Supersonic flow over rounded contour bumps with vortex generators or passive longitudinal jets

An experimental study has been conducted to investigate the flow characteristics over two rounded contour bumps. Vane-type vortex generators or longitudinal aligned passive by-pass jets were implemented in attempt to achieve wake flow control in rounded contour bumps. According to the results collected from the surface oil flow visualisation experiments, it was observed that the use of both the vane-type vortex generators and the longitudinally aligned passive by-pass jet could reduce the size of the spanwise vortices in the bump valley. In addition, a pair of streamwise horseshoe vortices was observed downstream of the bump crest of the contour bump that equipped with the vane-type vortex generators. From the data collected in the particle image velocimetry measurements, it was found that the use of both the vane-type vortex generators and the longitudinally aligned passive by-pass jet could not reduce the size of the wake region but they could reduce its strength. It is deduced that the two streamwise horseshoe vortices generated by the vane-type vortex generators enhance flow mixing which results in reducing the strength of the wake region. In contrast, blowing passive by-pass jet in the bump valley increases the local flow velocity in order to reduce the strength of the wake region. 2017 The Authors. Published by Elsevier Inc. This is an openaccess article under the CCBY license (http:// creativecommons.org/licenses/by/4.0/).