Broadband suppression of aerodynamic pressure on the high-speed bluff body surface with periodic square-cavity acoustic metasurface

Abstract

In this paper, a Multiphysics coupling simulation model of flow and acoustics is proposed using COMSOL software, and its results are verified by comparing with experimental results of others. Then, the aerodynamic pressure above the bluff body surface at a speed of 350 km/h is simulated. Moreover, a near-zero-impedance acoustic metasurface composed of periodic square cavities is theoretically studied with respect to the lowest acoustic pressure, which is consistent with simulation results. The wake vortices are greatly reduced due to the suction effect formed in the cavities when the fluid flow passes through the square-cavity metasurface. The vertical velocity above the square-cavity boundary is significantly increased, essentially leading to the decrease in acoustic impedance. The presence of high-speed fluid flow weakens the attenuation effect of the square-cavity acoustic metasurface on the acoustic field. The reduction in wake vortices and the near-zero-impedance of the boundary fundamentally suppress the acoustic pressure fluctuation above the bluff body surface. Finally, large broadband suppression of aerodynamic pressure and 7.3 dB reduction in the average acoustic pressure level are realized with the periodic acoustic metasurface. The greater the porosity of the square cavities, the smaller the fluctuating pressure amplitude. This work provides a new idea for the complete control of the aerodynamic pressure in a high-speed flow field and shows a great engineering application prospect.

Aerodynamic noise control with an acoustic metasurface comprising an array of low-flow-sensitivity Helmholtz resonators

“…The Reynolds number based on the length of the Ahmed body and the inlet flow velocity is equal to 8.93 × 10 5 . The flowcharacteristics is first analyzed by establishing a k-ε turbulence computational model and the wall function is used to describe the characteristics of the near-wall region [30,31]. The lower surface of the computational domain and Ahmed surface are set as non-slip boundaries, and the symmetric surface of the computational domain is set as symmetric boundary and the remaining surfaces are set as slip boundaries.…”