Relative contributions of drag and non-drag forces governing particle motion in pressurized gas-solid jets

This study numerically evaluated the relative contributions of drag ( F D ), fluid stress ( F SF ), added mass ( F AM ), and Basset history ( F H ) forces on particle motion as a function of particle size and gas pressure in a one-dimensional gas-solid jet. The analysis used particle and CO 2 gas properties representative of a pilot-scale pressurized oxy-coal combustor inlet at 300 K. Particle diameters of 20-125 μm and gas pressures of 5-40 bar were considered with an inlet velocity of 5 m/s. Force contributions were assessed through force-to-gravity ratios and cumulative force fractions. Results showed that drag was the dominant force beyond the velocity core. However, for larger particles at elevated pressures, F SF and F H locally exceeded F D in regions where gas-particle velocity differences were small. F SF and F AM peaked at the gas velocity gradient discontinuity at the jet core exit, while F H peak lagged this location due to its history effects. F SF and F H were consistently greater than F AM at all conditions. Cumulative force contribution results confirmed that non-drag forces influenced early particle motion for 125 μm particles at 20–40 bar, though their relative importance diminished with distance. Particle velocity responsiveness to changing gas velocity increased with both size and pressure, with non-drag forces most relevant when drag was weak. Findings demonstrate that under high-pressure conditions, forces often considered negligible in atmospheric gas-solid flows may contribute significantly to local particle dynamics.