二重反転形軸流ポンプの後段翼車設計に関する実験的考察

抄録

A contra-rotating rotor has been applied to an axial flow pump against the demand for higher specific speed. It was validated from the previous experiment with contra-rotating rotors that a rotational speed controlling of the rear rotor was capable of improving the efficiency at off-design point, though the specified pump head and maximum efficiency were not satisfied at design point. It was also concluded that the rear rotor design was important for further improvement of pump performance. In order to obtain the useful data for rear rotor design the rear rotor was redesigned under the condition of wider fl ow passage area. The new rotor has lower stagger angle, larger blade number and lower solidity than the previous one. In the present paper, experimental data for the present and the previous rotors under the same front rotor are compared in pump characteristics. Appropriate design parameters are discussed to obtain higher performance of rear rotor with help of measured results of radial distributions of flow in up-and downstream sections of rear rotor and blade to blade distributions of casing wall static pressures.