Numerical investigation of cavitation effect on two-phase oil film flow between a friction pair in hydro-viscous drive

摘要

This paper describes a three-dimensional computational model of oil film between a friction pair to investigate the characteristics of both single-phase and two-phase flow of the oil film in hydro-viscous drive. For the single-phase oil film, the distribution of pressure is very regular from inlet to outlet of the friction pair; its value decreases gradually. On the other hand, the temperature in the middle part of the oil film is considerably lower and the velocity increases at a faster rate near the outlet and has a parabolic profile, which is mainly caused by both the shear stress and extrusion force. By comparison, the physical phenomena at the outlet of the oil film are entirely different for two-phase flow with cavitation. For two-phase simulation of flow with cavitation, we first obtain the volume fraction of air bubbles at rotation speeds of 500, 1000, 2000, 3000, and 4000 revolutions/min. With increase in the rotation speed, the volume fraction of air bubbles increases, and their maximum value becomes even greater than 10. Furthermore, due to cavitation, the torque transferred by the oil film is no longer linear with the rotation speed; its value decreases gradually. These results are important in the study of hydro-viscous drive and its applications; they shed a new light on the mechanism of power transmission through oil film in the presence of cavitation.