飞机油箱水锤效应影响因素及其影响程度研究

水锤效应是飞机燃油箱的一种主要损伤模式,它可能引起油箱结构灾难性的破坏,分析水锤效应的影响因素及其影响程度,对燃油箱易损性的评估、燃油箱防护性设计具有重要意义。以破片速度衰减、箱内液体压力和壁板变形为对比参量,模拟一个等效飞机油箱在不同破片速度、质量(材料)、形状、入射角度、入射方向打击下及不同充液率时的水锤效应;并采用最小二乘法拟合油箱的入/出射壁板变形公式。结果表明:随着破片速度、质量和油箱充液率的增大,水锤效应的破坏能力显著增强;破片形状对液体压力和壁板变形均具有一定的影响;破片的入射角度、方向将改变其在油液中的运动路径,进而影响水锤效应。

Simulation Analysis of Hydrodynamic Ram Factors and Effects in Aircraft Fuel Tank

As one of the major damage modes of the aircraft fuel tank, hydrodynamic ram may cause a catastrophic destroy to the fuel tank structure. In order to analyze the hydrodynamic ram factors and effects systematically, this paper builds a validated model of the fuel tank by a full filled cube. Situations of different impact velocities, fragment masses, materials, shapes, incident angles, incident directions and various filling rates are studied. Parameters of the fragment speed decay, pressure inside the fuel tank and the deformation of the fuel tank wall are analyzed carefully. The results show that, the damage ability of the hydrodynamic ram will exacerbate with the increase of the impact velocity, mass and the filling rate. The shape of the fragment has a certain effect on the fluid pressure and the wall deformation. The incident angle and direction of the fragment will change its motion path in the fluid and then affect the hydrodynamic ram effect. Final in this paper, the least squares method is used to fit the deformation formula of the inlet and outlet wall of the simulation tank. The laws of the hydrodynamic ram of the fuel tank resulted from this paper can be used to assess the aircraft fuel system vulnerability and design reliable protection for the fuel tank.