Concurrent theoretical, experimental and numerical analyses of mixed-flow turbopump design

Abstract

The article expands on the ongoing assessment of the reduced-order model proposed by some of the authors for the geometric definition and noncavitating performance evaluation of mixed-flow centrifugal turbopumps. The most significant predictions of the model are compared with URANS (Unsteady Reynolds-Averaged Navier-Stokes) simulations of the non-cavitating flow through a typical six-bladed, unshrouded, mixed-flow turbopump for liquid propellant rocket engines, operating at design and off-design conditions with different values of the impeller tip clearance. Both methods are preliminarily and successfully validated against the experimental results of the reference turbopump. The comparison of the analytical and numerical approaches highlights the detailed features of the flow phenomena not explicitly accounted for by the theoretical model, but also indicates that the model predictions of the most relevant dynamic aspects of the flow through the machine are in satisfactory agreement with the simulations over a broad range of operating conditions. Therefore, the results confirm the capability of the proposed model to generate useful engineering solutions for the turbopump preliminary design problem at a negligible fraction of the computational cost required by 3D numerical simulations. This feature can be expected to prove useful in efficiently addressing the preliminary parametric optimization of centrifugal turbopump design.