Experimental analysis of hydrodynamic and acoustic pressure on automotive front side window

Comparison of hydrodynamic and acoustic pressure on automotive front side window

“…Considering the difference between acoustic and hydrodynamic pressure for low Mach number flow, CFAT has been used to extract acoustic pressure on the automotive front side window. 10,25 Both the distance of the measurement points D and the singularity at the coincidence frequency shown in Figure 8 have the influence on the accuracy and frequency resolution of CFAT, as discussed in Yuan et al 10 and Pezerat et al 25 In this paper, the measurement results in the efficient frequency (2 \ n \ 4) is used to validate the numerical results of acoustic pressure on automotive front side window.…”

“…The WFS can separate acoustic pressure through experiments 11 and simulation, 12 while CFAT through experiments. 10 In summary, in the existing research, it has been recognized that the pressure excitation on the front side window can reflect the unsteady flow in the front side window area, which has certain sensitivity to driving conditions and road environment. At the same time, the pressure excitation on the front side window is also a reference index of the sound field in the car, which can be used as an evaluation parameter for the early development of automobile wind noise.…”

“…For low Mach flow, as the amplitude of acoustic pressure is much smaller than hydrodynamic pressure, it is difficult to separate the acoustic pressure from the hydrodynamic pressure especially in near flow field. Some potential methods for achieving acoustic pressure on automotive front side window have been summarized in Yuan et al 10 Base on the decomposition of control equations, Acoustic Perturbation Equations (APE) can calculate the acoustic component directly. Both wavenumber-frequency spectrum separation (WFS) and Corrected Force Analysis Technique (CFAT) extract acoustic components by wavenumber filtering.…”

Noise emitted from a generic side-view mirror with different aspect ratios and inclinations

“…Previous works that have attempted to reduce noise in real vehicles have primarily modified the side-mirror topology or together with the A-pillar that have resulted in ~8-10 dB reduction on the side window. 9,[38][39][40] However, to date, the efforts to understanding the physics of aerodynamic noise reduction from a standard mirror have not been made. Bluff body aeroacoustics analyses performed on the cylinders, square prisms, and turret studies indicate that the change in aspect ratio (AR = h/D) tends to change the lateral vortex size resulting in changes in unsteady pressure foot-print on the mounting surface away from the body and reduced the far-field noise by up to 10 dB.…”

“…With modern electrified powertrains, the migration of more tonal noises can distract the driver. 9 The flow past the vehicle A-pillar is highly turbulent, and the position of the side view mirror in this region makes the mirror a significant contributor to wind noise generated. 10 Analysis of the side view mirror is critical in designing quieter interior cabins by taking into account factors such as the shape of the mirror, the alignment of the mirror to the side window and additional design features such as turn signals and rain gutters that are changed continuously due to aesthetic merits and to avoid any tonal noise characteristics.…”