Thermal management of hydrogen-powered aircraft

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This project is a collaboration with ZeroAvia who retrofits hydrogen-electric powertrains onto regional and general aviation aircraft. On the highest level, the aim is to experimentally and numerically interrogate aerodynamic features surrounding the thermal management system. Hydrogen fuel cells are rarely found on aircraft, leading to the technology being optimised for other industries such as automotive. Early tests using automotive-derived thermal management systems on testbed aircraft have shown undesirable parasitic drag increases. This requires a deeper level of understanding regarding dominant aerodynamic features associated with these retrofits, especially as the technology scales to higher power requirements. Key objectives/research questions are:- What aerodynamic features, steady or unsteady, dominate retrofitted installations? How are these affected by key design variables (e.g. prop-cooling duct distance)?- In this parametric study, development of an experimental test rig (using PIV/PLIF, cold/hotwires, unsteady probes) along with a CFD solver (adapting an existing DNS code with propeller model), will be required.- What are the performance penalties associated with the highlighted dominant features? - This will enable derivation of aerospace-specific thermal management system design metrics/procedures.- How can we improve performance using passive flow control and/or geometric optimisation?- This section will utilise the understanding derived in the first two stages. The applications of this project are closely coupled with two 'technology bricks', thermal management and aerodynamic structures, outlined as vital for the development of hydrogen aircraft by the Aerospace Technology Institute in their 2022 'FlyZero' report. Despite work being focussed on geometries associated with ZeroAvia's retrofits, research will be applicable to the hydrogen aircraft space as a whole. Small reductions in parasitic drag will present valuable range increases, helping improve the commercialisation of this technology. A parametric study, utilising high-level aerodynamic interrogation with PIV/PLIF, alongside quantification of the system-wide penalties from dominant aerodynamic features, presents as novel research. Prior works largely present simplifications and assumptions that are not applicable to the challenges ZeroAvia faces, for example, the absence of unsteady aerodynamic features in a cooling duct. This bias in the literature is generated from the high computing power required for unsteady CFD simulations, alongside the difficulties and expenses incurred with experimental interrogation. Additionally, research largely focusses on turbofan installations, leading to a lack of studies in the literature applicable to new geometries.