Print Email Facebook Twitter Aeroacoustics of sawtooth trailing-edge serrations under aerodynamic loading Title Aeroacoustics of sawtooth trailing-edge serrations under aerodynamic loading Author Lima Pereira, L.T. (TU Delft Wind Energy) Ragni, D. (TU Delft Wind Energy) Avallone, F. (TU Delft Wind Energy) Scarano, F. (TU Delft Aerospace Engineering; TU Delft Aerodynamics) Faculty Aerospace Engineering Date 2022 Abstract The impact of aerodynamic loading on a serrated trailing edge is studied experimentally. Aerodynamic and acoustic measurements are conducted on a sawtooth-shaped trailing edge, retrofitted to a flat plate featuring a trailing-edge flap, and placed at incidence to the free-stream flow. The turbulent flow across the trailing edge is inspected by time-resolved three-dimensional velocity field measurements obtained from 4D-PIV, while the wall-pressure fluctuations are measured with surface-embedded microphones. Results discuss the relation between the velocity fluctuations over the serrations, the surface pressure fluctuations, and the far-field noise spectra. The aerodynamic analysis discusses the effect of counter-rotating vortex pairs, generated by the pressure imbalance across the edges of the serrations under loading. It is shown that the interaction of these vortices with the incoming turbulence affects the intensity of the wall-pressure spectrum at the outer rim of the serration surface. On the suction side, the intensity of the pressure fluctuations from the incoming boundary layer dominates over that induced by the vortex pairs. On the pressure side, instead, the velocity gradient prescribed by the vortex pairs produces a significant increase of the pressure fluctuations around the edges. The resulting spatial distribution of the wall-pressure fluctuations directly affects the far-field noise. Scattering predictions carried out with the wall-pressure fluctuations in the centre and root (on the suction side) exhibit good agreement with the measured noise in the low-frequency range, whereas using the surface pressure data at the tip of the serration (on the pressure side) yields a better prediction in the high-frequency range. Subject aeroacousticsaerodynamic loadingstreamwise vorticestrailing-edge serrations To reference this document use: http://resolver.tudelft.nl/uuid:f2a23c5b-1afd-4ece-b6ac-1bfcef070970 DOI https://doi.org/10.1016/j.jsv.2022.117202 ISSN 0022-460X Source Journal of Sound and Vibration, 537 Part of collection Institutional Repository Document type journal article Rights © 2022 L.T. Lima Pereira, D. Ragni, F. Avallone, F. Scarano Files PDF 1_s2.0_S0022460X22003960_main.pdf 13.3 MB Close viewer /islandora/object/uuid:f2a23c5b-1afd-4ece-b6ac-1bfcef070970/datastream/OBJ/view