Aerodynamic of a refrigerated truck and improvement to reduce its aerodynamic drag

Abstract

Despite the fact that improving heavy vehicle fuel efficiency has received considerable attention, few investigations have been done on reducing the aerodynamic drag of a refrigerated truck. This study has two objectives; first, the aerodynamic of the refrigerated truck (REF-BSL) is investigated, and second, passive add-on designs to reduce the aerodynamic drag of the refrigerated truck are proposed. Flow structure around the truck at Reynolds number (Re) equals 0.2 × 106 is numerically investigated with a steady-state Reynolds-averaged Navier-Stokes (RANS) simulation with the Shear Stress Transport (SST) k- ω turbulence model. For a refrigerated truck, a high-pressure region at the trailer’s front surface is concentrated at the pocket area between the refrigerator and the tractor. The presence of the refrigerator alters the shear layer at the trailer’s roof as it propagates downstream, causing the saddle point location at the near-wake to shift. The refrigerator installation increases the total drag by 9%, relative to a truck without the refrigerator. Three add-on designs (REF-A, REF-B, and REF-C) positioned at the pocket area are examined to reduce the aerodynamic drag of REF-BSL. The working principle of the add-ons is to re-direct the incoming fluid toward the sides of the truck, preventing the formation of the high-pressure region at the pocket area, thus lowering the total drag of the refrigerated truck. The REF-B design is found to be the most efficient in terms of reducing drag by 16.5%.