新型叶片-机匣碰摩模型及其验证

针对航空发动机叶片-机匣碰摩故障,提出了一种新型叶片-机匣碰摩模型,该模型在传统弹性碰摩模型的基础上,考虑了叶片数和转静间隙变化对碰摩力的影响,能够模拟机匣单点、多点、局部及全周,转子的单点、多点、局部和全周的碰摩规律.将所提出的碰摩模型运用于转子-支承-机匣耦合动力学模型中,利用数值积分获取碰摩故障下的机匣加速度响应规律.利用带机匣的航空发动机转子实验器,进行了叶片-机匣的机匣单点-转子全周的碰摩实验,发现了机匣振动加速度信号的碰摩特征具有明显的周期冲击特征,其冲击频率为叶片通过机匣的频率,在数值上等于旋转频率与叶片数的乘积,在频谱高频段出现了叶片通过频率及其倍频,冲击的大小受旋转频率调制,倒频谱具有旋转频率及其倍频的倒频率成分,仿真和实验取得了很好的一致性,验证了所提出的叶片-机匣碰摩新模型的正确有效性.最后,在此基础上,仿真计算了多种碰摩模式下的机匣振动特征和规律. 

A new blade-casing rubbing model and its verification

For the aero-engine blade-casing rubbing fault, a new blade-casing rubbing model was put forward. On the basis of tranditional elastic rubbing model, the new model considerd the effects of blade number and the rotor-stator clearance change on rubbing forces, and it could simulate rubbing faults with various rubbing positions including single-point, multi-points, part and whole-cycle on casing and rotor. The new rubbing model was applied to the rotor-support-casing coupling dynamic model, and the casing acceleration responses under rubbing faults were obtained by the numerical integration approach. The aero-engine rotor tester including casing was used to carry out the rubbing test whose rubbing positions were the single-point on casing and whole-cycle on rotor, and it is found that the rubbing characteristics of the casing vibration acceleration signals have obvious periodic impact characteristics. The impact frequency is the frequency of the blades passing the casing, which equals to the product of the rotational frequency and blade number. There is a blade passing frequency and its multiple-frequency components in the high-frequency band of spectrum, and the impact is modulated by the rotational frequency. There are obvious quefrency components of rotational frequency components and its multiple frequencies in the signal cepstrum.The simulation results agree well with the test values, and the new blade-casing rubbing model is fully verified. Finnaly, based on the new blade-casing rubbing model, the other rubbing modes between rotor and casing were simulated, and the casing vibration charateristics were obtained.