Numerical Analysis And Experimental Study Of Pneumatic Blast Cleaning

Pneumatic blast cleaning widely used in aerospace,automotive,machinery,chemicals,petroleum,shipbuilding and other industries because of its many advantages of low cost,high efficiency,good quality,play an important role in the protection of materials and surface engineering.However,there are lack of in-depth analysis of the efficiency and the optimization of the nozzle structure,and the selection of the process parameters is mainly based on experience,random,which lack of theoretical guidance and experimental optimization.In this paper,the CFD method is used to study the distribution characteristics of the nozzle flow field and the erosion characteristics of the wall.The parameters of the shot peening are optimized by the cleaning test,which provides the theoretical basis for the structural design of the nozzle and the selection of the process parameters.Firstly,Fluent was used to simulate the gas-solid two-phase flow field of the different types of nozzles by using the Standard k~ε model.The flow field characteristics of the inflow field and outflow field in the Contraction,Venturi and Streamlined nozzles were studied,so the law of jet pressure,velocity and abrasive distribution was obtained.Studies have shown that Venturi-type nozzle,which the divergence is better and the processing cost is low.Comprehensive consideration,the selection of Venturi-type nozzle is cost-effective for shot peening.Secondly,by changing the structural parameters of the nozzle,the gas-solid two-phase flow field simulation of the Venturi-type nozzle is carried out,so the velocity field of the gas and particles and particle trajectory under different parameters are obtained.The comparison shows that the effect of the Venturi-type nozzle cleaning is better,which the blowing angle α=30 °,the diffusion angle β=7° and the ratio of nozzle outlet diameter to diameter is about 1.7,further,the nozzle structure is optimized.Third,the effects of the different injection pressure and jet distance on the flow field acceleration,as well as the effects of different shot peening parameters on the vertical Wall erosion,were obtained by studying the gas-solid two-phase impinging flow field with the application of the optimized Venturi-type nozzle.The results show that the average erosion rate is better and the shot peening efficiency is higher,which the distance from the nozzle is less than 100 mm and the diameter of the abrasive is about 0.5mm.Finally,the sprayed plate was subjected to shot peening test,the optimum process parameters were obtained by comparing the effects of working pressure,jetting distance,shot peening time and injection angle on the surface cleanliness and roughness of the sample.Pneumatic Blast Cleaning for the different abrasive and dirt castings,comparative analysis of the cleaning efficiency showed that the ceramic balls is better than glass beads and white corundum,besides,Pneumatic Blast Cleaning is suitable for cleaning up the organic and covering dirt adaptability,which has less surface damage.