Droplet behavior analysis in annular mist flow by two-way coupling method

Annular mist flow is an important flow regime in many industrials. Especially it is indispensable to understand the characteristics of annular mist flow for the prediction of liquid film dryout phenomena. Recently in order to analyze annular mist flow more accurately, the mechanistic model like three-fluid model, which deal with liquid film, droplets and gas as three separate fluids, has been developed. Three fluids model is a detailed model, but it needs many constitutive equations. Especially in the prediction of film dryout, the constitution equations of droplet deposition and entrainment are very important. So far, many constitutive equations based on experimental and theoretical results are suggested, but there is much difference among them. So we are trying to estimate droplet deposition behavior numerically by calculating a large number of droplet trajectories. To analyze droplet behavior in annular mist flow, the effect of liquid film flow, especially disturbance wave, on flow field must be considered. Liquid film is regarded as a moving rough wall in this paper. Rough wall increases turbulence of gas flow and turbulent diffusion of droplets. As a result, droplet deposition coefficient increases. We also estimated the effect of interaction between airflow and droplet flow by two-way coupling method and verified that deposition behavior is modified slightly in the case of 20% loading ratio. (author)