NUMERICAL STUDY ON THE INFLUENCE OF DEFLECTORS ON THE FLOW FIELD AROUND HEAVY-DUTY TRUCKS

To address the problem that the regulation mechanism of deflectors on the flow field of van-type trucks under a wide range of wind speed operating conditions remains unclear, this paper adopts the standard RNG k–ε turbulence model to perform numerical calculations on the external flow field of van-type trucks with and without deflectors under three typical wind speeds, and systematically analyzes the regulation mechanism of the deflector device on flow field characteristics. The results show that high stagnation pressure exists on the windward surface of the truck without deflectors, which increases sharply with rising wind speed; after the installation of deflectors, the pressure gradient transitions smoothly, thus reducing aerodynamic drag. Without deflectors, the velocity gradient between the low dynamic pressure regions at the cab and the front of the cargo compartment and the high dynamic pressure regions at the cab corners increases significantly with wind speed. The deflectors effectively eliminate the low dynamic pressure region at the cab roof, but have a limited improvement effect on the high dynamic pressure acceleration effect of lateral bypass flow. For the truck without deflectors, the total pressure deficit in the wake region is severe, and the energy dissipation increases non-linearly and sharply. The deflector device reduces part of the irreversible energy dissipation by reducing direct flow impingement.