隔板喷嘴对燃烧室切向声学模态作用研究

Baffled injectors have played an important role in suppressing high-frequency combustion instability in liquid rocket engines by changing acoustic characteristics of the combustion chamber. However, no appropriate model can successfully predict effects of baffled injectors on acoustic characteristics of a combustion chamber. In order to obtain the theoretical model of effects of baffled injectors on the transverse acoustic mode of the combustion chamber, the acoustic admittance of baffled injectors was deduced theoretically. Effects of gap, number and length of baffled injectors on the first transverse mode of the combustion chamber were studied by means of separation variable method and experiment. Results show that the maximum suppression effects on the first transverse acoustic mode occurs at a certain gap. The frequency and amplitude of the first transverse acoustic mode decrease with increasing the number and length of baffled injectors. Furthermore, suppression effects of gap are weakened with the increasing of number or length of baffled injectors. This model lays a theoretical foundation for the study of baffled injectors, and results offer some guidance to the design of baffled injectors in liquid rocket engines.