Rotordynamic characteristics prediction for scallop damper seals using computational fluid dynamics

Enhancing damping characteristic is one of the effective methods to solve the instability problem of the rotor system. The three-dimensional numerical analysis model of scallop damper seal was established, and the effects of inlet pressures, preswirl ratios, rotational speeds, interlaced angles and seal cavity depths on the rotordynamic characteristics of scallop damper seal were studied based on dynamic mesh method and multi-frequencies elliptic whirling model. Results show that the direct stiffness of the scallop damper seal increases with decreasing inlet pressure and increasing rotational speed and cavity depth. When the seal cavity is interlaced by a certain angle, which shows positive direct stiffness. The effective damping of the scallop damper seal increases with the increasing inlet pressure, the decreasing preswirl ratio and the rotational speed and cavity depth. There exists an optimal interlaced angle to maximize the effective damping and the system stability. The leakage of the scallop damper seal is significantly reduced with decreasing inlet pressure. The preswirl will reduce the leakage flowrate, and the rotational speed has a slight effect on the leakage performance. The leakage of the scallop damper seal decreases with increasing seal cavity depth.     

某电子设备耐大量级振动组合式减振器研制

某电子设备在飞行过程中遭受均方根加速度高达38 g的振动环境,为了降低其振动响应,采用有限元分析和试验验证相结合的方法,研制了一种新型的组合式橡胶减振器。通过与T型减振器进行对比试验,结果表明,设计的组合式橡胶减振器使电子设备的随机振动响应由38 g下降到11 g,减振效率高达71%,且共振峰放大倍数小于3。     

冲击/周期载荷作用下分布式调谐质量阻尼器对响应控制的影响

本文研究了采用分布式调谐质量阻尼器(TMD)对悬臂梁进行振动抑制的问题.首先建立了安装N个TMD的悬臂梁的动力学方程;然后通过有限单元法离散偏微分方程,使用Newmark-β法进行含TMD的悬臂梁动响应求解;最后基于数值计算模型,分别研究周期荷载与冲击荷载作用下,梁振动控制的效果.研究表明:TMD可以有效抑制悬臂梁振动...     

Pressure performance for a thin-walled ring and turbulent-jet orifice modeled elastic squeeze film damper

This paper explores an analytical model for Elastic Ring Squeeze Film Damper (ERSFD) with thin-walled ring and turbulent-jet orifices, and uncovers its Oil Film Pressure Performance (OFPP). Firstly, the ring deformation is addressed by using the Fourier series expansion approach and the orifice outflow rate is characterized with the Prandtl boundary layer theory. Secondly, applying finite difference scheme, the influence of elastic ring flexibility, orifice diameter, and attitude angle on the OFPP is analyzed. Finally, Outer chamber pressure was measured experimentally at different rotor speeds. The results indicate that the outer chamber pressure coats an individual load-carrying region and spreads symmetrically pertaining to the attitude angle. Its amplitude drops as the elastic ring flexibility decreases but boosts with the reduction of the orifice diameter. For inner chamber pressure, the orifice diameter effects a similar trend to the outer cavity, but exhibits more stable distribution regarding the attitude angle. Minimizing the elastic ring flexibility causes an increase in amplitude. The model is validated by the test results giving that the outer chamber pressure shifts synchronously and periodically with the variation of the attitude angle, while the pressure amplitude increases slightly at higher rotor speeds.     

同心与非同心型挤压油膜阻尼器减振能力的实验比较

为了比较带定心弹簧的同心型与不带定心弹簧的非同心型挤压油膜阻尼器(SFD)的减振能力，在同心型与非同心型SFD 多盘柔性转子系统实验装置上进行了不同转子不平衡质量及油膜径向间隙条件下的系列试验。结果表明:相对于刚性及纯弹性支承，两种SFD都能够有效地减小转子系统的振动。在同心型SFD 柔性转子系统中，当SFD的作用相对定心弹簧的作用较弱时，可以用定心弹簧来调整转子系统临界转速的位置，转子的临界转速在弹支临界转速附近；当SFD的作用相对定心弹簧的作用较强时，定心弹簧对转子系统临界转速的影响不大，转子的临界转速在刚支临界转速附近。非同心型SFD 转子系统的非线性特性比同心型SFD转子系统更为复杂，不仅会出现主共振，而且还会出现超谐共振及亚谐共振。