**Acknowledgements**

quantitativeness in comparison to the primary zone. Measurements at the burner exit are not available for the configuration investigated in the previous section; however, temperature measurements are available for a similar rig, featuring a similar injector and the same flow configuration of **Figure 13**. Comparisons between experimental data and FlaRe-LES results are shown in **Figure 15** for two operating conditions at the same pressure and inlet temperature, but different flow split. These configurations are representative of approach and cutback conditions of

*Comparison of temperature profiles from measurements (symbols, courtesy of DLR Cologne, Germany) and LES (lines) at the exit plane of the DLR OCORE-2 rig of a practical single-sector aero engine combustor for two*

(*y=y*max ¼ �0*:*5) are due to the effusion cooling that lowers the temperature below the minimum detectable from the experiment (about 1200 K). Except for this region, the FlaRe model prediction matches very well that from experiment, which shows that this type of modelling is capable to represent the correct statistical behaviour even at high pressure when the intricate balance between turbulence, dissipation and heat release is correctly taken into account. Recent advances in the modelling in context of flamelets are thus promising for future design cycles of aero

In this chapter, an overview for the current status of the use of combustion CFD in modern gas turbine engine combustor design is presented. There is a general tendency in the industry to move from the conventional RANS to the more powerful LES modelling paradigm, and thus the discussion is focused on the application of LES. The various challenges for LES modelling of gas turbine combustion are discussed and a number of representative subgrid combustion models are briefly described. Flamelet approaches are more attractive for industry because of their significantly higher computational efficiency and relatively simple implementation in different CFD codes. The particular focus was given to a recently developed model called FlaRe, which is a revised flamelet approach keeping the physical consistencies among various SGS models and physical processes. To assess the performance of FlaRe, the LES results are compared with experimental measurements for several typical laboratory and practical combustors. A broad range of phenomena of high practical interest are involved in these test cases including flamevortex interaction, self-excited thermoacoustic oscillations, flame root dynamics close to lean blow-off, high pressure conditions, liquid fuel combustion, etc.

an airplane. The differences observed near the walls of the combustor

engines, although additional validations are still needed.

*Environmental Impact of Aviation and Sustainable Solutions*

**5. Summary and future outlook**

**Figure 15.**

**66**

*operating conditions.*

The authors IL and NS thank the DLR Institute of Propulsion Technology in Cologne for kindly providing measurement data for some of the figures shown in this chapter, and in particular Dr C. Willert, Dr T. Behrendt and Dr J. Heinze for their useful advice on Section 4.2. The support from Mitsubishi Heavy Industries, Takasago, Japan is acknowledged by ZXC and NS. The presented simulations used the ARCHER UK National Supercomputing Service and the CSD3 Cluster of Cambridge University.
