分形格栅生成湍流场的粒子成像测速研究

2018/12/14   下载量： 6 次

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应用领域 其他
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采用英国Litron公司Nano系列200毫焦532nm双腔激光器，两台4百万像素相机从两个相对的方向，拍摄大视场和小视场的粒子图像。用LaVision的DaVis8.0数据采集和分析软件，分析用分形格栅生成的湍流场。

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An experimental investigation involving space-filling fractal square grids is presented. The flow is documented using particle image velocimetry (PIV) in a water tunnel as opposed to previous experiments which mostly used hot-wire anemometry in wind tunnels. The experimental facility has non-negligible incoming free-stream turbulence (with 2.8% and 4.4% in the streamwise (u0=U) and spanwise (v0=U) directions, respectively) which presents a challenge in terms of comparison with previous wind tunnel results. An attempt to characterize the effects of the incoming free stream turbulence on the grid-generated turbulent flow is made and an improved wake-interaction length scale is proposed which enables the comparison of the present results with previous ones for both fractal square and regular grids. This length scale also proves to be a good estimator of the turbulence intensity peak location. Furthermore, a new turbulence intensity normalization capable of collapsing
u0=U for various grids in various facilities is proposed. Comparison with previous experiments indicates good agreement in turbulence intensities, Taylor microscale, as well as various other quantities, if the improved wake-interaction length scale is used. Global and local isotropy of fractal-generated turbulence is assessed using the velocity gradients of the two-component (2C) two-dimensional (2D) PIV and compared with regular grid results. Finally, the PIV data appear to confirm the new dissipation behaviour previously observed in hot-wire measurements.

上一篇 在一个双稳湍流涡旋火焰中，对间歇性动态的时间-频率定位
下一篇 采用千赫兹重频多模激光泵浦光学参量振荡器构成的CH平面激光诱导荧光成像系统性能

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北京欧兰科技发展有限公司
金牌会员 丨 第17年
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