The flow pattern developed by a cavity inmersed in a turbulent incident flow is the solution of a complex relation between its geometry and the incident flow characteristics. There are cavities of many different shapes and sizes which in some situations generate important adverse effects such as wind confort reduction or severe structural problems due to resonance phenomena. Besides the need of reducing this negative consequences associated to the cavity, it is possible to think about the idea of modifying the inner cavity flow pattern to make indirect active control over the external flow under turbulent incident free stream. This reasons make the study of cavity flow a very interesting topic not only from a scientific but also from practical point of view. We intend to use the cavity flow generated as an active flow control system to manage the turbulent boundary layer outside it, using a blowing and/or suction system inside it. An experimental setup was made in the LaCLyFA's lm by 1.4m test section turbulent boundary layer wind tunnel, in order to study the vortex behavior and its incidence on the turbulent boundary layer configuration. According to the proposed objectives a wooden cavity was constructed which has an aspect ratio (L/D) of 1 (wide, height and long 10 cm.), with a glass wall for flow visualization. Also, in each vertical wall 18 spanwise air injection tubes for the flow injection system were located. This study consist on HWA velocity measurements with and without flow injection at different frequencies (from 10Hz to 250Hz) for a flow rate of 4L/min per pipe. In the present work we analyse the flow interaction near the upstream edge of the cavity by means of HWA measurements on three longitudinal stations at the centerline starting from 2mm and up to 24mm downwind.
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