超音速等离子射流中飞行粒子的熔化行为研究

Melting behavior of in-flight particles in supersonic plasma jets

耐高温陶瓷材料氧化钇部分稳定的二氧化锆(Yttria Partially Stabilized Zirconia,YSZ)以其优异的隔热、抗高温氧化等特性,近年来在核电军工、航空航天等领域得到关注。本研究基于计算流体动力学(Computational Fluid Dynamic,CFD)方法,建立了关于超音速喷涂(Supersonic Atmospheric Plasma Spraying,SAPS)等离子流场三维模型,分析了不同喷涂参数在拉伐尔喷嘴中产生的射流特性和飞行粒子的熔化和受力状态。当喷涂参数从71 kW降低到36 kW,喷涂功率降低了49.2%,等离子体射流的最高速度降低了8.5%,最高温度降低了22.2%;使用在线监测设备Spray Watch 2i(Osier,Finland)对飞行粒子的速度和温度进行在线实测,与模拟结果的对比表明:两者的相对误差在15%以内,模拟与试验结果得到了有效地相验证,这为核反应中的耐事故燃料包壳所需的高性能隔热涂层结构的精确控制提供理论指导。

[Background]Nuclear high-temperature resistant ceramic materials have been widely used in nuclear energy,military,and aerospace fields in recent years owing to their excellent thermal insulation and high-temperature oxidation resistance.[Purpose]This study aims to investigate the mass and heat transfer process between plasma fluid and flying particles in supersonic plasma spraying during the preparation of yttrium-stabilized zirconia thermal barrier coatings,so as to reveal the process parameters of flying particles.[Methods]Firstly,the computational fluid dynamics(CFD)approach was employed to simulate the interaction between flying particles in the plasma spraying process.Then,a three-dimensional mathematical model of the plasma spraying flow field was established,and the jet characteristics of different spraying parameters in the de Laval nozzle and the melting and stress state of flying particles were analyzed by using this model.Furthermore,the online monitoring device Spray Watch 2i(Osier,Finland)was used to compare the online measurement of the velocity and temperature of flying particles obtained with the simulation results.[Results]The comparison results show that relative errors are within 15%,verifying the simulation results effectively by experimental results.When the spraying power is reduced from 71 kW to 36 kW(i.e.,reduced by 49.2%),the maximum velocity of the plasma jet is reduced by 8.5%,and the maximum temperature is reduced by 22.2%.[Conclusions]A correlation between plasma spraying parameters,jet characteristics,and melting of flying particles is revealed in this study,providing theoretical guidance for the precise control of high performance thermal insulation coating structures required for accident resistant fuel cladding in nuclear reactions.