槽间垫片功用分析及减振机理试验

Functions and experiment on damping mechanism of spacer

针对国内高涵道比涡扇发动机风扇叶片的设计亟需,分析得到槽间垫片功用及设计要求,并通过机理试验揭示了槽间垫片减振机理。研究结果表明:在常规简谐激励作用于风扇叶片时,槽间垫片并不能提供有效阻尼,无法起到减振作用。在高能冲击载荷作用于风扇叶片时,槽间垫片可以起到较好的阻尼作用,快速地衰减自由振动,降低疲劳损伤积累。金属橡胶或橡胶槽间垫片能使叶片的冲击响应时间减少50%以上。槽间垫片应设计足够大的预紧力以实现叶片稳定的径向定位,降低风扇叶片在风车状态时的晃动幅值,减小榫头榫槽接触磨损;应具备足够大的柔度,确保高能冲击载荷下允许叶片偏摆一定的角度,通过垫片变形吸收冲击能量,从而降低叶片根部应力峰值。

For the imperious internal demand of designing wide-chord blades of the high bypass ratio turbofan engines,the functions and design requirements of a spacer of the widechord blade were analyzed firstly,and the damping mechanism was revealed by the way of experimental study as well.Experimental results showed that the effect of vibration absorption of the spacer on the steady-state response of the blade under harmonic excitation was poor,while the effect under impact excitation was obvious,which reduced free vibration and cumulative fatigue damage effectively.The impact response time of the blade with a rubber spacer or a metal rubber spacer can be reduced by more than 50%.The preload of the spacer should be enough to locate the radial direction of blade steadily,decreasing the swing amplitude of blade and the mass loss by contact wear between dovetail and groove under windmilling condition.On the other hand,the flexibility of spacer should ensure that blade can swing an angle under high energy impact,so that the spacer absorbs impact energy by mean of deformation,in order to reduce the stress peak of the blade root.