Characterization of the ventilation flow in a real car cabin: an experimental benchmark

This study presents an experimental investigation of airflow inside the cabin of a commercially available car, aimed at establishing a benchmark for validating numerical simulations. The analyses were conducted by operating the panel-vent mode at four different fan flow rates, with fresh air intake. Vent-exit velocities were first characterized by 5-hole pressure probe measurements, revealing non-uniform jet distributions with peak velocities between 4 m/s and 5 m/s and noticeable asymmetries between vents. Subsequently, Particle Image Velocimetry (PIV) was employed to measure velocity fields in three longitudinal sections of the cabin. Results show that the ventilation jets generate a confined flow with peak velocities of about 2 m/s for fan speed 3 at 25 cm downstream of the vents, along with a progressive jet spreading from 7 cm at the outlet to 16 cm near the ceiling. Velocity fluctuations were examined in terms of turbulent kinetic energy (TKE) and Reynolds stresses, with TKE values exceeding 0.4 m2/s2 in the jet core. A detailed uncertainty analysis is provided. The dataset was used to validate a Computational Fluid Dynamics (CFD) tool, showing good agreement with discrepancies below 0.25 m/s. All data is publicly available via the 4TU.ResearchData repository with DOI: 10.4121/7dda9523-e628-4855-bfb7-fa17b6d3825c.