| 论文简介 |
Probability Density Function of Velocity Fluctuations in a Rectangular T-junction Duct
Mei Lin1*, Bo Su1, Shi-Cong Li1, Yan-Tao Yin1, Qiu-Wang Wang1, Yi-Tung Chen2
1. School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an, 710049, China
2. Department of Mechanical Engineering, University of Nevada-Las Vegas, Las Vegas, NV 89154-4027,USA
*Corresponding author: janeylinm@mail.xjtu.edu.cn
Tel and Fax: +86-29-82667936
Abstracts: The streamwise and the spanwise velocity time series are measured from the wall to the center of the cross duct for the flow in a rectangular T-junction duct, which is similar to airflow conditions of high-speed train ventilation system. The turbulent statistical properties are reported at three streamwise locations which correspond to the upstream/downstream and the centerline of the T-junction (x/D=±1 and 0, respectively). Turbulence intensity, skewness and flatness factor, as well as probability density functions, have been investigated at the range of Reτ=5400-8700. Furthermore, the multiscale properties of the flatness factor are analyzed by using orthogonal wavelet transform. It is found that the turbulent intensities remain a constant in the center region for three streamwise locations while they are weakened in the turbulent boundary layer at x/D=1 by effect of suction. The location of the strongest intermittency is located at y/h=0.56 for x/D=-1 and 0. While at downstream of T-junction (x/D=1), the location of the strongest intermittency shifts down to y/h=0.28. Also, the wavelet flatness factor is more clearly distinguished the intermittency of the small-scale turbulent structure compared with the conventional flatness factor and, the global flatness factor is proposed to assess the intermittent intensity of the turbulent structure.
Key words: Probability density function, Velocity fluctuation, T-junction duct, Suction, Wavelet transform. |
(创新港)
