The present research was carried out in the framework of the ASTRAEA IIproject, in collaboration with Cobham Mission Equipment. One part of theoverall ASTRAEA II project is to design an autonomous air-refuelling systembased on a wake model computed in real-time, which allows the flow field to bevisualised in a Synthetic Environment. In a previous part of the ASTRAEAproject a MATLAB® code was developed based on the extended lifting linemethod (referred to as the ELL code) which provides a refuelling tanker wakemodel. The aim of this project is to understand the tanker wake, to providemore detailed flow field predictions and to compare the results with the resultsfrom the ELL code to validate this reduced fidelity method.The understanding of the tanker wake and tip vortices was carried outthrough the use of computational fluid dynamics (CFD) methods. CFDsimulations of three geometries were carried out and post-processed: the DLR-F6 aircraft geometry, the CRM aircraft geometry (both similar to the A330) andthe NACA0015 swept wing model of Gerontakos and Lee. The latter was used asa validation test case for the CFD modelling of the wake and the tip vortex. TheCFD simulations were performed using a geometry definition compatible withthe idealised model scale aircraft definitions used in the wind tunnelexperiments. Finally comparisons between the available CFD results and theELL code were carried out.The ELL code computes a qualitatively similar wake and tip vortex flow field,but only when the code is run with a different set-up which requires morecomputing resources. The addition of the simple fuselage model to the ELL codehas provided an improvement in the results compared with the CFD solutions.The ELL code does not model the vortex roll up and there are notabledifferences in the near-field region in particular. Although the flow fieldstructure is similar between the ELL and the CFD results, there are notabledifferences in the local disturbance flow field. In particular, for someconfigurations, the tip vortex strength is underpredicted by up to a factor ofthree relative to the CFD results.
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