Experimental and Computational Analysis of the Aerodynamic Performances of a Maxi-Scooter 2003-01-0998

In the last three decades, with the growing concern on environmental impact and with the market demand for safety and lower fuel consumption, aerodynamic development has become a standard part of the automobile design area and it is easy to foresee that this is going to happen very fast also for motorcycles. Furthermore, a new concept of motorcycle called maxiscooter has successfully entered the European market. Maxiscooters represent an evolution of the small size engine scooters (from 50 to 125 cc) that were created in the 50s for city use. This category of motorcycles is aimed to a wealthy and more adult market, which needs a pleasant design, riding comfort and stability at higher speed. On the other hand, such vehicles for city use are passing a critical moment in terms of development of the engines, because of the stricter limits imposed by the environmental regulations and for the consequent and significant effects on performance. Force and moment determination is important for all ground vehicles and becomes more critical as the speed increases. Virtually all aspects that have to do with any sort of air flow in a new vehicle require the help of aerodynamic investigations. As wind tunnel measurements and road tests continue to be the most common and extensively used approach to isolate, reproduce and measure aerodynamic forces and moments, it cannot be sufficient to reach optimal performance. The rapid evolution of computers in terms of electronic data processing and storage and the progress obtained in computational fluid dynamics (CFD), suggest its utilization to support and reduce experimental tests.

This paper presents the aerodynamic performances of a 500 cc scooter determined both experimentally and numerically. The measurements have been made at the University of Perugia wind tunnel and balance facility. Numerical simulations have been performed with a commercial code based on the “lattice technique”, which is an alternative approach to solve fluid dynamics problems, without directly employing Navier-Stokes equations.

Once the code has been adequately validated, detailed pressure and velocity distribution around the vehicle can be predicted by computational simulations. CFD can therefore contribute greatly to better understanding of vehicles aerodynamics.