Abstract

One consequence of increasing efficiency of gas turbine combustors is higher temperatures within the combustor. Management of larger heat load has been advanced to protect the combustor wall and turbines, and among those are thermal barrier coatings (TBCs). Historically, both the flame and TBCs have received a simplified radiation treatment using effective absorptivities and emissivities. In this study, non-gray radiation is compared to gray and black radiation by combining three-dimensional Monte Carlo Ray Tracing solution of non-gray flames in a model gas turbine combustor to one-dimensional energy balance within combustor liners. A recent large eddy simulation of a gas turbine combustor is analyzed, where both gray and non-gray models are exercised. A two-band spectral model is employed for the TBC, where a translucent band and an opaque band are identified. A line-by-line treatment for gas-phase radiation is adopted, and the incident radiative energy on the combustor wall is collected using the MCRT solver, where the fraction of radiative energy within the translucent band is collected and compared with those obtained from the blackbody assumption. The temperature along the multi-layered combustor wall is computed and parametric comparison is conducted. The effects of the nongray flame radiation are more prominent at elevated pressures than at atmospheric pressure. The gray model is found to over-predict the TBC temperature, which leads to a difference of approximately 150 K in the prediction of peak temperature on the hot side of the TBC.

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