Experiments on Air-Water Two-Phase Flow Pump Impeller with Rotating-Stationary Circular Cascades and Recirculating Flow Holes

Abstract

Gas accumulation and its extension in a centrifugal impeller of a two-phase flow pump cause head degradation. In order to decrease the head degradation, a special type of impeller has been designed based on the following concepts. The open impeller consists of two stages of rotating and stationary circular cascades with an appropriate number of thin blades for creating a dispersive effect of each cascade inlet for gas-phase flow. The outer rotating cascade has a large blade outlet angle to keep the pump head high even at high void fraction. Holes on the rotating disk, through which recirculating liquid flows may blow off the gas accumulation region, are equipped in each flow passage. The newly conceptualized impeller was examined experimentally. Results are discussed in the present paper with help of visual observation of gas behavior in the impeller flow passage.