Cavitation Characteristics during Startup Process of a Condensate Pump with Splitter Blades

Abstract

The present study aims to describe characteristics of cavitation during the startup process of a condensate pump. The pump is featured by an impeller equipped with five splitter blades. A computational fluid dynamics (CFD) work was conducted to plumb the evolution of cavitation in the pump. Effect of the volumetric flow rate on instantaneous cavitation patterns as the rotational speed of the pump increased was analyzed. The results show that high resistance to cavitation of the pump depends greatly on large area of the impeller eye, which is related to the deployment of the splitter blades. The splitter blades are insignificantly affected by cavitation. During the startup process, both the pump head and the pump efficiency vary drastically, which is insensitive to the flow rate. At a net positive suction head (NPSH) of 2.0 m, high flow rates are responsible for intensified cavitation. High volume fraction of cavitation arises near the inlet of long blades. As the rotational speed increases, the evolution of cavitation is featured by intermittency and diversified cavity patterns. Furthermore, the sum of the volume fraction of cavitation fluctuates with continuously increasing rotational speed.