The use of Liquid Hydrogen (LH2) as civil aircraft fuel is gaining attention due to increasing environmental concems associated with conventional fossil fuels. The EUfunded HASTA project (Hydrogen Aircraft Sloshing Tank Advancement) aims to investigate both experimentally and numerically the storage of LH2 in civil aircraft, ultimately providing design guidelines for cryogenic fuel tanks. A critical phenomenon affecting airbome cryogenic tanks is ullage pressure drop, which can occur due to in-flight excitations that induce mixing between the liquid and gas phases. As a preliminary step toward understanding the sloshing dynamics in LH2 tanks, this study investigates isothermal sloshing in a small-scale, horizontal cylindrical tank. An experimental campaign was conducted using an 80 mm x 120 mm cylindrical horizontal tank, partially filled with deionised water and subjected to vertical sinusoidal excitation. The objective was to map the liquid response regimes to the excitation frequency-amplitude range of interest. A sloshing regime map was obtained, providing a key understanding of the liquid dynamics, indicating excitation amplitudes and frequencies that can lead to phase mixing. Ten distinct sloshing modes were observed within the 4-10 Hz excitation frequency range, with this study focusing on mode (1,0), the lowest-frequency response and particularly critica! for such systems. The modal frequency and damping were obtained using a sloshing surface identification algorithm, and the relationship between sloshing force and tank displacement/ velocity was analysed to provide insight into the sloshing regimes. Apart from providing important insights into the sloshing regimes inside horizontal cylindrical tanks, this research also establishes the experimental characteristics needed for future numerical model calibration.
Festila et al. (Mon,) studied this question.