Film Thickness and Velocity Distribution in a Splash-Plate Atomizer: Comparison between Simulations and Experiments Fard M.P. 1 , Ashgriz N. 2 , Mostaghimi J. 2 , Levesque D. M. 3 and Morrison S. 3 1 Simulent Inc., Toronto, Canada (mpasand@simulent.com , http://www.simulent.com ) 2 Professors, Mechanical Engineering, University of Toronto 3 Alstom Canada Inc. A 3D computational model is presented for the simulation of fluid flow and spray in a splash-plate atomizer. The model combines the solution of continuity and momentum equations with an algorithm for free surface tracking in presence of an arbitrary nozzle shape. The model simulates the flow through the nozzle and predicts the formation of a liquid film and spray droplet size at the nozzle exit. Close agreement between numerical results and measurements for film thickness and velocity distributions validates the model and its underlying assumptions. The effect of viscosity on liquid film thickness and velocity is also investigated; for a liquid with a higher viscosity, the liquid film is thicker and its velocity is smaller. 1. Introduction In a splash-plate atomizer, a flat plate of usually rounded cross-section is attached at an angle to the end of a liquid carrying pipe. The liquid flows through the pipe and when it exits from the end of the pipe it strikes the flat face of the plate at an angle. The flow is turned and flattened into a film of liquid. The film leaves the plate and breaks up into ligaments and droplets. Splash-plate atomizers are widely used in recovery boilers where the use of slurries such as black liquor from wood pulp is utilized in combustion systems as an alternative to oil and gas. Spray droplet size and size distribution are key variables in controlling spray combustion in these systems. Splash- plate atomizers are designed based on experimental measurements. Because of the complexity of the flows existing in these systems, there is no accurate technique that can relate the nozzle design to the spray droplet size and velocity distribution. To better understand the performance of a particular nozzle, the determination of the droplet size distribution is critical. This particle size distribution is usually determined by physical experimentation in spray booth, using either black liquor or corn syrup. Most spray nozzles are characterized in ambient conditions and may not provide the same results under different conditions. If a computer code makes it possible to see the resulting spray of a specific nozzle design, it will be of great interest to any one working in this field. Such a code can be used to: design new nozzles; improve current nozzle designs; obtain the spraying characteristics of a nozzle such as mean droplet size, droplet size distribution, spray angle, spray pattern, mixing within the spray, droplet velocity in a certain distance from the nozzle exit; and investigate the spraying characteristics of a nozzle under different operating conditions.