标题： 冲击扫掠射流的瞬态热流和流动结构 显示英文标题

标题： Unsteady Thermal and Flow Structures of an Impinging Sweeping Jet

摘要： 振荡射流由于其固有的非定常性和覆盖大面积表面的能力，在热管理和流动控制应用中日益受到重视。 本研究调查了撞击式振荡射流的非定常传热和流动结构，特别关注雷诺数和喷嘴到平板间距的影响。 采用结合非同步高速红外热成像和平面粒子图像测速的综合诊断方法，独立测量壁面热通量分布和流动场动力学。 时间平均努塞尔数图显示，随着喷嘴到平板距离的增加，热影响区域逐渐扩大，同时峰值传热强度降低。 相比之下，波动分量表现出双瓣结构，并且在较高雷诺数下更加明显。 速度测量证实了分叉射流核心的存在以及由剪切驱动的非定常性，波动速度分量和雷诺剪切应力在增强传热波动的区域上空间相关。 速度和传热波动之间的直接空间比较表明，在较小的喷嘴到平板间距下，壁面法向速度的非定常性主导热响应，而在较大间距下，沿流向的波动变得越来越显著。 最后，全场传热数据被嵌入到一个降阶参数空间中，表明复杂系统行为可以通过由雷诺数和喷嘴到平板间距控制的低维流形有效表示。 研究结果强调了振荡射流撞击中波动热分量的重要性，并突出了数据驱动模型在预测振荡射流系统表面传热方面的潜力。 显示英文摘要

摘要： Sweeping jets are increasingly employed in thermal management and flow control applications due to their inherent unsteadiness and ability to cover wide surface areas. This study investigates the unsteady heat transfer and flow structures of an impinging sweeping jet, with particular emphasis on the influence of Reynolds number and nozzle-to-plate spacing. A combined diagnostic approach, utilising non-synchronous high-speed infrared thermography and planar particle image velocimetry, is adopted to independently measure wall heat flux distributions and flow field dynamics. Time-averaged Nusselt number maps reveal a progressive widening of the thermal footprint as the nozzle-to-plate distance increases, accompanied by a reduction in peak heat transfer intensity. In contrast, the fluctuating component exhibits a double-lobe structure that becomes more pronounced at higher Reynolds numbers. Velocity measurements confirm the presence of a bifurcated jet core and shear-driven unsteadiness, with fluctuating velocity components and Reynolds shear stress spatially correlated with zones of enhanced heat transfer fluctuations. A direct spatial comparison between velocity and heat transfer fluctuations demonstrates that wall-normal velocity unsteadiness dominates the thermal response at low nozzle-to-plate distances, while streamwise fluctuations become increasingly significant at larger spacings. Finally, the full-field heat transfer data are embedded into a reduced-order parametric space, demonstrating that the complex system behaviour can be effectively represented by a low-dimensional manifold governed by Reynolds number and nozzle-to-plate spacing. The findings underscore the importance of the fluctuating thermal component in sweeping jet impingement and highlight the potential of data-driven models for predicting surface heat transfer in oscillatory jet systems.