Quasi-Static Thermal Modeling of Multiscale Sliding Contact for Unlubricated Brush Seal Materials

Abstract

Prediction of contact temperature between two materials in high-speed rubbing contact is essential to model wear during unlubricated contact. Conventionally, assumptions of either a steady or an annular heat source are used for slow and high speed rotation, respectively. In this paper, a rotating heating source is solved using an in-house finite element method code. This captures the full geometry and rotating speed of the rubbing bodies. Transient heat transfer is modeled quasi-statically, eliminating the need for a transient 3D simulation. This model is shown to be suitable for contact temperature prediction over a wide range of rotating speeds, anisotropic thermal conductivity, and nonuniform thermal boundary conditions. The model calculates heat partition accurately for a thin rotating disk and short pin combination, which cannot be predicted using the existing analytical solutions. The method is validated against ansys mechanical and experimental infrared thermography. Results demonstrate that the annular source assumption significantly underpredicts contact temperature, especially at the rubbing interface. Explicit modeling of a thin disk results in higher heat partition coefficients compared with the commonplace semi-infinite length assumption on both static and rotating components. The thermal anisotropy of tuft-on-disk configurations is evaluated and compared to a uniform pin-on-disk configuration. Despite the effective thermal conductivity (ETC) in the bristle tuft being approximately 1 order of magnitude lower than along the bristle length (treating the bristle pack as a porous medium), its impact on heat partition and contact temperature is shown to be limited.