Solid Volume Fraction Measurement of Gas–Solid Two-Phase Flow Based on Terahertz Time-Domain Spectroscopy Technique: A Preliminary Study and Static Experimental Results

Recent advances in terahertz wave sources and detectors have resulted in a wide range of applications of the terahertz technique. In this paper, the feasibility of using the terahertz technique for the measurement of gas-solid two-phase flows is reported. Static experimental studies were carried out on a terahertz time-domain spectroscopy (THz-TDS) system to assess the use of the terahertz technique for solid volume fraction measurement of gas-solid two-phase flows with a high concentration of particles. Measurement models based on transmission attenuation and transmission time delay are developed and compared. Meanwhile, the effects of particle size and particle material on the measurement are examined. Results indicate that the terahertz technique may provide a new solution to the problem of high-solid-volume-fraction measurement of gas-solid two-phase flows. Experimental results also suggest that the transmission time delay model is more appropriate than the transmission attenuation model in the measurement of solid volume fraction with a high concentration of particles.