Abstract: A dual-tip conductivity probe for measurement of bubble parameters in a gas-liquid flow was studied. The effects of the probe structure, measurement circuit and sampling method on the bubble signal quality measured with the probe were investigated, and the measures to improve the signal quality were proposed. The experimental results show that the signal response is faster when the conductive length of probe tips is smaller. This effect becomes insignificant when conductive length is smaller than 0.025 mm. The probe tip should be connected to the cathode of measurement circuit to avoid the electrical oxidation corrosion that caused damage of the probe tip. The better bubble signal response is obtained by using optimum electrical resistance in the measurement circuit with smaller electrical resistance of the probe tip. The improved signals with large difference of 3 V, fast response and little noise are obtained with the optimal conditions.

Key words: dual-tip conductivity probe, signal response, output difference, signal noise, electrical oxidation corrosion

摘要： 制作了一种用于测量多相流气泡参数的双探针电导探头，研究了探针参数、测试电路和采样方法对气泡信号质量的影响，并提出了改进方法. 实验结果表明，探针导通距离越小，信号响应越快，当导通距离小于0.025 mm时，对信号响应影响不明显. 将探针电极与测试电路输入端的负极相连，以保护探针电极，避免其因电氧化腐蚀而减短使用寿命. 选取小阻值探针，并根据其在液相中的阻值大小对外接限流电阻进行优化，可实现采样电路的电阻匹配，从而获得理想的信号响应幅值. 通过对所分析的各影响因素进行控制后，得到了电压幅值变化达3 V、噪音小且响应快的电导探针气泡信号.

关键词: 双探针电导探头, 信号响应, 信号幅值差, 信号噪音, 电氧化腐蚀