Non-equilibrium diffusion combustion of a fuel droplet

A mathematical model for the non-equilibrium combustion of droplets in rocket engines is developed. This model allows to determine the divergence of combustion rate for the equilibrium and non-equilibrium model. Criterion for droplet combustion deviation from equilibrium is introduced. It grows decreasing droplet radius, accommodation coefficient, temperature and decreases on decreasing diffusion coefficient. Also divergence from equilibrium increases on reduction of droplet radius.Droplet burning time essentially increases under non-equilibrium conditions. Comparison of theoretical and experimental data shows that to have adequate solution for small droplets it is necessary to use the non-equilibrium model.

► Criterion for droplet combustion deviation from equilibrium is introduced. ► Criterion grows decreasing droplet radius, accommodation coefficient, temperature. ► Criterion decreases on decreasing diffusion coefficient. ► Divergence from equilibrium increases on reduction of droplet radius. ► Droplet burning time essentially increases under non-equilibrium conditions.