Wind tunnel investigation of an ICE 3 endcar on three standard ground scenarios

An ICE 3 model has been investigated in an automotive wind tunnel on three different ground configurations by means of force measurements and tuft flow visualisations. The aerodynamic force and moment coefficients reveal a strong dependency on the ground configuration, with the embankment configuration giving the highest measured coefficients only for yaw angles β<40∘β<40∘. The coefficients obtained through the Baker hypothesis are found to be larger than those measured directly on the embankment. The poor agreement between the “measured on embankment coefficients” and the “flat ground with Baker transformation coefficients” is attributed to the fundamental mismatch of relative flow velocities between wind, train and ground during the wind tunnel measurements with the train situated on the embankment. The mismatch of flow velocities causes a strong longitudinal vortex on the leeward side of the embankment which does not exist in reality and significantly alters the overall flow field.It is thus recommended, for the determination of aerodynamic forces acting on a train on an embankment, to measure the aerodynamic coefficients for the flat ground configuration and subsequently apply the Baker hypothesis.