INTERACTION OF A DILUTE MIST FLOW WITH A HOT BODY

The flow of an aerosol containing liquid droplets around an overheated body is considered. The liquid mass flux is assumed small enough to prevent formation of a liquid film on the body surface. Depending on the relative normal velocity, impinging droplets are either captured by the surface and ultimately evaporated or almost elastically thrown away, this change in the droplet behaviour causing the onset of a heat transfer crisis. The theoretical description of the dynamic and thermal interaction between the droplets and the surface is reduced to solving two independent problems. The first problem consists in the analysis of the dynamic Leidenfrost phenomenon and further calculation of the critical normal velocity of a single droplet as a function of physical and process parameters. The second problem involves determination of the field of droplet trajectories around the body on the basis of the conventional theory of inertial capture of suspended particles and subsequent calculation of the total liquid mass flux onto the surface, conditioned by a requirement that the droplet fall velocity exceeds the indicated critical value. Both these problems are studied. The distributions of the specific coefficient of heat removal due to evaporation over the sphere, cylinder and plate surfaces in a uniform aerosol flow are obtained under different circumstances.