Validation of a benchmark methanol flame using OpenFOAM

Abstract

The spray combustion simulation includes the modelling of many physical processes that interact with each other such as droplet breakup, evaporation, mixing, and reaction which pose a challenge to the modelling effort. The present study evaluates the accuracy of an unsteady spray combustion solver based on a benchmark methanol spray combustion database. Extensive validation has been done to evaluate the accuracy of the models and improvements to the state-of-the-art of spray combustion model are proposed. A monocomponent fuel, methanol is chosen due to its well established physical and chemical properties. A comprehensive boundary condition for spray is modelled in OpenFOAM to capture the size and velocity of different droplet groups in the radial direction near the burner. A qualitative validation of the global spray-combustion characteristics along with a quantitative validation of the gas phase velocity and droplet size show a good agreement between the simulation and the experiment. The overpredicted inter-phase momentum transfer is observed in the velocity prediction of the gas phase and further supported by the overprediction of the droplet drag. The modified RNG k−ε model shows an enhanced capability in predicting the gas velocity profile in the near-field.