Experimental Analysis of Non-Spherical Particle Dynamics and Airflow Interaction in a Rotor Spinning Trash Ejector

Abstract

This study investigates the aerodynamic behaviour of non-spherical impurity particles within the trash removal system of a Rieter R36 rotor spinning machine. Utilizing high-speed visualization and Particle Image Velocimetry (PIV), the research compares the velocity fields of the airflow (u mean = 4 m/s) against the trajectories of discrete impurities. Morphological analysis of 1,500 particles established a median circularity of 0.74 and a D{50} of 50 μm, parameters which were integrated into a Lagrangian framework using drag correlation. Results reveal a significant velocity slip and decoupling from fluid streamlines near the opening roller exit, where centrifugal forces dominate over aerodynamic drag. The measured mean particle velocity of 2.17 m/s shows excellent agreement with the theoretical prediction of 2.2 m/s. This inertial lag causes particles to follow ballistic-like trajectories, suggesting that further optimization of the ejector wall geometry based on these trajectories could enhance separation efficiency and prevent fibre re-contamination.