Concealed HVAC air duct and vent systems are increasingly adopted in modern
electric vehicles due to their improved cockpit integration capability and
compatibility with intelligent airflow management strategies. However, the
complex internal geometry and distributed airflow characteristics of concealed
vent configurations often introduce increased broadband aeroacoustic noise,
particularly at middle and high frequencies, where cabin masking effects are
significantly reduced in electric vehicles.
In this work, a high-fidelity aeroacoustic methodology based on the Lattice
Boltzmann Method (LBM) was applied using PowerFLOW to investigate concealed HVAC
vent aeroacoustic mechanisms and design sensitivities. Detailed vent geometry
was preserved using the Precise Wrap tessellation approach, while acoustic
porous media and wall absorption treatments were incorporated to represent the
acoustic behavior of foam materials inside the duct system. Numerical
predictions were correlated with semi-anechoic chamber measurements under
representative test conditions.
The study hypothesized that concealed vent cavity structures and flap–louver
interaction dominate broadband aeroacoustic generation above 1000 Hz and that
high-fidelity LBM simulation with detailed geometric representation can capture
these mechanisms within engineering-level prediction accuracy. Good agreement
between simulation and experiment was achieved for both overall sound pressure
level (SPL) and narrow-band spectrum distribution. The average OASPL deviation
was approximately 2 dB, with a maximum deviation of 3.3 dB among the
investigated microphone locations, while the narrow-band SPL deviation mainly
remained within 5 dB for frequencies below 5000 Hz. The predicted broadband hump
near 1500–2500 Hz was shown to correlate strongly with vent cavity
characteristics and flap–louver interaction.
Flow field analysis identified pronounced vortex shedding within concealed vent
branches and localized flow separation near the flap leading edge and louvers.
Parametric investigations further demonstrated that suppressing leading-edge
vortex impingement reduced the broadband hump near 1500 Hz, while removal of
flap–louver interaction significantly reduced high-frequency broadband noise
above 1500 Hz.
The present work demonstrates that high-fidelity LBM simulation can provide
reliable engineering-level aeroacoustic prediction for concealed HVAC vent
development during the early design stage. The study also provides practical
design guidance for developing low-noise concealed HVAC systems for electric
vehicle applications.
