同轴射流突片激励混合的数值研究

通过数值方法对同轴射流的突片激励混合特性进行研究,分析了突片数目、突片顶角和安装角对同轴射流混合过程的流向涡和温度分布的影响. 研究结果表明,突片的激励作用使得同轴射流之间的混合流在突片对应位置下游形成阵列涡对,导致温度分布等值线发生“指型”局部变形,增强了两股气流之间的混合. 随着突片数目的增加,单个突片诱导的流向涡强度和影响范围存在较大的差异,过多的突片数导致相邻涡对的“挤压”,流向涡的强度有很大的减弱; 在相同的堵塞比下,突片顶角为90°时或安装角为30°时,单个突片诱导的流向涡强度和作用范围均体现最为显著,从而有利于改善同轴射流的混合程度.

Numerical Investigation on Mixing Behavior of Co-Axial Jets Excited by Triangular Tabs

Numerical investigation is carried out to illustrate the mixing behaviors of co-axial jets by the fluidic excitation of tabs. The effects of the tab number,tab apex angle and tab tilted angle on the sreamwise vorticity and temperature distribution of co-axial jets mixing flow are analyzed. The results show that the tabbed excitation induces array pairs of streamwise vortices at the trailing of corresponding tabs,making the local temperature contours to take on finger-shaped distortion and enhancing the co-axial jets mixing process. The intensity as well as the affecting zone of the individual streamwise vortex varies from the tab number. Larger tab number degrades the vortex intensity obviously due to the interaction between the adjacent tabs. Under the same total blockage of the tabs into the internal flow,the tab apex angle of 90 degree or the tab tilted angle of 30 degree seem to introduce stronger sreamwise vorticity and co-axial jets mixing,in relative to the other geometric parameters in the present.