Investigation of Droplet Impingement onto Wet Walls Based on Simulation Using Particle Method

概要

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In order to investigate the mitigation effect brought by the water film, liquid droplet impingement (LDI) on a wet rigid wall has been simulated using the moving particle semi-implicit (MPS) method. Propagation of the shock waves has been well resolved. High peak pressures that appear at the contact edge in the dry-wall impingement are mitigated or even eliminated by the water film. Furthermore, the magnitude of the average pressure load is reduced by the water film. Effects of the flow conditions, including the thickness of the water film, droplet velocity, droplet diameter, and impinging angle, have been investigated through a parametric study. Based on the parametric study, a correlation for the maximum average pressure is devised as \\tildeP=f1+f2\\tildeV, where f1=a+be−p\\tildeδ+(1−a−b)e−q\\tildeδ and f2=ce−p\\tildeδ+(κ−c)e−q\\tildeδ. The coefficients are a=0.240, b=0.213, c=3.50, p=3.70, and q=36.0. The valid parameter ranges of the correlation are 0≤\\tildeδ≤1.0 and 1⁄15≤\\tildeV≤1⁄5. In the oblique impingement, the normal velocity to the wall determines the pressure load. The shear stress is found playing a minor role in the overall mechanical load in the wet-wall impingement.
2011-01-01