Verification of Low NOx Performance of Simple Primary Rich Combustion Approach by a Newly Established Full Annular Combustor Test Facility
In the TechCLEAN project of JAXA, experimental research has been being conducted to develop a combustor for a small aircraft engine (with pressure ratio of about 20). The combustor was tuned to show the behavior of the Rich-Lean combustion through tests under atmospheric and practical conditions. And in 2006, by a designed multi-sector combustor, NOx emissions were reduced to lower than 42% of the ICAO CAEP4 standard. Based on the tuned combustor, full annular combustors were designed. In parallel, an experimental facility to test the full annular combustors under practical conditions was newly constructed in the spring of 2007. The inlet air conditions were set to the ICAO LTO cycle conditions of the target engine; 0.3–1.8MPa for pressure, 400–700K for temperature and 4–18kg/s for air mass flow rate. Through the full annular combustion experiments under practical conditions, the combustors were tuned to keep good combustion performance which was verified by the multi-sector combustors. The optimized full annular combustor finally achieved the following performance; NOx emissions were reduced to lower than 40% of the ICAO CAEP4 standard, maintaining low CO and THC emissions, good exit temperature profiles (P.T.F. = 0.19 at the take-off condition) and good lean blow-out performance (AFR>200 at the idle condition). The process of the optimization is discussed in this report.