Print Email Facebook Twitter The internal and external flow fields of a structured porous coated cylinder and implications on flow-induced noise Title The internal and external flow fields of a structured porous coated cylinder and implications on flow-induced noise Author Arcondoulis, Elias J. G. (Southern University of Science and Technology) Ragni, D. (TU Delft Wind Energy) Rubio Carpio, A. (TU Delft Aircraft Noise and Climate Effects) Avallone, F. (TU Delft Wind Energy) Liu, Yu (Southern University of Science and Technology) Yang, Yannian (Southern University of Science and Technology) Li, Zhiyong (Southern University of Science and Technology) Date 2019 Abstract Porous coated cylinders have been shown to reduce the vortex shedding tone and broadband noise of a bare cylinder placed in uniform flow within specific Reynolds number regimes. The processes by which the vortex shedding and thus tone suppression take place are still uncertain despite numerous numerical and experimental studies. It is understood that adding a porous medium to a bare cylinder will have an influence on the Reynolds number of cylinder, yet the increase of outer diameter alone and the influences of surface roughness are insufficient to explain the changes in the shedding tone magnitude and frequency that are observed by many. Investigating the internal flow field of a porous coated cylinder could lead to a deeper understanding of the flow processes that result in the tonal noise reduction. This has not been achieved to date, as commonly used materials such as metal foam and polyurethane possess randomized porous structures, which make investigating the internal flow field nearly impossible without affecting the structure itself. This paper presents a preliminary analysis of the internal and external flow fields of two structured porous coated cylinders. The cylinders were manufactured using solid transparent materials that possess direct lines of sight through the pores in the axial and spanwise directions. Such structured porous coated cylinders have been previously successful in reducing the typical vortex shedding tone. Tomographic and 2-D planar Particle Image Velocimetry (PIV) were used in a water-tunnel facility to visualize the internal and external flow fields. To date only the 2-D planar PIV results have been post-processed that reveal differences in the wake for the two different cylinder types such as recirculation of flow around the pores. Vorticity flow structures are observed to vary along the cylinder span in the same pattern as the porous structure and streamlines at the windward cylinder side reveal the entry of flow into the porous medium. To reference this document use: http://resolver.tudelft.nl/uuid:cb365e80-edac-4575-b0c6-418ac0145b45 DOI https://doi.org/10.2514/6.2019-2648 Publisher American Institute of Aeronautics and Astronautics Inc. (AIAA) ISBN 978-1-62410-588-3 Source 25th AIAA/CEAS Aeroacoustics Conference: 20-23 May 2019 Delft, The Netherlands Event 25th AIAA/CEAS Aeroacoustics Conference, 2019-05-20 → 2019-05-23, Delft, Netherlands Bibliographical note Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public. Part of collection Institutional Repository Document type conference paper Rights © 2019 Elias J. G. Arcondoulis, D. Ragni, A. Rubio Carpio, F. Avallone, Yu Liu, Yannian Yang, Zhiyong Li Files PDF 6.2019_2648.pdf 9.96 MB Close viewer /islandora/object/uuid:cb365e80-edac-4575-b0c6-418ac0145b45/datastream/OBJ/view