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.
Highlights
The emergence of Lighthill’s acoustic analogy theory in 1952 opened the prelude to the study of flow noise.[1]
Extensive research has shown that the aerodynamic noise of the fluid flow passing through the body surface is one of the main noise sources under the action of viscous stress and is mainly determined by the fluctuating pressure when the Mach number does not exceed 0.3.5–8
Under the premise of a deep understanding of the aerodynamic noise sources in high-speed flow fields and on the basis of high-efficiency calculation performance and unique multi-field fully coupled analysis capabilities of COMSOL Multiphysics, we propose a coupling simulation model of the flow and acoustics and conduct detailed research on the control mechanism of the aerodynamic pressure above the surface of the bluff body with a squarecavity acoustic metasurface at a speed of 350 km/h
Summary
The emergence of Lighthill’s acoustic analogy theory in 1952 opened the prelude to the study of flow noise.[1]. It is of great significance to establish an efficient and accurate coupling simulation model of the flow and acoustics field to better analyze and control the high-speed flow noise. The key to this is whether the interaction between the flow field and acoustic field can be accurately obtained. Under the premise of a deep understanding of the aerodynamic noise sources in high-speed flow fields and on the basis of high-efficiency calculation performance and unique multi-field fully coupled analysis capabilities of COMSOL Multiphysics, we propose a coupling simulation model of the flow and acoustics and conduct detailed research on the control mechanism of the aerodynamic pressure above the surface of the bluff body with a squarecavity acoustic metasurface at a speed of 350 km/h.
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