Effect of Disk Friction Loss Reduction on Flow Phenomena in Low-specific Speed Centrifugal Pump: An Experimental and Numerical Approach

Disk friction loss (LDF) plays an important factor in the performance of the low-specific speed (NS) centrifugal pump. Reducing the rear axial clearance (Cs,a,r) is profound method to lower the LDF and improve the efficiency of pump (η). In this research article, a low NS = 19 rpm centrifugal pump was evaluated using computational fluid dynamics (CFD) and experimental analysis at different 1000, 900 and 800 rpms over a range of flow rates (Q). Two models: Model A with original Cs,a,r of 23 mm and Model B with reduced Cs,a,r of 1 mm were analyzed. To grasp the knowledge about internal flow physics, the pressure contours, velocity contours, velocity vectors and streamlines have been thoroughly studied. CFD results were found in good agreement with the experiments performed on the test setup. The experimental improvements in η at their respective best efficiency points (BEP) were determined to be 3.94%, 3.91%, and 2.81% for 1000, 900, and 800 rpms respectively. While an average 3.43%, 1.79% and 0.76% improvement in head (H) was obtained for 1000, 900, and 800 rpms respectively. Considering the lower disk friction coefficient (Cm) and power loss (PL) due to LDF, the Model B works optimum at higher rpm.