涡轮后机匣的结构动力学精确建模

构建精度高、规模适中的部件动力学模型,是航空发动机在研制初期实现从结构部件到整机的动力学特性准确分析的有效途径。为构建满足工程需求的部件结构动力学模型,依据某装配组合式涡轮后机匣的结构特点,提出了其各构件的“超模型”建模及装配组合形式的连接件分类建模的方法,实现装配组合式涡轮后机匣的整体“超模型”建模。同时,进一步介绍了各构件的“超模型”建模步骤、基于有限元单元网格尺寸变化的收敛准则,建立了自由度490万的后机匣构件“超模型”,“超模型”构件的频差精度可达1%以内;利用薄层建模法模拟多螺栓连接结构、采用接触对模拟支板搭接处的接触连接。装配组合后的涡轮后机匣“超模型”通过动力学分析,结果表明后机匣前8阶为整体振动模态。整体“超模型”的建立,可以代替研制样机提供虚拟试验数据,实现简化模型的修正和确认,为研制初期的结构动力学特性精确分析提供技术支撑。可推广应用到发动机其他部件及整机的精确建模中。

Accurate Structural Dynamic Modeling of a Rear Spokes-frame Casing of the Turbine

It is an effective way to accurately analyze the dynamic characteristics of aeroengine from components to the whole engine in the early stage of the aeroengine development.to construct a component dynamic model with high precision and moderate scale In order to build the component structural dynamics model that meets the engineering requirements,according to the structure features of a combined rear spokes-frame casing of the turbine,the“supermodel”modeling of the various components of the turbine casing assembly and the modeling of connecting parts were put forward to realize the establishment of“supermodel”of the rear spokes-frame casing.Meanwhile,the“supermodel”modeling procedure of the various components based on iteration of the meshing size of the finite element and the“supermodel”convergence criterion were introduced.A“supermodel”of rear spokes-frame casing with 4.9 million degrees of freedom was established,and the frequency difference accuracy of the"supermodel"component is less than 1%.The multi-bolt connection components was simulated with the thinlayer modeling and the contact connection between the struts and laps with the contact pairs was simulated.Dynamic analysis of the'supermodel'of the rear spokes-frame casing of the turbine assembly showed that the first 8 orders of the casing were overall vibration modes.The establishment of the“supermodel”can be used for the purpose of replacing the prototype manufacture to create the virtual test data,can be used to update and validate of the simplified or reduced design model.The proposed method can be extended to the accurate modeling and analysis of other engine components as well as the whole engine modeling(WEM).