用于流场可视化实验的有机玻璃折射率匹配液研究

Study on Refractive Index Matching Liquid of Polymethyl Methacrylate Employed in Flow Field Visualization Experiment

为减小流动工质与燃料组件模型之间因折射率差异给可视化流场测量带来的影响,将四氢化萘和无水乙醇混合得到一种新型有机玻璃(PMMA)折射率匹配(RIM)液。实验测量了不同浓度混合溶液的折射率、密度、动力黏度和雷诺数,并研究了4个变量对温度的敏感性。结果表明:在25℃时,四氢化萘(72.2%)-无水乙醇(27.8%)混合溶液与PMMA的折射率相等;Newton方程在预测混合溶液的折射率时与实验测量数据偏差最小。由于雷诺数对温度敏感,建议在实验装置中设置热交换设备来控制流动工质的温度。该RIM液具有成本低、密度适中、动力黏度小和稳定性高等优点,可用于流场可视化实验。

In order to reduce the impact induced by the difference in refractive index between the working fluid and fuel assembly model on the visualization flow field measurement,tetralin and ethyl alcohol were mixed to produce a new refractive index matching(RIM)liquid.The refractive index,density,dynamic viscosity,and Reynolds number of the mixed solutions with different concentrations were measured,and the sensitivities of these four variables to temperature were investigated.The results show that,the refractive index of the mixed solution of tetralin(72.2%)-ethyl alcohol(27.8%)is equal to that of polymethyl methacrylate at 25℃,and the Newton equation has the smallest deviation from experimental data when the refractive index of mixed solution is predicted.Since the Reynolds number is sensitive to temperature,it is suggested to set up heat exchange equipment in the experimental facility to control the temperature of the working fluid.This RIM liquid has the advantage of low cost,moderate density,low dynamic viscosity,and high stability,which can be used in the flow field visualization experiment.