Interactions of a fully modulated inclined jet with a crossflow

Graduation date: 2006Jets in crossflow are used in a wide range of engineering applications and have been\ud studied for more than 60 years. The transversal penetration and structure of a jet placed\ud in a crossflow is known to be strongly three-dimensional. It is believed that, by using a\ud pulsed jet inclined in the crossflow direction, the momentum transport can be controlled\ud in two very efficient ways: the pulse can increase the jet penetration and the mixing\ud downstream, while the inclination avoids the creation of a reverse flow at the jet exit\ud and may extend the mixing area further downstream. Although some results are\ud available in the literature focusing on components of this problem, none addresses the\ud combination of these two factors. Moreover, most of these studies use elaborate flow\ud visualizations and 2-D velocity measurement methods that may not be adequate to\ud elucidate the complexity of such a flow.\ud This study addresses these issues by using stereoscopic PIV measurements for a\ud steady and fully modulated jet at a constant mean velocity ratio, V[subscript r], of 3.4. For the\ud steady jet case, the effect of the jet Reynolds number, Re[subscript j], is investigated. For the\ud pulsed case, the effect of a low pulsing frequency is considered as well as the pulse duty\ud cycle. For each case, the mean three-component velocity field is examined. Proper\ud Orthogonal Analysis (POD) of vorticity and turbulent kinetic energy are used to further\ud evaluate the vortical and turbulent characteristics of the jet. In addition, a vortex\ud detection algorithm, and 3D rendering of the flow streamlines are used to study the near\ud field vortical flow structure of the jet flow