发动机非包容失效下的大尺寸碎片冲击数值模拟及防护方法

NUMERICAL SIMULATION FOR LARGE UNCONTAINED ENGINE DEBRIS IMPACT AND PROTECTION METHODS

为研究商用发动机发生非包容失效时转子碎片对飞机结构的冲击损伤,数值模拟了三分之一高压涡轮盘碎片在机翼油箱不同剩余油量情况下以不同散射角飞出的过程,确立了碎片依次与涡轮机匣和机翼整体油箱相互作用的连续动态响应。仿真采用Johnson-Cook本构模型和失效准则定义固体材料属性,SPH模型定义燃油粒子,分析对比了撞击过程中碎片的速度变化,机翼油箱的破坏变形和应力分布情况。结果表明:碎片的速度损失和能量衰减都随散射角和剩余油箱增加而增加;涡轮机匣吸收了绝大部分的转子能量,同时由于燃油的阻滞能力,对碎片的能量也有一定的吸收作用;燃油对油箱壁的液压冲击破坏作用在大尺寸碎片撞击下表现不明显。针对数值模拟结果最后对油箱结构边界设计进行了定性分析。

In order to evaluate the impact process induced by uncontained failure, numerical simulation for one-third HPT （High Pressure Turbine） disk impact was carried out under different obliquity angles and residual fuel volumes in the wing structure. The study, which resulted in continuous dynamic response, focused on the interaction among debris, turbine cowl and integral fuel tank. The constitutive material mode and failure criteria proposed by Johnson-Cook were applied in solid element definition, while SPH （ Smooth Particle Hydrodynamics ） model was used for fuel particles. The analysis involved the debris velocity history, fuel tank deformation along with the stress distribution changes during the whole process. It is shown from the results that with the increase of obliquity angle and residual fuel volume, the velocity loss and energy reduction rise correspondingly. The turbine cowl absorbs most of the debris energy while fuel also contributes to the absorption due to its viscidity. Hydrodynamic ram fails to cause lethal destruction of the tank structure under large debris impact. In the last part, fuel tank boundary design has been discussed qualitatively according to the simulation results.