Influence of Alternative Fuels on the Liner Metal Temperatures in a V2500 Combustor

To reach ambitious emission goals, the use of sustainable aviation fuels (SAFs) is a short-term option in current aero engines. The combustion of such fuels can, due to their low soot formation, have an impact on the thermal radiation inside the combustor. This in turn can affect the combustor liner temperatures, which are directly linked to the lifetime of the combustor. To study the impact of SAFs, the authors numerically simulated the flow inside a V2500 aero engine combustor using an OpenFOAM-based solver capable of capturing multi-physics phenomena such as combustion, conjugate heat transfer, thermal radiation and soot formation. The complex cooling system of the V2500 combustor makes the evaluation of the wall temperatures extremely challenging. To achieve results with the resources available, the authors replaced the densely packed pins inside the cooling channel with a boundary condition. This boundary condition was derived from a highly detailed simulation of a section of the cooling system. With this model reduction, the wall temperatures could be evaluated at four operating points. Back-to-back comparisons of the predicted wall temperatures with pictures of deteriorated combustor hardware out of the field operation reveals the plausibility of the numerical results. Finally, this numerical model was extended to include the effects of thermal radiation and soot formation. To predict the combustion of Jet-A, both models were used with settings derived from former validation simulations. The SAF combustion with extremely low sooting level was mimicked by deactivating the soot formation completely. The comparison of the radiation source term reveals — as expected — locally a higher radiation emission in areas where soot is formed in the combustor. As consequence, this leads to higher net radiative heat flux into the combustor liners. However, due to its minor importance in the overall energy balance, this change did not lead to significantly different liner temperatures.