贮箱轻量化设计几何参数优化方法

Geometric Parameters Optimization for Tank Lightweight Design

为有效减轻推进剂贮箱质量、提高液体火箭的有效载荷运载能力,提出一种推进剂贮箱几何参数优化方法。在建立椭球底圆柱贮箱模型的基础上,应用材料力学理论对贮箱结构进行应力分析,推导出了贮箱椭球下底、圆柱筒及椭球上底经向应力与环向应力的解析式。在保证贮箱应力强度可靠性的前提下,结合贮箱应力分布特征与材料强度理论定义贮箱最大等效应力,并据此确定贮箱设计所需壁厚参数。根据推进剂贮箱设计需求,确定贮箱质量与贮箱设计参数间的约束关系,以贮箱质量最小化为优化目标,对贮箱半径与椭球模数进行优化设计。以某型火箭贮箱的设计参数为例,将优化后贮箱的质量与原始质量进行了对比分析,结果表明:当半径不变、椭球模数减小0.02时,贮箱质量减小5.7 kg;当椭球模数不变、半径增加0.02 m时,贮箱质量减小15.2 kg。

To effectively reduce the mass of propellant tank and improve the payload carrying capacity of liquid rocket,an optimal method for the geometric parameters of propellant tank is proposed.Establishing the ellipsoid cylinder tank model and following theory of material mechanics,the stress of tank structure is analyzed,and the formulas of the meridional stress and hoop stress of tank bottom,cylinder and roof are derived.On the premise of ensuring the reliability of tank stress intensity,the maximum equivalent stress of tank is defined according to the stress distribution characteristics of tank and material strength criterion,and then the wall thickness parameters required for the tank design are determined.Obeying the design requirements of the propellant tank,the constraint relation between the tank mass and the design parameters are determined,and the tank radius and ellipsoid norm are optimally designed with the optimal objective to minimize the tank mass.Taking the design parameters of a rocket tank as an example,the mass of optimized tank and the original mass are comparatively analyzed.It is revealed that when the radius is unchanged and the ellipsoid norm is lowered by 0.02,the tank mass is then reduced by 5.7 kg;when the ellipsoid norm is unchanged and the radius increases 0.02 m,the tank mass is then reduced by 15.2 kg.