Abstract In many industrial pieces of equipment, such as ejectors, thermo-compressors, supersonic separators, etc., in which the condensation phenomenon occurs spontaneously, steam enters the nozzle in a saturated condition. Liquid droplets are likely to be present in the saturated vapor. In the present paper, the effect of the existence of a number (9 cases) of liquid droplets (with a fixed size of 20 nm in all cases) on the saturation steam has been studied. The results demonstrate that with the increase in the number of droplets at the nozzle inlet; pressure, temperature, liquid mass fraction, mass-generated rate and entropy increase in the convergent part. However, the growth of droplets and Mach number decrease. Furthermore, due to steam condensation and latent heat transfers to steam, the degree of supercooling, the supersaturation ratio and the flow rate at the nozzle inlet are decreased, the intensity of condensation shock is reduced, and shock occurs with delays. With an increase in the number of droplets, condensation shock and the nucleation phenomenon will not occur. The amount of entropy production decreases with the surge in the number of droplets at first, and then begins to increase. The results demonstrate that in the presence of 3 × 10+14 droplets, compared to the absence of water droplets at the nozzle inlet, generated entropy, liquid mass fraction and the mass flow rate will decrease by 9.4%, 12.5%, and 1.7%, respectively.

中文翻译：

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使用熵生成分析研究纳米水滴注入会聚-发散喷嘴入口对湿蒸汽流的影响

摘要 在喷射器、热压机、超音速分离器等许多工业设备中，自发发生冷凝现象，蒸汽在饱和状态下进入喷嘴。液滴很可能存在于饱和蒸汽中。在本文中，研究了大量（9 例）液滴（在所有情况下均具有 20 nm 的固定尺寸）对饱和蒸汽的影响。结果表明，随着喷嘴入口液滴数量的增加；收敛部分的压力、温度、液体质量分数、质量产生率和熵增加。然而，液滴的增长和马赫数减少。此外，由于蒸汽冷凝和潜热传递给蒸汽，过冷度、喷嘴入口过饱和比和流量降低，冷凝冲击强度降低，冲击延迟发生。随着液滴数量的增加，不会发生冷凝冲击和成核现象。熵产生量首先随着液滴数量的增加而减少，然后开始增加。结果表明，存在3×10+14个液滴时，与喷嘴入口不存在水滴相比，产生的熵、液体质量分数和质量流量分别下降9.4%、12.5%和1.7% ， 分别。不会发生冷凝冲击和成核现象。熵产生量首先随着液滴数量的增加而减少，然后开始增加。结果表明，存在3×10+14个液滴时，与喷嘴入口不存在水滴相比，产生的熵、液体质量分数和质量流量分别下降9.4%、12.5%和1.7% ， 分别。不会发生冷凝冲击和成核现象。熵产生量首先随着液滴数量的增加而减少，然后开始增加。结果表明，存在3×10+14个液滴时，与喷嘴入口不存在水滴相比，产生的熵、液体质量分数和质量流量分别下降9.4%、12.5%和1.7% ， 分别。