DLR-ONERA accurate CFD support for the Pre-X project

Abstract

During the development of Pre-X demonstrator supported by CNES , industrials are in charge of aerodynamic and aerothermodynamic defintion and characterisation of the vehicle. For this preliminary phase of the project, most of the time industrials only used Euler computations associated to boundary layer, so that a lot of parametric analysis can be carried out and the feasibility of the project was globally checked. It is clear that deeper analyses for some critical trajectory points are required to overcome potential infeasibilities. The main objective of the accurate CFD support, provided by DLR and ONERA consists in assessing these high level objectives. Two critical issues are investigated. The heat fluxes level on the windward side of the body, the deflected flap in the hypersonic regime and the aerodynamic static margin at the end of the trajectory in the supersonic regime. Two relevant codes where used: the TAU code from DLR and CELHYO3D from ONERA. * The unstructured TAU code is a finite volume Navier-Stokes solver which is validated in a wide range of sub- trans- and hypersonic cases. Different one and two equation turbulence models are implemented and chemical equilibrium as well as non equilibrium flows can be modelled. Furthermore adaptation of tetrahedral grids on any given output quantity is possible. * The structured CELHYO3D code is a finite volume Navier-Stokes solver with upwind schemes adapted to supersonic and hypersonic flows. Flows of air or CO2 in chemical or thermo-chemical non-equilibrium can be considered. A specific grid management procedure is used in order to provide shock-adapted grids together with information of the grid-convergence of the results. The results of the computations with TAU and CELHYO3D confirm the feasibility of the project with respect to the heat-flux and static-margin issues.