Transient flow in high-speed coolant pumps with impeller single-passage blockage

The reliability of the high-speed coolant pump, a critical component in electric vehicle thermal management systems, is paramount to ensuring vehicle thermal safety. However, blockage arising from impeller manufacturing defects or the deposition of coolant particles can significantly impair performance. To investigate the effects of impeller single-passage blockage on the internal flow characteristics of the pump, this study employs a combined experimental and numerical simulation approach. The analysis focuses on hydraulic performance, transient velocity, pressure fluctuations, and vortex evolution. The simulation results demonstrate good agreement with the experimental data. The results indicate that the single-passage blockage is the primary cause of performance degradation, resulting in maximum reductions in head and efficiency of approximately 14.9% and 4.0%, respectively. This blockage significantly disrupts the uniformity of flow in the impeller. In the passage immediately clockwise to the blockage, flow separation is exacerbated, creating an extensive low-velocity region. Conversely, in the adjacent counterclockwise passage, fluid deflection induces a localized velocity surge, accompanied by intense periodic fluctuations. Blockage not only amplifies pressure fluctuation amplitudes under all operating conditions but also alters the dominant frequencies, which are primarily the blade passing frequency (corresponding to seven blades) and the shaft frequency. Furthermore, the blockage intensifies vortex structures within the impeller, leading to an uneven distribution and more complex dynamic evolution. These findings provide solid theoretical support for enhancing the reliability of high-speed coolant pumps and lay a foundation for developing pressure-fluctuation-based fault diagnosis techniques.