High frequency longitudinal combustion instability of a modeled hypergolic propellants combustor was analyzed through concentrated combustion model

in which the distribution of droplet evaporation rate along flow axis was calculated. The peak position of evaporation rate was used as the position of concentrated combustion front when the chemical time was ignored and the empirical correlation of NASA was used to provide sensitive time and interaction index. Then the model for quantity analysis of high frequency longitudinal combustion instability was built considering the hypergolic propellants droplet evaporation. Based on the curves of system oscillation gain

stability tendency under different conditions of initial droplet radius and injection velocity was analyzed. It showed that the position of concentrated combustion front was critical to high frequency longitudinal combustion instability

improvement of averaged initial droplet radius and velocity could make the front far away from the injection face

and the corresponding oscillation gain could be reduced too

making the system more stable. Especially

when the averaged droplet radius got bigger than 150 μm

oscillation gain of the modeled combustor could be smaller than 10 and the combustor could become stable in theory.