Prediction, Verification and Control of Aerodynamic Noise on Ahmed Body Surface

To realize effective control of the low-frequency aerodynamic noise on the Ahmed body surface with a flow velocity of 40[Formula: see text]m/s, a nearly-tapered-neck Helmholtz resonator (TNHR) is proposed through flow-acoustic coupling simulation. The capture of the flow characteristics and the prediction of noise energy have been verified well by the experimental and simulation data of others. The TNHR exhibits more efficient suppression of acoustic pressure compared with HR at the same speed, which can be attributed to the fact that greater counterclockwise pressure difference generated at the TNHR interface forms strong multiple vortexes with larger vortex area in the TNHR neck and enhances the influence of fluid flow inside the neck on the external flow field, resulting in a significant increase in flow velocity at the interface and then the decreased impedance of TNHR. Moreover, the acoustic pressure of TNHR with larger diameters of holes and absorption area ratio could be further reduced to nearly zero with less effect of the increasing fluid flow. The low-frequency acoustic pressure suppression of TNHR proposed shows potential applications in aerodynamic noise control.