Liquid holdup optical measurements for horizontal stratified flows with an opaque fluid layer

This study presents a method to measure the void fraction in presence of stratified three-phase flow with an opaque fluid like foam. The commonly used resistive probes, which were successfully applied for air-water flows, fail detecting liquid/foam interface due variable conductivity To overcome this problem, new optical was developed. A probe consisting steel rod covered red vinyl plastic black measuring scale having 1 mm resolution introduced radially into flow; foam layer, being opaque, can be easily identified against side view flow. behavior over time liquid-foam thus recorded through video camera. couple small LED lamps provided lighting record scene. videos then processed count marks below layer order get instantaneous values liquid depth. Measurements performed at different pipe sections. results compared those obtained flows same superficial velocities, latter ranging from 0.76 2.30 m/s air and 0.03 0.06 water respectively. loading reduction up 41 % detected lowest gas velocity, i.e. m/s, while when velocity increases difference holdup lowers becomes negligible regardless value velocity. Since no specific model exists foamy as first attempt Zuber Findlay drift-flux finally adopted correlate data.