The significant impact of ribs and small-scale roughness on cylinder drag crisis
| Autor: | Lars Morten Bardal, Arne Kilvik Skeide, R. Jason Hearst, Luca Oggiano |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Drag coefficient
Materials science 010504 meteorology & atmospheric sciences Renewable Energy Sustainability and the Environment Mechanical Engineering Reynolds number Mechanics Wake Vortex shedding 01 natural sciences 010305 fluids & plasmas Physics::Fluid Dynamics symbols.namesake Drag Drag crisis 0103 physical sciences symbols Physics::Accelerator Physics Cylinder 0105 earth and related environmental sciences Civil and Structural Engineering Wind tunnel |
| Zdroj: | Journal of Wind Engineering and Industrial Aerodynamics |
| ISSN: | 0167-6105 |
| DOI: | 10.1016/j.jweia.2020.104192 |
| Popis: | The impact of flow-normal ribs and small-scale surface roughness on the drag and vortex shedding of a circular cylinder was investigated. Three rib heights, four relative rib spacings and three different forms of microroughness were combined to produce 28 unique surface coatings for the cylinder. The drag was measured in a wind tunnel for Reynolds numbers in the range 20; 000 < Re < 160; 000, representing nearly a decade change centred about the drag crisis. The drag measurements were complemented by hot-wire measurements in the wake to investigate the vortex shedding frequency. The results show significant average drag reduction, up to 23%, for most of the ribbed geometries compared to a smooth cylinder for Re < 160; 000. Increasing the rib height was found to reduce the critical Reynolds number and increase the minimum drag coefficient. Varying the rib spacing resulted in an ‘‘optimal” spacing, approximately five times the rib height, that caused the lowest critical Reynolds number. Increasing the micro-roughness resulted in a reduction in the critical Reynolds number and an increase in the minimum drag coefficient. © 2020 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). |
| Databáze: | OpenAIRE |
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