层流电弧等离子体射流发生机制与稳定性影响因素

Restricting the flow and energy fluctuation of a thermal plasma jet could be crucial importance to increase the processing stability and controllability for its more effective and wider application. This project attempted to generate a laminar plasma jet of stable flow, and to investigate systematically its characteristics compared with a turbulent jet. As results, a laminar plasma generator of simple structure, high stability and thermal efficiency was obtained; Relationship between arc root movement and the torch channel structure, arc current, gas feeding method and gas flow rate is made relatively clear now; A laminar plasma jet of stable flow, low temperature and velocity gradient along its axial direction was generated with quite low working noise; The length of a pure argon laminar plasma jet can over 550 mm, and the ratio of its length to diameter can over 70, at the input power of 10 kW. Based on the similarity theory analysis combining with the experiment results, formulas were obtained for calculating the arc voltage, thermal efficiency and jet length. At the same time, heat flux and pressure distribution were numerically calculated and experimentally measured when the laminar plasma jet impinges on a flat plate. The high stability of the flow and its low impinging pressure on the plate surface could make this kind of plasma jet suitable for cladding and remelting strengthening process of materials surface.

完成发生器的合理设计，采用多种测试手法，以实验分析为主计算为辅，把握等离子体发生各参数的相互作用规律及其控制方法，产生出有实用价值的直流大气压层流电弧等离子体射流，理解其形成机理和稳定性影响因系，证实这种等离子体状态比一般紊流等离子体射流，具有稳定性好、对周围气体卷吸少、热效率高、应用于材料加工的工艺可控性高的特点。