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目的:相较于常温流体,低温流体的物性存在显著不同,因而对流量计的工作特性也会带来相应的影响。本文旨在探讨多孔板应用于低温流体流量测量时的性能(即流出系数与压力损失系数)特征。创新点:基于数值研究结果,发现多孔板流量计应用于低温流体流量测量时,其稳定测量区间上限雷诺数显著增大,并基于物性特点从空化特性的角度探讨上限雷诺数显著增大的原因。方法:采用数值模拟的方法,经网格独立性验证(表1和图5)和模型验证(图6和图8)后,结合Realizableκ-ε湍流模型与Schnerr–Sauer空化模型,研究同一种结构的多孔板应用于液氮、液氧、液氢三种低温流体和水流量测量时其流出系数与压力损失系数变化的异同(图11、图12和表5);并基于低温流体的物性特点(表3),对其具有较大上限雷诺数的计算结果进行原因分析。结论:对于同一种多孔板结构,与水相比,低温流体具有较宽的稳定雷诺数测量范围,其中,与多孔板结构相关的下限雷诺数差异较小,而受空化影响的上限雷诺数差别较大;低温流体具有较大的上限雷诺数,其原因在于,与水相比较,低温流体的密度与运动粘度平方的乘积?v2明显较小。
OBJECTIVE: Compared to normal temperature fluids, the physical properties of cryogenic fluids are significantly different and therefore have a corresponding effect on the operating characteristics of the flowmeter. The purpose of this article is to investigate the performance (ie, outflow and pressure loss) characteristics of porous plates used in cryogenic fluid flow measurements. Innovative point: Based on the numerical results, it is found that when the perforated plate flowmeter is applied to the flow measurement of cryogenic fluid, the Reynolds number of the upper limit of the stable measurement interval increases significantly. Based on the physical properties, the upper Reynolds number the reason. Methods: By using the numerical simulation method, after verifying the grid independence (Table 1 and Figure 5) and model verification (Figure 6 and Figure 8), we combined the Realizable κ-ε turbulence model with the Schnerr-Sauer cavitation model to study the same species The structure of the porous plate used in liquid nitrogen, liquid oxygen, liquid hydrogen three kinds of cryogenic fluid and water flow measurement of its outflow coefficient and pressure loss coefficient changes in the similarities and differences (Figure 11, Figure 12 and Table 5); and based on the properties of cryogenic fluid (Table 3), the reason for the calculation of Reynolds number with larger upper limit is analyzed. CONCLUSIONS: For the same porous plate structure, compared with water, the low temperature fluid has a wide range of measurement range of the Reynolds number, and the difference between the lower Reynolds number and the upper limit Reynolds number The reason is that compared with water, the product of the density of cryogenic fluid and the square of kinematic viscosity? V2 is obviously smaller.