显式动力学子模型法在航空发动机整机瞬态冲击并行计算中的应用

Application of Explicit Dynamic Sub-Model Method in Parallel Calculation of Aero-Engine Transient Impact

【背景】商用航空发动机需要满足适航安全性要求,其中风扇叶片脱落载荷是在设计中必须考虑的安全设计载荷。发动机整机瞬态显式动力学分析是个有效的分析工具,但在模型规模、计算效率和计算精度方面存在矛盾。整机模型通过选用合适的并行计算策略,一般能提供较为准确的部件界面载荷,但对于单个部件的应力分析,往往由于网格密度不够而不能获得满意结果。【方法】整机瞬态显式动力学仿真子模型技术,采用航空发动机整机简化模型进行整机计算,通过预先设置的子模型边界输出零部件载荷,作为零部件精细模型动强度分析的输入,在保证计算精度的同时,使计算效率大幅度提高。【结果】本文通过一个机匣等效平板靶板冲击试验算例,将平板特定区域定义为子模型,计算结果表明,子模型法能够与局部细化的整体模型得到相同的计算结果。同时,以航空发动机风扇轴为例,将子模型技术应用于叶片飞脱载荷下零部件动力学分析,建立航空发动机整机瞬态显式动力学仿真子模型分析方法,既可以解决叶片脱落等效载荷方法整机层面对粗网格部件应力分析计算误差大的问题,又能够考虑零部件细观结构对强度计算结果的影响。

[Background]Commercial aero-engine needs to meet the requirements of airworthiness safety,in which the fan blade shedding load must be considered in the design.Transient explicit dynamic analysis of engine is an effective analysis tool,but there are some contradictions in model scale,calculation efficiency and calculation accuracy.Generally,the whole machine model can provide more accurate component interface load by selecting appropriate parallel computing strategy.However,for the stress analysis of single component,the grid density is not enough to obtain satisfactory results.[Methods]The submodel technology for whole engine transient explicit dynamic simulation uses the simplified model of aero-engine to calculate the whole machine.The load of parts is output through the pre-set sub model boundary,which is used as the input of dynamic strength analysis of the fine model of parts.The calculation accuracy is guaranteed and the calculation efficiency is greatly improved.[Results]In this paper,a specific area of the plate is defined as a sub model through an example of an equivalent plate impact test of a casing.The calculation results show that the sub model method can obtain the same calculation results as the whole model with local refinement.At the same time,taking the aero-engine fan shaft as an example,the sub model technology is applied to the dynamic analysis of parts under the load of blade flying off,and the sub model analysis method of aero-engine transient explicit dynamic simulation is established,which can not only solve the problem of large calculation error of the blade shedding equivalent load method for coarse grid component stress analysis,but also consider the influence of the microstructure of the components to the results of strength calculation.