In order to predict characteristics of high-thrust rocket launching noise,a sub-scale solid engine was chosen for experiment.The wavelet transform and FFT methods were used in processing experimental noise data,the following results can be found out: the low-frequency and high-amplitude shock components are found in the engine's working time,and their amplitude and frequency are very different from classic jet broadband noise;The filtered noise spectrum is typical turbulent broadband noise spectrum,and the sound efficiency of jet noise is 0.51%,which is in good agreement with empirical data of rocket launching,so it can be concluded that shock noise is not a part of jet noise.

In order to weaken the impact and ablation effect on the launcher by motor jet,an experimental study was developed on flow field of solid rocket motor plume injected by water.The films of flow fields were photographed and compared fewer than two conditions of no-water-injected and water-injected by two non-contact measuring devices of high-speed photography and infrared thermograph.The flow pattern and temperature distribution under two conditions were compared,analyzed and researched.It is concluded that the heat impact and ablation effect can be weakened,and the length and area of potential core has been reduced by water injection.

In order to decrease the temperature of flow field of engine plume impinging jet,and weaken the impact and ablation effect on the launcher,an experimental study was developed on flow field of high temperature supersonic impinging jet injected by water.The films of flow field were photographed and compared under two conditions of no-water-injected and water-injected by two non-contact measuring devices of high-speed photography and infrared thermograph,and the temperature of impinging region on bottom plate was measured by thermocouples.Two-phase impinging flow structure and temperature distribution under condition of water-injected were detailedly analyzed and researched,and then compared with condition of no-water-injected.It is concluded that the length and area of potential core have been reduced,the temperature of head face can be decreased,and the thermal impact and ablation effect can be weakened by water injection.