Experimental and Numerical Investigation of a Hydrogen Combustion Chamber Under Various Inlet Conditions

Flameless combustion, MILD (moderate or intense low oxygen dilution) combustion and HiTAC (high temperature air combustion) all refer to a combustion regime characterized by high temperatures and a high dilution of reactants. In most cases, this is achieved by recirculating exhaust gases. This leads to comparatively low oxygen concentrations, a largely uniform temperature field and to a drastically reduced NOx formation. Up to now, the application of this combustion technology for gas turbine combustion chambers is still in an early development stage. Most investigations of flameless or MILD combustion chambers have been carried out for methane or certain fuel blends.
Since this combustion technology has already successfully demonstrated low NOx emissions without the need of premixing with its potential risks of flashback and autoignition,
it might be a promising technology for hydrogen burning combustion chambers. The scope of this paper is to investigate a hydrogen combustion chamber for its NOx emission
characteristics and for its use in the flameless or MILD combustion regime. Thus, the influence of different inlet parameters (excess air ratio, thermal input of hydrogen, inlet velocity of the combustion air, pressure inside the combustion chamber) on the emission characteristics of the combustion chamber are examined experimentally. Additionally, for one operating point, a two–dimensional numerical simulation of the combustion chamber was carried out