Design optimization of a low specific speed centrifugal pump with an unshrouded impeller for cryogenic liquid flow

Abstract

Rocket engines require centrifugal pu mps used in its propellant feeding system to be smaller and lighter to increase the final speed of payloads, and be produced with lo wer costs. Reducing the number of stages and removing shroud rotating wall make pu mps lighter and easier to manufacture. Therefore, these pumps should be designed with higher head to reduce the number o f stages and have an unshrouded impeller. In this study, various shapes of shrouded and unshrouded impellers with the same meridional plane, that have various blade angle distributions, and splitter b lade shapes, have been analysed by a co mputational flu id dynamics(CFD) approach. Based on this survey, the impeller blade shape which demonstrates the highest head and efficiency has been designed considering the internal flow of the pump. As a result, it was observed that unshrouded impellers had the loss generation structure due to tip leakage flow wh ich was different fro m shrouded impellers had. Based on the above, a design method considering the tip leakage flow of unshrouded impeller was suggested.