Adibi Pouyan, Bagheri Reza, Hosseini Mohammad
Department of Mechanical Engineering, University of Hormozgan, Bandar Abbas, Iran.
Heliyon. 2024 Aug 15;10(16):e36359. doi: 10.1016/j.heliyon.2024.e36359. eCollection 2024 Aug 30.
This research has dealt with the simulation of liquid nitrogen cavitation inside a convergent nozzle. This is important in cryogenic industrial applications. So in this study, computational fluid dynamics methods have been used for simulating the cavitation phenomenon. The Two-phase model in this research has been a hybrid/mixed model. Also, k- ε turbulence model has been employed in realizable state. For meshing the nozzle geometry, Gambit software has been used, while for numerical simulation, Ansys Fluent software has been employed. For simulation of cavitation, Schnerr and Sauer cavitation model has been utilized. This research has also examined the effect of changing the nozzle outlet diameter and the impact of changing the pressure difference in the inlet and outlet of the nozzle on the cavitation. As a novelty and unlike what would have been expected based on the Bernoulli effect, the results obtained from the simulation showed that the increase/decrease in the nozzle's outlet diameter resulted in an enhanced/diminished extent of cavitation in the nozzle's outlet region. Also, the increase/decrease of the pressure difference in the input and output of the nozzle would lead to a higher/lower extent of cavitation. This research also found that the effect of altering the nozzle's outlet diameter on the extent of cavitation has been far higher than the effect of changing pressure difference in its inlet and outlet. The results also indicated that upon reduction of the nozzle's outlet diameter from the base state (1.02 mm) by 10, 20, 30, 40, and 50 %, the volume fraction of the vapor diminished by 22.23, 43.029, 60.66, 74.73, and 87.16 % respectively. Finally, with the increase in the nozzle's outlet diameter from the base state (1.02 mm) by 10, 20, 30, 40, and 50 %, the volume fraction of the vapor increased by 26.83, 55.27, 84.47, 117.12, and 149.31 % respectively.
本研究涉及收缩喷嘴内液氮空化的模拟。这在低温工业应用中很重要。因此，在本研究中，采用了计算流体动力学方法来模拟空化现象。本研究中的两相模型是一种混合/混合模型。此外，k-ε湍流模型已在可实现状态下使用。为了对喷嘴几何形状进行网格划分，使用了Gambit软件，而对于数值模拟，则使用了Ansys Fluent软件。为了模拟空化，采用了Schnerr和Sauer空化模型。本研究还研究了改变喷嘴出口直径的影响以及改变喷嘴进出口压力差对空化的影响。作为一个新颖之处，与基于伯努利效应的预期不同，模拟结果表明，喷嘴出口直径的增加/减小导致喷嘴出口区域空化程度的增强/减弱。此外，喷嘴进出口压力差的增加/减小将导致空化程度更高/更低。本研究还发现，改变喷嘴出口直径对空化程度的影响远高于改变其进出口压力差的影响。结果还表明，当喷嘴出口直径从基准状态（1.02毫米）分别减小10%、20%、30%、40%和50%时，蒸汽的体积分数分别减少22.23%、43.029%、60.66%、74.73%和87.16%。最后，当喷嘴出口直径从基准状态（1.02毫米）分别增加10%、20%、30%、40%和50%时，蒸汽的体积分数分别增加26.83%、55.27%、84.47%、117.12%和149.31%。
