A METHODOLOGY FOR MODELLING ENCLOSURE RADIATION HEAT TRANSFER UNDER LARGE STRUCTURAL DEFORMATION

摘要

Finite element method (FEM) numerical simulations of heat transfer for high-temperature regimes often require modeling of grey-body enclosure radiation where enclosure geometry definitions are obtained as part of the model grid generation process. Owing to the expense of solving the radiation problem, typical FEM approaches loosely couple the radiative transfer solution as boundary conditions to a standard conduction formulation. When the problem at hand is thermal-mechanical and relative motion occurs between enclosure surfaces, the simulation code is tasked with providing a means of updating the original enclosure surface geometry to reflect the deformed configuration. While this scenario is manageable for contiguously meshed discretizations, the difficulty of updating enclosure geometry is greatly increased when the model admits sliding. Here the analysis code must employ both mechanical and thermal contact, relying heavily on geometric search and contact constraints to enforce closure for the conduction formulation.General purpose large-deformation FEM structural codes employ surface contact utilities to provide geometric search and contact constraint definitions. This paper describes an ongoing effort to leverage contact utilities for solving the enclosure radiation problem in deforming and sliding mesh scenarios while having minimal impact to a traditional modeling approach. The current effort is divided into two areas, enclosure definitions and thermal contact, but the primary focus here is on enabling use of contact to provide definition of the enclosure. The proposed methodology is demonstrated on simple enclosure radiation models using SNL Sierra Mechanics Dash contact utilities and the Chaparral enclosure radiation library with Sierra Mechanics Structural and Thermal application codes.Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energys National Nuclear Security Administration under contract DE-AC04-94AL85000.