川崎重工完成氢燃料航空发动机测试 实现世界顶尖低氮氧化物排放Kawasaki Heavy Industries Completes Hydrogen Fuel Aircraft Engine Test, Achieves World-Leading Low Nitrogen Oxide Emissions

On October 8, local time in Japan, Kawasaki Heavy Industries announced that it had successfully completed testing of a hydrogen-fueled aircraft engine, achieving a world-leading low nitrogen oxide (NOx) emission level in Japan for the first time. This small aircraft engine uses 100% hydrogen fuel throughout and is equipped with Kawasaki Heavy Industries' newly developed low-NOx hydrogen burner.

Pure hydrogen combustion can completely eliminate carbon dioxide emissions, but the laminar combustion speed of hydrogen is about ten times that of conventional aviation kerosene Jet A-1, and the adiabatic flame temperature exceeds 2200 degrees Celsius. In conventional gas turbine combustors, such local high-temperature zones accelerate Zeldovich mechanism reactions, causing thermal NOx formation to rise exponentially. To solve this problem, Kawasaki Heavy Industries introduced its patented micro-mixing combustion technology, originally developed for power generation gas turbines and already commercialized, into the aviation field.

The core idea of this technology is to disperse the overall combustion into numerous micro flames, rather than concentrating the fuel into a single large flame zone. The specific approach is to distribute pure hydrogen fuel to a large number of micro fuel injection points, interacting with local crossflows, so that the reaction zones are diffusely distributed among many micro flames. This greatly reduces the physical volume of a single flame zone and the residence time of combustion gases at peak temperatures, suppresses the formation of local high-temperature hotspots, and significantly lowers nitrogen oxide emission concentrations. Test results show that under pure hydrogen combustion conditions, this combustion chamber can provide stable flame anchoring without flashback, while achieving world-class low nitrogen oxide emissions.

This test was conducted at the Noshiro Rocket Test Center of the Japan Aerospace Exploration Agency (JAXA) in Akita Prefecture. The scope of the test covered the entire operational range of an aircraft engine, rather than a single steady-state condition test. The verification parameters included ignition start and cold start dynamics, engine speed increase passing through the idle range, steady-state operation simulating hollow cruise conditions, transient acceleration and deceleration sweeps, up to controlled fuel cut-off and full engine shutdown. Throughout all operating mode transitions, the equipment maintained stable combustion, and the thrust output met expectations.

This project is part of the Japan New Energy and Industrial Technology Development Organization (NEDO) 'Next-Generation Aircraft Development' Green Innovation Fund project under the 'Hydrogen Fuel Aircraft Core Technology Development' initiative. The project period is set from 2021 to 2030, with the research and development goal of overcoming hydrogen combustion technology and supporting systems that can be practically applied to hydrogen-fueled aircraft engines, laying the foundation for commercial application. Prior to this, Kawasaki Heavy Industries completed the operation test of a small hydrogen-fueled aircraft engine in October 2024 and carried out Japan's first hydrogen aircraft liquid hydrogen tank fueling verification demonstration in November 2025. The advancement of the engine combustion stage and the fuel storage stage is simultaneous, completing the two core hardware components of hydrogen aircraft.

Based on the results of this test, the combustion chamber can achieve globally leading levels of low nitrogen oxide emissions, helping to meet the increasingly stringent aviation power emission regulations of the International Civil Aviation Organization (ICAO) and addressing the emission challenges during the implementation of hydrogen aircraft propulsion. The next step for Kawasaki Heavy Industries is to conduct integrated ground tests of the entire machine to evaluate the performance and feasibility of the coordinated operation of the aircraft body, engine, liquid hydrogen tank, and various supporting systems, further accelerating the development of key technologies required for hydrogen-powered aircraft.

[Source: Kawasaki Heavy Industries]

[Editor: Xiao Neng]