Generation characteristics of the airborne wear particles emitted from the wheel-rail contact for various train velocities and their generation relation with the train velocity

초록

Underground trains using electrical power release airborne wear particles (AWPs) from a wheel?rail contact that can adversely affect human health. Understanding the AWP generation characteristics may be helpful to reduce AWP generation from the wheel?rail contact and improving the air quality of underground subway systems. Therefore, the generation characteristics of the ultrafine, fine, and coarse particles generated in rolling/sliding and sliding contact were analyzed for five train velocities at a normal load of 15 kN using a twin-disk rig. In addition, the relation between the AWP generation amount and train velocity was investigated. The AWP number concentrations (NCs) were measured using a fast mobility particle sizer (FMPS) and an optical particle sizer (OPS). The particle sizes were classified into three categories based on their diameter (D): ultrafine (D ≤ 100 nm), fine (100 nm < D ≤ 1 μm), and coarse (D ? 1 μm) particles. The results revealed that the train velocity influenced the amount, trend, proportion, and particle size distribution of the ultrafine, fine, and coarse particles. The NCs of the three particle size categories increased nonlinearly with increasing train velocity. For all tested velocities, a significant amount of ultrafine and fine particles were produced during rolling/sliding contact. This study confirms that the wheel?rail contact generates a significant amount of highly inhalable particles even during rolling/sliding contact and that the underground train velocity could be an important factor characterizing the AWPs released from the wheel?rail contact.