Licentiate seminar

A new experimental setup for studies on wake flow instability and its control

Defendant Main Advisor Extra Advisor Date
Bengt Fallenius Jens Fransson Henrik Alfredsson 2009-05-06

Christoffer Norberg, LTU

Evaluation committee


A new experimental setup for studies on wake flow instability and its control, which has been designed and manufactured, is introduced and described. The main body is a dual-sided flat plate with an elliptic leading edge and a blunt trailing edge. Permeable surfaces enable boundary layer suction and/or blowing that introduce the feature of adjusting the inlet condition of the wake created behind the plate. This, in combination with a trailing edge that is easily modified, makes it an ideal experiment for studies of di fferent control methods for the wake flow instability. Additionally, a vortex detection program have been developed in order to detect, analyse and compare small-scale vortical structures in the wake behind the plate for di fferent inlet conditions and control methods applied to the wake flow. Instantaneous velocity fields behind a cylinder subjected to suction or blowing through the entire cylinder surface have been analysed with this program. The results of the analysis show that the major change for di fferent levels of blowing or suction is the location of vortices while the most common vortex size and strength are essentially unchanged.
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