Huang Junchao, Guo Ziwei, Tang Xiao-Yu, Ji Haifeng, Wang Baoliang, Huang Zhiyao
State Key Laboratory of Industrial Control Technology, College of Control Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China.
Rev Sci Instrum. 2021 Oct 1;92(10):105006. doi: 10.1063/5.0029772.
The flow parameter measurement of the gas-liquid two-phase flow in small channels is very crucial and challenging in both academia and industry. Conventional techniques based on radiations, optics, acoustics, or electrics most lose their superiorities in the scenario with small channels due to the spatial limitation and the online and contactless measurement requirements. In addition, the conductive characteristic of the two-phase flow is equivalent to an impedance rather than a resistance due to the existence of multi-phases. The equivalent impedance information of the two-phase flow, especially the imaginary part, is promising to provide more flowing details but has seldom been detected or analyzed. In this paper, a method for the void fraction measurement of bubble/slug flow in small channels is proposed. The method implements void fraction measurement in a contactless way, based on the acquisition of the total impedance information of the gas-liquid two-phase flow. First, a new contactless impedance detection sensor is designed, based on the simulated inductor technique and the analog phase sensitive demodulation technique, to obtain the complete equivalent impedance information of the two-phase fluid. Then, based on the flow pattern identification result, the void fraction measurement model is developed, which is a fusion of the relationships between the void fraction and the real part/the imaginary part of the equivalent impedance information, respectively. Experimental results on prototypes with different inner diameters (2.48, 3.64, and 4.52 mm, respectively) validate the effectiveness of the proposed void fraction method. The maximum void fraction measurement biases are within 5.0%.
小通道内气液两相流的流动参数测量在学术界和工业界都非常关键且具有挑战性。基于辐射、光学、声学或电学的传统技术，由于空间限制以及在线和非接触测量要求，在小通道场景中大多失去了优势。此外，由于多相的存在，两相流的导电特性相当于一个阻抗而非电阻。两相流的等效阻抗信息，尤其是虚部，有望提供更多流动细节，但很少被检测或分析。本文提出了一种测量小通道内泡状/弹状流含气率的方法。该方法基于获取气液两相流的总阻抗信息，以非接触方式实现含气率测量。首先，基于模拟电感技术和模拟相敏解调技术设计了一种新型非接触阻抗检测传感器，以获取两相流体的完整等效阻抗信息。然后，基于流型识别结果，建立了含气率测量模型，该模型分别融合了含气率与等效阻抗信息实部/虚部之间的关系。在不同内径（分别为2.48、3.64和4.52毫米）的原型上的实验结果验证了所提出的含气率方法的有效性。最大含气率测量偏差在5.0%以内。
