Large eddy simulations of side channel pump in different operating conditions

Large eddy simulations (LES) of a side channel pump are conducted at different operating conditions, including best efficiency point (BEP) and off-design conditions. To address the numerical challenges of this LES, a high-quality mesh consisting of 116 million cells is generated for the impeller and casing parts. These parts are connected by three mesh interfaces, allowing for mesh motion at 3,450 RPM. The impeller with 72 staggered blades embedded in the side channel cavity transfers momentum to the flows in flow rates in the range of Q/QBEP∈[0.8−1.2], where Q is the volumetric flow rate. The validation shows a 5.1% efficiency deviation at the off-design condition of 0.8QBEP, where the flow is more unsteady than at other flow rates. The results reveal the state of turbulence, the pressure fluctuations and the vortical structures at the impeller periodic frequencies. The turbulence intensity of about 40% increases exponentially as the flow progresses around the impeller, driven by the interaction between the impeller blades and the radial discharge from the casing. The study illustrates that the state of turbulence is homogeneous in circumferential locations as θ∈[π/2−3π/2] of the casing, while the inlet and outlet ports change the state of turbulence. The six large structures generated by the impeller are related to the pressure fluctuations. The pumped outflow illustrates a moderate level of swirl while retaining extreme turbulence intensity in all conditions. The highest level of outflow swirl and turbulence is reported in 0.8QBEP. The study provides a comprehensive understanding of the complex vortical patterns and recirculation zones, which contribute to potential design improvements for enhanced, pump performance.