INTRODUCING FUEL SLOSHING EFFECT IN MODELS FOR FLIGHT DYNAMICS AND CONTROL ANALYSIS

Kurzfassung

Increasing fuel-to-weight ratios of future fighter aircraft, as well as liquid hydrogen propelled civil airliners demand a good understanding of fuel-induced dynamic effects (i.e. "fuel sloshing") for preliminary aircraft design, flight control and clearance purposes. Learning from space and shipping applications can serve as feasible starting points, yet tank geometries, installation, environmental and operational aspects for the above-mentioned configurations differ significantly from these domains. Therefore, individual modeling and evaluation activities are required: The German Aerospace Center (DLR) at Oberpfaffenhofen in cooperation with Airbus Defence and Space at Manching aim for significant insight into these matters within the scope of the DLR DIABOLO project with a focus on fighter aircraft specific tank configurations. The DLR Institute of System Dynamics and Control (DLR-SR) is also involved within the DLR HYTAZER project for the analysis of LH2-tanks - applying similar, yet adapted methods for this domain. Within the DIABOLO project context, promising modeling and analysis methods are explored wrt. a potential application for the above mentioned use-cases. Basically the need for a broad spectrum of methods came up early: For the actual flight dynamics analysis loop-capable, yet sufficiently accurate low-fidelity methods and models are required. In order to validate and adapt these methods, higher-fidelity numerical methods up to experimental data are required as benchmark and for model validation and adaptation purposes. Based on the description of a previously described experimental campaign involving a wing-tank on top of a robotic motion platform, this paper focuses on post-processing of the experimental results, the current state of low-fidelity modeling (pendulum-based) as well as preliminary CFD-results. Finally a comparison of these methods based on experimental results is shown.