ANALYTICAL STUDY OF GAS PARTICLE 2-PHASE FREE JETS EXHAUSTED FROM A SUBSONIC NOZZLE

This paper is concerned with a numerical analysis of the flow field of gas-particle two-phase free jets exhausted from a subsonic nozzle. The flow properties of two-phase mixture in a nozzle are obtained by solving a system of equations numerically, and then two-phase flow fields in a free jet region are solved as a perturbation from the nozzle exit condition. Thus, a few numerical experiments are performed for mist flows composed of air and water-particles, which are commonly applied to the secondary cooling zone in the continuous casting. One of the most important results so obtained is that a completely steady solution, in the conventional sense, cannot be expected even in a long run. Rather, a ring vortical structure is produced near the nozzle exit somewhat periodically. This may be understood to be due to the velocity discontinuity between the two-phase jet and the ambient gas at the jet boundary. So, in this region, the gas flow fluctuates and the small particles follow the fluctuation. The fluctuation of particle motion becomes more remarable for the smaller of particle motion becomes more remarkable for the smaller particles. Also, an appreciable concentration of particles occurs near the jet boundary as the particle size becomes smaller.