Unsteady Flow in Centrifugal Pump at Design and Off-Design Conditions

Abstract

Understanding the three-dimensional, turbulent and unsteady flow is important to design a high efficiency pump. The current work objective is to numerically study strong impeller volute interaction and secondary flow in a centrifugal pump at three different flow rates, 70%, 100% and 130% of design flow rate. The unsteady flow development at intake section and impeller passage is coupled with flow rate. At different flow rates, flow field inside the impeller passage is strongly affected by secondary flow structures developed at intake section. The strong impeller volute tongue interaction depends on flow rates as well as the relative position between impeller blade trailing edge and volute tongue as well. A strong pressure pulsation and change of pressure distribution around the impeller blade and volute casing is observed when the impeller rotates. Due to jet wake flow formation within the impeller passage, the wake flow shedding and impingement is causing a distorted velocity profile at impeller exit and flow reversal around volute tongue.