A proposal of a hydrogen injection system in to a miniature turbojet engine

The solution proposed in this article, based on direct injection of hydrogen into the combustion chamber, offers many benefits, including a better volumetric efficiency, complete combustion (avoidance of premature ignition and backfire) and significant benefits in terms of power density when compared to engines, in which hydrogen is injected into the air inlet duct. The article discusses advantages and disadvantages of systems responsible for injecting hydrogen into the combustion chamber based on the operational phases of the GTM 400 engine developed by the JET-POL Company. The use of an electronic controller combined with an injector placed in an appropriate place inside the combustion chamber allow for the mentioned engine to be modified this way to optimize its power, performance and emissions. The article discusses matters related to challenges faced by materials used to make components of hydrogen injectors as well as research on the topic in question with the use of diesel engines. The article considers the impact of a low mass density and hydrogen energy, high speed of sound and low thickness on the injection system and components of a miniature turbojet engine. Physical attributes shaped by hydrogen fuel directly affect the size of components, selection of materials and tribology of turbojet engines. The authors suggest that the solutions used in the research on the GTM 400 engine can be used in the future to build hydrogen systems (hydrogen injection, storage and distribution) for fullscale passenger aircraft jet engines.