Rapid vaporization and heating of two parallel fuel droplet streams

Abstract

An analysis is presented of the mechanisms of heat transfer and vaporization in an idealized two-dimensional fuel spray consisting of two parallel droplet streams injected in a hot gas. By assuming a constant relative velocity between the gas and liquid phases (inviscid approximation), a system of partial differential equations with linear operators and nonlinear source terms is obtained. With the use of Green's functions, this system is transformed into a group of non-linear ordinary differential equations and integral equations which are readily solved with numerical techniques. The dimensionless groups influencing the problem are identified and a discussion is presented of the effects of four relevant parameters including: a vaporization-diffusion time ratio, a liquid-gas mass flow ratio, a Spalding transfer number, and a Reynolds number. The method yields qualitatively correct estimates of the behavior of the gas and liquid phases which may serve as guidelines in the development of costlier numerical schemes. The method can be further exploited to include chemical reactions and to predict ignition of parallel droplet streams.