Numerical studies on velocity, temperature history and heat transfer to the particles injected into the argon plasma

A new approach to study the particle velocity in a thermal plasma in relati on to input parameters (power, gas flow rate, injection velocity of the par ticle and particle size) and nozzle dimensions ( (nozzle length and diamete r) has been made. Injected particle's temperature and thermal history were calculated for particles of three different materials (alumina, tungsten an d graphite) in argon plasma. Allowable powder feed rate was calculated for the particles. Heat transfer per particle injected in to the plasma is repo rted. Liquid fraction of the particle after it reached the melting point is also reported. Particle velocity is found to increase with increase in pow er, gas flow rate and injection velocity and decrease with increase in part icle size, nozzle length and nozzle diameter. Thermal histories of the part icles in relation to the plasma temperature and particle diameter are prese nted. Particle's residence time is found to increase with increase in diame ter of the particle. Allowable powder feed rate for complete melting of the particle is higher at higher percentage utilisation of the plasma power. P owder feed rate is seen to decrease with increase in particle size and it i s higher for tungsten and lower for graphite particle. Heat transfer rate f rom plasma to particle is seen to decrease with increase in time and the sa me is higher for plasmas of higher temperature and smaller sized particle.