Water holdup measurement is always in the spotlight of the oil and gas industry. One way of determining water holdup in gas-liquid two-phase flow is through dielectric constant of flow. In this study, we proposed Superficial Dielectric Constant (SDC) and established the SDC model to describe the relationship between dielectric properties and water holdup. Firstly, we designed a Resonant Cavity Sensor(RCS), and the simulation models were established based on Ansys HFSS. Furthermore, a SDC simulation method based on rod-shaped material with HFSS was proposed. Totally 9 prototypes with different cavity D and bore diameters d were simulated with different water holdups ranging from 0 to 100%. Stratified distributed structure (SDS) and annular distributed structure (ADS), as two common flow regimes in gas-water flow, were included in the simulation and 198 data points were obtained. As a result, at a same water holdup, SDC of SDS was higher than that of ADS. At the same water holdup, with the decrease of D or the increase of d, SDC increased in SDS and decreased in ADS. Finally, SDC models of the two structures were established based on the two-thirds of simulation data. The remaining data points were utilized to verify models, the confidence probability of relative error in ±10% was 97% for SDS and the confidence probability of relative error in ±5% was 91% for ADS. In addition, the experimental validation was carried out with two dimensional prototypes under the two structures and the absolute values of relative error were lower than 10%. The results suggest that SDC model maybe provide potential for water holdup measurement in gas-liquid two-phase flow.

持水率测量始终是石油和天然气行业的关注焦点。确定气液两相流中持水率的一种方法是通过流的介电常数。在这项研究中，我们提出了表面介电常数（SDC）并建立了SDC模型来描述介电性能和持水率之间的关系。首先，我们设计了一个谐振腔传感器（RCS），并基于Ansys HFSS建立了仿真模型。提出了基于杆状材料的HFSS SDC仿真方法。总共模拟了9个具有不同空腔D和孔径d的原型，其持水率在0％到100％之间。分层分布结构（SDS）和环形分布结构（ADS）作为气-水流中的两种常见流态，模拟中包括了198个数据点。结果，在相同的持水率下，SDS的SDC高于ADS。在相同的持水率下，随着D的减少或d的增加，SDS的SDC增加，而ADS减少。最后，根据三分之二的仿真数据建立了两种结构的SDC模型。其余数据点用于验证模型，SDS的相对误差的置信度为±10％，为97％，ADS的相对误差的置信度为±5％，为91％。另外，在两个结构下使用二维原型进行了实验验证，相对误差的绝对值低于10％。结果表明，SDC模型可能为气液两相流中的持水率测量提供潜力。