Numerical modelling of braided ceramic fiber seals by using element differential method

Abstract

• A multi-physical coupled model is proposed for the braided ceramic fiber seals. • The coupled fields contain the process of heat conduction, seepage and deformation. • Element differential method (EDM) is used to solve the multi-physical problems. • The material-dependent parameters in model are obtained by an inverse procedure. • Compared to FEM, EDM is more easy and efficient dealing with the coupled model. A new kind of dynamic seal with braided ceramic fibers has been designed to seal the movable panels in the scramjet engines, which are used for the propulsion of hypersonic vehicle. The braided ceramic fiber structure can provide buffer forces when the seals are subjected to the external dynamical preloads. However, it also makes the seals difficult to analyze. Up to now, the analysis of the seals still uses 1D models so that one cannot implement the coupled analysis of seals and their surrounding structures and flows. In this paper, a novel 2D and 3D mechanics-thermal-seepage coupled model is proposed to describe these seals, which provides a possibility for the aforementioned coupled analysis. Meanwhile, a strong-form numerical method, element differential method (EDM) is employed to discretize the governing equations of the coupled model due to its efficiency and robustness. Three examples are given. The first one is to invert the material-dependent parameters of three kinds of seal strips from the experimental data by Levenberg-Marquardt (LM) algorithm. Other two implement the analyses of 3D square and circular cross-section seals, respectively, which verify that EDM is more efficient than FEM in seal analysis when using the same mesh sizes.