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The development of an efficient tool for predicting an accurate store separation trajectory for complex aircraft/store configurations using Computational Fluid Dynamics (CFD) is described. In the present work a pseudo -unsteady approach has been implemented to model the motion of the separating store relative to its parent aircraft, using a steady state Euler flow solver. A hybrid meshing strategy is adopted with the majority of the domain block structured and unstructured grid covering the expected extent of the store's trajectory. Considerable effort has been focused on developing methods to minimize the run times for a full trajectory calculation. These methods include efficient grid redefinition in response to the store's movement, intelligent flowfield initialisation and node renumbering to optimise the tool for use on RISC processors. The tool has been validated against flight test data for the under fuselage ejection release of a BL7.55 store from Tornado and for the under fuselage ejection release of an empty 1500 litre fuel tank from Tornado with a JP233 in carriage on the opposite shoulder pylon. The capability has also been tested on the powered rail launch of AMFWAM from a launcher positioned under the wing of EF2000. Nomenclature Dtixed = distance from nearest fixed boundary D moved = distance from nearest moving boundary X moved = position of node translated with the store X old = position of node in old grid X new = position of node in new grid 44 03 v = Euler angles of roll,pitch and yaw * Project Supervisor u,v,w V trans V store co store k E &Y,Z r r0 = Cartesian velocity components = transpiration velocity = translational velocity of the store = rotational rates of the store = diffusion coefficient = small parameter = Cartesian coordinates = position vector of point (x,y,z) = position vector moment reference point

SUMMARYA description is given of a method capable of automatically forming e cient, high-quality hybrid meshes for viscous ow calculations over complete aircraft, given engineers' requirements on mesh density and ÿrst cell-height. Mixed quadrilateral=triangular surface grids are constructed using the moving-front approach, with point placement and connection optimized to ensure high-quality, anisotropic panels are generated. The volume mesh is built in two stages. A near ÿeld mesh is formed using the advancinglayer approach, signiÿcantly enhanced through the use of mesh enriching=collapsing techniques and layer-intersection detection=front-termination algorithms. The remainder of the domain is then covered by a cut-cell Cartesian mesh of varying density that conforms to the outer-surface of the near ÿeld mesh. Examples of meshes generated using the described methods are presented and the user-input discussed.

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