A numerical investigation of the effects of crosswinds upon the aerodynamic characteristics of a high-speed passenger train and its slipstream

摘要

The main work presented within this thesis is a numerical investigation of the effects of crosswind yaw angles upon the aerodynamic characteristics of a high-speed passenger train. ududThe applicability of Computational Fluid Dynamic (CFD) approaches to the simulation of external flow around a passenger train were investigated. Results showed the Delayed DES (DDES) approach produced the highest correlation to experimental results.ududBallast heights of 0m, 0.3m and 0.75m were simulated and compared to existing experimental results. Comparisons between cases found that a vortex from the train’s underbody follows the ballast profile. udCrosswind simulations were conducted at yaw angles of 0o, 5o, 10o and 15o. The results obtained showed the formation of a large vortex upon the leeward side at yaw angles of 10o and above, this caused a region of low pressure which increased the overturning forces acting upon the train. Generally, crosswinds increased pressures upon the windward side of the train and decreased them upon the leeward side. Slipstream velocities on the windward side were seen to decrease whilst leeward side velocities increased. ududResults were compared to regulations currently in place for the operation and testing of trains. This enabled comments and suggestions to be made upon existing regulations.