Numerical investigation of the air tabs technique in jet flow

It is well known that the solid tab technique is effective in enhancing mixing in jet flow, but its protrusion nature will also incur thrust loss. Previous experimental results on the so-called air tab technique have revealed that the air tab can achieve a level of mixing enhancement similar to the solid tab, although it will not introduce any thrust loss. The present numerical investigation aims to study, in detail, the evolution and generation of the streamwise vortices by the air tab under both subsonic and supersonic conditions. For the air tab case, the injected air stream will be bent and twisted by the greater momentum of the primary jet and bifurcate subsequently into two streams. Each stream corresponds to one half of the counter-rotating streamwise vortices pair. The two sources that are responsible for the generation of the streamwise vortices in the solid tab can also be found in the air tab case.