NUMERICAL CALCULATION OF INTERNAL TURBULENT FLOW CHARACTERISTICS INSIDE A PUMP AS TURBINE

To address the issue of unclear internal turbulent flow characteristics when a centrifugal pump operates in reverse as a hydraulic turbine, the standard RNG k-ε turbulence model was adopted, with liquid water as the working medium. Numerical calculations were performed on the internal flow of this hydraulic turbine, and the turbulent flow characteristics of the fluid inside the turbine were analyzed. The results indicate that: the overall turbulent kinetic energy level of the volute is low, which increases slightly with the rise of inlet flow rate, and flow disturbances in the region adjacent to the impeller contact surface are weak; the turbulent kinetic energy at the volute tongue is significantly higher than that in other regions of the volute—it is uniformly distributed under low operating conditions, while under high operating conditions, it exhibits intense fluctuations and high concentration, with prominent vortex phenomena; for the impeller, the turbulent kinetic energy decreases monotonically along the flow channel under low operating conditions; under high operating conditions, the fluid disturbance at the outlet increases sharply, and the distribution of turbulent kinetic energy deviates from a steady state; the turbulent kinetic energy in the middle region of the outlet section is relatively high, which tends to result in a decrease in flow stability.