Simulation of the agglomeration in a spray using Lagrangian particle tracking

AbstractThis work aims to explore the possibility of simulating the agglomeration process in a spray using CFD methods. The model system consists of a spray nozzle within a uniform airflow in a square-section chamber. The CFD simulations are performed using a mixed Eulerian–Lagrangian approach. The flow is modelled by solving the usual Eulerian equations, and then representative droplets are tracked using the Lagrangian approach, with conventional gas–particle coupling.A number of representative particles are introduced at each time step, with each particle representing a group of real particles with the same properties, and are tracked in a transient flow. Due to turbulence, particles are dispersed and may coalesce when they are close. The inter-particle distance is used to calculate the collision probability from kinetic theory, and agglomeration is assumed to occur when the proximity function exceeds a critical value. This method is applied to the simulation of a round spray jet flow, and the results show some interesting insights regarding the role of particle size redistribution and agglomeration. The Sauter mean diameter is found to be the appropriate variable to quantify the agglomeration rate