Abstract A recently published pressure-based compressible multiphase flow model (Labois and Narayanan, 2017) is validated for applications relevant to safety of pressurized systems, such as flashing of high-pressure water through valves and nozzles. The pressure-based compressible multiphase flow solver is based on non-conservative discretization of the mixture continuity equation and has the advantage of being applicable to interface tracking and n-phase mixture formulations. For simulation of flashing, two well-known cavitation models (Singhal et al., 2002; Yuan et al., 2001) have been implemented along with thermodynamic effects such as latent heat of phase change, variable saturation pressure, and heat capacities. The limitations of the well-established cavitation models in terms of their applicability to compressible flows have been clarified. The model was applied to the Super Moby Dick experiment (Rousseau, 1987) Good flow rates, and pressure and void fraction variations were obtained for three chosen conditions by tuning the cavitation model under incompressible conditions. It was found that the void fraction stops increasing beyond the throat due to thermodynamic effects where the latent heat and heat capacity are functions of pressure and temperature. The reduction of latent heat and rapid changes in liquid and vapour heat capacities close to the saturation line at high pressures was shown to be important. The accuracy, robustness, and efficiency of the pressure-based method has been proven for flashing under strong depressurization conditions. The cavitation model predictions are strongly sensitive to model parameters such as the nucleate density making the models not general enough to be applied to different problems without calibration. It was shown that there is significant room for development of improved cavitation models especially focussing on the constant number density constraint due to the strong sensitivity of the current models to this input parameter. The assumption of incompressibility and homogeneity of the phasic velocitiesis also identified as serious limitations requiring further study.

中文翻译：

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使用基于压力的可压缩多相方法和热力学空化模型对闪蒸进行数值模拟

摘要 最近发布的基于压力的可压缩多相流模型（Labois 和 Narayanan，2017 年）在与加压系统安全相关的应用中得到验证，例如通过阀门和喷嘴的高压水闪蒸。基于压力的可压缩多相流求解器基于混合物连续性方程的非保守离散化，具有适用于界面跟踪和 n 相混合物公式的优点。为了模拟闪蒸，已经实施了两个著名的空化模型（Singhal 等人，2002 年；Yuan 等人，2001 年）以及热力学效应，例如相变潜热、可变饱和压力和热容量。完善的空化模型在可压缩流动适用性方面的局限性已得到澄清。该模型应用于 Super Moby Dick 实验 (Rousseau, 1987) 通过在不可压缩条件下调整空化模型，在三个选定条件下获得了良好的流速、压力和空隙率变化。发现由于潜热和热容量是压力和温度的函数的热力学效应，空隙率停止增加超过喉部。潜热的减少以及接近高压饱和线的液体和蒸汽热容量的快速变化被证明是重要的。基于压力的方法的准确性、稳健性和效率已被证明适用于强减压条件下的闪蒸。空化模型预测对模型参数（例如核密度）非常敏感，这使得模型不够通用，无法在没有校准的情况下应用于不同的问题。结果表明，由于当前模型对这个输入参数的敏感性很强，因此改进空化模型有很大的发展空间，特别是集中在常数密度约束上。相速度的不可压缩性和均匀性的假设也被认为是需要进一步研究的严重限制。结果表明，由于当前模型对这个输入参数的敏感性很强，因此改进空化模型有很大的发展空间，特别是集中在常数密度约束上。相速度的不可压缩性和均匀性的假设也被确定为需要进一步研究的严重限制。结果表明，由于当前模型对这个输入参数的敏感性很强，因此改进空化模型有很大的发展空间，特别是集中在常数密度约束上。相速度的不可压缩性和均匀性的假设也被认为是需要进一步研究的严重限制。