SPRAYSIM is a CFD code based on Lagrangian Particle Tracking for the simulation of sprays in reacting gas flows. The focus is on gas turbine combustor flows. This requires the modeling of primary and secondary atomization, particle dispersion, vaporization, and the calculation of retroactive effects of the spray on the gas phase. The flexibility of the particle model, particularly with regard to the type of material, the complexity of the mixtures (heterogeneity) and the states covered, makes it also a suitable tool for the numerical simulation of gasification or other thermochemical processes. SPRAYSIM is designed in such a way that it can be run as an independent program (for parameter studies) or coupled (via subroutine calls or via files) with node- or cell-centered CFD codes. So far, coupling possibilities with THETA, TASCOM and CFX have been established.
Liquid fuels in technical applications are often multi-component mixtures that consist of several hundred different components. SPRAYSIM is able to describe the fuel as a mixture of discrete species, but also as a mixture of species families (e.g. n-alkanes, cycloalkanes, aromatics,...). For this purpose, the Continuous Thermodynamics Model (CTM) was implemented. This method significantly reduces the computational costs compared to a description using discrete species without losing information about the evolving composition of the gas phase, which is relevant for the subsequent combustion processes. The coupling with the gas flow solver occurs via an equivalent species concept. This feature allows a reduced number of fuel vapor species and thus transport equations in the gas flow solver compared to the number of liquid species in the spray calculation. This is particularly useful for the coupling to gas phase reaction mechanisms with a limited amount of surrogate species. Particle-based parallelization using the Message Passing Interface (MPI) is applied to reduce the computing time.
To visualize the spray, SPRAYSIM provides trajectory and scatter plots. Beyond that, as this is not sufficient for the quantitative comparison with spray measurements, SPRAYSIM allows the definition of so-called registration planes in which the data of the passing droplets is accumulated. The evaluation of the registered data in a post processing step provides profiles of particle flows, characteristic spray diameters (e.g. the Sauter mean diameter (SMD), Mass mean diameter (MMD),...), droplet velocities and temperatures, as well as drop size distributions in the form of tables and plots.