Fuel Cell Gas Circulating Pump Rotor Chamber Internal Transient Research On The Flow And Pneumatic Properties

Hydrogen energy has been widely used in new energy transportation,distributed power supply,fixed power generation,military applications and other fields as a kind of renewable clean energy.Fuel cell has attracted worldwide attention as a key technology of hydrogen energy application.As the core component of fuel cell,cam-type gas circulation pump not only needs to meet its performance indexes such as high efficiency and high sealing,but also has special requirements of lightweight,small size and low power consumption.Rotor plays an important role for the whole operation process to pump as the core component of cam-type gas circulating pump.Reasonable rotor profile design and processing technology are the keys to improving the efficiency of the pump,but also can effectively suppress the vibration and noise of the pump operation,thus improve the pump reliability and durability in the practical work.Based on this,the internal and external pendulum type,internal and external arc type and arc-involute arc type rotor profiles are deduced respectively,and the internal flow laws of different types of cam-type gas circulation pump rotor cavities are studied.Taking the three-blade arc-involute rotor with different diameter-pitch ratio as the research object,the variation law of the performance of cam-type gas circulation pump under different rotor parameters was explored.At the same time,in order to reduce the natural exhaust pulsation of the gas circulation pump,this paper changes the traditional constant pump cavity structure,and designs a kind of gradually expanding pump cavity structure at the high pressure side of the rotor cavity.The influence of the gradually expanding segment on the exhaust pulsation of the gas circulation pump is revealed by numerical simulation,which provides a certain theoretical basis for the development of low noise gas circulation pump.The main contents and conclusions of this paper are as follows:（1）Arc-shaped rotors have the highest volume utilization coefficient,but the volume efficiency is the lowest,and the operation pulsation is the largest,the operation is unstable,involute and pendulum rotor volume efficiency is higher,about 70%;With the increase of blade number,the overall outlet average pressure of different profile rotors increases,which has an obvious inhibition effect on pressure pulsation,and the pendulum rotor has an obvious pressurization effect on medium.The straight-blade rotor is mainly affected by the force in the x and y directions,without the action of axial force.The rotor profile will affect the magnitude of the force and amplitude intensity,but the influence is not obvious.Pendulum and involute rotors have less vortex inside the rotor cavity and the flow is more stable,while arc-shaped rotors have more serious vortex inside and serious internal leakage.（2）The rotor diameter-distance ratio has an obvious effect on the performance of gas circulating pump.With the increase of rotor pitch ratio from 1.34 to 1.45,the average flow rate and instantaneous flow pulsation at the pump outlet show an upward trend,and the change is obvious at 1.38-1.40,and the average flow rate increases by0.001833m³/s（15.8%）.Rotor diameter-distance ratio has a certain suppression effect on the outlet pressure pulsation of gas circulating pump.When the diameter to pitch ratio is 1.40,the outlet pressure secondary pulsation decreases.When the rotor diameter to pitch ratio is between 1.38 and 1.40,the rotor force is better,and the influence on the radial excitation force component Fx is obvious,but the influence on the radial excitation force component Fy is not significant.The vorticity distribution in the rotor cavity changes obviously with the rotor diameter-distance ratio.When the rotor diameter-distance ratio is 1.40,the vorticity distribution in the rotor cavity is small,which effectively inhibits the gas backflow.（3）Different pump cavity structures have large energy dissipation in the rotor engagement region adjacent to the inlet.When r_max=0.08,the strong turbulent kinetic energy reaches the minimum,and there is no energy dissipation at the outlet.With the increase of pump cavity clearance r_max,the pressure pulsation at the outlet shows an overall trend of first decreasing and then rising.When r_max=0.08,the pressure pulsation at the outlet reaches the minimum value and the peak value is 243072Pa,and the curve is relatively stable.（4）Gradually expanding pump cavity structure can effectively reduce the flow pulsation at the outlet,but the suppression effect is not obvious.With the increase of pump cavity gap r_maxfrom 0 to 0.16mm,the instantaneous flow amplitude at the outlet decreases by 4.72%.The maximum torque of the rotor is mainly distributed between70°and 110°.With the increase of r_max of pump cavity clearance,the torque of the rotor decreases first and then increases,and reaches the minimum when r_max=0.08.The structure of gradually expanding pump cavity has a significant effect on the sound field in the rotor cavity of gas circulating pump.With the increase of pump cavity gap r_max,the sound pressure level of the internal sound field decreases first and then increases.