aFJR (Advanced Fan Jet Research) project
More environmentally friendly aircraft engine with low-fuel consumption and low CO2 and NOx emissions are anticipated to tackle global environmental issues such as global warming and diminishing fuel resources. Aviation-related organizations such as the International Civil Aviation Organization (ICAO) and International Air Transport Association (IATA) are setting stricter environmental standards step-by-step. To offset ever-increasing air traffic volume, which is expected to double during the next two decades, it is critically important to develop next-generation engine technologies that have less impact on the environment. As demands on more fuel-efficient aircraft engines are increasing among airlines and their passengers, developing higher-efficiency aircraft engine in joint efforts with Japanese aircraft engine manufacturers is expected to widen opportunities for them to compete in global markets.
The purpose of the "aFJR (Advanced Fan Jet Research)" project is to advance research on engine component technologies so that Japanese manufacturers can join more effectively in international joint-development projects on next-generation jet engines, and thereby secure larger roles in design and manufacturing responsibilities for collaboration. The aFJR puts special emphasis on increasing the environmental compatibility of "fans" and "low-pressure turbines" because Japanese aircraft engine manufacturers have a backed record of developing and supplying these engine components.
One technology that is necessary to improve current turbofan engines for use on passenger civil aircraft is to increase engine bypass ratios* while sustaining low engine weight. A higher bypass ratio engine can reduce CO2 emissions and exhaust noise. Nevertheless, increasing the bypass ratio requires a larger fan and larger low-pressure turbine to drive the fan. To compensate for the increased size of these components, lightweight solutions and other elements must be studied.
In the aFJR project, we are developing an ultra-high bypass ratio engine through development of high-efficiency, lightweight fan technology and lightweight, low-pressure turbine technology, securing the same durability and reliability as that of a conventional engine. Both technological developments can be achieved through (1) improving the fan aerodynamic efficiency of existing engines by at least 1 point and (2) reducing overall engine weight by approximately 10% by lowering the fan and turbine weight. The feasibility of those technologies will be verified through demonstration tests.
* : Technology to intake more air flow through the fan than through its core engine
High-efficiency, lightweight fan
To compensate for the increased fan diameter, which becomes larger relative to the increase in engine bypass ratio, we are developing lightweight fan blades that have higher aerodynamic efficiency by applying advanced simulation technology and composite materials evaluation technology. For the metal disk which holds the rotating fan blades, we are developing new technologies that will enable weight reduction while maintaining strength.
Lightweight, low-pressure turbine
To suppress the increase of weight of the low-pressure turbine, we are studying lightweight solutions such as using heat-resistant lightweight ceramic-matrix composites (CMC) for blades. We are also developing tangling design technology for maintaining and improving the reliability of low-pressure turbines.