大过载对固体火箭发动机粒子阻尼的影响

Large Overload Effects on Particle Damping in SRM

关键词:  固体火箭发动机  大过载  离散元算法（DEM）  空间分布  粒子阻尼

Key words:  Solid rocket motor  Large overload  Discrete element method（DEM）  Spatial distribution  Particle damping

摘要:

针对大过载条件下（30 g）固体火箭发动机粒子阻尼预估问题，采用离散元法（DEM）对大过载下固体火箭发动机内的粒子阻尼开展了数值模拟研究工作。通过考虑粒子空间分布的粒子阻尼预估方法来计算不均匀分布下的粒子阻尼，进而分析获得了过载下燃烧室内不同直径粒子的空间分布及阻尼特性。研究结果表明：30 g的大过载会显著影响燃烧室内粒子的空间分布及粒子阻尼特性，且不同大小的粒子受影响程度显著不同。横向过载下，燃烧室内粒径大于30μm的粒子在极短的时间内即会在局部区域形成聚集带和真空带。采用与空间分布相关粒子阻尼预估方表征粒子阻尼，发现非均匀分布下粒子的阻尼值比均匀分布时小；在横向大过载下，粒子阻尼的减小（可达30%）发生在极短时间（5 ms）内，且粒径越大的粒子其阻尼减小得越早、越快，这对发动机燃烧的稳定性是十分不利的。

Abstract:

Based on discrete element method （DEM）， the numerical simulation of particle damping in Solid Rocket Motor （SRM） under large overload （30 g） is carried out. The nonuniform particle spatial distribution is adopted to predict the particle damping under large overload to reveal the characteristics of particle space distribution and damping with different particle size. The results show that the spatial distribution and damping characteristics of particles in combustion chamber are significantly affected by overload （30 g）， and the particle size determines the degree of this influence. Under the transverse overload， the large particles （diameter>30μm） in the combustion chamber will accumulate into a small region and thus create another particle-free region within a short time. With this distinct nonuniform space distribution the predicted particle damping shows an obvious decrease compared to the conventional prediction with uniform assumption. Up to 30% of damping effect will be reduced when the large overload is exerted within 5 ms， and this reduce is growing with increasing particle size， which needs the caution since it can cause server consequence in combustion instability of motor.