Application of Friction Modifier to Railroad Tracks

该提案涉及UBC和德州福斯特铁路技术公司之间的两个不同但相关的合作项目。这两个项目都涉及在铁轨上应用摩擦改进剂，以优化车轮和轨道之间的摩擦系数。最佳摩擦系数应足够高，以允许爬山和安全制动，但要低于金属对金属的系数。与未涂覆的轨道相比，带有摩擦改进剂的铁路轨道的摩擦系数降低导致轨道磨损率和噪音的产生更低，并且提高了燃油经济性。目前用于将摩擦改进剂应用于铁路轨道的一种工艺是将粘性摩擦改进剂液体渗入轨道。当火车车轮经过水池时，液体覆盖在车轮上，车轮上的液体涂层被火车的运动带到下游，在更下游的轨道上涂层。这一过程的机制相当复杂，因为它们涉及水池的自由表面和移动的车轮之间的相互作用。我们已经开发了一个很好的过程模型，当车轮非常宽(即，流动是二维的)，液体是牛顿的，我们现在计划扩展理论和实验，以了解非牛顿液体的三维问题。正在考虑的第二个过程是使用静电粉末喷雾器将摩擦改进剂粉末从移动的列车输送到轨道上。要在这种应用中实现静电粉末喷涂，至少必须克服两个主要障碍：静电喷涂将暴露在侧风中，而油漆喷涂通常在喷漆室进行；摩擦改性剂粉末是半导体或导体，这对喷涂来说比典型的(绝缘)油漆粉末更具挑战性。本文的目的是使静电粉末喷涂在轨道涂层中变得可行。

This proposal involves two different, although related, collaborative projects between UBC and LB Foster Railroad Technologies Corporation. Both projects concern the application of friction modifier onto railroad tracks, to optimize the coefficient of friction between the wheel and the track. An optimal coefficient of friction is one that is sufficiently high to permit hill climbing and safe braking, but is lower than the metal-to -metal coefficient. The reduced coefficient of friction of a railroad track with friction modifier results in lower rates of track wear and noise production, and improved fuel economy, relative to an uncoated track.One process that is currently used to apply friction modifier to railroad tracks involves oozing a pool of viscous friction modifier liquid onto the tracks. As a train wheel passes over the pool, the liquid coats the wheel, and the liquid coating on the wheel is carried downstream by the motion of the train, coating the track farther downstream. The mechanics of this process are quite complex, as they involve the interplay between the free surface of the pool and the moving wheel. We have developed a good model for the process when the wheel is extremely wide (i.e., the flow is two-dimensional) and the liquid is Newtonian, and we now plan to expand both the theory and experiments to understand the three-dimensional problem with a non-Newtonian liquid.A second process under consideration is the use of an electrostatic powder sprayer to transfer friction modifier powder to the track from a moving train. There are at least two major hurdles that must be overcome to permit electrostatic powder spraying in this application: the electrostatic spray would be exposed to crosswinds whereas paint spraying is normally done in a spray booth, and friction modifier powder is either a semiconductor or a conductor, which is much more challenging to spray than the typical (insulating) paint powders. The goal here is to make electrostatic powder spraying practicable for track coating.