毕业于日本早稻田大学，获大阪大学工学博士学位。曾在日本三菱重工业株式会社供职长达二十多年，从事透平机械（压缩机、泵、抽水蓄能机组、螺旋桨等）相关技术研究，先后担任三菱重工技术本部研究员、主任研究员、主席研究员，长崎研究所副所长。在长期的实际工作中，积累了极其丰富的工程经验，在日本乃至世界透平机械工业领域享有盛誉，并一直活跃在国际流体工程学界。
宫川和芳先生于2011年被早稻田大学作为特殊人才引进，现任早稻田大学基干理工学部机械科学航空学科教授、航空系主任。

Abstract
Up to recent years, due to economic pressure, ?pumps, hydraulic turbines, and pump-turbines have been increasing in ?size, their operation range was extended, their rotational speed and ?head were increasing. For impeller/runner and diffuser/wicket gate, a ?large excitation force is caused by this tendency. This previously ?mentioned excitation force results in an increase in vibration and ?noise of the impeller and stationary blade row. This, in turn, ?increases the risk of damage due to high cycle fatigue. In addition, ?the loss due to unsteady flow also increases, which may cause ?performance drop. It is also necessary to deal with the issues that ?can arise due to further increase in size and load.
In this ?presentation, I introduce some cases and show our understanding and ?progress on the unsteady problem of blade row. First, the history of ?this problem will be introduced. Some examples achieved a good ?technical progress are shown as follows.
A high head pump-turbine ?in Japan has been developed in the 500 m class 40 years ago and in the ?750 m class 20 years ago. When developing a 500 m class pump-turbine, ?troubles caused by a strong fluid excitation force occurred, and the ?implemented countermeasures were successful in negating the blade row ?interaction problem. Because of this technological leap based on the ?high head pump-turbine developments, problems due to blade row ?interaction no longer arise at present. This research was focused on ?the mitigation of the fluid excitation force acting on the runner and ?the structural response of the vanes to investigate a nodal diameter ?and vibration mode.
In centrifugal pumps that have a high head ?and a high rotational speed such as boiler feed pumps, a large fluid ?excitation force is generated by the blade row spacing between the ?impeller and the diffuser similar to applied as the high head ?pump-turbine. Especially in the low flow rate range, rotating stall ?which becomes the radial force to the rotor, may occur, it also ?affects the performance, and it can also cause the positive slope ?characteristic in the Q-H characteristics. The propagation speed of ?the stall cell is influenced by many parameters, but the combination ?of the number of impellers and diffusers is an important ?factor.
Recently, the development of open-impellers has been ?carried out because of the cost reduction requirement in low specific ?speed centrifugal pumps used for the rocket turbo pump systems. In ?addition to the blade row interaction problem of the closed impeller, ?the tip leakage vortex of the open-impeller flows into the diffuser, ?which affects the loss and the fluid excitation force. Experimental ?and simulated investigations of the influence of the tip impeller ?vortex growth on the impeller and diffuser performance have clarified ?the unsteady loss mechanisms in the diffuser. In this development, the ?impeller with splitter was designed and optimized, and the influence ?on the tip leakage flow of this splitter is shown. Interactions ?between impeller and diffuser have to be considered to mitigate the ?total pressure loss in the diffuser in case of the open-impeller.