Improved accuracy of aerodynamic drag and energy savings calculation in rail freight transport

Kurzfassung

This study presents an advanced wind tunnel methodology designed to improve the accuracy of aerodynamic force predictions for rail freight transport, with a focus on energy efficiency and operational safety. By integrating real-world data from DLR's FR8-LAB field measurements - including surface pressures and integrated global forces - the wind tunnel setup has been optimized to better replicate actual operating conditions. Key improvements include the use of a boundary layer augmentation strategy, carefully selected based on preliminary analysis of real-world flow conditions, along with detailed representations of underbody structures and wagon geometries, ensuring that drag coefficients, average and fluctuating pressure distributions, and boundary layer behaviour closely match those observed in operation. The methodology enables precise assessment of loading-gap-dependent aerodynamic drag across various configurations, supporting the refinement of an incremental drag database. This database serves as foundation for the developed calculation tool, which facilitates accurate estimation of cumulative drag differences, energy savings, and cost benefits associated with aerodynamically optimized freight train designs. With validation against real-world operational data, the setup delivers reliable predictions under realistic environmental conditions, supporting current operational optimization and informing future recommendations for high-speed freight systems.