西安交通大学流体机械与工程系,西安,710049
网络首发:2010-11-10,
纸质出版:2010
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刘江 1, 王元 1, 杨斌 2. 高频测量输沙浓度对湍流脉动的频率响应[J]. 西安交通大学学报, 2010,44(11):113-118.
High-Frequency Measurements of Particle Response to Turbulence[J]. 2010, 44(11): 113-118.
为揭示风沙流中输沙浓度对湍流脉动的响应频率
在边界层风洞中对不同粒径沙样进行了两相同步测量.采用高速数字相机以2 000 帧/s拍摄跃移粒子连续图像以计算瞬时输沙浓度
配合热线风速仪同步记录跃移层内的湍流脉动.结果表明
沙粒瞬时浓度变化呈典型的随机过程
其频谱规律表明输沙浓度只能响应含能较高的低频湍流脉动.引入小波包变换分析两相数据的能量结构
结果显示沙粒浓度的能量波动约有90%集中在500 Hz内的低频段.输沙浓度对湍流脉动的响应频率受粒子尺寸的影响
对于100~125 μm的小粒径沙样
阈值响应频率约为40 Hz
对于300~500 μm的大粒径沙样
响应频率约为30 Hz.
In order to analyze the response frequency of saltating particles to turbulence
the fluid-particle synchronous measurements were carried out in a boundary layer wind-tunnel with different particle sizes. A high-speed digital camera was employed to record consecutive instantaneous images of the saltating particles at 2 000 frames per second to calculate the particle concentration
and the turbulent velocity fluctuation in the saltation layer was obtained simultaneously by a hot-wire anemometer. The results show that the saltation transport of sand particles is a typical stochastic process. The variations of the particle concentration are closely dependent only on the turbulent flow at low-frequency band. Moreover
the wavelet packet analysis shows that the low frequency section lower than 500 Hz of the particle concentration dominates the energy structure of sand-phase. In addition
the effects of a fluctuating wind on particle concentration are different for various particle sizes. For the smaller sand(100-125 μm)
the threshold response frequency of particle concentration to turbulence is about 40 Hz while the frequency value is roughly 30 Hz for the larger sand(300-500 μm).
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