Primary/Leakage Flow Interaction in a Pump Stage

The finite-element analysis of the combined primary and leakage Jiow streams in a centrifugal pump is presented. To date, this computational model provides the most accurate "zeroth-urder" flow field for rotordynamic calculations, short of analyzing the entire flow field on a fully three-dimensional basis. In formulating the problem, the shaft work is modeled via the angular momentum it imparts to the primary flow stream across the impeller blade region. In casting the boundary conditions, special attention is paid to the multi-connectivity of the newly-contoured computational domain in such a way to avoid over-specification of the problem. The analysis is applied to a typical pump stage with a face seal being part of the leakage passage. The numerical results are. then compared to the outcome of the existing lower-order analysis where the impeller subdomain was totally extracted.