Role of Solidification, Substrate Temperature and Reynolds Number on Droplet Spreading in Thermal Spray Deposition: Measurements and Modeling
Role of Solidification, Substrate Temperature and Reynolds Number on Droplet Spreading in Thermal Spray Deposition: Measurements and Modeling
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热喷涂沉积中凝固、基材温度和雷诺数对液滴铺展的作用：测量和建模
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
V. Prasad
中科院分区：
文献类型：
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作者：
Y. Wan;Hui Zhang;X. Jiang;S. Sampath;V. Prasad
对等离子喷涂钼和氧化锆熔滴在不同基体材料上沉积的扁平度进行了数值分析和实验测量。研究了凝固速度和润湿角对液滴铺展的影响。采用Madejski-Zhang模型对凝固过程进行了一维处理，同时考虑了熔体、凝固层和基体中的传热。参数研究进行检查的液滴尺寸，冲击速度，过热的液滴，基板温度，热接触电阻，和润湿角上的飞溅和其平坦化程度的蔓延的影响。数值结果表明，凝固时间可以和铺展时间一样短，凝固速率对压扁程度有很大影响。当润湿角和表面张力对液滴变形的影响可以忽略不计的准则。推导出了考虑凝固时扁平度与雷诺数的关系式，给出了液滴凝固对冲击动力学影响可以忽略的判据。文中还讨论了等温衬底假设的局限性。数值计算结果与实验数据吻合较好。
Numerical analysis and experimental measurements of the flattening degree of plasma sprayed molybdenum and zirconia droplets deposited on different substrate materials are presented. Investigation is focused on the influence of rate of solidification and wetting angle on droplet spreading. Madejski-Zhang model with one-dimensional treatment of solidification as well as heat transfer in the melt, solidified splat and substrate is employed to perform a numerical analysis. A parametric study is conducted to examine the effects of droplet size, impact velocity, superheating of droplets, substrate temperature, thermal contact resistance, and wetting angle on spreading of the splat and its flattening degree. Numerical results show that the time for solidification can be as small as that for spreading and the rate of solidification can greatly influence the flattening degree. A guideline for when the effect of wetting angle and surface tension on droplet deformation can be neglected is derived. A correlation for the relationship between the flattening degree and Reynolds number with the consideration of solidification is deduced, and a criterion for the effect of droplet solidification on impact dynamics to be negligible is given. The limitations of the assumption of isothermal substrate are also discussed. The numerical predictions agree statistically well with the experimental data.