The present work provides an overview on the possible phase transitions associated with supercritical fluid injection and a detailed evaluation of the mixing process between injectant fluid and quiescent ambience. The experiments cover superheated liquid disintegration, pseudo-boiling transition and single-phase jets under different nozzle pressure ratios. Pseudo-boiling effects emerge when rapid, subsequent changes in pressure/temperature interact with the non-linear behavior of thermodynamic response functions across the Widom line. The associated density fluctuations cause a significant increase in the scattering cross section and may lead to thermo-convective instabilities. Our analysis of the mixing process demonstrates the limited applicability of the adiabatic mixing model, which is often restricted to short residence times even in highly turbulent jets ($\mathit{Re}=\mathcal{O}({10}^5)$). Specifically, our findings show the importance of considering all coupled transport processes in the analysis of mixing problems at high pressures, in particular in presence of large mass concentration and temperature gradients.

本工作概述了与超临界流体注入相关的可能的相变，并详细评估了注入流体与静态环境之间的混合过程。实验涵盖了在不同喷嘴压力比下的过热液体崩解，伪沸腾过渡和单相射流。当快速的，随后的压力/温度变化与整个Widom线的热力学响应函数的非线性行为相互作用时，就会出现伪沸腾效应。相关的密度波动会导致散射截面显着增加，并可能导致热对流不稳定性。我们对混合过程的分析表明，绝热混合模型的适用性有限，$\mathit{回覆}=\mathcal{Ø}（{10}^5）$）。具体而言，我们的发现表明，在分析高压下的混合问题时，尤其是在存在较大质量浓度和温度梯度的情况下，考虑所有耦合的运输过程非常重要。