Abstract
In the history of aerodynamic research around the bluff bodies like SUV, trucks and trailers, it has always been observed that their shapes with square base have served as an obstacle improving vehicle fuel economy. When the air passes over the vehicle surface, it makes the air over the surface change its behavior, resulting in a low pressure region and a high pressure region. This pressure difference along with the vortex shedding causes drag thereby increases the fuel consumption. Researchers around the world have tried to reduce the drag of trailers or truck by using external devices like spoilers, vortex strake device (VCD) and under-carriage flow device (UFD). The purpose of this thesis is to check the feasibility of using such external devices for reducing drag on the large size SUV. The generic SUV model created by previous research experiments along with the Ahmed's reference model is considered as a benchmark for validating all the simulation results. Simple external devices like boat tail plate and the foot step are simulated and optimized using commercial software packages like FLUENT, GAMBIT, T-grid and Solidworks. Fifteen different angular combinations of upper and lower boat tail plates are simulated and optimized to get the best angle suitable for drag reduction of Generic SUV model. The second external device commonly known as the foot step is simulated with five configurations by varying the width of the foot step. The foot step bypasses the air around the rear wheel and thereby reduces drag coefficient of the complete SUV model compared to the original SUV model. The optimal sizes of the width favorable for the drag reduction are discussed in this thesis.