Abstract
Liquid sloshing in next-generation sub-cooled liquid hydrogen aircraft fuel tanks can induce rapid ullage pressure and temperature drops, potentially causing cavitation in cryogenic pumping systems and compromising fuel delivery systems. Sloshing events may be initiated during taxiing, take-off, landing, and turbulence, with large accelerations producing highly non-linear liquid motion and wave-breaking conditions. Understanding such phenomena is essential for cryogenic hydrogen fuel tank design and certification for next generation aircraft.A systematic experimental methodology was employed to investigate both the wave kinematic and thermodynamic aspects of sloshing. Initial water–air experiments in a simplified horizontal circular tank were conducted to validate measurement techniques, using high-speed imaging for free-surface visualisation alongside an image processing algorithm (IPA) that enables accurate determination of liquid kinematics. These preliminary tests characterised fundamental wave modes, resonance behaviour, soft-spring nonlinear response, and wave-breaking limits, providing a robust baseline for subsequent experiments with cryogenic surrogate fluids.Two isothermal experimental campaigns were carried out in a quasi two-dimensional tank. Horizontal excitation of the fundamental antisymmetric mode provided the first parametric study reporting both free surface shape and centre of gravity (COG) motion under resonance across a range of forcing amplitudes and fill levels. A linear relationship between COG motion and local free surface displacements was determined. Vertical excitation near the primary parametric resonance (PPR) of the fundamental symmetric mode explored Faraday waves and wave breaking limits, including high acceleration tests up to 1.5g. Period tripling, harmonic interactions, and antinode asymmetries were observed, with higher fill levels exhibiting nonlinear effects and wave breaking at smaller wave amplitudes. Results demonstrated that wave amplitude alone is insufficient to predict breaking onset, emphasising the importance of nonlinear interactions and fill level dependent behaviour.Building on these isothermal sloshing results, non-isothermal experiments were conducted using HFE7100 as a surrogate cryogenic fluid, with transparent tank faces coupling high-speed imaging, to pressure and temperature sensors capturing the thermodynamic response. The experiments showed that even modest wave breaking significantly accelerates ullage pressure drops, with reductions of up to 60% of the initial pressure. Lower initial pressures corresponded to smaller pressure drop magnitudes, while higher fill levels required smaller wave amplitudes to initiate pressure drops. Large amplitude sloshing cases exhibited complete destratification and enhanced liquid–vapour mixing, whereas small amplitude sloshing maintained a (reduced) degree of thermal stratification.
Awarding Institution(s)
University of Plymouth
Award Sponsors
Airbus UK
Supervisor
Yeaw Chu Lee, Deborah Greaves, Francesco Gambioli, Edward Ransley
Keywords
Sloshing, cryogenic, hydrogen
Document Type
Thesis
Publication Date
2026
Embargo Period
2026-02-10
Deposit Date
February 2026
Additional Links
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
Colville, S. (2026) Cryogenic Sloshing in Aircraft Fuel Tanks. Thesis. University of Plymouth. Available at: https://doi.org/10.24382/d9ah-py60
