固体火箭发动机喷管扩张段型面参数对其性能影响仿真分析

Study on the effect of divergence contour parameters on performance of solid rocket motor nozzle

固体火箭发动机喷管扩张段型面直接影响喷管内燃气膨胀和壁面压力分布,优化扩张段型面参数是提高喷管效率的有效途径。采用欧拉-拉格朗日数值方法仿真分析了椭圆-三次曲线型喷管在扩张段不同出口半角、初始扩张半角、长径比和扩张比等型面参数下的两相湍流特性及推力性能,数值模拟与基准型面喷管试验结果对比良好。不同型面参数喷管计算结果对比显示,出口半角对喷管推力影响较小,而初始扩张半角对其影响相对明显。流场特性分析表明,扩张段不发生内激波相交时,因避免燃气二次压缩而有利于提升喷管推力。与基准型面喷管相比,适当增大初始扩张半角和减小出口半角,能够改善扩张段内激波结构,提高喷管性能。此外,固定扩张比,长径比小于1.2时,随长径比增大,喷管出口轴向速度积分增长较快,推力收益增速明显。固定长径比,扩张比增大能提高喷管推力系数,但两相流损失随之增加,导致喷管效率降低,综合来讲喷管推力呈上升趋势。

The divergence contour of solid rocket motor(SRM)nozzle directly affects its internal gas expansion and the wall pressure distribution in the nozzle,so the optimization of divergence contour parameters is an effective way to improve nozzle effi⁃ciency.The Euler⁃Lagrange numerical method was used to simulate and analyze the two⁃phase turbulence characteristics and thrust performance of ellipse⁃cubic nozzles with different divergence contour parameters,including half⁃angle of outlet,initial expansion half⁃angle,length⁃diameter ratio and expansion ratio.The results of numerical simulation and basic nozzle test are in good contrast.Comparing the calculation results with different contour parameter nozzles show that the half⁃angle of outlet has little influence on the nozzle thrust,while the initial expansion half⁃angle has a relatively obvious effect on it.And the analysis of flow field characteristics indicates that when the inner shock wave does not intersect,the secondary gas compression is avoided then the nozzle thrust is im⁃proved.Compared with the basic nozzle,appropriately increasing the initial expansion half⁃angle and reducing the half⁃angle of outlet can improve the internal shock structure in the divergence section,as well as improve the nozzle performance.In addition,when the expansion ratio is fixed and the length⁃diameter ratio is less than 1.2,with the growth of length⁃diameter ratio,the outlet axial veloci⁃ty integral of nozzle increases rapidly then its thrust gains increase obviously.When fixing the length⁃diameter ratio,increasing the expansion ratio can improve nozzle thrust coefficient but reduce the nozzle efficiency because of two⁃phase loss growth,and the noz⁃zle thrust is in increasing tendency comprehensively.