Investigating the drag torque in wet clutches using warped friction pairs

Purpose Drag torque reduces the efficiency of the rotating system and affects the stability of transmission. This study aims to investigate the influence of warped friction pairs on drag torque characteristics. Design/methodology/approach Considering the geometrical characteristics and shearing mechanism of the lubricating film in the friction pair gap, the mathematical model and finite element model of the friction pair gap flow field are established for the no-load characteristics of the warped friction pair. Simulation results are used to verify the theoretical model, and the effects of warping amount and inlet flow on the no-load characteristics of the warped friction pair are studied. Findings For the warped friction pair, the drag torque exhibits an initial increase followed by a decrease as the relative speed rises, and this trend is mirrored by the ordinary friction pair; a greater oil film gradient is observed in the Type 1 friction pair when the drag torque has a descending trend; the pair exhibits a higher drag torque than the ordinary type; for the warped friction pair, with an increase in the warping amount, a decrease in the gap size and an increase in the inlet flow, the oil film volume within the gap decreases, which leads to a decrease in the theoretical flow, and an increase both in the critical relative speed for oil film contraction and the peak drag torque. Originality/value The findings of this study provide a valuable reference for subsequent research on aviation wet clutches featuring warped friction pairs.