Wind-Load and Surface-Pressure Measurements of the Aerodynamic Interactions of a Passenger Vehicle with Adjacent-Lane Vehicles

Abstract

<div class="section abstract"><div class="htmlview paragraph">The mutual aerodynamic influence of road vehicles in close proximity is known to alter significantly the drag performance of the vehicles. This paper presents an extended analysis from a study of two open-access road-vehicle shapes (a DrivAer Notchback model and an AeroSUV Estateback model) in close lateral proximity with each other, or with other vehicle shapes. Wind-tunnel measurements were conducted for a yaw-angle range of ±10°, for lateral distances representing 75%, 100%, and 125% of a typical highway lane spacing, and for longitudinal distances up to 2 vehicle lengths forward and back. The results of a previous analysis of the data, which examined aerodynamic force measurements only, showed changes in drag coefficient of ±20% or more depending on the relative locations and wind conditions. In this paper, the force-coefficient results reexamined, and surface-pressure measurements are introduced to investigate the sources of the performance changes.</div><div class="htmlview paragraph">The results suggest that the changes in aerodynamic performance of vehicles in close lateral proximity arise from three mechanisms: 1) from a combination of locally-reduced static pressure, due to the combined blockage effect of the two vehicles on the local flow field; 2) from local flow-angularity changes altering the effective yaw angle of each vehicle; and 3) from wake-body interactions. The results also demonstrate a small increase in proximity effect when a proximate Ahmed body is introduced instead, likely as a results of its larger internal volume, but with trends that match the DrivAer/AeroSUV results. Proximity-induced loads and pressures are shown to increase with reduced distance and with increased adjacent-body size.</div></div>