ディフューザポンプの低流量域不安定性能

概要

論文の詳細を見る
Low specific speed pumps with vaned diffusers sometimes encounter performance curve instabilities at flow rates smaller than 30 percent of the optimum one. In order to determine the cause of this phenomena, measurements of the steady and unsteady flow characteristics at the impeller outlet and the diffuser vane inlet were performed using a single-stage diffuser pump with a specific speed of 34 min^<-1>. The results have revealed that the present instability is caused by a rotating stall at the diffuser vane inlet, and that a sharp drop of the head curve is caused by a rotating stall at the diffuser vane inlet, and that a sharp drop of the head curve is caused by a sudden deceleration of the peripheral velocity of the main flow at the diffuser inlet. With an increase in the deviation of the impeller center toward the suction side, the reverse flow regime at the diffuser inlet becomes considerably larger and a periodic reverse flow is forced into the impeller, which increases the performance curve instability. In such cases on of the effective ways of avoiding the instability is to install a spacer at the back of the front shroud.
1988-12-25