Rotational Flow in a Narrow Annular Gap Based on Lattice Boltzmann Method

For comprehensive characteristics of flow in a gas bearing,lattice Boltzmann method(LBM)is applied for study of the two-dimensional flow between two eccentric cylinders with the inner one rotating at a high speed.The flow pattern and circumferential pressure distribution are discussed based on critical issues such as eccentricity ranging from 0.2 to 0.9,clearance ratio varying from 0.005 to 0.01 and rotating speed in the range of 3×104—1.8×105 r/min.The analysis and discussion on the circumferential pressure distribution affirmed the quasilinear relation between the extremum pressure and rotating speed.Furthermore,a high eccentricity and small clearance ratio contributes most to the fluctuation of the circumferential pressure distribution.The flow pattern inside the channel exhibits separation vortex under a large eccentricity.The conclusions drawn in this work give rise to prediction of the flow pattern in the gas bearing which is beneficial for evaluating the performance of as well as instructing the design and development.

基于光纤偏振特性的压力传感中测量范围的拓展方法

测量范围的拓展对提升基于偏振特性的光纤压力传感系统的实用性有着重要意义。以拓宽测量范围并保持原有传感灵敏度为目标,提出了一种基于斯托克斯多参量融合的传感方案。通过理论仿真得到传感头目标偏振轴。利用偏振控制器,压力装置和偏振检测计,在实验中得到了线性度为99.8%、灵敏度为0.1938 N^(-1)、测量范围为28 N的传感性能,多参量融合方案的测量范围比单参量测量方案提高了5倍。实验结果与理论预期吻合较好。所提方案可以大幅度提升基于光纤偏振特性的传感系统的性能并扩展了其实用价值。