Investigation on effectively suppressing sunroof wind buffeting noise through utilizing vortex-based energy characteristics

Abstract

Through dynamic mode decomposition (DMD), it is discovered that the significant pressure fluctuations between the center and trailing edge of the sunroof are caused by the vortices expanding and pushing against each other. To effectively improve the squeezing state of vortices within the sunroof, an effective method for suppressing wind buffeting noise has been proposed via precisely arranging the crossbar positions. Specifically, a cylindrical transverse rod is placed at the position where the velocity diffusion term of the first-order mode is minimized, and it is also aligned with the movement trajectory of the vortex. The results of numerical simulations demonstrate that this method achieves noise reduction of more than 14.2 dB. To further explore the modal characteristics of this scheme, the main pressure and velocity fluctuations associated with wind buffeting noise are extracted via DMD, and the modal characteristics of the original scheme and this scheme are compared and analyzed. The results show that the proposed crossbar scheme based on DMD is highly effective in mitigating pressure and velocity fluctuations. The transverse rod is able to effectively disrupt vortices and pressure clusters within the sunroof, leading to a suppression of the prominent resonance peak. By improving the squeezing state between vortices, velocity and pressure fluctuations are subsequently reduced. Compared to the original scheme, the crossbar scheme exhibits more vortices in each dynamic mode, the vortices and pressure clusters of each order dynamic mode have inconsistent streamwise evolutions, thereby suppressing the formation of large single-core vortex and pressure cluster. This is advantageous for suppressing wind buffeting noise.