CFD-Based Analysis of Aerodynamic Drag Reduction in a Sedan Model Using Passive Flow Control Devices

الملخص

Aerodynamic drag on passenger cars significantly affects fuel efficiency and performance. This study reviews and synthesizes both experimental and computational (CFD) investigations on passive flow control techniques for reducing drag in a generic sedan model. Various devices such as vortex generators, diffusers, spoilers, flaps, and boat-tails are examined. We reference published wind-tunnel tests and CFD simulations to quantify drag reduction. Key findings include the efficacy of small flaps (gurney flaps) in reducing drag by up to 67.7% and vortex generators achieving modest reductions (around 4-6% for typical sedan models). Spoilers and diffusers can yield reductions of about 5-10% under optimal conditions. Combined devices often produce greater benefits; for instance, one study predicts nearly 19% improvement using a boat-tail extension. Experimental wind-tunnel tests have largely confirmed CFD predictions of reduced drag and fuel savings. The passive devices work by delaying flow separation and filling the low-pressure wake behind the car, thereby lowering pressure drag. Even small changes in drag coefficient yield fuel savings (e.g. a 5% drag drop can save ~3% fuel). This comprehensive analysis highlights that well-designed passive modifications can significantly improve sedan aerodynamics and suggests directions for combined device use. Future work should integrate these insights into production vehicles and further correlate CFD with real-world experiments.