Modeling of Fuel Sloshing and its Physical Effects on Flutter

Abstract

The sloshing effects of an internal fluid on the flutter envelope of an aeroelastic system have received little attention in the open literature. This issue is nevertheless relevant for many aircraft, especially high-performance fighter jets carrying stores. This paper addresses some aspects of this problem as well as related modeling and analysis issues. These include the importance or insignificance of accounting for the hydroelastic effect when modeling an internal fluid and its container as well as accounting for that container when modeling the aerodynamics of the overall aeroelastic system. The paper also reports on the findings of four independent sets of flutter analyses performed for a wing-store test configuration and various fuel fill levels in the subsonic, transonic, and early supersonic regimes. Two of these sets of numerica l experiments relied on a computational-fluid-dynamics-based computational technology, and two of them on the doublet-lattice method or a supersonic lifting-surface theory, where applicable. The geometry of the chosen test configuration is that of the AGARD Wing 445.6 with a blunt-nosed store. The obtained computational results show that, at least for the considered wing-store configuration, ignoring the aforementioned hydroelastic effect tends to overestimate the added-mass effect and underestimate the critical pressure and flutter speed. They also reveal that, whereas the aerodynamics of the store may be neglected in the subsonic regime, they cannot be ignored in supersonic air streams. Finally, the performed computational study suggests that, in general, the critical pressure and flutter speed decrease with an increasing fuel fill level.

Modal Analysis of Liquid–Structure Interaction

“…The possibility to predict the coupling between the vibrations of the structure and the liquid sloshing using this formulation has been illustrated on test cases and on some more realistic examples [7,19] and then validated by comparison with experimental results [18]. An application to the specific case of free structures containing liquids and a validation by comparison with some benchmark results have been published in [17].…”

“…is very common and many industrial domains are interested in this issue especially in the transport and aerospace industries (for instance liquid propelled launchers and satellites). Computational aspects of fluid-structure interaction and sloshing (with or without surface tension effects) may be found in [1,4,5,6,7,9,13,14,15,21]. We are here interested in the linear vibrational response of elastic structures partially filled with a liquid.…”

Aeroelastic stability of cylindrical shells interacting with internal annular fluid flow

“…On the one hand, depending on the prescribed boundary conditions and flow velocity a combined action of both flows might be of additive nature, providing a strong destabilizing effect on the examined system and, on the other hand, might enlarge the stability boundaries [3][4][5][6]. However, in recent years there have been a number of publications, in which the aeroelastic stability is studied taking into account the influence of a quiescent liquid with a free surface located inside the shell or at its outer surface [7][8][9][10]. The panel flutter of isotropic and heated functionally-graded cylindrical shells completely filled with a quiescent or flowing ideal liquid has been analyzed in our recent papers [11,12].…”

“…For numerical implementation of the problem, the equation of perturbation velocity potential (6) and boundary conditions (7)(8) are transformed using the Bubnov-Galerkin method [16].…”

Accurate Measurement of Nonlinear Liquid Sloshing

“…IQUID sloshing is of interest in fundamental fluid dynamics and control research, as well as for various practical applications including liquid-filled natural gas carriers, elevated water towers, underground motion when subject to earthquakes, fuel tanks for the automotive industry, and preventing dam breaking [1][2][3][4][5][6][7][8]. This is especially important for the aerospace industry in order to accomplish long and complicated space missions, such as orbit insertion, orbit maintenance, and momentum unload, as modern spacecraft require large amounts of liquid propellant, most of which have high transparency and fluidity.…”