Experimental and Numerical Investigations of a Dual-Fuel Hydrogen–Kerosene Engine for Sustainable General Aviation

Abstract

<div class="section abstract"><div class="htmlview paragraph">Reducing CO₂ emissions is an increasingly important issue. In aviation, approaches such as e-propulsion only represent a solution for special applications due to the low energy density of batteries. Because of the low-cost and robust design of combustion engines, this concept is still the most suitable for general aviation. For defossilization, besides e-fuels and bio-fuels, which represent the so-called sustainable aviation fuels (SAF), hydrogen can serve as a promising energy carrier for CO₂ reduction. For this purpose, the combustion process of a dual-fuel hydrogen–kerosene (Jet A-1) engine was developed and investigated for use in small aircrafts. This study explores the influence of hydrogen addition on combustion parameters, emissions, and efficiency.</div><div class="htmlview paragraph">An advantage of this special design as dual-fuel engine (hydrogen and kerosene) is the possibility of redundancy operation in the event of a H₂ fuel system failure as well as full operational capability of the aircraft in the event of hydrogen supply difficulties at various airports. Besides test bench investigations, 3D CFD simulations were performed to optimize hydrogen injector position, ensure backfire-free operation, and improve mixture formation. In addition to a low load and high load point, a high-altitude point was investigated based on real flight data.</div><div class="htmlview paragraph">The maximum achievable hydrogen energy shares, limited by abnormal combustion, and the respective CO₂ reductions are shown. Furthermore, the influence of the hydrogen mass distribution in the inlet ports was investigated to achieve an advantage in the homogenization of the hydrogen–air mixture. Finally, the efficiency losses in hydrogen dual-fuel mode compared to base kerosene operation are shown in a detailed analysis.</div></div>