Numerical Investigation on the Influence of Blade Profile Deviation on the Performance of Centrifugal Impellers

To investigate the influence of blade profile deviation on the performance of centrifugal impellers, the Krain impeller is selected as the research object. A blade deviation model based on actual manufacturing processes is developed to examine the effects of both local and global blade deviations on impeller performance. For local blade deviations, the impact of uniform-thickness profile deviations at different chordwise positions on impeller performance is analyzed. At the chordwise position with the most significant influence on performance, the relationship between different deviations and impeller performance is examined. For global blade deviations, the effects of both profile and twist deviations on impeller performance are explored. Numerical results indicate that local deviations near the leading edge have the greatest impact on impeller performance. A corresponding relationship exists between suction-side deviations and performance changes: deviations where the suction side is first undercut and then overcut degrade impeller performance, whereas deviations where the suction side is first overcut and then undercut optimize the curvature variation near the leading edge, increasing the flow passage area prone to blockage and thereby improving impeller performance. Specifically, under large-flow conditions, the isentropic efficiency increases by 1.5%, and the blockage flow rate rises by 0.6%. Global blade profile and twist deviations influence impeller performance by altering the entire flow passage area and the blade inlet/outlet installation angles, respectively. At the design condition, the total pressure ratio improves by up to 1.2% and 1.4% for global negative profile deviation and positive twist deviation, respectively. This study provides valuable insights for the manufacturing and blade profile optimization of centrifugal impellers.