Calculations on the Time-Dependent Potential Flow in a Centrifugal Pump

Abstract

In this paper a finite element based method is presented for the calculation of two-dimensional time-dependent potential flows through a rotor/stator configuration. An algorithm was developed that numerically evaluates the time derivative of all relevant field quantities. For that purpose the computational domain was split into a region containing the rotor and one containing the stationary parts, each region being treated in a different coordinate system. The corresponding finite element grids are matched by an interface consisting of connect-elements which move in time. The pressure field was then obtained from the unsteady Bernoulli equation. The Kutta condition was imposed by a method using the linear property of the operators. The algorithm was in particular applied to calculate the two-dimensional quasi-steady flow through a volute laboratory pump which made an experimental verification possible. For various mass flows the lateral fluid forces, the axial moment, the total head of the pump were computed and analyzed. The agreement with the experimental data, with respect to the quantities in the volute, was reasonable. The deviation was quantitatively greatest at low mass flow, the maximum deviation in the velocity being 10%. The overall behavior of the pump could be well predicted.