激光测量大型转轴动载波动系数原理

PRINCIPLE OF DYNAMIC LOAD FLUCTUATION COEFFICIENT MEASUREMENT FOR LARGE ROTATING SHAFT USING LASER TECHNOLOGY

为能够对大型复杂旋转机械转轴动态载荷特性进行在线监测,给出一个表征转轴动载特性的参量——动载波动系数K_(ID)。应用动力学理论推导出动载波动系数K_(ID)测量模型的数学表达式,该式表明测得转轴转速波动值即可求得K_(ID)值。基于激光多普勒技术,提出一种直接提取动载波动系数K_(ID)的激光测量方法。通过构造光学测试系统测量相邻时刻转轴轴段两端面的瞬态转速,得到轴段转速波动值及两端面相对转速波动值,代入K_(ID)测量模型,能够直接得到动载波动系数K_(ID)值,从而实现对转轴扭振强度的实时监测。通过试验验证了该方法的可行性,结果表明,动载波动系数K_(ID)较好地反映了转轴的动态载荷波动特性,能为工程中大型复杂旋转机械转轴动态扭振监测提供新方法。

In order to monitor the dynamic load characteristic of rotating shaft of large-scale rotary machine, a new measured parameter---dynamic load fluctuation coefficient KID is presented. The mathematical model of KID measurement method is deduced by utilizing the principle of dynamics. Based on laser Doppler technology, a novel approach to KID measurement is proposed. Speed fluctuation values of rotating shaft segment end relative speed fluctuation values of between sections are obtained directly by measuring instantaneous rotational velocity of double sections in two successive times by designed optical measurement system, and then the values of KiD are obtained by submitting the values of speed fluctuation into the measurement model. The feasibility is validated by experimentation. Experimental results indicate that dynamic load fluctuation coefficient KID reflects accurately the dynamic load fluctuation characteristic of rotating shaft. The technique provides a new means for monitoring dynamic load characteristic of large-scale rotating machine in engineering.