Cross wind train interactions are one principal risk for train derailment of modern high-speed trains with a still existing lack of knowledge of the related aerodynamic mechanisms. This paper contributes to the enhancement of the understanding of the influence of the unsteady flow field on the induced aerodynamic loads on a highspeed train under cross wind conditions. Therefore a wind tunnel experiment has been performed with a scaled high-speed train model. Simultaneously when force measurements were performed with a strain-gauge balance installed inside the train model, the unsteady velocity field was measured with the laser optical technique particle image velocimetry. A direct influence of the leeward velocity field on the aerodynamic loads could be detected and is analysed in detail. Measurements of the aerodynamic loads with an integrated force transducer and investigations of the leeward velocity field were performed for a model of the NGT2 high-speed train model under cross wind. To show that Reynolds number independence is reached, measurements were performed in the SWG (Side Wind Test Facility Göttingen) up to Reynolds numbers of 4.00×105 and in the KKK (Cryogenic Wind Tunnel Cologne) up to 7.50×105. No significant effect could be detected for the side force and the rolling moment coefficient. The influence of the averaged leeward velocity field on the mean aerodynamic coefficients was demonstrated for different cross wind conditions. It was shown that the characteristics of the upper quasi stationary leeward vortex depend on the inflow conditions and directly influence the force coefficient relevant for train stability. At a yaw angle of 65° the upper leeward vortex separates from the train's surface combined with a strong reduction of the side force and rolling moment coefficient. With regard to unsteady effects the unstable behaviour of the leeward vortex could be demonstrated for different yaw angles. Results of large eddy simulations were confirmed with the vertical and the horizontal motion of the upper vortex core.
Wind tunnel experiments with a high-speed train model subject to cross wind conditions
2012
17 Seiten, 18 Bilder, 16 Quellen
Aufsatz (Konferenz)
Datenträger
Englisch
Research of Train Wind Characteristics in High-Speed Railway Tunnel
Trans Tech Publications | 2014
|Operating Safety of High Speed Train under Strong Cross Wind
British Library Conference Proceedings | 2006
|High-Speed Train Crosswind Analysis: CFD Study and Validation with Wind-Tunnel Tests
British Library Conference Proceedings | 2016
|High-Speed Train Crosswind Analysis: CFD Study and Validation with Wind-Tunnel Tests
Springer Verlag | 2015
|