Velocity field measurements of entilation flow in a vehicle interior

Abstract

The ventilation flow in a 1/10-scale model of a vehicle interior was investigated experimentally. Five different ventilation modes with the same total flow rate were tested to study the effect of ventilation mode on the velocity field in the vehicle compartment. For each mode, more than 450 instantaneous velocity fields were measured using a PIV (particle image velocimetry) velocity field measurement technique. These fields were ensemble averaged to obtain the spatial distribution of the mean velocity and vorticity. The panel-vent ventilation mode was more effective than the foot-vent ventilation mode in terms of active momentum transfer and the uniformity of the speed distribution in the rear compartment. The foot-vent mode was characterised by a large-scale vortex structure in the rear compartment, which suppressed the heat and momentum transfer in this region. In contrast to the panel-vent and foot-vent modes, the hybrid-vent modes did not have a large-scale re-circulation flow in the rear passenger compartment; thus, the hybrid-vent modes are expected to efficiently reduce the thermal non-uniformity in the vehicle interior. The present work highlights the usefulness of the PIV velocity field measurement technique for the analysis of HVAC (hearting, ventilation and air conditioning) problems. These experimental results can be used not only to understand the ventilation flow in the passenger compartment in order to improve passenger comfort, but also to validate numerical predictions.