The arc plasma torch can be used for pre experiments on ground erosion performance testing of spacecraft flight materials，which can save costs. The three-phase AC arc plasma torch has the advantages of simple power supply and reliable operation. The hollow electrode structure with dual inlet channels can not only improve the electrode life, but also achieve a wider range of power control. However, the design of plasma torches with this type of electrode structure is more complex and there is limited research and application in China. A three-phase AC plasma torch with magnetic motion, tangential inlet, and supersonic jet was developed and numerically modeled and experimentally studied.
Firstly, a three-dimensional turbulent MHD multiphysics coupling simulation model of a hollow electrode three-phase AC arc plasma torch with a dual end inlet structure was established, and the flow state and electric thermal characteristics of the arc plasma inside the torch were obtained. Secondly, the influence laws of air intake, working current, air intake distribution ratio, and working frequency on the electric field, magnetic field, temperature field, flow field distribution, and arc characteristics inside the plasma torch were studied and revealed. Finally, the correctness of the numerical model was verified by comparing the arc voltage, nozzle outlet temperature, and arc root position under various operating conditions in simulation and experiment.
The conclusion drawn from the study is as follows: (1) In a three-phase AC plasma torch, aerodynamic and electromagnetic forces dominate the flow characteristics of the arc root. During the process of increasing the intake volume from 30 g/s to 60 g/s, the cooling effect of the gas flowing along the wall is greater than the heat generated by the arc column, resulting in a downward trend in temperature; And the larger the intake volume, the more obvious the compression effect of the cold air layer on the arc, and the higher the arc pressure; The higher the working current, the higher the plasma temperature and jet velocity. (2) In a hollow electrode AC plasma torch with dual inlet ducts, changing the air intake distribution ratio can alter the position of the arc root along the electrode axis and the magnitude of the output power. Increasing the air intake distribution ratio can make the arc more significantly stretched in the axial direction, the arc longer, and the arc root closer to the arc back cover. (3) When the operating frequency is 1 kHz, the arc has a more stable motion trend, and the rotation speed of the arc root is five times that of the power frequency. The contact area with the electrode is reduced, which reduces the degree of electrode erosion and can improve the electrode life.