Effect of aspect ratio on the drag of straw particles: A numerical simulation

Entrained-flow gasification is an effective approach for biomass waste utilization, where the flow behavior of large, non-spherical pulverized particles significantly affects gasification performance. This study numerically investigated the drag characteristics of industrial straw particles, examining the effects of aspect ratio （2–10）, particle Reynolds number （10–1000）, and orientation angle （0°–90°）. The results showed that the aspect ratio's influence on drag was strictly governed by its coupling with the orientation angle and Reynolds number. Except for specific conditions with high Reynolds numbers and small orientation angles, an increased aspect ratio led to a higher drag coefficient, an effect further amplified by increasing the orientation angle or decreasing the Reynolds number. Based on these findings, a multi-parameter coupled drag coefficient model incorporating the aspect ratio was proposed. This model outperformed traditional ones in accuracy and applicability, offering crucial guidance for the structural design of biomass entrained-flow gasifiers.