Effect of Impeller Design on the Performance of a Small-Scale Regenerative Blower With Semi-Circular Side-Channel and Rotor Cross-Sections

Abstract Small-scale side-channel or regenerative blowers are used in various applications, e.g. as components in medical system solutions, for air-circulation in space suits or as hydrogen recirculation blowers in PEM fuel cells. These non-conventional turbomachines are characterized by high energy transfer rates, generating large pressure differentials at low volumetric flow rates and low flow pulsations. They are simple in construction, reliable and require little maintenance. Typical drawbacks of these machines are their low aerodynamic efficiencies and unfavorable sound radiation. The present study examines the performance of a small-scale side-channel blower with semi-circular side-channel and rotor cross-sections (in the meridional plane) as function of impeller design, i.e., blade angle and inner-to-outer radius ratio, for different rotational speeds. Head/flow performance curves are determined via experiments and selected machine designs are further evaluated by means of numerical simulation using the commercial CFD solver ANSYS Fluent v. 2022 R1. Unsteady simulations are carried out using the transient sliding mesh method and predictions from different turbulence models, i.e., RSM (Reynolds stress model), DDES (Delayed Detached-Eddy Simulation) and k-ω SST turbulence model, are evaluated for selected machine configurations. While the RSM and DDES models capture smaller vortical structures relevant for accurate predictions of acoustic behavior, mean meridional velocities are overestimated by these models, thereby overpredicting the pressure rise in comparison to the experiments. In contrast, the k-ω SST model is found to only slightly overpredict the pressure rise across the machine.