Understanding the condensation process of turbulent steam jet using the PDPA system

In the present study, we investigated condensation characteristics of water droplets in a turbulent steam jet with the Reynolds number from 78,400 to 140,700, such as Particle Size Distribution (PSD), Total Number Concentration (TNC), and Liquid Water Content (LWC) obtained from the Phase Doppler Particle Analyzer (PDPA) system and measured the temperature profile. The temperature decay rate and the temperature half width (rT, 0.5) were obtained for steam jets. The increased latent heat release due to condensation was found to have an effect on the decreased temperature decay rate and the increased spread rate with an increase of the steam jet's Reynolds number. Along the radial direction at z/d = 10, TNC and LWC increased up to the range within r / rT, 0.5 = 1.2, but the turbulence intensity continued to increase beyond the range. These results suggest that the evaporation effect started to occur due to the mixing with the surrounding air. Along the axial direction, we used the effective diameter in order to confirm the Reynolds number effect. As the Reynolds number became larger, particle formation started to occur further downstream along the axial direction. At the downstream of the peak position, the values of TNC and LWC were found to decrease due to the mixing process.