The lifting-line theory of a wing in an exponential shear flow proposed by the first author is applied to partial cavitation. The governing equation due to Chen et al with respect to velocity potential far down stream is solved and a general solution is utilized to obtain induced attack angle. A relation of lift force to effective attack angle is described by the Taylor series expansion in the vicinity of geometrical attack angle. From both induced attack angle and lift force, a lifting-line equation is derived, and effects of shear parameter, cavitation number and aspect ratio on the partially cavitating wing characteristics are clarified through some numerical calculations.

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To suppress the cavitation and to make the pump life long, the inducer and the main impeller were driven independently. The performances and the flow conditions were investigated experimentally and the following results were obtained. (l) The main impeller contributes to the flow interaction between the inducer and the main impeller. (2) The rotational speeds of both impellers can be controlled independently so as to suppress the cavitation not only in the main impeller but also in the inducer simultaneously.

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Sewage pumps are designed with a wide flow channel by, for example, sacrificing some efficiency and reducing the number of blades, in order to prevent plugging with foreign bodies. This paper proposes a new type of sewage pump impeller designed to further improve pump efficiency and performance in passing foreign bodies. This sewage pump impeller has a structure in which the suction flow channel of closed type non-clog pump is wound in a helical spiral. The focus of this research was to investigate pump performance, internal flow and radial thrust in this single blade sewage pump impeller. The results clearly indicated the following facts. The developed sewage pump impeller had high efficiency and exhibited high efficiency over a wide range of flow rates. Internal flow of this pump is very complicated, and a state of internal flow largely changes when flow rate changes, and force which is non-uniform in the circumferential direction is applied to the impeller.

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In the analytical theory, a fluid loss caused by biased flow around the impeller was proposed. The upper limit of the solidity on linear design was 2.5. The total pressure of the fan based on the analysis of the fluid loss was estimated with a reasonable validity. When the solidity of the impeller was designed large, the total pressure of the fan at the same operation point became low. The slip factor and the fluid loss of vortex flow changed corresponding with the solidity. It was experimentally proved the influence of the slip factor on the total pressure of the fan was greater than the total fluid loss.

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To utilize the wind energy in various ways, more research and development of VAWTs (vertical axis wind turbines) are expected since variation of wind direction is relatively large in Japan. In this study, we have carried out theoretical and experimental studies to clarify the aerodynamic performance of a new type VAWT called as drag-controlled vertical axis wind turbine, which has such structure that a horizontal shaft with a pair of flat-plate vanes is assembled to the vertical main shaft. Thus, it has the following features : Each vane angle from the wind direction is varied oppositely by the wind during the rotation. Namely, the maximum drag acts on one vane in the wind direction while the minimum force acts on the other against the wind. Using a wind tunnel, we tested the aerodynamic performance of a single stage wind turbine consisting four vanes. The corresponding results are summarized together with a momentum theorem in this paper.

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