In recent years, sudden and a large quantity of rainwater in the urban area flows into the drainage pumping station by the expansion of the drainage district by the city area promotion, the decrease of the basement osmosis area by the pavement rate improvement, the squall die rain by the heat island effect, and the problem that submergence damage occurs by a starting delay of the rainwater drainage pump. In order to prevent such submergence damages, what is called as full speed standby pump system makes carry out idling reserve operation of the pump in preparation for a flood, and it enables to drain immediately at a flood condition are adopted, and the pump system is introduced into the drainage pumping station. However, since usually bigger excitation force than in usual operation of single phase occurs in gas-liquid two phase operation. In the present paper, the excitation force in gas-liquid two phase operation in a vertical volute pump is investigated. The changed of excitation force and the causes of its increasing with experimental data. Finally the important matter in actual designing is summarized.

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Transfer matrix, unsteady cavitation characteristics, cavitation compliance and mass flow gain factor of the cavitation in the draft tube were obtained by an upstream and a downstream flow excitations with non-cavitating and cavitating conditions. The flow rate fluctuations were evaluated from the fluctuation of pressure difference at different locations using unsteady Bernoulli's equations. The cavitation compliance and the mass flow gain factor were evaluated numerically for the steady state and experimentally for the unsteady state using the transfer matrix.

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For centrifugal compressors used in automotive turbochargers, it becomes very important to suppress the compressor surge because of a demand for higher boost at lower engine speed, i.e., smaller mass flow rate. In order to clarify the cause of compressor surge, authors investigated a small-sized compressor used in automotive turbochargers by measuring wall static pressures at diffuser exit. It was revealed that surge occurred in the diffuser due to its positive slope of compressor pressure curve which was induced by the scroll locally. These may increase the compressor instability near the surge. Furthermore, oil flow visualizations were conducted. These results showed that reverse flow occurs near the tongue at small mass flow rate and the reverse flow induces positive slope locally for compressor pressure curve. In this paper, PIV was conducted on the same compressor to understand diffuser internal flow in more detail. The results revealed impact of reverse flow at different diffuser span position.

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The efficiency of pediatric left ventricular assist centrifugal blood pump is about 10％ or less at 0.5 /min. It is important to improve efficiency and to prevent blood trauma. However, the improvement of the efficiency of a centrifugal blood pump is difficult, because the specific speed is low and the viscosity of the working fluid is about four times water. In general, a positive displacement pump is suitable for the low specific speed. However, when the enclosed chamber is formed in the pump, the red blood cell might be destroyed in the contact point of a rotor and a stator. In this research, a single screw blood pump which has narrow gap between a rotor and a stator was designed to prevent blood trauma. The fundamental performance such as leakage and pump characteristic was investigated, and it was found that this pump has enough performance for assisting infant left ventricular.

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The purpose of this paper is to study flow field of a lockup clutch inside a torque converter. The performance of a torque converter has been one of the most important areas of improvement for an automatic transmission equipped automobile. Improving the torque converter's performance and efficiency is key to saving fuel consumption, which is an important consideration with recent environmental awareness. Moreover, the locking up operation or slipping control of an automatic transmission is another good opportunity for improving fuel economy. In this paper, the flow field around the lockup clutch has been simulated with CFD using new techniques, the results of the CFD solution show good qualitative agreement with experimental results.

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Small hydropower generation is one of important alternative energy, and potential of small hydropower is great. Efficiency of small hydro turbines is lower than that of large one. Then, there are demands for small hydro turbines to keep high performance. Therefore, we adopted contra-rotating rotors, which can be expected to achieve high performance. In this research, experimental apparatus of the contra-rotating small hydro turbine with 60 mm casing diameter was manufactured and performance of it was investigated by an experiment. Efficiency of the contra-rotating small hydro turbine was high in pico-hydro turbines and high efficiency could be kept in wide flow rate range. Unsteady internal flow conditions, which were difficult to measure experimentally, were shown by the numerical flow analysis. Further, pressure distributions and wake interactions with a rotor rotation were clarified. Then, a relation between the performance and unsteady internal flow condition was considered by the experimental and numerical analysis results.

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