Proper Orthogonal Decomposition Of The Turbulent Flow In An Impeller Of A Centrifugal Pump

The flow field in the channels of a centrifugal pump impeller contains eddy motions of a wide range of time and length scales and identifying coherent structures and their dynamic behavior is not a trivial task. Thus, modal decomposition techniques have been used in order to improve the knowledge on turbulence and coherent structures. In this work, the proper orthogonal decomposition (POD) method is employed to identify the occurrence and development of the dominant unsteady flow structures in a centrifugal pump impeller. For this, experiments using a time-resolved PIV system for different operating conditions of pump impeller were carried out. The results show that in the range of the pump's best efficiency point (BEP) there is no significant flow separation. As the flow rate starts to decrease from the BEP flow rate, unstable flow phenomenon begin to appear and develop in the impeller. The POD analysis reveals that for low flow rates, the flow is dominated by large-scale structures with higher energy, while for the BEP and high flow rates, the flow is dominated by smaller-scale structures.