摘要
层流等离子体射流冲击基板是等离子体喷涂、等离子体表面处理等典型制造工艺中的关键共性过程,但其涉及的流动和传热特性尚未完全揭示,使得工艺参数的确定缺乏依据。本文根据电信号分析了氮氩混气层流等离子炬的弧压和功率特性,再结合图像分析方法研究了层流等离子体射流的流动特性,最后结合相变硬化法研究了射流撞击基板的传热特性。结果表明:增加电弧电流会少量增加发生器的实际输出功率和射流的速度和温度,略微减少空气的夹带和增加射流高温区长度,但传输到基板的热能变化不大,总的传热效率降低;增加气流量和氮气比例可以大幅提高射流的功率,提高射流出口的速度和温度,减少空气的夹带,增大高温区的半径和长度,提高传输到基板的热流密度和总的传热效率,除此之外,改变工作参数对热影响区半径的影响不大。
Laminar plasma jet impinging on the substrate is a common working condition in typical process like plasma spraying, plasma surface hardening, etc. However, its flow and heat transfer characteristics have not been fully revealed, resulting in the difficulty in the determination of the working parameters in these processes. This paper analyzed the arc voltage and power characteristics of a laminar plasma torch with nitrogen-argon mixed gas based on the electrical signal, and studied the flow characteristics of laminar plasma jet with an image processing method, finally studied the heat transfer characteristics of plasma jet impinging upon the substrate with a surface phase transformation hardening method. Results showed that the increase of the arc current resulted in a slight increase of the jet power, outlet velocity and temperature, a slight reduction of the air entrainment and a slight increase of the length of the high temperature zone, but the heat energy transferred to the substrate was almost the same and the overall heat transfer efficiency was reduced.Increasing the air flow rate and the ratio of nitrogen can greatly increase the jet power, the velocity and temperature of the plasma jet, reduce the air entrainment, increase the radius and length of the high temperature zone, and increase the heat flux density and total heat transfer efficiency transferred to the substrate. In addition, the variation of the working parameters has little effect on the radius of the heat-affected zone.
作者
宋文杰
余德平
张斌
彭科铭
吴淦炀
SONG Wenjie;YU Deping;ZHANG Bin;PENG Keming;WU Ganyang(School of Mechanical Engineering,Sichuan University,Chengdu 610065,China)
出处
《工程热物理学报》
EI
CAS
CSCD
北大核心
2022年第9期2501-2511,共11页
Journal of Engineering Thermophysics
基金
国家自然科学基金资助项目(No.51875372)
四川大学宜宾市人民政府市校战略合作项目(No.2019CDYB-7)。
关键词
层流等离子体束
射流冲击
传热特性
热流密度
laminar plasma jet
jet impingement
heat transfer characteristics
heat flux density
