Design and performance test of circumferential crankle guide vane of multistage centrifugal pumps

To design compact multistage centrifugal pumps, a circumferential crankle guide vane was proposed to match their compact structure. The basic design principle originated from the twisted centrifugal impeller design method and the design method of this guide vane was investigated systematically. By fixing the top curve of the guide vane and extending the bottom curve forward along a circumferential direction, a crankle surface is shaped. This design method has two merits. Firstly, the bottom curve of the first guide vane is extended circumferentially forward to guarantee a large throat flow area. And secondly, a diffuser-like passage is naturally formed by the extended surface and the cylindrical surface of the next blade, which enhances its pressure recovery ability. In addition, the blade surface is divided into two segmented parts, that is, a full twisted surface and a cylindrical surface, thus the casting and molding of the guide vane is more convenient. To reduce the design cycle of the guide vane, a hydraulic design system of the circumferential crankle guide vane was developed using the secondary development technique. Based on this system, different configurations of guide vane were developed. Through evaluation of the different configurations of guide vane, an optimal configuration was obtained by means of CFD analysis. To validate the CFD results, a prototype multistage pump was developed and manufactured. The prototype pump testing showed that the stage head was 9 m, and its efficiency was 57.8%, which could meet the design requirement. To conclude, the guide vane design method is beneficial for energy-saving in multistage centrifugal pumps, and this method could provide useful guidance for the development of compact multistage centrifugal pumps.