Nowadays, outer surface design of passenger cars is not just a
matter of styling and safety but air flow around car body and
exterior accessories has significant effect on fuel consumption,
performance and dominantly on the wind noise. In recent years,
passenger comfort is one of the most challenging and important
automotive attributes for car makers. Controlling the turbulence
eddies that causes aerodynamic noise can remarkably affect
passenger's comfort quality. Identification of aerodynamic
sources is considered as the first step in order to control the
wind noise.
In this research, computational fluid dynamics method is applied
to simulate the wind flow around the car and the investigation of
aerodynamic noise pattern is performed by numerical method which is
the most prevalent way that is used by auto industries. By the
advent of virtual simulations and by implementing these methods for
the purpose of predicting and modifying in the whole car design
phase, a considerable reduction in the automotive design process
time and cost has been achieved. This study includes two main
sections: Firstly, identification of aerodynamic noise source
around a coupe passenger car is investigated. For this purpose
after CAD modeling, preparing model for simulation is performed in
preprocessing CAE software and numerical calculations are done by
using finite volume method. In fact, fluctuations of pressure on
external surfaces of body are considered as the main cause for
aerodynamic noise and in practice this phenomena is detected for
the identification purpose. Hence, acoustic power level is the
reference parameter for studying the wind acoustic quality. In
order to investigate acoustic power, broad band noise model is
applied for acoustics and realizable k-ε model is used for solving
turbulence fluid. In the second section, rear spoiler is added to
the vehicle and acoustic effects are studied. Results are compared
with each other and the acoustic effects of the rear spoiler on the
rear section of the car surface including the windshield, trunk lid
and rear end parts are summarized using CAE tools.