Experimental Study Of The Impingement Process Of A Liquid Droplet Upon A Corrugated Cardboard Surface
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A water transport model is one of the key components in fire modelling of sprinkler protection of solid combustible commodities. In order to provide preliminary measurements to validate and improve the water film transport model, a series of measurements were conducted to study the impingement process of a liquid droplet upon a corrugated cardboard surface. The impact surface is a wetted cardboard covered by a water film with different thicknesses. Two liquids with different surface tension, droplet sizes and impact velocities were investigated. The sizes and velocities of the splashed droplets were measured by a laser-based Shadow-Imaging system. The evolution of the water film thickness and the contact angle with the number of impact droplets was measured. The results show that the splashing fraction increases with the film thickness and the Weber number. The distribution of cumulative volume fraction of splashed droplets was correlated with the normalized droplet size using a Rosin-Rammler function. The volume-median droplet diameter was expressed as a function of the relative film thickness and the Weber number. The maximum velocity magnitude of a splash droplet was correlated to its size, the Weber number and the relative film thickness. These test data and empirical correlations can be incorporated into a numerical model to simulate the splashing fraction, size and velocity distributions of the splashed droplet. Keywords: cardboard, splashing, water droplet, fire protection.
Keywords: cardboard, splashing, water droplet, fire protection.