Abstract:
The computational modelling of positive displacement pumps based on Reynolds Averaged Navier Stokes (RANS) equations on unstructured meshes by the finite volume method is addressed in this study. The Volume of Fluid (VOF) method is used to capture the interface between the working fluid and air. Turbulence is modelled using a two equation k-ɛ RANS turbulence model. The main aim of the study is to compute the flow variables in the pump and to extract pump performance characteristics over a range of varying flow conditions. Experimental studies of pumps only provide data related to flow rates and heads which the pumps can achieve, while with computational study, it is possible to obtain insight on the flow physics inside the pump, and use these insight to propose design improvements for more efficient pump operation. Overset mesh techniques are used to facilitate the motion of the pump components in this computational study. Leakage between pump components has also been considered in this computation. The pump characteristics have been defined in terms of volumetric efficiency, effective flow rate, pressure rating and pump torque. These performance characteristics are used for evaluating optimum range of pump speed, with highest efficiency and flow-rate. This study aims to provide a basis for further research on several design aspects of the pump.