The team created a separate mesh for the cabin boundary and interior, with the glass surfaces being shared by the exterior and interior geometries. The engineers mapped the pressure onto surfaces of the vehicle body to act as external excitations. With the exterior SPL predictions in hand, the Corning team used them as inputs in ANSYS Mechanical for the vibro-acoustics analysis. As expected, the predicted exterior wind noise was reduced as vehicle speed decreased. In addition to the modified geometry, the team ran the simulation twice more at air flow speeds of 60 mph andģ0 mph. The modified design predictions indicated an exterior noise reduction of up to 5 dB on the front side windows. ”ĭesign with a smooth transition (no under-flush) between the windshield and A-pillar. Lighter-weight glass material would have an impact. “Corning engineers wanted to determine which glass surfaces were the most important paths for glazing noise transmission, and also whether The team’s baseline vehicle model considered a design with 5 millimeters of under-flush, which they compared to a modified In a standard windshield design, there is usually a small under-flushingĭiscontinuity between the glass surface and the A-pillar where the edge of the glass extends under the pillar.
#ANSYS ACOUSTIC TUTORIAL PDF WINDOWS#
The initial CFD analysis showed greater exterior SPL values at the lower corners of the windshieldĪnd on the front side windows when compared to the rest of the glazing. This large case required use of ANSYS HPC on Corning’s HPC cluster. Them to evaluate the sound pressure levels (SPL) of glazing in the more commonly understood dB scale. Corning converted the transient data from the time domain to the frequency domain using the fast Fourier transform (FFT) capability, which allowed Such a small time step was required because the team needed to resolve frequencies up to 5 kHz to cover the wide range of airborne noise. Vk.com/club152685050 | vk.com/id446425943Ī Window into Automotive Noise (continued)Ġ.5 seconds of actual turbulent flow. The team ran the DES model for 10,000 time steps to simulate LES is computationally moreĮxpensive, and was used in the coarser domain away from the vehicle, while RANS was used to solve the more finely resolved areas at the wall boundaries. Solution and large eddy simulation (LES) modeling based on the mesh Q-criterion, colored by velocity magnitude Main vortex shedding regions from the turbulent flow field using the The size of the domain was chosen so that vortex shedding, flow separation and reattachment phenomena could be captured. Taking advantage of symmetry, the engineers used ANSYS CFD meshing capability to create a computational fluid dynamics (CFD) mesh of 55 million hexcore cells to model the fluid domain surrounding half Because the study focused on sound transmission through glazing, detailed vehicle features in the regions surrounding the glass - such as mirrors and the A-pillar - were maintained, while areas around the bumpers and tires were modeled with less detail. sport-utility vehicle to reduce the cost of meshing and overall computation. The DAVA process began with a simplified geometry of a common U.S. The team employed a simulation method called deterministic aero-vibroacoustics (DAVA) using fluid and structural analysis tools in ANSYS Workbench. Modeling with vibro-acoustic modeling used in the DAVA method.įor glazing noise transmission, and also whether lighter-weight glass This results in turbulent flow that causes fluctuations in theĪir pressure field on the outer surface ofįull-vehicle wind noise model illustrates the combination of aerodynamic At highway speeds, the air surrounding a vehicle is disturbed by the vehicle’s front end, the A-pillar (windshield support structure) and side mirrors. To help mitigate this problem, engineers at Corning have been studying the physical mechanism by which exterior wind translates into cabin noise.
0 kommentar(er)
