Abstract：According to the length and the inlet boundary conditions of the injector, the gas-liquid coaxial injector of the liquid rocket engine is simplified into four categories: 1/4 wavelength closed tube, 1/2 wavelength closed tube, 1/4 wavelength open tube and 1/2 wavelength open tube. Linear acoustics is adopted to analyze the influence of the inlet opening ratio on the acoustic damping capability of the injector in order to obtain the law of the acoustic influence of opening ratio. It is found that the inlet opening rate has a very different effect on the damping capability of the injector under the conditions of standard length and optimal length. The damping capability can be greatly improved if the inlet opening rate and the length of the injector be chosen reasonably. The research results can provide reference for the optimum design of the length and inlet jet of the injectors, and acoustic damping of the combustion chamber.
