弯扭耦合颤振过程中的能量转换机理

Energy Transformation Mechanism of Coupled Bendingtorsional Flutter

摘要:

采用激励反馈机制建立了耦合颤振的能量分析方法并给出了颤振稳定的能量判据.结合平板的风洞试验研究了颤振临界风速下结构气流系统内部的能量变化规律.分析结果表明,联合气动导数A*1H*3（A*1为竖向运动的速度对扭矩的贡献，H*3为扭转运动的位移对升力的贡献）建立了能量从竖向自由度向扭转自由度的传递途径,使气流能量在扭转自由度上大量聚集,并最终超越了气动阻尼的耗能能力,造成了扭转振动稳定性丧失的颤振失稳形态.参数A*1H*3cos θ1（θ1为竖向运动和扭转运动的夹角）对系统扭转振动的能量影响很大,而能量的主要消耗项是扭转气动阻尼,机械阻尼的耗能远小于该项.扭转系统的惯性力、弹性力和扭转气动刚度在一个周期内均不消耗系统能量.

Abstract:

The method of coupled flutter energy analysis is proposed on the basis of the incentivefeedback mechanism and the energy stability criterion for flutter is also defined.System energy change regularity of structureair system under flutter critical wind speed is analyzed according to plate wind tunnel test.The results show that the transfer channel of the energy from the vertical degree of freedom to torsional degree of freedom is built by the aerodynamic derivatives of A*1H*3,which cause a large amount of energy accumulation in the torsional degree of freedom,and ultimately beyond the energy dissipation capacity of aerodynamic damping,resulting in the loss of torsional vibration stability of the flutter instability patterns.The research finds that A*1H*3 cos θ1 has great influence on the main energy source of system torsional motion.The main energy expenditure is torsional aerodynamic damp and the expenditure of mechanical damp is less.Inertia force,elastic force and aerodynamic stiffness of torsional system are all have no energy expenditure in oneperiod.