燃气射流冲击载荷的修正模型与仿真验证

Modified model and simulation verification for impact load of gas jet

为了研究火箭发射系统燃气射流冲击载荷的特性,该文建立了金属薄壁圆管轴向撞击载荷理论模型,并采用数值仿真方法对模型进行了验证。分析了Alexander金属薄壁圆管轴向压缩理论的不足并进行修正。利用金属薄壁圆管对刚体撞击的缓冲特性,对基础型薄壁圆管(BCT)进行改进,设计了均匀开槽型薄壁圆管(UGT)和周向开口开槽型薄壁圆管(CGT)。通过改变金属薄壁圆管的塑性铰半长来控制平均轴向撞击力变化规律。对3种薄壁圆管进行了数值仿真验证,对比了修正模型结果和仿真结果,分析了3种类型薄壁圆管的吸能性能。结果显示,3种薄壁圆管的平均撞击力与该文模型吻合较好,经BCT缓冲的轴向撞击力呈现不规则变化,而经UGT和CGT缓冲的撞击力的变化规律与燃气射流冲击载荷相似,说明通过设计金属薄壁圆管的塑性铰半长可以控制轴向撞击载荷的变化规律。

To study the characteristics of the impact load of the gas jet in a rocket launching system,a theoretical model for the axial impact load of a metallic thin-walled tube is established here,and verified by a numerical simulation method.The deficiencies of Alexander’s theory of axial compression for metallic thin-walled tube are analyzed and modified.The basic circular tube(BCT)is improved by the use of the metallic thin-walled tube’s buffering characteristics against rigid body impact,and the uniform grooved thin-walled circular tube(UGT)and circumferential opening grooved thin-walled circular tube(CGT)are designed.The change of mean axial impact force is controlled by changing the half length of the plastic hinge of the thin-walled circular tube.Numerical simulation verification is carried out on 3 types of thin-walled circular tubes,and the energy absorption performance of the 3 types of thin-walled circular tubes is analyzed by comparing the corrected theoretical results and the simulation results.The results show that the mean impact force of the 3 types of tubes is in good agreement with the model.The axial impact force buffered by BCT shows irregular changes,while the impact force buffered by UGT and CGT changes in accordance with the impact load of the gas jet,indicating that the change of axial impact load can be controlled by designing the half length of the plastic hinge of the metallic thin-walled tube.