Excitation of Acoustic Vibrations upon Combustion of Droplets of Liquid Fuel at Supercritical Pressure

Theoretical investigation of the excitation of acoustic vibrations upon combustion of liquid fuel droplets at a supercritical pressure of a gaseous mixture is carried out. The droplets are assumed to be spherical and mono-dispersed. The combustion is assumed to run in the diffusion regime. The binary diffusion coefficients are taken equal and independent of the concentration of the components of the gaseous mixture. The Lewis number is assumed to be unity. The flow is considered to be one-dimensional; the mixing in the transverse direction is assumed to be complete, with no mixing in the longitudinal direction. The rate of combustion at supercritical pressure of the gaseous mixture is calculated on the basis of the modified quasi-stationary theory. Expressions for the frequency and excitation increment of acoustic vibrations are obtained in this paper; the properties of the fuel and the oxidizer are explicitly taken into account.