One of the consequences of increasing the efficiency of gas turbine combustors is the higher combustion temperatures and pressures within the chamber. Larger heat loads have to be sufficiently managed to protect the combustor wall and turbines. Conventional thermal management techniques include the thermal barrier coatings (TBCs) deposited on the metal walls and forced air cooling such as effusion cooling. Therefore, complex coupling between conduction, convection and radiation directly impacts the heat flux through the multi-layer combustor wall. For radiation, conventional methods treat both the flame and TBCs as gray media using effective absorptivities and emissivities. However, studies have shown that the gray analysis can considerably under-predict the cold metal side temperature, leading to misguided combustor life estimates.  In this study, the combined radiation, convection and conduction are solved using a two-flux method for a one-dimensional multi-layer media that represents the combustor liner. A synthetic turbulent flame that is generated using a flamelet generated manifolds (FGM) method is superimposed to an isotropic homogeneous flow field to represent the turbulent flame at elevated pressure. The flames with and without soot radiation are considered, to quantify the impact of soot radiation on the wall. A Monte Carlo Ray Tracing (MCRT) method combined with the line-by-line (LBL) spectral model is employed to compute the incident radiative heat flux. The radiative heat flux will then be used as a boundary condition to conduct the two-flux simulations within the solid media. Compared to the convectional method, the MCRT solver could provide the probability distribution of the heat flux as well as its spectral properties along the combustor wall. Parametric variation is then made within the two-flux model, using the probability distribution of the radiative flux as an input, to quantify the potential deficiency of the 1D gray assumptions for estimating the engine wall temperature. 


Analysis of the Heat Transfer Within Combustion Liners Using a Combined Monte Carlo and Two-Flux Method

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

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