CHODE, Kushal Kumar (2023). An Investigation of Aerodynamic Noise from Standard Ground Vehicles using Computational Aeroacoustics. Doctoral, Sheffield Hallam University. [Thesis]
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Chode_2024_PhD_AnInvestigationOfAerodynamic.pdf - Accepted Version
Restricted to Repository staff only until 2 January 2025.
Available under License Creative Commons Attribution Non-commercial No Derivatives.
Chode_2024_PhD_AnInvestigationOfAerodynamic.pdf - Accepted Version
Restricted to Repository staff only until 2 January 2025.
Available under License Creative Commons Attribution Non-commercial No Derivatives.
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Abstract
The noise radiating from ground vehicles and its detrimental effects on occupants,
pedestrians, and the environment have spurred vehicle manufacturers to seek effective noise
prediction methods and mitigation strategies. This thesis focuses on predicting
aerodynamically generated noise from vehicles using a hybrid Computational Aeroacoustics
(CAA) method. This study aims to explore how geometrical features influence noise generation
and provide valuable insights for noise reduction. A hybrid CAA approach is proposed,
employing Stress Blended Eddy Simulation (SBES), and Ffowcs-Williams and Hawkings
(FW-H) acoustic analogy to predict noise radiation from standardised vehicle geometries.
Initially, SBES is validated against experimental data for scaled notchback geometry, followed
by assessing SBES coupled with FW-H to predict noise radiated by half-round mirrors.
Subsequently, the methodology is applied to full-scale vehicle geometry with a bluff mirror
mounted on one side.
The SBES predictions indicate that the flow behaviour behind the backlight of notchback
becomes increasingly asymmetric with a higher backlight angle, which is consistent with the
experimental findings. As the backlight angle increased, the strength of the vortex generated
from the lateral edges of the backlight decreased on one side and increased on the other side,
leading to an asymmetrical flow. The hybrid CAA approach predicts the flow and noise
radiated from the half-round mirror in agreement with experiments and reveals increased noise
radiation with higher aspect ratios but reduced noise when the mirror is inclined towards the
mounting plate. Notably, the radiated noise from the half-round mirror exhibited a dipole-like
structure near the plate and a monopole-like structure away from it. This observation is
consistent for both variations introduced into the half-round mirror. For the full-scale vehicle
model, the absence of the A-pillar is identified as the primary contributor to overall noise
radiation. However, in the presence of a side-view mirror, the side window becomes a
significant contributor to noise. Additionally, when the mirror is inclined, a linear reduction in
the radiated noise is observed, although the vehicle's overall drag becomes nonlinear and highly
dependent on the flow behaviour past the mirror.
The proposed hybrid CAA approach provides valuable insights into noise prediction for ground
vehicles. By considering the impact of mirror inclination and geometric factors on noise
radiation, this research contributes to the development of quieter and more aerodynamically
efficient vehicles, thus fostering a comfortable and sustainable transportation environment.
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