Flow regime identification based on local parameters of axial upward two-phase flow in vertical tube bundles, at high-temperature and high-pressure, was performed using optical probes. A staggered arrangement of the tube bundles was simulated inside a non-circular test channel, the tube size and pitch are same as that in a real steam generator of a PWR under design. Optical probes were utilized to acquire the void fraction, interface frequency, and fluctuation characteristics of the local void fraction at two typical locations (centroid of the three tubes, named op-1, and centre of the minimum gap between two tubes, named op-2). The system pressure ranged from 5 to 9 MPa, mass flux from 100 to 350 kg m⁻² s⁻¹, thermodynamic steam quality from 0 to 1, and inlet fluid temperature from 263.9 to 303.3 °C, depending on the saturation pressure. This study investigated local parameters and flow pattern characteristics of high-pressure steam-water two-phase flow in vertical tube bundles using optical probes, with the measurement error of less than 2%. Results showed that local void fraction at op-1 was much larger than that at op-2, and the local void fraction difference between op-1 and op-2 increased first and then gradually decreased, which was primarily affected by the transition in flow regimes. The flow pattern characteristics of steam-water two-phase flow were described based on three aspects, namely, variation in interface frequency with local void fraction, fluctuation characteristics of local void fraction, and statistical analysis of local void fraction deviating from the average. Additionally, the flow regime identification criteria, applicable to the steam-water two-phase flow in vertical tube bundles, were proposed based on local parameters.

使用光学探针，基于高温和高压下，基于垂直管束中轴向向上的两相流的局部参数的流态识别。在非圆形测试通道内模拟了管束的交错排列，管的尺寸和节距与设计中的压水堆的真实蒸汽发生器中的管径和节距相同。利用光学探针获取两个典型位置（三个管的质心，称为op-1，以及两个管之间的最小间隙的中心，称为op-）在两个典型位置处的空隙率，界面频率和局部空隙率的波动特征。 2）。系统压力为5到9 MPa，质量通量为100到350 kg m ^-2  s ^-1，从0到1的热力学蒸汽质量和从263.9到303.3°C的入口流体温度（取决于饱和压力）。本研究利用光学探针研究了垂直管束中高压蒸汽-水两相流的局部参数和流型特性，其测量误差小于2％。结果表明，在op-1处的局部空隙率要比在op-2处大得多，而op-1和op-2之间的局部空隙率之差先增大后逐渐减小，这主要受流动过渡的影响政权。从界面频率随局部空隙率的变化，局部空隙率的波动特性，局部空隙率的波动性等三个方面对汽水两相流的流型特性进行了描述。局部空隙率偏离平均值的统计分析。此外，基于局部参数，提出了适用于垂直管束中汽水两相流的流态识别准则。