Abstract: Curve squeal noise is an urgent problem to be solved in urban rail transit, however there is less research on it in China at present. Taking the 70% low-floor tram traversing the tight curves of embedded rail track as the research object, the characteristics and mechanisms of wheel/rail squeal are investigated by measurements and analyses. The radiuses of the measured curves are 25 m and 50 m, the velocities of the tram traversing the measured curves are 3~9 km/h and 4~20 km/h respectively. During the field test, the state of the wheel/rail contact surface is considered natural state, water lubrication, oil lubrication and solid lubrication respectively. Measured results show that the exterior noise L_Aeq is in the range of 56 to 91 dB(A), in which 87%~92% of the measurements occur curve squeal when not adopting lubrication; the squeal emitted by the inner wheel of the leading wheelset(the first wheelset) is the most significant, the mechanism is that the lateral creep between the wheel and rail excites the (0,3) axial wheel mode at 1 811 Hz so that the wheel vibrates significantly at the single frequency and squeals. The effects of different lubrication conditions (water, oil lubricant, solid lubricant) on controlling the squeal are also investigated. It is found that the percentage of the measurements occurring curve squeal or slight curve squeal reduces to 19% to 50%, and the exterior noise L_Aeq reduces significantly when adopting lubrication. The domestic measured data on the tram-embedded rail track curve squeal are supplemented with the research,, and based on the measured data, the mechanism of squel noise emitted by the tram is basically understood.

Key words: curve, embedded rail track, lubrication, squeal, tram