An inclined rectangular jet in a turbulent boundary layer-vortex flow

A model test study was performed on streamwise vortices generated by a rectangular jet in an otherwise flat-plate turbulent boundary layer. The study was conducted in a low speed wind tunnel. The rectangular jet had a cross-section size of 28 mm by 5.5 mm. The oncoming boundary layer had a 99.5 percent thickness of 25 mm. The freestream speed of the oncoming flow was 20 m/s. Measurements were performed with a three-element LDA system. The effects of skew angle and streamwise development of vortex were investigated and the mean flow properties are presented. The study showed that the rectangular jet was able to produce a streamwise vortex of higher strength than that of a round jet, while at the same time keeping the same size and shape as that of a round jet. A 63% increase in the maximum vorticity was found. The 45^∘ skew angle was identified as the optimal skew angle for vortex production. Received: 24 June 1998/ Accepted: 21 May 1999