复合材料风扇叶片-机匣碰摩振动的数值模拟

Numerical investigation of composite fan blade vibration characteristics due to blade-casing rub

基于全三维模型的复合材料风扇叶片-机匣碰摩动力学特性的数值研究。建立了复合材料三维风扇叶片-机匣实体有限元模型,考虑叶片离心刚度的影响,机匣由贝塞尔曲面拟合,风扇叶片采用3种不同铺层形式。基于该模型,在机匣二节径变形的情况下,计算了不同铺层叶片在不同转速下与机匣碰摩后的动力学响应。计算结果表明:铺层形式对叶片中、低转速下的碰摩振动形式影响较大,带有90°铺层的叶片的最高振幅及不稳定振动所在区域的转速相对较低,改变铺层形式可以对复合材料风扇叶片-机匣的碰摩动力学特性加以控制。当转速靠近由3倍频与叶片1阶模态造成的共振点附近,或由6倍频与叶片2阶模态造成的共振转速附近时,叶片与机匣的碰摩会导致非稳定振动的产生。该方法与结果对复合材料风扇叶片的碰摩动力学特性研究具有一定指导意义。

A full three-dimensional composite fan blade rubbing vibration calculating model was established.A complete composite fan blade modeling method was used to establish composite fan blade and casing solid element models.The influence of the blades’centrifugal stiffness was taken into consideration,Bezier surface was used to fit casing nodes.Rubbing phenomena of three blades with difference stacking sequences were studied under the assumption of a two-nodal diameter casing distortion.Results indicated that the stacking sequence pattern had a great impact on the blade rub-impact vibration characteristic at low rotational speeds.The rotating speeds of maximum amplitude and unstable vibration regions of blade with 90°layers were relatively low.The rubbing dynamic characteristics of the composite fan blade can be controlled by the stacking sequence,and when the rotating speed was close to the first-order mode resonance point of the blade caused by the third engine order,or close to the second-order mode resonance position of the blade caused by the sixth engine order,non-steady blade rubbing vibrations were generated.The method and results have certain guiding significance to the study of the rubbing dynamic characteristics of composite fan blades.