Hydraulic Characteristics of a Single-channel Pump Designed by the Affinity Law

Recently single-channel pumps are widely applied for wastewater treatment in Korea. To be able to apply this type of pump in the world, which is different in power frequency, this study uses the affinity law to redesign the impeller geometry of the single-channel pump optimized from the previous work. Meanwhile, the volute is designed by two methods which are the affinity law and the cutting diameter method. The numerical approach is performed by using steady and unsteady Reynolds-averaged Navier-Stokes equations and a shear stress transport reattachment modification (SST k-ω) turbulence model. The hydraulic efficiency curves and internal flow field including contours and streamlines are investigated and evaluated thoroughly. The numerical result is verified by the experimental test based on the 11SUPth/SUPAPI610 standard. At the design flow rate condition, the novel pump models meet the design requirement with a minimum total head coefficient. The efficiency of the novel models remains almost unchanged compared to the base model. The sweep area of the unsteady radial force distribution in the novel models is smaller than that of the base model at low flow rate and design flow rate conditions while at high flow rate conditions show the opposite. In addition, the distance between the center of the radial force and the origin of the novel models is also reduced compared to the base model. The pressure amplitudes of the novel models are also decreased significantly. These improvements in the novel models mostly result in the reduction in noise and vibration in pump operation.