捆绑火箭气动载荷分布不确定性分析

针对带捆绑火箭气动载荷分布受飞行状态及本身外形参数变化影响存在波动的现象，提出了依据多项式混沌理论对捆绑火箭气动载荷分布特征进行全局灵敏度分析及不确定性量化的方法，并以两助推构型火箭为例对所提方法进行验证。首先，提出了捆绑火箭气动载荷分布不确定性分析的方法，并给出仿真分析流程。其次，以两助推构型火箭为例对所提方法进行验证，建立火箭气动外形参数化模型，验证气动特性分析结果。最后，对该模型开展影响因素灵敏度分析及载荷分布不确定性分析，得到了不同因素的影响程度，以及气动轴力和法向力的不确定性分布形式，分析了流场流动情况及气动载荷波动的主要原因。分析结果为捆绑火箭气动载荷波动控制提供了一定参考，通过定量描述气动载荷分布不确定性，可以有效降低安全系数冗余，为开展精确结构设计提供依据。 

Uncertainty analysis of aerodynamic load distribution on strap-on launch vehicle

Aimed at the uncertainty of the aerodynamic load distribution of strap-on launch vehicles due to the uncertainty of flight status and shape parameters, a method based on the polynomial chaos theory to analyze the aerodynamic load distribution characteristics and quantify the uncertainty of the strap-on launch vehicle is proposed. A two-strap-on configuration was used as an example to verify the method. First, a method for uncertainty analysis of aerodynamic loads of the strap-on launch vehicles was proposed, and the simulation analysis process was given. Second, the method was verified by a two-strap-on configuration, the aerodynamic shape parametric model was established, and the aerodynamic characteristic analysis result was verified. Finally, the sensitivity analysis of influencing factors and the uncertainty analysis of load distribution were carried out, the influencing degree of different factors and the uncertainty distribution form of aerodynamic axial force and normal force were obtained according to the proposed method, and the flow mechanism was analyzed. The analysis results provide reference for the aerodynamic load control of strap-on launch vehicle. By describing the aerodynamic load uncertainty quantitatively, the safety factor redundancy can be reduced effectively and the basis of accurate structural design can be provided.