Aerodynamic Shape Optimization of High-Speed Trains

Artikel i vetenskaplig tidskrift, 2012

The paper presents a new, fully automatic multi-objective shape optimization method for improving the aerodynamic properties of trains. The optimization method was applied to a multi-objective optimization problem of crosswind stability of a train placed on an embankment. The train was optimized with two objective functions and the geometry was changed according to two design parameters. Furthermore, two flow scenarios were used in the optimization where the train was placed either on the windward or the leeward side of the two-track embankment. The optimization resulted in an optimal shape of the train which was the same regardless of the train's location on the embankment. The present approach is shown to be robust and capable of obtaining an optimal design of the train without the influence of the user during the optimization process. The example of the optimization problem presented in this paper was multi-objective but one objective was chosen to be the dominant one. Although there are no limitations in the number of design parameters or objective functions in the method developed, an increase in the number of parameters will result in an increase in the computational effort required for the optimization. An interesting result of the present work is that almost identical optimal shapes for the train were obtained for both trains traveling on the windward and the leeward sides of the embankment. This is a desirable outcome of the optimization as it does not require selecting the shape that is optimal for only one operational condition of the train.