Aerodynamic optimization of railway motor coaches

Abstract: The rapid development of very high speed trains and the increasing operational speeds of conventional passenger and freight rolling stock are the cause of a growing interest in railways aerodynamics. Environmental issues, comfort demands and reduction of energy consumption are the key points to which aerodynamic improvements can largely contribute. Railways aerodynamics has to be performed on the complete system and the influence of the many individual shape parameters is strongly coupled. It is therefore very difficult to systematically predict how a given parameter will affect the aerodynamic properties and, more generally, what combination of the parameters yields the best performance. An optimization procedure using a genetic algorithm and relying on a commercially available CFD software for the flow simulations has been developed to bring out train shapes with lowest possible aerodynamic drag. Results are presented for a first two-dimensional application, showing the efficiency and the flexibility of the method