Heat Transfer in a Thin-Film Flow in the Presence of Squeeze and Shear Thinning: Application to Piston Rings

The governing equations and appropriate numerical solutions are presented for the heat transfer and the flow of a shear thinning fluid confined between a curved and plane surface in a thin-film configuration. One surface undergoes a reciprocating motion and the fluid experiences transverse squeeze action, as in a typical piston ring of an internal combustion engine. The effect of viscosity variations with temperature, in conjunction with the non-Newtonian shear thinning behavior of multigrade oils, are included in the analysis. Extensive numerical simulations of the performance of the piston are presented and compared to the isothermal Newtonian solutions. Computations show that shear thinning can have a significant effect on parameters such as film thickness, viscous drag force, and power loss. The thermal effects from viscous dissipation in the clearance space along the piston ring also influence these parameters, but to a lesser degree.