Study Of Turbulent Flow And Erosion Wear In Centrifugal Compressor Impeller

Centrifugal air compressor is a crucial equipment in petroleum and chemical industry, often used in heavy industry area where the environment is seriously polluted and the air quality is poor. Rotating impeller works at high speed under high temperature and high pressure and the compressed medium contains small solid particles or corrosion. So impeller failure frequency is higher. Therefore, it is of significant importance meaningful to research the wear mechanism of impeller blade and repair method for prolonging the service life of the impeller, reducing the failure rate and instructing deciding manufacture or remanufacture of the compressor impeller.By applying viscous standard two-equation turbulent model, three-dimensional Reynolds time-averaged control equations, numerical simulation was adopted to study the distribution of turbulent flow field in a centrifugal air compressor impeller with long and short blades, comparing the feature parameters such as absolute pressure, air flow relative velocity and turbulent intensity on the pressure and suction surface of long and short blade. The unsteady pressure change of different positions on the pressure surface of long blade and the change of the mass flow on impeller outlet are shown. According to the simulation results, the absolute pressure on pressure surface is greater than that on suction surface in the corresponding position and the greatest pressure is located on the trailing edge of pressure surface. The greatest relative velocity is located on the blade inlet. There is backflow phenomenon around the suction surface of the long blade and the short blade has significant effect to reduce backflow. The turbulent intensity on suction surface is greater than that on pressure surface in the corresponding position and the greatest turbulent intensity is located on the leading edge of suction surface.Based on Lagrangian tracking of solid particles’motion trajectories in a gas-solid flow, by applying discrete phase model and ductile materials erosion model, through orthogonal test, numerical simulation was adopted to study the distribution of erosion wear on blade pressure surface and the erosion rules in the centrifugal air compressor. According to the simulation results, in the geometric parameters of discrete particles, particle diameter has most influence on erosion wear of blade, the particle mass flow in the second place and particle initial speed’s impact is minimal. The most serious erosion wear part in impeller is blade pressure surface. The erosion wear position on blade pressure surface caused by particles impacting primarily locates on blade trailing edge roots, and blade middle part also has a certain degree of wear and tear.By using erosion wear test device, studies on the relation between the impact angle and the erosion wear of FV520B were carried out, in which the particle size (7μm), the impact velocity (180m/s) and the total quality of solid particle (100g) are fixed, the impact angles are12°,18°,24°,30°,45°,60°,90°. By applying test equipment (electronic microscope, handheld digital microscope and white-light interferometer), the erosion wear rate, microstructure and surface roughness of FV520B were measured respectively. With small impact angles, the erosion wear rate is high and the wear mechanism is given priority to micro cutting; With large impact angles, the erosion wear rate is not big, but the surface pits and grains are deeper and the wear mechanism is given priority to deformation and extrusion forging. Through error analysis, the experiment error is less than10%.