Prediction of inlet recirculation for centrifugal impellers with body force modeling

Body Force Modeling (BFM) has been used for decades in the field of axial turbomachinery but studies applied to radial turbomachinery are very few in number. This work aims at evaluating this approach and enriching the state of the art for radial geometries. Blade and BFM simulations are performed for six different centrifugal impellers, exploring their operating range as much as is numerically possible with a steady RANS approach. The performance maps show a variable discrepancy between BFM and blade results. An inlet flow recirculation appears at low massflow rates for all the configurations. Special attention is drawn to its prediction. For four impellers, the BFM simulations exhibit a stability bifurcation leading to two different solutions in this massflow range. Spanwise velocity profiles are compared, proving that the BFM results are relevant near the leading edge. Finally, the usual definition of the massflow coefficient is modified and a design criterion is proposed to anticipate on a possible inlet recirculation inside of a performance map.