Aerodynamic optimization in light weight solar vehicle design

Solar car racing has created a competitive platform for research into alternative energies, particularly the utilization of solar energy. This paper reports on a numerical optimization of the vehicle body shape, utilizing Computational Fluid Dynamics (CFD). Optimization and validation of the body shape, fairing position, body-and-fairing fillet blend, fairing leading edge curvature, driver position and canopy design were considered. For the purposes of this study, the fairing and driver position optimization will be discussed as a case study to illustrate the design and optimization methodology with the improved product of area and the coefficient of drag (AC_d) values recorded. The algorithms developed and procedures followed to adapt the design of the vehicle are presented. The algorithms applied relied on comparing designs based on evaluating shape function curves representing the normalized (body length) sectional area of the body under consideration. With the aid of numerical analysis software and applying the design optimization algorithm by evaluating AC_d, it was possible to optimize the shape of the main wing and the placement of the fairings and the driver compartment/canopy. The results of the CFD simulation showed there was a direct correlation between the drag coefficient and the shape function. By utilizing this methodology, significant improvements to the coefficient of drag could be realized. A reduction of 31% in the coefficient of drag was achieved by moving the centered driver position to the side. This design change then also contributed to an energy saving of 442.6 Watt at a speed of 100km/h.