Experimental investigation of influence of Reynolds number on synthetic jet vortex rings impinging onto a solid wall

详细信息    查看全文

• 作者：Yang Xu ; GuoSheng He ; Varun Kulkarni ; JinJun Wang
• 刊名：Experiments in Fluids
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：58
• 期：1
• 全文大小：
• 刊物类别：Engineering
• 刊物主题：Engineering Fluid Dynamics; Fluid- and Aerodynamics; Engineering Thermodynamics, Heat and Mass Transfer;
• 出版者：Springer Berlin Heidelberg
• ISSN：1432-1114
• 卷排序：58

文摘

Time-resolved particle image velocimetry was employed to study the effect of Reynolds number (Re_sj) on synthetic jet vortex rings impinging onto a solid wall. Four Reynolds numbers ranging from 166 to 664 were investigated for comparison while other parameters were kept constant. It is found that the Reynolds number has a significant impact on the spatial evolution of near-wall vortical structures of the impinging synthetic jet. Velocity triple decomposition reveals that periodic Reynolds shear stresses produced by both impinging and secondary vortex rings agree well with a four-quadrant-type distribution rule, and the random velocity fluctuations are strengthened as Re_sj increases. For radial wall jet, radial velocity profiles exhibit a self-similar behavior for all Re_sj, and this self-similar profile gradually deviates from the laminar solution as Re_sj is increased. In particular, the self-similar profile for low Re_sj (166) coincides with the laminar solution indicating that periodic velocity fluctuations produced by vortex rings have little effect on the velocity profile of the laminar wall jet. This also provides evidence that the impinging synthetic jet is more effective in mixing than the continuous jet for the laminar flow. For the high Re_sj, the mean skin friction coefficient has a slower decay rate after reaching peak, and the radial momentum flux has a higher value at locations far away from the impingement region, both of these can be attributed to the enhanced random fluctuations.