PENETRATION OF WATER SPRAY DROPLETS THROUGH WIRE MESH

Water was sprayed through a full-cone nozzle with a droplet Sauter mean diameter of 35 µm onto stainless-steel meshes with pore sizes of 178, 457, or 787 µm that were held either horizontally or vertically. The mass flow rate of liquid penetrating the mesh was measured continuously by capturing droplets that passed through pores and weighing them using an analytical balance. High-speed videos were taken of droplets landing on the mesh. Droplets accumulated rapidly on mesh wires and blocked pores so that the mass flux of water passing through the mesh decreased rapidly after the spray was started. Droplets landing near an unblocked pore were leached by neighbouring pools of liquid, delaying the blockage of that pore. Water captured on vertical meshes drained downwards due to gravity, unblocking pores, so that eventually the mass flux penetrating the vertical mesh reached a steady state. A stochastic model was developed to predict the spray mass that penetrates a vertical mesh before it becomes fully blocked. The volume required to block the mesh was found to be a function of both the open-area ratio and the number of surrounding blocked pores. Predictions from the model of the mass fraction penetrating the mesh and the time required for blockage agreed well with experimental measurements.