Evaluation of the airflow distribution of a vertical air ventilation system in a car cabin using PIV measurements and CFD simulations

Abstract

The main goal of a ventilation system in the car cabin in general is to guarantee an adequate thermal comfort for all passengers and to enable a good air quality with sufficient air supply into the cabin. Quantifying the indoor air distribution is essential to provide the necessary thermal comfort and the required air quality. The aim of this study is therefore to analyze the subsequent airflow distribution of the vertical air ventilation system presented as a possible solution for future cars with modern interior designs. With the vertical air ventilation concept, air vents are located at the ceiling and floor area of the car cabin, as ceiling and floor regions enable a large-area influx of air into the car cabin and allow accessibility to passengers in every seating position. For the analysis of the airflow distribution of the ventilation system, Particle Image Velocimetry (PIV) measurements have been performed with a test vehicle in a climate chamber under specific conditions. Two different thermal manikins, one heated and the other unheated, have been used in the experiments. The results of the comparison between the two thermal manikins reflect a relatively low to medium impact of the human thermal natural convection on the airflow pattern around the manikin in the different air distribution modes of the vertical air ventilation system. Using the same ventilation settings, numerical simulations have been performed. The results of the numerical simulations are analyzed and compared with the results of the PIV measurements. The developed numerical model shows a good agreement with the experiments. It can hence be used for example in further studies to evaluate the thermal comfort or the air quality of the vertical airflow system as a new ventilation concept for future car interior designs.