Development of a combustor with optical accesses for pressurized flameless oxidation experiments

The paper discusses the development of a combustor for research towards the application of flameless oxidation to micro gas turbines. This requires operation at high wall temperature (up to 860°C), medium pressure and high power density. A function separation approach made this possible, so that the thermal and pressure loads are taken by distinct shells. Separate cooling and combustion air flows allow the wall temperature to be regulated independently from combustion conditions. Quite innovative is that in spite of the three-shells arrangement, the cylindrical combustor features: multiple optical accesses to most of the combustion space, radial traverses of probes, variable combustion chamber length. CFD and an analytical heat transfer model aided in the design of such a versatile equipment. The system has successfully operated in flameless mode even at the extreme conditions of 4.74 bar_a, 464 kW and power density greater than 70 MW/m³.