Computational Fluid Dynamics are widely used as a design tool for a variety of thermo-fluid systems. Advantages of those numerical approaches are clearly the fairly detailed degree of valuable data at low computational costs, when RANS (Reynolds Averaged Navier Stokes) methods are used in the system design process.
In this work, a combustion system operated at elevated pressure conditions is re-designed with CFD RANS methods. The combustor is operated with liquid fuel and is positioned between an upstream recuperation and a downstream turbine section. System design is carried out on the basis of a commercially available C30 configuration from the Capstone® Turbine Corporation. The micro turbine produces 30kW of electrical power and is therefore highly suited for micro gas turbine related applications.
In the design process, as presented in the paper, several modifications are carried out. The system recuperation is changed, thus inflow modifications are given. Recuperation was explicitly simulated and is used as a combustor inflow boundary condition. The system is then analyzed and modified in terms of air splits in order to achieve certain combustion characteristics. Optimization is carried out for combustor air splits and turbine inlet temperature profile conditions are significantly improved. Reacting multi-phase simulations are used in order to characterize flow field and combustion. Further on, conjugated heat transfer is taken into account in order to characterize temperature distribution in the combustor. Additionally, combustor residence times are determined. It is demonstrated that the pursued methods and procedures are computationally cheap but at the same time highly suited and sufficient for thorough combustion system development.