22nd Congress of International Council of the Aeronautical Sciences, Harrogate, UK, 28 August - 1st September, 2000
Paper ICAS 2000-5.2.2

VORTEX SYSTEM AND THE INTERFERENCE BETWEEN AN AIR INTAKE AND THE GROUND

A. Karlsson (1) , L. Fuchs (2)
(1) Dep. of Mechanics and Dep. of Aeronautics, KTH, Stockholm, Sweden; (2) Div. of Fluid Mechanics, LTH, Lund, Sweden

Keywords: cfd, les, air inlet, inlet vortex system

The flow in the neighbourhood of and into an inlet to a gas turbine engine close to the ground is studied through Large Eddy Simulations (LES). When air is sucked into the air inlet a vortex system develops between the air inlet and the ground. The flow influenced by this vortex system is not only turbulent but also contains larger unsteady vortex structures. These larger vortex structures are characterized by their shape and their frequencies. From the frequencies it is shown that there are several modes in the dynamics of these vortex structures following upon each other. The duration of each of these modes can vary and the character of the flow can be either clearly turbulent or become partially laminar and transitional. This behaviour is qualitatively compared to and verified by experimental data found in the literature. Results indicating that part of the dynamics of the vortex system can survive a mode transition is presented. It is also shown that a velocity gradient far upstream with vertical vorticity lines will have influence on the vortex system.

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