In recent decades, jet impingement cooling has gained significant attention due to its ability to remove large thermal loads from local heating zones. This study demonstrates the performance of pulsed jet impingement cooling on a Ti-coated glass window. Infrared (IR) thermography data are analyzed to generate heat transfer coefficient (HTC) maps for a range of heat fluxes ($q{}^{\prime \prime }\approx 20$–60 W/${\mathrm{cm}}^2$) and jet pulsation frequencies ($f_p\approx$ 7–25 Hz). Heat transfer coefficients are observed to scale as $h\propto \sqrt{2f_p}$ with local maximum values at the center of the jet stagnation zone. For reference, $h^{\max }\approx 15\mathrm{kW}/{\mathrm{m}}^2\mathrm{K}$ is found for $q{}^{\prime \prime }\approx$ 60 $\mathrm{W}/{\mathrm{cm}}^2$ and $f_p\approx 25$ Hz. Moreover, a jet pulsation frequency of $f_p\approx 15$ Hz matches well with both the bubble release rate and dry-out occurrence rate within 50 and 80 ms, respectively, at $q{}^{\prime \prime }=60 \mathrm{W}/{\mathrm{cm}}^2$. At heat fluxes $>40$ $\mathrm{W}/{\mathrm{cm}}^2$, boiling regimes were captured in terms of cyclic events of bubble growth, bubble collapse, dry-out, partial rewetting, and full rewetting. Finally, a theoretical model is proposed based on both the HTC expected for a steady jet and HTC augmentation due instantaneous heat flux matching for a pulsed jet at the jet-wall interface. The correlation between experiments and theory are reasonable, yet there are still unresolved complexities associated with thermofluid instabilities, decoupling the transient latent heat and sensible heat transfer mechanisms, and first-principles modeling of the spatiotemporal surface temperature and flow-field oscillations induced by a pulsed jet.

中文翻译：

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通过固-液界面处的瞬时热通量匹配了解脉冲射流冲击冷却

在最近的几十年中，射流冲击冷却由于其能够消除局部加热区域的大热负荷而备受关注。这项研究证明了在钛涂层玻璃窗上进行脉冲射流冲击冷却的性能。分析红外（IR）热成像数据以生成一系列热通量的传热系数（HTC）图（$q{}^{\prime \prime }\approx 20$–60瓦/${\mathrm{厘米}}^2$）和喷射脉动频率（$F_p\approx$7–25 Hz）。观察到传热系数按比例缩放$H\propto \sqrt{2F_p}$局部最大值位于射流停滞区的中心。以供参考，$H^{\mathrm{最高}}\approx 15\mathrm{千瓦}/{\mathrm{米}}^2\mathrm{ķ}$ 被发现 $q{}^{\prime \prime }\approx$ 60 $\mathrm{w\; ^}/{\mathrm{厘米}}^2$ 和 $F_p\approx 25$ 赫兹。而且，喷射脉动频率为$F_p\approx 15$ 在50和80毫秒内，Hz分别与气泡释放率和变干发生率都非常匹配 $q{}^{\prime \prime }=60 \mathrm{w\; ^}/{\mathrm{厘米}}^2$。在热通量下$>40$ $\mathrm{w\; ^}/{\mathrm{厘米}}^2$，根据气泡增长，气泡破裂，变干，部分再润湿和完全再润湿的周期性事件来捕获沸腾状态。最后，基于预期的HTC和稳定的喷射流，以及在喷射流-壁界面处的脉冲喷射的瞬时热通量匹配，提出了基于HTC增强的理论模型。实验与理论之间的相关性是合理的，但是仍然存在与热流体不稳定性，瞬态潜热和显热传递机制脱钩以及时空表面温度和脉冲引起的流场振荡的第一性原理建模相关的复杂问题。喷射。