An Evaluation of Impeller Blade Torque During an Impeller–Diffuser Interaction

An evaluation of the torque on an impeller blade interacting with a diffuser blade is presented. Comparisons of time averaged quantities are made between computed and measured results. The calculation of the impeller blade torque was based on the axial moment from fluid forces acting on a control volume surrounding an impeller blade passage. Unsteady flow field contributions were incorporated in the computational model. Results are compared to numerical predictions of the impeller blade torque based on pressure and shear stress terms integrated over the blade and wall surfaces. From the fluid forces perspective the major contribution to the time averaged impeller torque originated on the impeller inlet and outlet control surfaces. Contrarily the major contribution to the unsteady impeller torque originated in the unsteady flow field within the impeller control volume.