Transient jet impaction on a high speed moving surface

In the railroad industry liquid friction modifiers are applied on the rail track in the form of a liquid jet in order to reduce the friction and fuel consumption. In this application, the transfer efficiency of the liquid on the rail track is very important. To maximize the transfer efficiency, Newtonian and non-Newtonian transient liquid jet impingement on a dry moving surface was studied. Five different water glycerin solutions with widely varying shear viscosities were used as Newtonian test liquids to isolate the effect of shear viscosity from other fluid properties. Furthermore, the effect of surface roughness on the impaction was investigated using four different roughness heights. The effects of jet velocity and surface speed were also studied. High speed imaging was performed to visualize the interaction between the jet and the moving surface. For surface roughness heights between 0.02 μm and 0.64 μm, it was found that as the roughness increases, the jet becomes more prone to splash. It was also shown that increased jet and surface speeds trigger the splash. The transient jet characteristics were also investigated for Newtonian liquids at different nozzle back pressures. It was found that at higher Reynolds and Weber numbers the transient jet breaks up downstream of the nozzle; However, it was shown that the Weber number has the dominant role in jet break-up compared to the Reynolds number. A numerical study was also undertaken to determine the drag force exerted on the plunger of the solenoid valve in the nozzle. The simulation results were in reasonable (16% on average) agreement with experiment.Applied Science, Faculty ofMechanical Engineering, Department ofGraduat