Abstract:

This study conducts a numerical simulation of a coaxial dual-chamber plasma generator based on MHD theory. The research aims to reveal the distribution characteristics of the arc-plasma and the behavior of the flow field, further analyzing the relationship between external parameters and arc behavior. An axisymmetric model is adopted, incorporating coupled calculations of the flow field and electromagnetic field to investigate the correlations among arc voltage, cathode spot distribution, and airflow parameters. The simulation results indicate that arc voltage is relatively insensitive to radial airflow; within the studied parameter range, fluctuations in radial airflow pressure have a maximum impact of only 4.2% on arc voltage. In contrast, arc voltage exhibits a strong positive correlation with axial airflow velocity, and a fitted correlation equation has been obtained. Temperature and velocity distribution analyses show that the maximum nozzle temperature exceeds 3500 K, ensuring sufficient ignition capability for low-quality coal and stable combustion performance. Moreover, the results confirm that with appropriate airflow settings, the coaxial dual-chamber structure enables the plasma igniter to achieve both high power and extended electrode lifespan. The study reveals the anti-ablation mechanism of this structure, wherein the alternating sweeping effects of the two airflow paths play distinct roles: axial airflow primarily regulates output power, while radial airflow controls arc root movement through periodic oscillations, effectively preventing single-point ablation and prolonging electrode life. Furthermore, an optimized design analysis has identified the equilibrium point between the two airflow paths, providing theoretical support for future research on the longevity of plasma generators.

Key words: plasma igniter, numerical simulation, Megnetohydrodynamics, anti-ablation mechanism