INFLUENCE OF DIFFERENT IMPELLER DIAMETER ON CAVITATION PERFORMANCE IN AN ENGINE COOLING WATER PUMP

The engine cooling water pump (ECWP) is an important part in the motor and engine. Using the advanced numerical methods and tools to enhance the ECWP performance, not only could reduce the power consumption and weight, but also can promote the safety and reliability of the vehicle system. The cavitation damage in the ECWP shortens the reliability and life of the motor cooling system, as well as produces vibration and noise. Cavitation in the ECWP has been become an important research topic. To investigate the cavitation performance of ECWP with different impeller diameter, the three dimensional turbulent flow in the ECWP with different impeller diameter was numerically simulated employing the time averaged N-S equation, the standard k-epsilon turbulent model and multiphase flow model by ANSYS-CFX software. The structured hexahedral mesh has been generated for improving the accuracy of numerical simulation. Comparing with the experimental pump performance results, the cavitation performance is accurately predicted based on structured mesh and cavitation model. The comparison of fluid static pressure and vapor volume fraction contours, hydraulic and cavitation performance was made among different impeller diameter. The cavitation performance curve and bubble distributions under different impeller diameter were compared and analyzed, we find that absolute pressure at the critical cavitation point becomes higher with the decreasing of the impeller diameter, and the anti-cavitation performance becomes worse caused by the increasing of the volume fraction in-the impeller. Therefore, there is an optimum impeller diameter value to guarantee the anti-cavitation performance and hydraulic performance of the investigated pump.