Aerodynamic Analysis and Cab Geometry Optimization of an Electric Heavy-Duty Truck

Abstract

This thesis investigates the influence of cab geometry and aerodynamic add-ons on the aerodynamic performance of a heavy-duty electric truck using computational fluid dynamics. A parameterized 3D-CAD tractor-trailer model was developed in STAR-CCM+ and evaluated using steady Reynolds-Averaged Navier–Stokes sim ulations with the SST k-ω turbulence model. Two cab geometries were studied: a baseline flat-front cab and a more streamlined electric-truck cab. For each cab geometry, configurations with a large side skirt and a side extender were simulated to assess the effect of add-ons on the tractor-trailer gap and underbody flow. A two-stage cab optimization was then performed using the SHERPA algorithm, first on a simplified model and then on the complete Model 1 configuration. The results show that cab geometry has a strong influence on both the front pres sure distribution and the effectiveness of the add-ons. For Model 1, the combined large side skirt and side extender reduced the drag coefficient from 0.407 to 0.391, corresponding to a reduction of approximately 3.9%. For the more streamlined Model 2, the same add-on configuration reduced the drag coefficient from 0.411 to 0.364, corresponding to a reduction of approximately 11.4%. The complete Model 1 optimization reduced the drag coefficient from 0.391 to 0.373, giving an additional reduction of approximately 4.6% relative to Model 1 configuration 3. The accumu lated drag and pressure-coefficient results indicate that this improvement mainly originates from the optimized cab-front shape, while the downstream flow remains strongly affected by the side skirt, side extender, and trailer arrangement. The work provides a foundation for continued research on aerodynamic analysis and optimization of zero-emission heavy-duty vehicles. The parameterized model and CFD workflow can be further refined to include additional design concepts, experimental validation, and more realistic operating conditions such as crosswind.