Aerodynamic Optimization of the Front of a Blunt Body

Abstract

The present thesis deals with the shape optimization of the frontal area of blunt bodies. It starts with a literature review of previous authors and an introduction to the science of CFD and its methods. 3 different frontal shapes were simulated of a specific blunt body. Validation of experimental data was successful with similar geometries for no yaw angle for fully separated as well as for fully attached flows. The first model represents a rectangular box. Despite its simplicity the flow phenomena that occur around it are significant because the flow is fully separated and strong vortices occur around it and the frontal area is dominated by pressure forces, leading to an increased drag coefficient. The second model which represents roughly a real truck shows a more smooth flow around it with by far smaller in size bubble separations but due to some recirculations that occur at the front of it as it has a more complex geometry, as well as significant pressure forces at its frontal area, it has a significant drag coefficient. The last model has an elliptical frontal shape and the flow is fully attached for high Reynolds numbers which correspond to average velocities for real trucks, lead to a low drag coefficient and it is very promising for future work.