The experiment and analysis of transitional flow in pipe

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• 作者：Jun WANG ((王军))^a ; ^b ; ^{wwjjy99@126.com" class="auth_mail" title="E-mail the corresponding author}Author Vitae ; Guang-sheng DU ((杜广生))^a ; ^{du@sdu.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Jing-ying WANG ((王京盈))^a ; Jie GENG ((耿介))^a ; Dong LI ((李冬))^a
• 关键词：transitional flow ; attenuation ; velocity gradient ; flow instability ; energy coefficient
• 刊名：Journal of Hydrodynamics, Ser. B
• 出版年：2016
• 出版时间：April 2016
• 年：2016
• 卷：28
• 期：2
• 页码：313-318
• 全文大小：961 K

文摘

The transitional flow in a pipe is important for delivery, but its characteristics remain to be explored. In this paper, the two-dimensional laser Doppler velocimetry (LDV) is used for the study, focusing on the attenuation characteristics of the axial velocity, the variation of the velocity gradient, the effect of the angle between the axis and the resultant velocity vector, and the relationship between the energy coefficient and the flow state. The attenuation characteristics of the axial velocity along the radial direction are obtained. It is shown that with the increase of the Reynolds number, the change rate of the velocity gradient slows down with a similar distribution, and a rapid decrease is seen in the near wall region. The amplitude and the frequency of the angular variation are obviously improved with the increase of the Reynolds number. The instability of the velocity field is enhanced with the increase of the energy coefficient.