Transient Analysis Methods for Hypersonic Applications with Thermo-Mechanical Fluid-Structure Interaction

A numerical framework developed for coupled fluid-structure interaction problems is presented, with emphasis on the numerical methods employed for time integration and equilibrium iteration. The framework has been succesfully used in the German IMENS project for the simulation of hypersonic applications. The framework uses a modular concept with stand-alone solvers for the disciplines involved (fluid and structure) with a thoroughly designed data interexchange interface [

1

].

The solution approach used for mechanical quasi-stationary and thermal transient coupled analyses is presented, taking into account different time scales of the physical domains and efficiency aspects, which are essential when dealing with complex models and solution strategies (e.g. Navier-Stokes codes). For time integration both iterative and simple staggered methods have been used to account for accuracy and efficiency demands of the different problem cases. Several means to accelerate the time integration have been studied. For iterative staggered methods the acceleration methods for the equilibrium iteration presented in [

2

] have been adopted and improved for the present study case. For example, the gradient method proposed in [

2

] has been modified to suit the modular concept approached here, where neither the Schur complements can be explicitly computed nor is it possible to easily switch off boundary conditions, as demanded in [

2

]. The control theory approach for adaptive time stepping presented in [

3

] has been tested and adapted for the present application area of hypersonic fluid-structure interaction (thermo-mechanical interaction with compressible Navier- Stokes flows and geometrically and physically non-linear structures). The benefits of this approach over the classical time stepping strategies have been evaluated on the basis of selected parameter studies.

The different numerical methods have been tested, evaluated and compared using some generic example models from the IMENS project, e.g. a flap-gap configuration or a nosecap model, which are the subject of this presentation.