Research On Aerodynamic Characteristics Of Helical Groove Radial Bearings In Fuel Cell Air Compressors

Fuel cell is an electric vehicle’s power generation device.Fuel cell works by reacting oxygen at the cathode with hydrogen at the anode to produce electricity.Therefore the fuel cell system must rely on air compressor to provide compressed air for the fuel cell cathode,and to the requirement of air compressor is must be free of oil,this is because the lubricating oil can make the catalyst poisoning in the fuel cell stack,and better dynamic performance requirements of air compressor,air compressor speed is quite high,therefore,the bearing,as important parts of air compressor,Oil bearing due to its own defects,do not meet the conditions,and the spiral groove dynamic pressure radial air bearing has good stability,high precision,high speed,resistance to radiation,high temperature resistant,pollution-free advantages are widely used in medical equipment,medicine industry,precision lathe,gas turbine and expansion turbine machinery,is one of the most applications of all the mechanical air dynamic pressure bearing.But it also has some shortcomings,low bearing capacity,stiffness,less research on static characteristic of this kind of bearing,also because of the spiral groove the particularity of dynamic pressure radial air bearing structure,very easy to cause the spiral groove bearing surface contamination,the surface of the spiral groove bearings pollution mainly comes from air bearing under the rev.Drop by continual contact wear particles,Although it took a variety of means to clean up,but the effect is not obvious,is not completely solve this problem,also did not master the solid particles in the trajectory and sedimentary rule of bearing,so for the study of static properties of this type of bearing and solid particles in the trajectory and sedimentary rule of bearing,It is of certain practical significance to improve the bearing life to make the excess particles entering the bearing automatically eliminate the bearing or guide the solid particles to deposit in the designated area of the bearing.Thesis paper mainly studies the static characteristics of gas bearings and the law of particle movement and deposition in bearings.The main technical routes are shown as follows.1)Based on the navier-Stokes equation of gas lubrication,some basic assumptions are made for gas and bearings,and the compressible unsteady Reynolds equation and the bearing capacity expression of spiral groove air radial bearings are derived.2)The three-dimensional spiral groove dynamic pressure air bearing physical model is established by using Solid Work software,and the basic gas lubrication equation Navier-Stokes equation is directly solved by CFD technology and fluid dynamics Fluent software.Meanwhile,the bearing characteristics of radial air bearing are studied.The pressure cloud diagram of the bearing under different rotational speeds and the variation law of the gas film pressure distribution and bearing capacity of the spiral groove dynamic pressure radial air bearing affected by the structural parameters and operation parameters of the spiral groove dynamic pressure radial air bearing were obtained,which provided a theoretical basis for the further study of the spiral groove radial air bearing.3)In the process of bearing operation,the inhalation of particulate matter will cause the bearing to be blocked.Therefore,the DPM model is introduced into spiral groove dynamic radial air bearings to study the movement law of metal particles in spiral groove air bearings in the bearing clearance and the deposition law of metal particles in the bearing.When the structural parameters of spiral groove radial bearing and the properties of solid particles change,the movement track and deposition rule of particles in the bearing are obtained.4)in view of the particulate matter in the bearing structure parameters and the particulate matter itself changes,the trajectories of particles and sedimentary rule,designed a new type of surface groove structure,surface groove is relative to the face to face with groove machining hard,but found by numerical simulation,the surface groove can improve bearing system itself spontaneous discharge particulate matter,achieve the purpose of purifying,It is of great significance to improve the life of bearings and even machinery.