Aerodynamic Coefficients of Lift-Generating Space Transportation Systems: Modeling and Simulation

Abstract

The current rapid changes in the space transportation market, in part due to the partially reusable launcher provided by SpaceX, dictates a European answer to stay competitive. One possible option is the SpaceLiner, a winged, lift-generating launcher, currently in development at DLR Bremen. An important aspect of this development is the investigation of the aerodynamic characteristics. Especially interesting are the e�ects that �ap de�ections have on the pitching moment and subsequently the trimmed �ight position. Since conventional handbook methods are limited in their ability to take this into account, a CFD solution was investigated. The chosen CFD software was the open-source package OpenFOAM. Within this work a work�ow for generating aerodynamic coe�cients using OpenFOAM was developed. This included the pre-processing of the geometry to be investigated, the generation of a surface and computational mesh, the numerical setup of the solver and the application of the post-processing tools. The surface mesh was generated using the open-source tool Salome, which has implemented functions for the utility used for generating the computational mesh, cfMesh. The OpenFOAM native post-processing utility forceCoeff�s was used to both generate the aerodynamic coe�cients as well as observe convergence. To validate the methods used, results from the ENTRAIN study were reproduced. During this validation process, it was discovered that the coarseness of the mesh was altering the results. After re�ning the mesh, the data set was successfully reproduced. Both the Euler data set, as well as the data obtained using OpenFOAM showed higher drag values, then the RANS simulations. Finally the aerodynamic coeffi�cients for the SpaceLiner 8 booster stage were generated at an altitude of 5km, a Mach number of 0.5 and at an angle of attack between -4° and 10°. The resulting data was compared to the internally used tool CAC. Both lift and pitching moment could be determined with a satisfactory accuracy. However only the lift-induced drag could be calculated correctly, with the base drag being to high. Additionally to the aerodynamic coe�cients, CFD is able to the accurately calculate pressure distribution, which can be further of use in the structural analysis.