Combustor Cooling

Gas temperatures in aero-engine combustors can reach 2500K, considerably higher than the allowable temperatures for typical combustor wall materials. At the same time the temperature of the cooling air reaches 900K at full power conditions. Consequently there is only a small temperature difference available for cooling. Hence efficient cooling concepts for the combustor walls are required.

Lean-burn combustors are designed to significantly reduce emissions of nitric oxides, but

are especially challenging with respect to wall cooling. In lean combustion the air flow distribution is strongly modified in comparison to conventional combustors and less air is available for cooling.

The combustor department works on cooling concepts for both metallic and ceramic wall materials.

• The development of new additive manufacturing technologies for metallic parts and components (e.g. Selective Laser Melting) enables the design and manufacturing of innovative cooling concepts and geometries, that can not be realized with conventional manufacturing technologies.
• Ceramic wall materials re-enforced with ceramic fibres (Ceramic Matrix Composites CMC) promise  higher operating temperatures than alloys. CMC have an increased damage tolerance in relation to monolithic ceramics. In comparison to alloys the thermo-mechanical material properties differ significantly and specific cooling concepts are required.

The combustor cooling activities are based on numerical and experimental research. Apart from numerical simulations, experiments at realistic operating conditions are essential for the understanding of the aerodynamic and thermal process as well as for the design of cooling concepts. For these experiments a high pressure cooling rig (HPCR) is operated. In addition the results are used to validate correlations derived on atmospheric test rigs and numerical simulations.

Wall temperature distribution measured with IR camera