کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4493621 1318657 2015 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
A numerical study on optimal rotation ratio and bottom shear stress in the counter-rotation mode of an annular flume
ترجمه فارسی عنوان
یک مطالعه عددی نسبت به نسبت چرخش مطلوب و تنش برشی پایین در حالت ضد چرخش یک جریان حلقوی است
موضوعات مرتبط
علوم زیستی و بیوفناوری علوم کشاورزی و بیولوژیک علوم کشاورزی و بیولوژیک (عمومی)
چکیده انگلیسی


• The position of secondary flow cells is changed in large by rotation speed.
• The equation for optimal rotation ratio in the counter-rotation mode is presented.
• The optimal rotation ratio increases and converges to a uniform value.
• The equation for the averaged bottom shear stress is also presented.
• The proposed equation can be used easily and conveniently in the experiments.

In this study, the optimal rotation ratio that minimize both the secondary flow and the variation of the bottom shear stress in the radial direction in the annular flume was found from flow analysis using a computational fluid dynamics technique. The numerical model was verified from the measured data given in the literature. Forty-eight numerical calculations were carried out for the flow fields given with various rotation speed ratios of the top ring to the flume body. Some cases showed quite fluctuating non-uniform bottom shear stress profiles in the radial direction without any effective reduction of the secondary flow so that they were excluded in determining the optimal rotation ratio. It was found that the rotation ratio became optimal when both the maximum velocity ratio and the difference between the largest and smallest values of the stream function were minimal. Characteristically, in the range of relatively small top ring rotation speed (<10) the optimal rotation ratio increased rapidly with it, but it converged to a fixed value as it became larger. The relationship between the optimal rotation ratio and the rotation speed of the top ring is presented. An equation for the averaged bottom shear stress under the optimal rotation ratios is also proposed as a function of the top ring rotation speed.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Hydro-environment Research - Volume 9, Issue 4, December 2015, Pages 473–481
نویسندگان
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