The internal and external flow fields of a structured porous coated cylinder and implications on flow-induced noise

Elias J. G. Arcondoulis, Daniele Ragni, Alejandro Rubio Carpio, Francesco Avallone, Yu Liu, Yannian Yang, Zhiyong Li

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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.
Original languageEnglish
Title of host publication25th AIAA/CEAS Aeroacoustics Conference
Subtitle of host publication20-23 May 2019 Delft, The Netherlands
PublisherAmerican Institute of Aeronautics and Astronautics Inc. (AIAA)
Number of pages15
ISBN (Electronic)978-1-62410-588-3
DOIs
Publication statusPublished - 2019
Event25th AIAA/CEAS Aeroacoustics Conference - Delft, Netherlands
Duration: 20 May 201923 May 2019
Conference number: 25
https://arc.aiaa.org/doi/book/10.2514/MAERO19

Conference

Conference25th AIAA/CEAS Aeroacoustics Conference
CountryNetherlands
CityDelft
Period20/05/1923/05/19
Internet address

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    Arcondoulis, E. J. G., Ragni, D., Rubio Carpio, A., Avallone, F., Liu, Y., Yang, Y., & Li, Z. (2019). The internal and external flow fields of a structured porous coated cylinder and implications on flow-induced noise. In 25th AIAA/CEAS Aeroacoustics Conference: 20-23 May 2019 Delft, The Netherlands [AIAA 2019-2648] American Institute of Aeronautics and Astronautics Inc. (AIAA). https://doi.org/10.2514/6.2019-2648