Mitsumasa Makida

Utilization of Cold-Flow Numerical Simulation With Overset Grid Method in Development Process of Aeroengine Combustor

In the TechCLEAN project of JAXA, a combustor for a small aircraft engine has been developed. The combustor was tuned to show the behavior of the Rich-Lean combustion through combustion tests under atmospheric and practical conditions. In the development process of the combustor, numerical simulation methods were also utilized as analysis tools to accelerate the development of the combustor. To use in the screening process of the combustor design, we focused on cost-effective simulation methods and adopted the cold-flow RANS simulation code UPACS which has been developed in JAXA. And to simplify the treatment of calculation grids of the combustor with complicated configuration, we also utilized combination of the overset grid method with the attached multi-block grid method. This simulation method was applied to three phases in the combustor development process; first to the analysis of the combustor configuration to adjust the overall pressure loss, secondly to the analysis of flame stability, and thirdly to the tuning of air flow ratio to optimize emission characteristics of full annular combustors. Finally, the full annular combustor was successively tuned to reduce NOx emissions to 38.1% of the ICAO CAEP4 standard under ICAO LTO cycles, also sustaining basic performances as an aircraft combustor.Copyright

Emission Characteristics Through Rich–Lean Combustor Development Process for Small Aircraft Engine

Following increasing awareness of aircraft emissions and demand for technologies to reduce NOx emissions, experimental research has been conducted to develop a combustor for a small aircraft engine in the TechCLEAN of Japan Aerospace Exploration Agency project. The combustor was tuned to produce rich–lean combustion behavior through combustion tests, including full annular combustion experiments, under atmospheric and actual operating conditions of the target engine. Excellent combustion performance was observed. The final, optimized full annular combustor achieved a reduction of NOx emissions below 40% of the standard regulated by Committee on Aviation Environmental Protection/4 of International Civil Aviation Organization while maintaining low CO and total hydrocarbon emissions and showing superior exit temperature profiles and lean blow-out performance. Through the combustor development process, the dependence of combustion characteristics on combustor configuration was also clarified.

Influence of Injection Ratio of Dual-Injection Type Air-Blast Fuel Nozzle on Emission Characteristics Applied to Rectangular Single-Sector Combustor Under Atmospheric Condition

In the TechCLEAN project of JAXA, experimental research had been conducted to develop a combustor for a small aircraft engine. The combustor was tuned to show the behavior of the Rich-Lean combustion through tests under atmospheric and practical conditions. Finally, through full annular combustion experiments under practical conditions, the combustor was tuned to reduce NOx emissions to almost 40% of the ICAO CAEP4 standard, also sustaining low CO and THC emissions. In the developing process of above combustors, to simplify the combustor system, air blast type fuel nozzles with single fuel injection and dual swirlers were applied. Successively, in this report, the fuel nozzle is modified to dual fuel injection type with triple swirlers, aiming to control combustion performance under varying load conditions. Fuel is injected from inner and outer injection circuits, and the injection ratio between them is treated as one of the parameters.The combination of swirl direction of the three swirlers is selected at first through ignition and blowout tests. Secondly, spray patterns of the selected fuel nozzle are observed with different fuel injection ratios. Thirdly, the nozzle is applied to a rectangular single-sector combustor, and tested under atmospheric pressure with inlet temperature of 500K. NOx, CO, CO2, THC and O2 compositions in the exhaust gas are measured, and correlation among measured emissions data and fuel injection ratio is estimated to examine the influence of the injection ratio on combustion characteristics of the Rich-Lean type aero engine combustor.Copyright

Detailed Research on Rich-Lean Type Single Sector Combustor for Small Aircraft Engine Tested Under Practical Conditions Up to 3MPa

In the TechCLEAN project of JAXA, experimental research has been conducted to develop a combustor for a small aircraft engine. The combustor was tuned to show the behavior of the Rich-Lean combustion through tests under atmospheric and practical conditions. Finally, through full annular combustion experiments under practical conditions, the combustor was tuned to reduce NOx emissions to almost 40% of the ICAO CAEP4 standard, also sustaining low CO and THC emissions. To investigate the performance of the combustor in detail, parametric experiments were conducted with single-sector combustors under additional test conditions in addition to design conditions of the target engine. Also the performance as a combustor for higher-efficient aircraft engine is examined by increasing inlet air pressure and temperature up to 3MPa and 825K in combustion tests. Obtained results of emission characteristics are discussed in this report.Copyright

Detailed Cold-Flow Simulation to Estimate Mass Flow Distribution of Aircraft Combustor

In the TechCLEAN project of JAXA, a combustor for a small aircraft engine has been developed. The combustor was tuned to show the behavior of the Rich-Lean combustion through combustion tests under atmospheric and practical conditions. Finally, the full annular combustor was successfully tuned to reduce NOx emissions to 38.1% of the ICAO CAEP4 standard under ICAO LTO cycles, also sustaining basic performances as an aircraft combustor. In the development process of the combustor, numerical simulation methods were also utilized as analysis tools to accelerate the development of the combustor. To use them in the screening process of the combustor design, we focused on cost-effective simulation methods adopting the cold-flow RANS simulation code UPACS which has been developed in JAXA. Moreover, to simplify the treatment of calculation grids of the combustor with complicated configuration, we also utilized combination of the overset grid method and the attached multi-block grid method. In the previous report, we introduced the overview of the application of the cold-flow simulation in the combustor development process. Subsequently, in this report, we focus on the effect of combustor configuration parameters to the air mass flow ratio among fuel nozzles, dilution air holes and cooling air holes on the combustor linear. Then we also show the estimation method of the effective open area of combustor liners, mass flow ratio between air holes, and total pressure loss of the combustor.Copyright

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.Copyright

Optimization of a Small Aircraft Combustor to Reduce NOx Emissions Under Practical Conditions

A series of research experiments under practical conditions has been conducted to develop a combustor for a small-class aircraft engine (with the pressure ratio of about 20). In the previous research experiments, including ignition and emission tests under atmospheric pressure, we applied a single airblast fuel nozzle and utilized the rich-burn quick-quench lean-burn (RQL) combustion approach. The combustor was tuned to show the behavior of the RQL under the atmospheric condition. In this paper, the results of single-sector combustor experiments under the practical temperature and pressure conditions are presented, in which RQL behavior is observed and NOx emissions in the ICAO (International Civil Aviation Organization) LTO (Landing and Take-Off) cycle are reduced to 45% of the ICAO CAEP4 (Committee on Aviation Environmental Protection 4) standard. Also the results of successive multi-sector combustor tests to optimize combustion performances with a more practical combustor configuration under the practical conditions are presented. The emission characteristics which are obtained are compared with those of the single-sector tests, and combustor size and configuration, air mass flow ratio and air hole positions are tuned through a series of multi-sector experiments. After the optimization, the combustor achieved the following performances; NOx emissions are reduced to less than 42% of the ICAO CAEP4 standard, CO and THC (Total Hydrocarbon) are reduced to those of 2% and 50% respectively, the lean blowout limit is kept over 220 AFR (Air to Fuel Ratio) at the idle condition and the exit temperature profile at the full load condition is sufficiently uniform (P.T.F.<0.15). The process of optimization will be discussed in this report.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