(220e) Challenges in Local Flow Structure Measurements of Gas-Solids Fluidized Beds

Local flow behaviour in gas-solids fluidized beds are heterogenous, always consisting of a dilute (bubble) phase and a dense phase. Researchers in early days often used visualization techniques in a two-dimensional bed to study the two-phase flow behaviour such as bubble size, bubble rise velocity, jet/bubble formation and bubble eruption at the upper bed surface. Pressure sensors, optical probes and capacitance probes were deployed for local dynamic measurement, coupled with the high-speed data acquisition system, with the local flow structure extracted or reconstructed using dynamic signals. In a complex two-phase flow system, where pressure signals coming from different sources, it is critical to properly identify and link the measured signals with the origin/source of signals, preferably through the establishment of a physical-mathematical relationship. In this presentation, I will give an overview of what we have done at the UBC Fluidization Research Centre over past 40 years in advancing the local measurement of two-phase flow structure using pressure, optical and electrostatic sensors, spanning from identification of dominant mechanisms, to establishment of physical-mathematical relationships and the filtration and extraction of local flow parameters of interest. Advanced statistical analysis techniques such as chaotic analysis were applied in identifying the origin of signals and decoupling signals from different sources to extract desired signals for analysis.