Flow characteristics of a low-head and high-discharge hydraulic turbine under various operating conditions

A low-head and high-discharge hydraulic turbine holds significant potential for energy recovery across various engineering applications, owing to its capacity to manage substantial flows. However, the intricate mechanisms of energy loss within this turbine, particularly concerning its impeller and discharge tube, have received limited investigation. In this study, we present a comprehensive examination of the energy dissipation mechanisms, flow characteristics, and streamwise vorticity of the low-head and high-discharge hydraulic turbine. Utilizing the enstrophy dissipation theory, we conducted analyses under diverse operational conditions. Our findings reveal that energy dissipation predominantly occurs within the impeller and discharge tube. Volume enstrophy dissipation power contributes to over 80% of the total hydraulic loss under three flow rate conditions. Flow separation and intricate turbulence patterns emerge as primary factors contributing to energy loss within the impeller, while backflow and turbulence are that in the discharge tube. The regions with high energy loss in impeller is near the leading and trailing edges and in the discharge tube that is around the entrance.