In order to investigate the effective method of individual rocket burned gas jet noise reduction

a designed liquid column was placed in the tail tube. The dispersion processes of high-temperature high-pressure combustion-gas driving the liquid column in the air was observed by using a high-speed photographic system

and gas-liquid mixture jet noise was also measured; the test results of jet were compared under two conditions of no-water-column and water-column. The experimental results show that then liquid column was put in the tail tube

the jet flow structure was changed and the jet flow parameters were decreased due to the interaction of gas jet with water. It is concluded that the sound pressure level peak is reduced to some extent in whole test points region with the liquid column

compared with the result of no liquid column gas jet; and the impact of the ground on the acoustic wave is weakened. With the increasing angle of the measuring points deviating from the jet central axis

the sound pressure level peak decreases. So the liquid column plays an important role in suppressing noise

the peak sound pressure level decreases by 6.4dB at the angle of 45°

validating the feasibility of noise reducing scheme.