Study on aerodynamic force acting on a sphere with and without boundary layer trips around the critical Reynolds number with a magnetic suspension and balance system
Study on aerodynamic force acting on a sphere with and without boundary layer trips around the critical Reynolds number with a magnetic suspension and balance system
复制标题
利用磁悬浮和平衡系统研究作用在临界雷诺数附近有和没有边界层行程的球体上的气动力
DOI：
10.1007/s00348-010-0920-2
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发表时间：
2011
影响因子：
2.4
通讯作者：
S. Suda
中科院分区：
文献类型：
--
作者：
H. Sawada;S. Suda
成功地测量了作用在临界雷诺数附近的五种边界层作用在球体上的气动力，以及作用在光滑球体上的气动力。这是利用日本宇宙航空研究开发机构的60厘米磁悬浮和平衡系统在进行详细模拟和调整球体质量及其控制参数后实现的。在无支承干扰条件下，光滑球体的最小阻力系数约为0.19。带有边界层跳闸的球体在临界范围内的阻力系数没有观察到滞后现象。使用三个串联的二阶巴特沃斯低通滤波器，从测量的模型位置估算了振动频率小于15赫兹的惯性力，并以合理的精度估算了作用在球体上的非定常气动力。根据球体表面条件的不同，在临界范围内会出现两种气动力振荡：光滑球和高度为0.17 mm的轴对称球体的气动力均绕平行于均匀流的轴线旋转，而0.35 mm厚的带褶皱胶带作为小涡产生器时，气动力在包括平行于流轴的平面内的振荡力。对于超临界范围内的光滑球体，还观察到一个绕平行于流动的球轴不规则旋转的力，其旋转角度小于180°。
Aerodynamic force acting on a sphere for five kinds of boundary layer trips around the critical Reynolds number, together with the force on a smooth sphere, was successfully measured. This was achieved using JAXA’s 60-cm Magnetic Suspension and Balance System after performing detailed simulations and adjusting the sphere mass and its control parameters. The minimum drag coefficient of a smooth sphere was evaluated around 0.19 in the support-interference-free condition. No hysteresis was observed for the drag coefficient in the critical range for tested sphere with boundary layer trips. Using three serially connected 2nd-order Butterworth low-pass filters, an inertia force oscillating at less than 15 Hz was evaluated from the measured model position, and the unsteady aerodynamic force acting on the sphere was also evaluated with reasonable accuracy. Two kinds of oscillatory aerodynamic forces appeared in the critical range depending on the sphere surface condition: a force rotating around an axis parallel to the uniform flow for both a smooth sphere and a sphere with axially symmetric 0.17-mm-high backward step, and an oscillating force in the plane including the axis parallel to the flow for a sphere with axially symmetric step implemented with 0.35–mm-thick tape with wrinkles acting as small vortex generators. There was also observed a force irregularly rotating through less than 180° in the range about a sphere axis parallel to the flow for a smooth sphere in the supercritical range.