Dynamic behavior of straw biomass particles in gas flow: A novel motion model and experimental validation

Straw biomass particles, characterized by their complex non-spherical geometries, exhibit intricate motion and coupling mechanisms with combustion processes in gas flow fields, which remain largely unexplored. Current models, predominantly based on spherical particle assumptions, fail to accurately describe the dynamic behavior of biomass particles with high aspect ratios (Ar) and complex shapes, particularly when translational and rotational dynamics are coupled. This study focuses on the Motion characteristics of non-spherical, cylindrical straw biomass particles. By integrating visualization experiments and computational fluid dynamics-discrete element method numerical simulations, a novel non-spherical motion model applicable to particles with varying aspect ratios was developed and validated, building upon the findings from our previous Particle-resolved Direct numerical simulations research. The study systematically analyzed the translational and rotational behavior of particles with aspect ratios of 6, 10, and 15 in upward gas flows with a particular focus on the dynamic variations in drag coefficients (C_D), lift coefficients (C_L), and torque coefficients (C_T) and their influence on particle motion. Experimental results demonstrate that the developed model effectively predicts the trajectories of particles with different aspect ratios. The prediction errors for vertical and lateral positions were both below 5%, while errors for incident angles and angular velocities remained within 8% under different aspect ratio geometries, indicating the model's high accuracy and applicability. Beyond its ability to accurately simulate the detailed motion of particles, the model also addresses the coupling of translational and rotational dynamics in non-spherical particles. In the future, this model can serve as a theoretical and optimization tool for studying the transportation and combustion of biomass particles in coal-fired boilers. Moreover, it lays a solid foundation for further research on the dynamics of complex-shaped particles and their applications in intricate flow fields and industrial environments.