Numerical simulation of internal flow fields of swirl coaxial injector in a hot environment

Based on the fractional volume of fluid (VOF), a pure Eulerian model for defining and capturing the gas/liquid interface is developed in this paper. This model can describe gas/liquid interface in high refinement, which is better than the original VOF methodology. To validate the proposed model and the algorithm, the computational code is employed to predict the flow performance in a cylindrical swirl injector under cold-flow condition, and the predicted results agree well with experimental measurements. Furthermore, the proposed model is used to simulate gas-liquid reacting flows inside a gas/liquid coaxial swirl injector operating in a hot environment. The turbulent combustion process is simulated with the k−ε−f−g model. The numerical simulation is carried out under actual operating condition of the coaxial injector. The injector performances, such as liquid film thickness, liquid film injection velocity, spray angle, pressure drop, are obtained based on the detailed information of the internal flow field. The predicted results also show that droplets are shed from the liquid film in the recess cup of the coaxial injector because of the large velocity gradient between the gas and liquid streams, and a burning area, which is characterized by high temperature, is present inside the injector.