Keywords: high-speed trains, potential theory, Reynolds-averaged Navier-Stokes simulation, shape optimization, adjoint methods, mesh morphing, aerodynamic loads, trackside objects..

Fast passing trains induce aerodynamic forces which can be dangerous for trackside objects and for passengers on station platforms. To develop theoretical and numerical approaches for optimizing the shape of train heads with the objective of minimizing the amplitude of the induced pressure wave and the resulting forces on trackside objects is the aim of the present work. In the first part, we consider shape optimization of a potential train head modeled by superposing monopole sources to a uniform flow. To demonstrate the reliability of the potential flow model, we determine the aerodynamic loads on a sphere induced by the head pressure pulse of a passing train and compare them with results measured in a moving model rig, the so-called "Tunnel Simulation Facility" (TSG). Since good agreement is obtained , we conclude that the potential flow model is suitable to predict the pressure induced forces on track side objects. Then, the validated simplified potential model is used to select the shape of a train head which minimizes the sucking force on a cylindrical object passing the train at a specified lateral distance. In the second part, we apply the continous adjoint optimization approach, first on the potential train body and then on a more detailed shape of a train performing Reynolds-averaged Navier-Stokes (RANS) simulations. The focus of this ongoing research is to develop a process chain using the continous adjoint-based shape optimization approach in conjunction with a potential flow on the one hand and with RANS simulations, filtered gradients and CAD-free mesh morphing based on radial basis function interpolation on the other hand. In the RANS study, shape optimization is performed with the objective of minimizing the amplitude of the generated pressure wave. This part of the paper includes new results of the work started in Jakubek et al. [1].

[1]

D. Jakubek, S. Herzog, C. Wagner "Shape Optimization of High Speed Trains using Adjoint-based Computational Fluid Dynamics", IJRT, 1(2), 67- 88, 2012. doi:10.4203/ijrt.1.2.4

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