Validation experiment with 4-vortex wake in large tow tank (FAR-Wake Subtask 1.2.2)

Stereo PIV measurements on a 2- and 4-vortex system have been performed in a large tow tank of SVA (Schiffbau-Versuchsanstalt Potsdam GmbH). The considered 4-vortex system consists of two counter-rotating vortex pairs with a span width ratio of b2/b1 = 0.3 and a circulation ratio of Γ2/Γ1 = -0.3. For comparisons also the corresponding 2-vortex system is measured. A submersible Stereo PIV system attached to a vertical traversing system was employed. Cross-sectional velocity fields are obtained of the descending wake vortex system to access the vortex dynamics well into the wake far field. The SVA provided the necessary measurement equipment consisting of a submersible Stereo PIV system, a vertical traversing system and a six component force balance. DLR provided the vortex generator (F13 model), a programmable sequencer unit enabling an adaption of the PIV recording system to the high dynamic range of the velocity fields and defined the test program of the measurement campaign.