Numerical Discovery and Experimental Validation of Vortex Ring Generation by Microramp Vortex Generator
Micro vortex generators are a new kind of passive flow control instruments for shock-boundary layer interaction problems. In contrary to the conventional vortex generator, they have heights approximately 20-40% (more or less) of the boundary layer. Among them, Mircoramp vortex generators (MVG) are given special interest by engineers because of their structural robustness. The mechanism of the flow control was thought that a pair of streamwise vortex is generated by MVG and remains in the boundary layer for relatively long distance; the down-wash effect by the streamwise vortices will bring about momentum exchange, which makes the boundary layer less liable to separation. During such process, a specific phenomenon called as momentum deficit will happen , i.e., a cylindrical region consisted of low speed flows will be formed after the MVG. It was pointed out by Li and Liu  that the origin of deficit comes from the shedding of boundary layer over MVG.
Numerical simulations have been made on MVG for comparative study and further design purposes. Ghosh, Choi and Edwards  made detailed computations under the experimental conditions given by Babinsky by using RANS, hybrid RANS/LES and immersed boundary (IB) techniques. Lee et al [4, 5] also made computations on the micro VGs problems by using Monotone Integrated Large Eddy Simulations (MILES). Basic flow structures like momentum deficit and streamwise vortices were reproduced in the computation. Further studies were also conducted on the improvement of the control effect.
KeywordsParticle Image Velocimetry Shear Layer Vortex Ring Streamwise Velocity AIAA Paper
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