转子碰摩运动的非稳态分析

本文研究了一个柔性单圆盘挤压油膜阻尼器转子系统的非稳态碰摩运动。转子以定常角加速度通过临界转速时产生碰摩, 碰摩力由库仑摩擦定理确定。通过数值计算揭示在各种系统参数下, 角加速度对反向涡动的影响规律, 为防止转子通过临界转速时产生碰摩失稳提供一定参考。      

挤压油膜阻尼器失效分析方法

着重论述分析挤压油膜阻尼器失效的方法. 首先介绍了国际上主要的航空发动机制造厂家对挤压油膜阻尼器的研究, 那些厂家是General Electric公司、Pratt & Whitney公司和Rolls Royce公司.这不仅有助于我国研制挤压油膜阻尼器的工作,同时也提出一种启示, 研究挤压油膜阻尼器的失效, 应基于综合性参数的选配. 因此,用了轴承参数B和质量偏心率U为基本参数,来说明分析失效的方法.并定义了两种失效的情况,一是转子系统过不了临界转速,二是出现双稳态特性.作出了过不了临界转速的特性图,并带有数据,还提供了3种典型的双稳态特性曲线和产生双稳态特性的数据点.     

Passive attitude stabilization of ionic-wind-powered micro air vehicles

The ionic-wind-powered Micro Air Vehicles (MAVs) can achieve a higher thrust-to-weight ratio than other MAVs. However, this kind of MAV has not yet achieved controlled flight because of the unstable thrust produced by the ionic wind and the dynamic instability related to the small size. In this paper, a passive attitude stabilization method of the ionic-wind-powered MAV using air dampers is introduced. The key factors that influence the performance of the air dampers, including the layout, position, and area of the air dampers, are theoretically studied. The appropriate optimal position of the air dampers is also obtained by Monte Carlo stochastic simulations. Then the proposed passive attitude stabilization method is applied to the ionic-wind-powered MAVs of different wingspan (2 cm and 6.3 cm). Finally, the experimental results show that using the proposed method, attitude stabilization is achieved for the first time for the ionic-wind-powered MAV. Moreover, the altitude control of an ionic-wind-powered MAV with a wingspan of 6.3 cm is also demonstrated.