Research on cryogenic two-phase flow imaging of spherical container based on electrical capacitive volume tomography

Numerical simulation-based research on measuring the three-dimensional two-phase structure of cryogenic fluid transport processes holds significant value in aerospace applications. Based on electrical capacitance volume tomography (ECVT) technology, three types of ECVT sensors with varying electrode numbers, namely 32-electrode, 16-electrode, and 8-electrode, are designed for cryogenic spherical containers. The detailed theoretical derivation of ECVT sensitivity calculation is given. Numerical simulation is conducted to obtain the sensitivity field distribution and image reconstruction quality for the three types. Two cryogenic working mediums, liquid nitrogen (LN2) and liquid hydrogen (LH2), are used to evaluate the imaging quality. The results indicate that the 32-electrode sensor achieves a uniform sensitivity field distribution and demonstrates excellent image reconstruction accuracy. Furthermore, a performance comparison is made between the four image reconstruction algorithms: LBP, Landweber, Tikhonov, and Conjugate Gradient. Under stratified flow patterns, Landweber exhibits the highest image reconstruction accuracy with <10 % mass conservation error and minimal centroid localization deviation, while Conjugate Gradient demonstrates superior efficiency for bubble flow imaging with high precision. Tikhonov proves suitable for bubble flows, whereas LBP serves effectively as an initial guess. The influence of mesh quantity on computational efficiency and reconstruction accuracy is also studied. Imaging consistency between LN2-VN2 and LH2-VH2 flows confirms ECVT’s adaptability across cryogenic media. The results provide the theoretical optimization method and application potential of ECVT technology for monitoring cryogenic two-phase flows.