ACTA AERONAUTICAET ASTRONAUTICA SINICA >
Junction flow horseshoe vortex control based on upstream cavity
Received date: 2016-09-18
Revised date: 2016-11-21
Online published: 2016-11-30
Supported by
National Natural Science Foundation of China (11372027)
Two and three dimensional cavities have been studied by experimental and numerical simulation to control horseshoe vortex formed when the flow passes a cylinder-flat plate junction. The cavity is located on the flat plate upstream of the cylinder. The results indicate that both two and three dimensional cavities can delay boundary layer separation and weaken the horseshoe vortex. At the same time, the upstream surface pressure and adverse pressure gradient of cavity are both reduced, and at the downstream the pressure is increased while the global adverse pressure gradient is reduced. The study also indicates that the two dimensional cavity can reduce about 61.15%-66.51%, while the three dimensional cavity can reduce 66.65%-80.93%, of the horseshoe vortex strength. The effect of cavity geometry parameters, including distance, width and depth, is discussed. It is shown that the cavity distance plays major role in weakening the horseshoe vortex. The mechanism for controlling the horseshoe vortex by cavity is discussed. It is shown that the sub-layer of the incoming boundary layer which contains high vorticity is swallowed into the cavity to form the cavity vortex. The cavity vortex is transported to the downstream of the junction. As the cavity gets closer to the cylinder, more sub-layer of boundary layer will be swallowed into cavity. It is this cavity-effect that reduces the surface adverse pressure gradient upstream of the cylinder and diminishes the horseshoe vortex and separation region.
LI Jian , ZHANG Hua , WU Xinggang . Junction flow horseshoe vortex control based on upstream cavity[J]. ACTA AERONAUTICAET ASTRONAUTICA SINICA, 2017 , 38(6) : 120796 -120796 . DOI: 10.7527/S1000-6893.2016.0304
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