A combined experimental-numerical study towards the elucidation of spray-wall interaction on step geometries

In this research, a coupled numerical-experimental approach is employed to investigate the spray-wall interaction on step geometries with slope angles from 0° to 90° as well as impinging on and off the step geometry. Spray contours are used to compare the numerical and experimental results and, in general, good agreement between them is found. The results from the model are used to provide deeper knowledge about the macroscopic and microscopic behavior of the impinging spray influenced by step geometries. The numerical results provide a three-dimensional perspective that reveals the deflection of the flow by the geometry along the slope and to the sides. Additionally, the quantitative results show the mass distribution over time on droplet behavior (such as moving droplet mass, wall film mass and evaporation mass) for the whole domain, but forward and backward directions separately. A strong dependency on the impinging position, but a smaller effect of the slope angle, on spray propagation is found. Consequently, these impinging positions have a strong influence on spray behavior in the forward and backward directions regarding moving droplet mass and the wall film mass. In general, this study reveals the severe consequences of step geometry on impinging spray behavior.