Optimization of Helical Capacitance Sensor for Void Fraction Measurement of Gas-Liquid Two-Phase Flow in a Small Diameter Tube

A helical capacitance sensor is proposed to measure the void fraction of gas-liquid two-phase flow in a small tube with 5 mm diameter in this paper. The structure of helical capacitance sensor is analyzed by using the finite-element method (FEM) and the orthogonal array testing strategy. According to simulation, the optimal structure of helical capacitance sensor is suggested. The results of simulation and experiments show that the optimized sensor has a more homogeneous sensitivity field. The helical capacitance sensor demonstrates a good linearity between the capacitance value and the void fraction to be measured. In addition, the helical capacitance sensor has a good adaptability to different flow patterns.