涡桨飞机发动机进气道排除异物特性数值方法研究

根据适航规范针对常见的两种外来异物：冰雹与冰块进行本体特性研究,确定两种外来异物的几何、质量以及初始姿态特性。耦合计算流体力学(CFD)以及六自由度方法(6DOF),开展涡桨发动机进气道以及旁通道中的异物运动排除特性数值模拟,分析其气动特性以及运动轨迹。针对运动中可能存在的碰撞现象,进一步联合LS-DYNA软件进行仿真分析,建立合理有效的涡桨发动机进气道外来异物排除数值模拟方法。以某型涡桨发动机为例,两种异物的计算结果表明,一旦异物与壁面发生碰撞,碎裂成若干很小的碎块,能量损失,对发动机威胁较小,无论是进入主发动机或者旁通道,均可认为排除。但是,由于下壁面结冰区的冰块容易直接进入主发动机,有可能造成严重影响,需要重点关注。

Numerical simulation on excluding foreign objects from engine inlet of turboprop aircraft

Based on the airworthiness specification, the geometry, mass and initial attitude characteristics of two foreign objects: the hail and ice cube, are analyzed and determined. The aerodynamics and trajectories of the foreign objects in engine inlet and bypass duct of turboprop aircraft have been simulated by coupling the Computational Fluid Dynamics (CFD) and six degrees of freedom methods. In view of the possible collision phenomenon in the movements, we further develop a reasonable and effective method combined with LS-DYNA software. The method is verified through a turboprop. The results indicate that once the foreign objects collide with the inlet or bypass duct, they lose their kinetic energy and can be broken into very small pieces, then these foreign objects do less harm to the engine and can be considered to exclude from the bypass duct. However, the ice cubes on the lower wall of the inlet may directly move into the main engine, and cause serious consequences, which should be carefully noted and researched.