航空发动机鸟撞适航符合性数值模拟研究

Numerical simulation on the airworthiness compliance of aircraft engines during bird strikes

航空发动机鸟撞适航认证通常基于整机试验,整机鸟撞数值仿真,受发动机结构复杂性影响,存在计算效率、吸鸟关键参数不易确定等问题,而不被工程采纳。而为验证航空发动机吸鸟符合性,进行整机鸟撞数值分析是一种经济高效的方式。基于航空发动机整机鸟撞数值仿真需求,开展航空发动机模型简化建模和关键吸鸟参数提取方法研究。首先,基于光滑流体动力学方法,考虑工作条件下发动机鸟撞损伤和传力路径上关键部件关系和相互作用,建立了基于航空发动机整机关键零部件等效建模的鸟撞有限元模型。其次,对航空发动机鸟撞适航符合性要求进行分解,确定了造成叶片结构损伤的关键吸鸟参数。最后,基于最严苛情况的整机鸟撞有限元模型,研究了大鸟、中鸟鸟群和大型群鸟导致的转动不平衡、不平衡载荷传递和叶片损伤。数值模拟结果表明大鸟的撞击对航空发动机结构安全的威胁最大,鸟群撞击导致的叶片损伤范围更广。基于整机的鸟撞数值模拟对于航空发动机的结构安全性设计和适航认证是非常具有价值的。

Airworthiness certification of aircraft turbine engines with respect to bird ingestion is conventionally reliant on physical tests of a full scale engine.Due to the complexity of the engine structure,there are problems,such as low computational efficiency and difficulty in determining critical ingestion parameters in the numerical simulation of the whole engine during bird strikes,so,it is not adopted by engineering works.However,for the bird injestion certification of the aeroengine,the numerical analysis of the whole aeroengine subjected to bird strikes is an economical and efficient method.Based on the numerical simulation requirements of aircraft engine under bird strikes,the simplified modeling method of aircraft engine and the way to determine critical ingestion parameters were investigated.Firstly,considering relationships and interactions among engine components under operating conditions,the finite element model of a full-scale aeroengine was developed using the smoothed particle hydrodynamics method.Secondly,based on the simulations of fan blades during a bird-strike event,critical ingestion parameters in the case of a large single bird and medium flocking birds were determined.Finally,with regard to the full-scale FE model of the turbine engine subjected to bird strikes under the most critical condition,the impact force,rotating unbalance,unbalancing load and blade damage induced by a large single bird,medium flocking birds,a medium single bird and large flocking birds,respectively,were studied.The numerical results show that the bird-strike damage generated by the large single bird poses the greatest threat to the safety of engine components,while the blade damage induced by flocking birds strikes coveres a wider area.It is invaluable for engine manufacturers to incorporate a predictive modeling methodology for the turbine engine under bird strikes into the structural safety design and bird ingestion certification.