Evaluation of Lean Axially Staged Combustion by Multi-Sector Combustor Tests Under LTO Cycle Conditions of a Small Aircraft Engine

Abstract

JAXA is conducting research and development on aircraft engine technologies to reduce environmental impact in the Technology Development Project for Clean Engines (TechCLEAN). As a part of the project, combustion technologies have been developed with an aggressive target that is an 80% reduction over the NOx threshold of the fourth Committee on Aviation Environmental Protection (CAEP/4) of the International Civil Aviation Organization (ICAO). Lean staged fuel nozzles have been developed and tested using a single-sector combustor under Landing and Take-off (LTO) cycle conditions of the target engine with a rated output of 40 kN and an overall pressure ratio of 25.8. A reduction of 82.2% in LTO NOx emissions relative to the ICAO CAEP/4 standard and drastic reductions in smoke and carbon monoxide (CO) emissions were resulted by single-sector combustor tests of a lean staged combustor with an additional premixed fuel nozzle (ECF: Emission Control Fuel nozzle). After the test, the pilot mixer of the single-sector combustor was improved and an additional 2.5% NOx reduction was achieved by combustion tests. As a next step, a multi-sector combustor with ECF was developed and tested. The test results show that the combustor enables a reduction of 82.2% in LTO NOx emissions relative to the ICAO CAEP/4 standard, though unburnt hydrocarbons (HC) and CO emissions are increased. Temperature distributions in the combustor exit plane were also evaluated.