Influence of Groove Orientation on Transmission Characteristics of Hydro-viscous Clutch Considering Oil Film Cavitation

In order to investigate the influence of oil film cavitation on the transmission characteristics, a single oil film of the hydro-viscous clutch was taken as the research object. Considering the groove orientation, the mathematical model and phase transient model of the oil film were established. Based on the Reynolds equation of viscous flow, the oil film flow field is solved. Both numerical analysis and simulated results show that the oil film cavitation will occur first in the upstream position of the groove area at the outer radius of the oil film, and the cavitation bubbles will diffuse into the innerradius area of the groove and the non-groove area with the increase of the rotational speed, which is consistent with the cavitation morphology captured in the experiment. Considering that the cavitation in the groove with a negative inclination angle is more severe than that in the groove with a positive inclination angle, the influence of groove orientation on oil film transmission characteristics was analyzed experimentally. Results show that the cavitation bubbles in a negatively inclined groove are more likely to destroy the integrity of the oil film when the rotational speed is greater than 600 r/min, resulting in a decrease in the oil film bearing capacity and transmission torque. Therefore, the friction pair with positively inclined grooves will have better transmission performance.