Abstract Time-resolved infrared thermography through infrared-transparent windows provides a novel measurement approach for non-invasive quantitative analysis of near-wall fluid flows. Here, we apply this approach to study a water flow induced by an axisymmetric submerged impinging jet in the immediate vicinity of the impingement plate. The variations in thermal radiation emitted from a thin near-wall layer result from passive scalar mixing of the weakly heated jet with ambient water. We analyze the magnitudes and turbulent behavior of the thermal fluctuations captured at a frame rate of 300 Hz for various jet impingement configurations and a wide range of jet Reynolds numbers (4000–35000). The results suggest that changes in root mean square and power spectra of the thermal signal are linked to changes in mixing intensity and flow structure in the near-wall region extending up to 16 nozzle diameters from the stagnation point.

中文翻译：

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浸没冲击水射流近壁流的时间分辨热成像分析

摘要 通过红外透明窗口的时间分辨红外热成像为近壁流体流动的无创定量分析提供了一种新的测量方法。在这里，我们应用这种方法来研究由紧邻冲击板的轴对称水下冲击射流引起的水流。从近壁薄层发出的热辐射的变化是由弱加热射流与周围水的被动标量混合引起的。我们分析了在 300 Hz 帧速率下针对各种射流撞击配置和各种射流雷诺数 (4000–35000) 捕获的热波动的幅度和湍流行为。