Pumping performance of a wind-driven axial pump: experimental evaluation of pump geometry and destratification performance

This study presents an experimental investigation of a vertical axial flow pump operating under varying impeller configurations, including different blade numbers, blade pitch angles, and submergence ratios. An empirical correlation for predicting the nondimensionalized pumping flow rate was developed using a Genetic Algorithm based on the collected dataset. The pump was further coupled with a Savonius type wind turbine rotor to assess its efficiency for destratifying thermally stratified water layers of varying intensities in a custom-built tank. The results indicate that most operating conditions fall within a stable regime at rotational speeds between 1900 and 2600 rpm, corresponding to dimensionless discharge in between 0.04 and 0.09. Higher flow rates where dimensionless discharge is greater than 0.15, were primarily associated with pitch angles of 30–40°, highlighting the dominant influence of geometric parameters. Pitch angle exhibited the strongest effect on dimensionless discharge, while blade number and submergence ratio produced weaker but systematic trends. Additionally, increased with rotational speed, suggesting incomplete turbulent development within the system. Experiment results revealed that mixing operations could successfully eliminate the thermal stratification within the efficiency range in between 88% and 94%.