Regulation mechanisms of impeller geometry on hydraulic loss and impeller–volute pressure pulsations in a submersible centrifugal pump

Flow separation, strong shear, and periodic impeller–volute interaction are major sources of hydraulic loss and pressure pulsations in centrifugal pumps. This study investigates how impeller geometry regulates these phenomena in a submersible centrifugal pump using steady computational fluid dynamics (CFD) simulations validated against hydraulic-performance measurements of the original prototype, together with transient CFD calculations. Blade outlet width, blade outlet angle, and blade wrap angle were examined, while the entropy-generation-theory-based volumetric energy dissipation rate, including viscous and turbulent contributions, was used to evaluate local hydraulic losses. Response surface methodology and the non-dominated sorting genetic algorithm II identified a representative design within the prescribed geometric space. The three parameters were changed from 25 mm, 22.6°, and 90° to 26.33 mm, 24.8°, and 102.2°, respectively. Under the design operating condition, the CFD-predicted head increased from 35.92 to 38.32 m, while the CFD-predicted efficiency increased from 62.52% to 66.39%, corresponding to an increase in 3.87 percentage points, or 6.19% relative to the original value. The CFD results over 0.6–1.4 times the design flow rate indicate that the modified geometry is associated with a more continuous pressure-rise process, weaker recirculation and separation, less pronounced outlet-flow distortion, and reduced high-dissipation regions on the blade surfaces, at the impeller outlet, and near the volute tongue. The numerically evaluated integrated dissipation also decreases in both the impeller and the triple-volute casing. The dominant deterministic pressure components occur at the blade-passing frequency of approximately 290 Hz and its harmonics. The numerically predicted amplitudes decrease after modification, particularly near the volute tongue.