Evaluation of the Uniform Conditional State model for gas turbine combustor design

A universally applicable user-friendly tool has been developed for numerical simulations of turbulent combustion in gas turbines and is being evaluated in this work. Ultimately the goal is to reliably predict emissions of interest at low computational cost while maintaining a large degree of flexibility with regards to the fuel type and the complexity of the chemical kinetic mechanism as well as the type of combustion that may be present. Premixed, non-premixed as well as partially-premixed combustion could potentially be present in a technical application. Maintaining this versatility gives freedom of design to the user. In this work the criteria necessary for a combustion model suitable for such a tool will be defined and measures of success identified. The Uniform Conditional State (UCS) model allows for the chemistry to be computed a priori and disconnected from physical space using so-called conditioning variables; variables describing specific characteristics, which are deterministic for the combustion process. With that the computational cost is very low and a large degree of flexibility can be achieved compared to other modelling approaches. In theory, the recently developed model of UCS promises to satisfy the required criteria and thus an extensive study was conducted putting this model into practice for the first time. Initially a number of parameters within this modelling approach were defined based on weak assumptions and needed to be evaluated and verified as part of this work as well. With that a valuable report was completed to outline the ability of UCS to serve as a reliable predictive model of turbulence-chemistry interaction in its current state. For instance, while the computational cost indeed proved to be only 20% of that of a comparable simulation in one of the test cases, the accuracy of predictions of emissions such as NOx remains below the aspired target in another test case. The evaluation of this new approach was carried out based on a non-premixed swirl-stabilized model aero engine combustor, a premixed swirl-stabilized flame series and a partially-premixed lifted jet flame, while exploring different modelling parameters and limitations of the modelling approach.Applied Science, Faculty ofMechanical Engineering, Department ofGraduat