Analysis on the Load Carrying Mechanism of Two Types of Thermal Wedges in Parallel Gap

Thermal wedges include thermal density wedge and thermal viscosity wedge. The influence of thermal wedge on the load-carrying capacity was investigated in this paper under four classes of surface boundary conditions, i.e., 1) the moving surface is with constant temperature while the stationary surface is adiabatic; 2) the moving surface is adiabatic while the stationary surface is with constant temperature; 3) both surfaces are adiabatic; and 4) both surfaces are with constant temperature. It was pointed out that, comparing with the oil film in a traditional geometry wedge, the oil film in a parallel gap also possesses considerable load-carrying capacity due to the action of thermal wedge. The relationship between the thermal density and viscosity wedges was analyzed and the relative importance of each wedge was studied. The load-carrying mechanism of parallel gaps was explained not only with the traditional principle based on the temperature difference between solid surfaces, but also with a complemetary idea obtained through numerical analysis that the load-carrying capacity can be produced by an uneven distribution of the film temperature even though there is no temperature difference between the surfaces.