Cryogenic Hydrogen Thermofluids Global Research Landscape

The Aerospace Technology Institute’s (ATI) FlyZero project concluded that liquid hydrogen (LH2) is the most viable zero-carbon emission fuel for future commercial aircraft. The FlyZero reports highlighted technologies which would be required to enable such aircraft to become a reality and the gaps in liquid hydrogen capability. The technological change to a liquid hydrogen architecture is revolutionary and the cryogenic hydrogen storage and fuel system faces the greatest disruption. To get to a certifiable, commercially viable system design it requires a breadth of knowledge relating to cryogenic hydrogen that does not currently exist within the sector. As such, the Hydrogen Capability Network (HCN) has identified three key areas which need to be supported: • Fundamental research into material behaviour in cryogenic hydrogen environments. • Fundamental research into cryogenic hydrogen thermofluids behaviour. • Fundamental research into cryogenic hydrogen health and safety. Workshops on these three topics were held, to identify subtopics that were of particular interest to both industry and academia. The HCN commissioned global landscaping projects to investigate the current state-of-the-art fundamental research on these subtopics in each of the three key areas, and a report has been written by academic experts on each of them. Each report highlights the global research status and gaps in which research and development is needed to enable the liquid hydrogen aircraft of the future. The key areas identified within the thermofluids workshop were used to identify the areas of investigation within this report. This document reviews ongoing and seminal works in twelve different areas of fundamental thermofluids research across the globe to develop maps of gaps and opportunities. Fundamental research is defined as being at a TRL of between 1 and 3; it can be experimental, analytical, computational, or a combination of these. To understand the impact the fundamental research gaps have on research and development of aviation fuel systems five scenarios have been investigated, with the implications of the research gaps highlighted. Publications have been analysed from 1950 to February 2025. The majority of the publications reviewed are from the last 15 years. Figure 1 shows the publication count from 1951 to 2025 by decade for liquid hydrogen fluid properties publication in the engineering field. Whilst this does not cover the whole Thermofluids research area it provides a good guide to the trends in publications in liquid hydrogen low TRL Thermofluids which quadrupled between the decade from 2001 to the decade from 2011.