Aerodynamic Performance Investigation on a Co‐rotating Scroll Hydrogen Recirculation Pump for Fuel Cell Engines

The hydrogen recirculation pump is the core component of the hydrogen supply system of the vehicle fuel cell engine. This paper innovatively put forward a conceptual design of a high‐speed co‐rotating array scroll hydrogen recirculation pump with the fixed radial sealing position to ensure easy sealing on radial clearance leakage and without the dynamic balance weight. The array scroll structure has advantages in reducing the radial size and could significantly improve the pumping efficiency and realize the compact and lightweight design. The parametric design of the hydrogen recirculation pump was carried out. Then the aerodynamic performance of the hydrogen recirculation pump was analyzed via the three‐dimensional unsteady numerical simulation with the advanced and effective dynamic mesh technology combining morphing and remeshing functions. Firstly, the transient flow field characteristics in the scroll hydrogen recirculation pump under the design operating condition were investigated. Secondly, the effects of rotating speed on performance parameters such as mass flow rate and isentropic efficiency of hydrogen recirculation pump were analyzed. Finally, the study focused on the effects of hydrogen humidity on the aerodynamic performance of the designed co‐rotating scroll hydrogen recirculation pump. The results show that the fluid in the compression chamber is low‐speed, and the turbulence at the inlet of the suction chamber and the central exhaust chamber is intense. For the co‐rotating hydrogen recirculation pump, the increase of speed will not only aggravate the gap leakage but also aggravate the over‐compression phenomenon, resulting in the increase of exhaust loss as well as a decrease of isentropic efficiency at high speed. The highest isentropic efficiency occurs at the design speed, which is 84.31%. The humidity of hydrogen has a certain effect on aerodynamic performance. Compared with dry hydrogen, the isentropic efficiency decreases by 2.3% at 100% humidity, but the pressure and temperature rise change lightly, increasing by 0.63Kpa and decreasing by 0.3k respectively. Different hydrogen humidity has a great influence on the flow rate. With the increase of humidity, the gap flow velocity at the same rotating angle decreases by about 30m/s.