气动喷丸清理的数值分析及试验研究

发布时间：2018-04-06 02:37

本文选题：气动喷丸清理　切入点：喷嘴结构　出处：《重庆理工大学》2017年硕士论文

【摘要】：气动喷丸清理因其成本低、效率高、质量好等诸多优点,广泛地应用于航天航空、汽车、机械、化工、石油、船舶等行业,在材料保护和表面工程中发挥着重要作用。然而,现在工业喷丸清理技术缺乏深入地效率分析和喷嘴结构优化,工艺参数选取主要凭经验,随意性大,缺乏理论指导和试验优化。本文采用CFD的方法研究喷嘴流场分布特性及壁面的冲蚀特点,通过清理试验优化喷丸清理工艺参数,为气动喷丸喷嘴结构设计和喷丸工艺参数的选择提供了理论依据。首先,应用Fluent软件,采用Standard k~ε模型对不同类型喷嘴进行气固两相流场模拟仿真,深入研究收缩型、文丘里型和流线型喷嘴内流场及外流场的流场特性,获得了射流压力、速度以及磨料发散分布的规律。研究表明,文丘里型喷嘴发散性较好,加工成本低。综合考虑,选用文丘里型喷嘴进行喷丸清理性价比较高。其次,通过改变喷嘴的结构参数,对文丘里型喷嘴进行气固两相流场模拟仿真,获得了不同参数下气体和颗粒的速度场及颗粒的运动轨迹。分析比较得出:收缩角α=30°,扩散角β=7°,喷嘴出口直径与通径之比为1.7左右的文丘里型喷嘴清理效果较好,进而优化了喷嘴结构。然后,利用优化后的文丘里型喷嘴对壁面进行气固两相冲击流场的仿真研究,得出了不同喷射压力和喷射距离的气体对流场加速的影响,以及不同喷丸工艺参数对垂直壁面冲蚀的影响。研究表明:壁面离喷嘴出口距离在小于100mm,磨料直径为0.5mm左右,平均冲蚀率较好,喷丸清理效率较高。最后,对喷漆钢板进行喷丸清理试验,通过比较喷射压力、喷射距离、喷射时间和喷射角度对试样的表面清洁度和粗糙度影响,获得了最佳的工艺参数值。通过对不同磨料和污垢铸件喷丸清理,清理效果的对比分析表明,陶瓷丸的清理效果优于玻璃珠、白刚玉的清理效果,喷丸清理对有机物污垢或覆盖性污垢适应性强,表面损伤较小。
[Abstract]:Pneumatic shot peening is widely used in aerospace, automobile, machinery, chemical industry, petroleum, ship and other industries because of its low cost, high efficiency, good quality and so on. It plays an important role in material protection and surface engineering.However, the industrial shot peening cleaning technology is lack of in-depth efficiency analysis and nozzle structure optimization, the selection of process parameters is mainly based on experience, randomness, lack of theoretical guidance and test optimization.In this paper, CFD method is used to study the characteristics of nozzle flow field distribution and wall erosion. Through cleaning test, the parameters of shot peening cleaning are optimized, which provides a theoretical basis for the structure design of pneumatic shot peening nozzle and the selection of shot peening process parameters.Firstly, using Fluent software and Standard k- 蔚 model to simulate gas-solid two-phase flow field of different types of nozzles, the characteristics of flow field and flow field of condensed, Venturi and streamline nozzles are studied in depth, and the jet pressure is obtained.Velocity and distribution of abrasive divergence.The results show that Venturi nozzle has good divergence and low processing cost.Considering synthetically, the Venturi nozzle is selected for shot-peening cleaning with high cost-effective ratio.Secondly, by changing the structure parameters of the nozzle, the gas-solid two-phase flow field of Venturi nozzle is simulated, and the velocity field and particle motion track of gas and particle are obtained under different parameters.Analysis and comparison show that the Venturi nozzle with contraction angle of 30 掳, diffusion angle of 7 掳and the ratio of nozzle diameter to path diameter of 1.7 is better, and the nozzle structure is optimized.Then, by using the optimized Venturi nozzle to simulate the gas-solid two-phase impingement flow field on the wall, the effect of different injection pressure and injection distance on the acceleration of the gas flow field is obtained.And the effect of different parameters of shot peening on the erosion of vertical wall.The results show that the distance between the wall and nozzle outlet is less than 100mm, the abrasive diameter is about 0.5mm, the average erosion rate is better, and the efficiency of shot peening is higher.Finally, a shot peening cleaning test was carried out on the painted steel plate. By comparing the effects of spray pressure, injection distance, injection time and injection angle on the surface cleanliness and roughness of the sample, the optimum technological parameters were obtained.The comparative analysis of shot peening effect of different abrasive and fouling castings shows that the cleaning effect of ceramic pellets is better than that of glass beads, white corundum, and shot peening has a strong adaptability to organic dirt or overlay fouling, and the cleaning effect of ceramic pellets is better than that of glass beads, white corundum and shot peening.Surface damage is small.
【学位授予单位】：重庆理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG668

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