Analysis of internal flow characteristics in hydrogen circulation pump with variable trochoid ratio profile

For the roots hydrogen circulating pump (HCP), different rotor profiles result in variations in flow pulsation, pressure pulsation, and pressure-velocity distribution within the pump. In this study, unsteady numerical simulations were conducted on the HCP with variable trochoid ratio profiles to analyze its flow characteristics. The findings indicate that employing a variable trochoid ratio to design the rotor profile enhances the amplitude of the HCP's inlet and outlet flow rates, with a greater impact on the pulsation of the inlet flow rate. In comparison to an ordinary trochoid profile, the variable trochoid ratio profile exhibits reduced vortex in the suction chamber and is less affected by leakage flow between the rotor and casing. Furthermore, due to the lager area utilization rate of the variable trochoid ratio profile, the volume of the HCP's suction chamber increases, facilitating the full development of inlet flow and generating a high kinetic energy vortex, thereby further augmenting the inlet flow.