Eiji Asakura

Effects of Inlet Flow Pattern on Cavitation Inception of Centrifugal Pumps

Flow patterns near the inlet portion of an impeller and cavitation inception were examined experimentally using a centrifugal pump with 3, 7 and 9 blade impellers. At low flow rates, velocities at the inlet of seven and nine blade impellers have non-uniform distributions inbetween hub and shroud, which cause a large drop of pressure on the suction surface of the blades near the shroud. In the impeller with three blades, a large vortex was created near the suction side of its inlet and this prevents severe drop in the pressure as seen in the seven blade impeller. Three kinds of cavitation were observed in the impeller passages according to the pressure distribution on the blade surface.

Velocity distributions in the impeller passages of centrifugal pumps. Effects of outlet edge form of the impeller blades on the pump performance.

遠心ポンプ羽根車の先端形状および先端の削除量を種々に変えたときのポンプの性能変化,羽根出口近傍の流れの変化について実験的に明らかにした.羽根前面あるいは後面の先端を削除すると,流出角度が変わるほか流路面積が増す.このため羽根出口における絶対速度の周方向成分が変化してポンプ揚程が変わる.この揚程変化量と羽根先端削除量との関係を実験的に示すとともに,理論的考察を行った.