Experimental Measurement And Calculation Of Solid Rocket Motor’s Plume

Recently,the domestic researches about the solid rocket plume are in the rising stage.However,there are few studies on the combination of theoretical calculations and experimental measurement,which is mainly due to the harsh experimental environment.Now some foreign researchers have conducted a lot of experiments about solid bundled rocket plume and formed a series of empirical formula by the experimental data.As the sizes of solid rocket nozzles in our country are different from the others,some limitations still exist in the application of above empirical formula.Therefore,it is of great importance for us to investigate the solid rocket plume.This article is aimed to investigate the bottom thermal environment and solid booster plume of the next generation of Long March rocket,which are two key issues in the field of solid rocket.Firstly,the CFD method has been used to carry out the numerical simulation of single-nozzle solid rocket plume and some critical parameters have been obtained,including temperature,pressure,axial velocity,etc.Then a set of integrated measuring device suitable for the solid rocket plume have been designed and fabricated.A series of experiments on the specified solid rocket under the ground condition have been conducted to verify the accuracy of the calculation model.By comparing with the results from experiments,a modified model has been developed.Finally,the modified calculation model has been applied in simulating the liquid-core and solid-boost bundled launch rocket,and the structure of the external environment and bottom plume at different flying height(low altitude)have been achieved.Considering the thermal environment at the bottom of the bundled rocket,this method has the potential to provide data support in the design basis for the subsequent thermal protection.The results show that the solid rocket can generate high temperature and high velocity two-phase plume,which is accompanied by a string of obvious shock waves.As the flying height continues to rise,the plume fully expands its work and the angle of plume is increasingly larger.Then the integrated measuring device is fixed on the mobile platform which in helpful in adjusting the test distance.When the distances between the measuring device and the solid nozzle are 3m,2m and 1.5m,the steady temperatures are 479℃,612℃,735℃,respectively.When the distance between the measuring device and the solid nozzle is 3m and 2m,the steady heat fluxes are 2.68 MW/m~2 and 8.21 MW/m~2.The error between these two parameters are both within 10%.Finally,the modified model is used to simulate the bundled rocket.The results indicate that the solid plume,the liquid plume and external air can collide with each other at the bottom of rocket and form a high-temperature region.As the flying height continues to rise,the external air condition plays a vital role in the above region.And the maximum heat flux is based at the center of core rocket,which is 0.104MW/m~2.