涡发生器控制平板边界层分离的大涡模拟

为了研究涡发生器(VGs)间距λ对控制边界层分离效果的影响,选取了4种涡发生器间距,λ/H(H为涡发生器高度)分别为5,7,9,11.采用大涡模拟(LES)方法对带逆压梯度的平板边界层分离流动及VGs控制分离流动进行了数值模拟.分析了有无VGs控制时,湍流场中大尺度相干结构及其演化规律,分别从旋涡间距、边界层内流体动能、压差损失等方面考察了VGs间距对控制流动分离效果的影响.研究结果表明当λ/H为5时,VGs间距过小抑制了旋涡的展向发展,λ/H为9,11时,VGs间距过大边界层内流体动能偏低,当间距λ/H为7时流动控制效果更优,此时计算域压差损失最小,相比较无VGs控制时,压差损失降低了30.95%. 

Vortex generators control flat boundary layer separation of large eddy simulation

In order to study the effect of spacing λ of vortex generators(VGs) on the control boundary layer separation, 4 kinds of vortex generators spacing were selected, and λ/H(H is the height of vortex generators) respectively were 5, 7, 9, 11. The boundary layer separation flow of adverse pressure gradient and VGs control flow separation were simulated by large eddy simulation(LES) method. The evolution of the large scale coherent structure in turbulent flow field were analyzed with and without VGs control, and the influence of VGs spacing on the flow separation control effect were investigated from vortex spacing, fluid kinetic energy in the boundary layer, loss of pressure difference, etc. The research results show that when λ/H is 5, the spacing of VGs is too small, so that the spanwise development of vortex are suppressed, when λ/H are 9, 11, the spacing of VGs is too large lead to the fluid kinetic energy in the boundary layer is too low, when the spacing of VGs is λ/H is 7, the effect of flow control is better, then the pressure loss of calculation domain is minimum, compared with no VGs control, pressure loss is reduced by 30.95%.