Subcooled degree is the direct drive potential of condensing phenomena happening and developing. The nucleation process of cascade passage sharply occurs in a narrow flow section. Water droplets distribution is affected by boundary layers and wakes. Due to the condensing parameters distribution steep and sensitive

high resolution second-order TVD scheme and time-marching technique were adopted in numerical algorithm. Using numerical algorithm

the condensing parameter distributions was calculated and compared with measured data to verify the accuracy of the numerical algorithm. Basic physical phenomena of non-equilibrium condensing flow and the influence of inlet subcooled degree on the homogenous nucleation were examined. Varying pattern of pressure

nucleation rate

droplets number

droplets radius and wetness were investigated. It was found that the inlet subcooled degree had a significant influence on non-equilibrium phase change in transonic condensing flow.