Experimental investigation of the impact of blade number on energy performance and pressure fluctuation in a high-speed coolant pump for electric vehicles

The high-speed coolant pump is a critical component of the thermal management system in electric vehicles, responsible for circulating coolant to regulate the temperature of batteries. However, the impact of the impeller blade number on the energy performance and pressure fluctuation of high-speed pumps is still undetermined. An experimental bench for coolant pumps of high rotational speeds is built, a mathematical model of the theoretical head is proposed, and comprehensive studies on blade numbers (Z) ranging from 2 to 7 are conducted. Both head-curve and efficiency-curve decline as the blade number decreases, with the reduction rate progressively increasing. At the design flow rate, the head and efficiency for Z = 6 are 12.3 m and 66.4 %, respectively, with the hydraulic performance of Z = 7 being close to that of Z = 6. For each blade number, integer multiples of the impeller rotation frequency dominate. Z = 6 has the smallest amplitude at the blade passing frequency and impeller rotation frequency, with a 30.7 % reduction compared to Z = 7 at the design condition. Z = 6 is identified as the optimal solution, considering energy performance and pressure stability. This research greatly promotes the development of energy-saving and low-noise pumps.