The Study Of Control Of Junction Flows

Junction flows occur widely in nature and practice, and the study about it is theoretically and practically significant. In this paper, control method of the bump-plate junction flows is studied mainly. The boundary layer on the flat plate separates in 3-dimension under the influence of the bump, and the horseshoe vortex system forms with the vortex legs wrapping the bump. Weaking or elimination the horseshoe vortex system is the priority task in the control of junction flows. The proposed control method does not consume any additional power. Therefore, it is a kind of passive control method with a great practical application prospect.This paper puts forward three kinds of new passive control method.1. A typical circular-cylinder-plate or rood-plate junction region is presented. In order to conduct the control of horseshoe vortex, a cylinder or rood with a slot placed upstream in the flat plate and a venturi tube mounted on the other side of the plate has been established. Because of the venturi principle, when the flow passes over the throat, the slot acts as a quality injector. Numerical simulation has been conducted to investigate turbulent junction flow with different positions of the slot. The results show that the horseshoe vortex can be controlled well, and furthermore eliminated completely horseshoe vortex, through the modification of the slot position relative to the cylinder or rood. 2. A ventilated hole in the root of the cylinder can modify the flow structure in the circular-cylinder-flat-plate junction region is presented. Using four different kinds of the holes, numerical simulation has been conducted to investigate turbulent junction flow with different kinds of the holes. The results show that the horseshoe vortex can be controlled well with the suitable ventilated hole.3. A typical wing-body junction region is presented. In order to modify the horseshoe vortex, a vortex generator was placed upstream of the wing on the flat plate. Numerical simulation has been conducted to investigate the effects of the vortex generator’s heights on the turbulent junction flow. The results show that the horseshoe vortex can be weakened well with 2mm of the vortex generator’s height.In this paper, the condition of the junction flows can be controlled well through different methods have been conducted to investigate junction flow. These methods are promising in the engineering application since it is very simple and applicable.