Numerical study of wheel-rail adhesion performance of new-concept high-speed trains with aerodynamic wings

Wheel-rail adhesion is a complex tribological problem of wheel-rail rolling contact and is closely related to the operational safety of high-speed trains. A new design concept of high-speed trains was recently proposed with an expectation of a reduction of equivalent weight and total energy consumption by installing aerodynamic wings (aero-wings) on the roof, but it was accompanied by the disadvantage of deteriorating wheel-rail adhesion performance. In this study, a comprehensive multi-body dynamics (MBD) model of the high-speed train with predesigned aero-wings is established using the commercial software SIMPACK, in which the real aerodynamic characteristics of the train are taken into account. The available adhesion and adhesion margin are employed to evaluate the wheel-rail adhesion performance. The influences of aero-wing lift, train speed, and contact conditions on the wheel-rail adhesion level are discussed. The results show that the load transfer caused by the action of aerodynamic load and braking torque was the main reason for the inconsistent adhesion condition of four wheelsets. The influences of aero-wing lift and train speed on the wheel-rail adhesion performance are coupled; the available adhesion of both motor car and trailer is negatively correlated with aero-wing lift and train speed under all contact conditions, while the variation law of adhesion margin with train speed shows differences under different contact conditions. When the wheel-rail interface was polluted by a 'third-body medium' such as water and oil, the wheel-rail adhesion performance was dramatically reduced and the wheelset tended to reach adhesion saturation and slide. However, track irregularity had little effect on the adhesion performance and could be ignored to save calculation time. These results are of positive significance for reducing the wheel idling or sliding phenomenon and to ensure the safe operation of high-speed trains with aero-wings.