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Wind and Structures Volume 39, Number 1, July 2024 , pages 31-45 DOI: https://doi.org/10.12989/was.2024.39.1.031 |
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Flow patterns and related vibrations around an inclined U-profile |
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Johannes Strecha, Stanislav Pospíšil and Herbert Steinrück
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| Abstract | ||
| This paper examines the flow characteristics around an inclined prism with a U-shaped cross-section ("U-profile") and investigates the connection between the flow and flow-induced vibrations. The study employs a combined approach that involves wind tunnel experiments and computational fluid dynamics (CFD) using an unsteady Reynolds-averaged NavierStokes (RANS) turbulence model. Distinct vortex formation patterns are observed in the flow field surrounding the stationary inclined profile. When the cavity of the profile faces away from the incoming flow, large vortices develop behind the profile. Conversely, when the cavity is oriented towards the oncoming flow, these vortices form within the cavity. Notably, due to the slow movement of these large vortices through the cavity, the frequency at which vortices are shed in the negative inclination case is lower compared to the positive inclination, where they form in the wake. Wind tunnel experiments reveal an intermittent transition between the two vortex formation patterns at zero inclination. Large vortices sporadically emerge both in the cavity and behind the profile. The simulation results demonstrate that when these large vortices occur at a frequency close to the structure's natural frequency, they induce prominent pitch vibrations. This phenomenon is also sought after and presented in coupled vibration experiments. Additionally, the simulations indicate that when the natural frequency of the structure is considerably lower than the vortex shedding frequency, this type of vibration can be observed. | ||
| Key Words | ||
| bluff body; flow pattern; particle image velocimetry; U-profile; unsteady RANS; vortex shedding frequency | ||
| Address | ||
| Johannes Strecha:TU Wien, Inst Fluid Mech and Heat Transfer, Getreidemarkt 9, 1060 Vienna, Austria Stanislav Pospíšil :Inst Theoret & Appl Mech of the Czech Acad Sci, Prosecka 76, 190 00 Prague, Czech Republic Herbert Steinrück:TU Wien, Inst Fluid Mech and Heat Transfer, Getreidemarkt 9, 1060 Vienna, Austria | ||