一种局部相含率测量方法

在局部电导探针和单丝电容探针的基础上,提出一种新型局部电容探针,用于测量两相流的局部相含率。静态研究表明,局部电容探针能够测量空气水两相流的局部相含率,测量结果不受导电相电导率变化的影响。从工业蒸馏水变化到饱和食盐水(NaCl的质量分数0～5%),局部电容探针输出结果没有明显变化。电极距离在0～30 mm的范围内变化,测量结果变化小于1%。动态实验表明,局部电容探针测量的两相流的局部相含率,能够很好反映流动过程(以弹状流为例),和实验观察结果完全一致。只需要设置简单的阈值大小,就可以得到相含率的大小。

A New Measurement Method for Local Phase Fraction

Based on needle-contact conductance probe and single-wire capacitance probe,this paper presents a novel probe,namely needle-contact capacitance probe,to measure local phase fraction in air-water two-phase flows.Compared with the traditional one,needle-contact conductance probe, the new one is more independent of water conductance when the salt content is less than 5%.The amplitude of the output signals,up to 6.4 V,is much bigger between high and low levels.For the new probe,the variation of the measured value is less than 1%when the electrode distance is below 30 mm.The two electrodes of the probe can be separately placed in order to decrease the disturbance to the flow field.Dynamic experimental results showed that the time traces of phase identification are completely consistent with flow structures.The phase fraction can be easily calculated provided a threshold is specified in advance.