Simultaneous particle and vapor deposition in a laminar boundary layer

Abstract

A number of industrial and technical applications involve simultaneous particle and vapor deposition from a hot gas onto cold surfaces. For example, deposition of particles and corrosive vapors reduces the lifetime of heat exchangers in power plants and in blades of gas turbines. On another hand, in the OVD (outside vapor deposition) process used in manufacturing optical fibers, a controlled deposition of silica particles and dopant vapors is necessary for obtaining products with prescribed characteristics. In the present paper, a detailed mathematical and numerical model of this process is developed for the flow region near a stagnation point of a two-dimensional body, such as a cylinder. Using an inverse scavenging factor as a small parameter, an analytical asymptotic solution is found for vapor distribution in a condensation layer adjacent to the surface. The results of numerical calculations are presented in the form of surface temperature dependencies of dimensionless deposition rates and profiles of physical parameters of the system at a wide range of surface/gas temperature ratios.