Active aerodynamic drag reduction on morphable cylinders
We study a mechanism for active aerodynamic drag reduction on morphable grooved cylinders, whose topography can be modified pneumatically. Our design is inspired by the morphology of the Saguaro cactus (Carnegiea gigantea), which possesses an array of axial grooves, thought to help reduce aerodynami...
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| Format: | Article |
| Language: | English |
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American Physical Society
2018
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| Online Access: | http://hdl.handle.net/1721.1/114398 https://orcid.org/0000-0002-0703-4989 https://orcid.org/0000-0003-3984-828X |
| _version_ | 1826217507268067328 |
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| author | Guttag, Mark Andrew Reis, Pedro Miguel |
| author2 | Massachusetts Institute of Technology. Department of Civil and Environmental Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Civil and Environmental Engineering Guttag, Mark Andrew Reis, Pedro Miguel |
| author_sort | Guttag, Mark Andrew |
| collection | MIT |
| description | We study a mechanism for active aerodynamic drag reduction on morphable grooved cylinders, whose topography can be modified pneumatically. Our design is inspired by the morphology of the Saguaro cactus (Carnegiea gigantea), which possesses an array of axial grooves, thought to help reduce aerodynamic drag, thereby enhancing the structural robustness of the plant under wind loading. Our analog experimental samples comprise a spoked rigid skeleton with axial cavities, covered by a stretched elastomeric film. Decreasing the inner pressure of the sample produces axial grooves, whose depth can be accurately varied, on demand. First, we characterize the relation between groove depth and pneumatic loading through a combination of precision mechanical experiments and finite element simulations. Second, wind tunnel tests are used to measure the aerodynamic drag coefficient (as a function of Reynolds number) of the grooved samples, with different levels of periodicity and groove depths. We focus specifically on the drag crisis and systematically measure the associated minimum drag coefficient and the critical Reynolds number at which it occurs. The results are in agreement with the classic literature of rough cylinders, albeit with an unprecedented level of precision and resolution in varying topography using a single sample. Finally, we leverage the morphable nature of our system to dynamically reduce drag for varying aerodynamic loading conditions. We demonstrate that actively controlling the groove depth yields a drag coefficient that decreases monotonically with Reynolds number and is significantly lower than the fixed sample counterparts. These findings open the possibility for the drag reduction of grooved cylinders to be operated over a wide range of flow conditions. |
| first_indexed | 2024-09-23T17:04:41Z |
| format | Article |
| id | mit-1721.1/114398 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T17:04:41Z |
| publishDate | 2018 |
| publisher | American Physical Society |
| record_format | dspace |
| spelling | mit-1721.1/1143982022-10-03T10:15:40Z Active aerodynamic drag reduction on morphable cylinders Guttag, Mark Andrew Reis, Pedro Miguel Massachusetts Institute of Technology. Department of Civil and Environmental Engineering Massachusetts Institute of Technology. Department of Mechanical Engineering Guttag, Mark Andrew Reis, Pedro Miguel We study a mechanism for active aerodynamic drag reduction on morphable grooved cylinders, whose topography can be modified pneumatically. Our design is inspired by the morphology of the Saguaro cactus (Carnegiea gigantea), which possesses an array of axial grooves, thought to help reduce aerodynamic drag, thereby enhancing the structural robustness of the plant under wind loading. Our analog experimental samples comprise a spoked rigid skeleton with axial cavities, covered by a stretched elastomeric film. Decreasing the inner pressure of the sample produces axial grooves, whose depth can be accurately varied, on demand. First, we characterize the relation between groove depth and pneumatic loading through a combination of precision mechanical experiments and finite element simulations. Second, wind tunnel tests are used to measure the aerodynamic drag coefficient (as a function of Reynolds number) of the grooved samples, with different levels of periodicity and groove depths. We focus specifically on the drag crisis and systematically measure the associated minimum drag coefficient and the critical Reynolds number at which it occurs. The results are in agreement with the classic literature of rough cylinders, albeit with an unprecedented level of precision and resolution in varying topography using a single sample. Finally, we leverage the morphable nature of our system to dynamically reduce drag for varying aerodynamic loading conditions. We demonstrate that actively controlling the groove depth yields a drag coefficient that decreases monotonically with Reynolds number and is significantly lower than the fixed sample counterparts. These findings open the possibility for the drag reduction of grooved cylinders to be operated over a wide range of flow conditions. National Science Foundation (U.S.) (CAREER CMMI-1351449) 2018-03-27T15:43:15Z 2018-03-27T15:43:15Z 2017-12 2017-02 2018-02-07T20:55:52Z Article http://purl.org/eprint/type/JournalArticle 2469-990X 2469-9918 http://hdl.handle.net/1721.1/114398 Guttag, M. and P. M. Reis. "Active aerodynamic drag reduction on morphable cylinders." Physical Review Fluids 2, 12 (December 2017): 123903 © 2017 American Physical Society https://orcid.org/0000-0002-0703-4989 https://orcid.org/0000-0003-3984-828X en http://dx.doi.org/10.1103/PhysRevFluids.2.123903 Physical Review Fluids Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. American Physical Society application/pdf American Physical Society American Physical Society |
| spellingShingle | Guttag, Mark Andrew Reis, Pedro Miguel Active aerodynamic drag reduction on morphable cylinders |
| title | Active aerodynamic drag reduction on morphable cylinders |
| title_full | Active aerodynamic drag reduction on morphable cylinders |
| title_fullStr | Active aerodynamic drag reduction on morphable cylinders |
| title_full_unstemmed | Active aerodynamic drag reduction on morphable cylinders |
| title_short | Active aerodynamic drag reduction on morphable cylinders |
| title_sort | active aerodynamic drag reduction on morphable cylinders |
| url | http://hdl.handle.net/1721.1/114398 https://orcid.org/0000-0002-0703-4989 https://orcid.org/0000-0003-3984-828X |
| work_keys_str_mv | AT guttagmarkandrew activeaerodynamicdragreductiononmorphablecylinders AT reispedromiguel activeaerodynamicdragreductiononmorphablecylinders |