摘要
为了排查前掠风扇叶片低转速性能录取试验过程中发生疲劳断裂的原因,并对风扇叶片改进设计,仿真分析排除了叶片共振和颤振致破坏,高周疲劳分析得到风扇叶片2阶模态危险点与裂纹起始位置吻合,分析认为在低转速下风扇叶片叶尖处存在不稳定气流,产生6.5倍转频激振力,激起了风扇叶片2阶固有模态,进而引发叶片非同步振动。叶尖振幅测量和动态压力测量试验验证了分析结果,在断裂故障转速,动态压力信号出现多个非同步频率,同时风扇叶尖振幅3.7 mm,裂纹起始位置振动应力671.2 MPa。风扇叶片前掠过大,导致前掠部分局部弯曲模态频率低,易被激起共振。改进措施是切除叶片部分前掠,消除前掠部分局部弯曲模态,试验验证改进措施有效。对前掠小展弦比风扇叶片规避非同步振动设计有借鉴意义。
The fatigue fracture occurred during the low speed performance test of swept-forward fan blades.The cause was investigated to improve the design.The damage caused by blade resonance and flutter was excluded through simulation analysis.The high-cycle fatigue analysis showed that the secondorder modal danger point of the fan blades was consistent with the crack initiation position.The analysis suggested that the unsteady flow at the tip generated 6.5 times the rotational frequency exciting force,which stimulated the second-order natural mode of the fan blades.Blade tip amplitude and dynamic pressure measurement experiments verified the analysis results.At the fracture speed,the dynamic pressure signal exhibited multiple non-synchronous frequencies.The amplitude of the fan blade tip was 3.7 mm,and the vibration stress at the crack initiation position was 671.2 MPa.The fan blade skimmed forward greatly,resulting in low local bending mode frequency of the forward-swept part,which was easy to be resonated.Blade improvement measures were taken to remove partial forward-swept of the blade and eliminate the local bending mode.The experiment verified the effective improvement measures.This scheme is of reference significance for the design of forward swept small aspect ratio fan blades to avoid asynchronous vibration.
作者
吕彪
孟卫华
陈剑
张鹏
侯明
LYU Biao;MENG Weihua;CHEN Jian;ZHANG Peng;HOU Ming(Hunan Aviation Power Plant Research Institute,Aero Engine Corporation of China,Hunan Zhuzhou 412002,China)
出处
《航空动力学报》
北大核心
2025年第11期23-30,共8页
Journal of Aerospace Power
关键词
风扇叶片
前掠
非同步振动
疲劳断裂
不稳定气流
动态压力
叶尖振幅
fan blade
forward-swept
non-synchronous
fatigue crack
unsteady flow
dynamic pressure
blade tip vibration amplitude
