A finite volume method was applied to determine rocket jet noise reduction due to water injection.Mass

momentum and energy equations based on the control volume were built and solved

and the equivalent jet parameters due to mix of the jet and water were obtained.The effect of the water-to-jet mass flow rate ratio on equivalent jet parameters and noise reduction was analyzed.The calculation results show the agreement with experimental data.The results indicate that the efficiency of noise reduction reduces when the mass flow rate ratio exceeds the critical value.