Gap flow between two circular plates with temperature-controlled wall: application of thermohydrodynamic lubrication theory and comparison with an iso-viscous model

Gaskets are widely used as static seals in industry, machinery, and living ware. Generally, leakage is reduced or eliminated by clamping seal components and blocking flow passages. However, strong clamping sometimes leads to surface damage. Surface roughness and waviness form partial paths and excitation and vibration loosen clamping bolts. Leakage is directly proportional to the cube of gap height and inversely proportional to viscosity. Moreover, the viscosity of fluids, particularly oil, strongly depends on temperature, as lower temperatures correspond to higher viscosities. In other words, oil leakage can be reduced by decreasing its temperature. Therefore, it is possible to control leakage by changing the gap temperatures. In this paper, a flange-type gasket with a gap is modeled using two circular plates with a central recess. The thermohydrodynamic lubrication (THL) theory is applied to the gap flow. The effects of wall temperature, gap height, and recess pressure on the leakage flow rate are numerically solved. The basic equations comprise the generalized Reynolds equation, the energy equation, and the heat conduction equation and the THL solutions are compared with a simple model based on the iso-viscous theory. In conclusion, the oil temperature in the gap can be controlled by the wall temperature. If the wall temperature is decreased, the oil temperature falls. Subsequently, viscosity increases, helping to decrease leakage in a wide range of operating conditions. The leakage can be estimated by the iso-viscous model with the viscosity at the wall temperature.