The response of droplet cloud decomposition to the gas phase excitation

Abstract

The purpose of the present work is to investigate the response of an evaporating and decomposing droplet cloud to applied excitations in the surrounding. The classic and conjugate models are utilized in two different developed flow solvers for investigations. The analysis is performed for low droplet cloud density, as a single droplet, and also for high droplet cloud density, in a closed chamber problem. The excitation is applied in such a way that small oscillations occur in temperature and pressure of the gas phase around evaporating droplets. The results show that the classic model is not suitable for studying response behavior of droplet burning at all. The conjugate model demonstrates the transient burning behavior in the form of regression rate amplitude augmentation during excitation, both for low and high droplet cloud densities. It is illustrated that in a closed chamber, the low droplet cloud density is more sensitive to unsteadiness at low excitation frequencies, but high cloud density is more sensitive at high frequencies. It is emphasized that in highly transient problems, such as combustion instability, the conjugate model must be used to obtain accurate results.