Investigation of Impact of Steam Addition on Combustion Behavior and Pollutant Emissions in an RQL Combustor at High Pressure

Emissions reduction in aviation is of paramount importance, due to the associated global warming effects. One way of combating the emissions of NOx and non-volatile particulate matter is the injection of steam into the combustion reaction. In this study, steam injection successfully reduced the production of both NOx and soot in a rich-quench-lean (RQL) combustor, which is promising in aircraft engine applications. The tests were conducted at relevant high-pressure (up to 14.4 bar), preheated inlet conditions with kerosene (Jet A-1) as the fuel. In addition to typical pressure, temperature and exhaust gas measurements, additional laser diagnostic techniques (Mie-scattering spray characterization, and laser-induced incandescence) were applied. Furthermore, simultaneous optical emissions measurements of OH* (312 nm) and black body radiation of soot (660 nm) provided insight into the locations in the flame for heat release and soot production for various operating conditions with and without steam. These promising results offer a step towards a more complete understanding of the underlying processes of the production of soot in RQL combustors.