Experimental Study on the Flow Pattern of Double-hemisphere Rough Elements with Different Streamwise Spacing
Publish place: Journal of Applied Fluid Mechanics، Vol: 16، Issue: 8
Publish Year: 1402
نوع سند: مقاله ژورنالی
زبان: English
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شناسه ملی سند علمی:
JR_JAFM-16-8_003
تاریخ نمایه سازی: 27 خرداد 1402
Abstract:
Particle image velocimetry is used to study the variation around single- and double-hemisphere rough elements with different streamwise spacings immersed in the boundary layer. Instantaneous velocity field information in the streamwise–normal and streamwise–spanwise directions is collected at a Reynolds number of ۱۸۰۰. ۳R, ۵R, and ۷R are determined as the rough element spacing used in the double-hemisphere rough element experiment, representing the smaller, medium transition, and larger rough element spacing, respectively. The average velocity, Reynolds shear stress, shedding frequency, and proper orthogonal decomposition results of the flow field around the rough elements under various working conditions were compared. The downstream hemisphere will encroach on the streamline following the upstream hemisphere, and changing the spacing means changing the position of the encroached area. When the spacing is smaller, the streamline reattachment is destroyed, and the momentum and mass exchange between the two-hemisphere rough elements decreases. The double-hemisphere rough element is a slender, blunt, rough element. At the medium transition spacing, the shear layer and vortex structure shed from the upstream hemisphere are over the downstream hemisphere, and the double-hemisphere rough elements will cause disturbance in a larger wall-normal range. The streamline has been reattached at the larger streamwise spacing, and the interaction between the two hemispheres is the weakest. Here, the double-hemisphere rough element will form the recirculation zone, recirculation arch vortex, and periodic hairpin vortex.
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Authors
P. Chen
Department of Process Equipment and Control Engineering, Hebei University of Technology, Tianjin, ۳۰۰۱۳۰, China
J. Sun
Department of Process Equipment and Control Engineering, Hebei University of Technology, Tianjin, ۳۰۰۱۳۰, China
Y. T. Cheng
Department of Process Equipment and Control Engineering, Hebei University of Technology, Tianjin, ۳۰۰۱۳۰, China
W. Y. Chen
Department of Process Equipment and Control Engineering, Hebei University of Technology, Tianjin, ۳۰۰۱۳۰, China
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