Kazuaki Matsuura

Suppression of NOx Emission of a Lean Staged Combustor for an Aircraft Engine

Due to the increasing demands for environment protection, the regulation of NOx emissions from aircraft engines specified by ICAO have become more stringent year by year. A combustor with lean staged fuel injectors is one of the effective methods to reduce NOx emissions. Kawasaki heavy industries Ltd GTBC and Japan Aerospace Exploration Agency (JAXA) have been conducting joint research on a lean staged concentric fuel nozzle for a high pressure ratio aero engine. High pressure combustion tests were performed to clarify the effect of the contour of the air flow passage of the main premix duct, the arrangement of the swilers and the fuel injection position on the NOx emission especially at high power. Visualization of the fuel spray at elevated pressure inside of the premix duct using a model with transparent walls and a laser diagnostics technique showed clear relationship between the distribution of the fuel spray and the NOx emission.Copyright

Investigations of a Staged Fuel Nozzle for Aeroengines by Multi-Sector Combustor Test

The reduction of NOx emissions from aeroengines is very important to protect the local air quality near the airports and prevent the climate change. ICAO CAEP has been stepped up the NOx standard frequently. Therefore, the engine manufacturers and national research institutes are actively working on the low-NOx technologies to meet the lower NOx emissions standard. JAXA is conducting research and development of the aeroengine technologies for the environmental adaptation in the TechCLEAN project. As a part of the project, combustion technologies have been developed with an aggressive target that is an 80% NOx reduction of CAEP/4. For the drastic reduction of NOx emissions, the fuel nozzles were designed based on the lean staged combustion concept. At first, five fuel nozzles were tested in a single-sector combustor at LTO cycle conditions of small aeroengine and it was confirmed that one fuel nozzle enabled 72% NOx reduction of CAEP/4. This lean low NOx fuel nozzle was tested in the present work in a multi-sector combustor at the same conditions with the single-sector combustor test. Test results showed that the combustor had combustion characteristics enabling 70% NOx reduction of CAEP/4, which was almost same with the single-sector combustor. For the improvement of combustion efficiency at middle power conditions, fuel staging among the main fuel injectors was also investigated at the MCL condition. The results showed that the fuel staging among the main fuel nozzles is effective to improve the combustion efficiency of the annular combustor.Copyright

Preliminary Experimental Research to Develop a Combustor for Small Class Aircraft Engine Utilizing Primary Rich Combustion Approach

A series of experimental researches, including ignition and combustion tests at atmospheric pressure conditions, were conducted to develop a combustor for a small class aircraft engine (with pressure ratio about 20). Under restrictions of the combustor size and cost, in order to satisfy the requirement for ignition and blowout performance with sufficient combustion efficiency and NOx reduction for wide range of operating conditions, we applied single fuel nozzles and utilized the rich-burn-quick quench-lean-burn (RQL) combustion approach. Preliminary combustion tests were conducted to optimize the ignition and blowout characteristics, approximately determining positions of air holes and igniter, and selecting fuel nozzle parameters. Consequently, tubular combustor tests with exhaust gas analysis were also conducted to optimize the air mass flow ratio and the air holes’ positions to suppress NOx emissions. Obtained results showing the RQL characteristics of the combustion, decreasing NOx emissions at high equivalence ratio range, are presented in this report, and the optimized air mass flow ratio and position of air holes, which will be applied to a single sector combustor for the testing at practical pressure and temperature conditions, are also presented.© 2006 ASME