Cryogenic Flow Physics to Advance Liquid Hydrogen-Based Aviation

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Commercial aviation emits more than 900 million tonnes of carbon dioxide (CO2) each year into the atmosphere, accounting for 3% of total anthropogenic CO2 emissions. If it were a country, commercial aviation would rank just ahead of Germany as the sixth largest emitter of CO2. Aviation must urgently decarbonize to avoid catastrophic climate impacts. Over 70% of emissions come from medium-range flights (2000-4000 km) for which battery electrification remains infeasible for the foreseeable future. Hydrogen presents an alternative route for decarbonizing aviation-it has a large energy density by mass; it can be generated from renewable sources such as wind and solar; it can be combusted in aircraft engines with few modifications; and it can generate electricity directly via a fuel cell. However, hydrogen's low volumetric energy density means that it must be stored as a pressurized gas or cryogenic (ultra-cold) liquid. Per unit energy, liquid hydrogen requires about half the volume, making it most suitable for aviation. Adopting liquid hydrogen as a low-carbon aviation fuel will require significant re-engineering of aviation technologies, mainly due to the complexity associated with its cryogenic state. The interactions of cryogenic conditions with flow turbulence, phase transition, thermal non-equilibrium, geometrical complexities, and interfacial effects are poorly understood, despite the major impacts these processes have on the fuel storage conditions, fuel system layout, and ultimately the aircraft safety and efficiency. Without an in-depth physical understanding of cryogenic flows, liquid hydrogen-based aviation cannot advance. My research program will advance the liquid hydrogen pathway for decarbonising the aviation sector through three parallel activities. First, we will generate new computational fluid dynamics approaches that will be specifically tailored for accurate and robust simulation of cryogenic flow physics, building especially on the strengths of non-continuum approaches such as the lattice Boltzmann method. Second, we will use the developed tools to address fundamental questions that remain unanswered regarding the cryogenic behaviour of liquid hydrogen. Finally, using the insights produced by such investigations, we will develop simple yet physically-realistic models to predict the thermohydraulic behaviour of liquid hydrogen for use in engineering design. My research program will directly impact the aviation industry, enabling innovations in low-carbon aviation systems and supporting the aspirational hydrogen pathway for decarbonizing the aviation sector. It will also promote the development of hydrogen-based technologies in other hard-to-decarbonize sectors, including heavy-duty trucking, rail, and marine transportation. Therefore, the proposed program will support economic and energy diversification efforts within Canada while simultaneously helping Canada reach its urgent environmental and climate goals.