Comparison of CFD simulations against TMK wind tunnel data of the DLR ReFEx flight experiment

The topic of this work is the analysis of the aerodynamic coefficients of the DLR Reusability Flight Experiment (ReFEx), covering the supersonic flight regime. CFD simulations are compared against experimental data gained at the DLR trisonic wind tunnel TMK in Cologne, Germany. The goal of ReFEx is to demonstrate a flight trajectory representative for a first stage of a Reusable Launch Vehicle. The focus of the CFD simulations is the comparison of force and moment coefficients with TMK measurements at different Mach numbers and a range of angles of attack. First, the effect of three different turbulence models is investigated. It is shown, that the SA turbulence model presents the best agreement with TMK data for all Mach numbers. The agreement is best at Ma=4.5 and declines with decreasing Mach number. The effect of the sting is studied and found to be considerable for all Mach numbers, in particular at high angles of attack for the axial force coefficient Cx. CFD simulations of the pitching moment coefficient Cm show a good agreement with TMK data in terms of the stable range of angles of attack. The Reynolds number effect should be considered for the flight databases for lower Mach numbers. For the additional analysis of the roll moment coefficient and control reversal, a model with asymmetrical canard deflections is used. In contrast to TMK data, CFD simulation results do not indicate control reversal. However, the principal course of the roll coefficient curves do show a good agreement. Finally, the sensitivity of the coefficients to sideslip angle variations is studied, showing an impact on the roll moment coefficient values, which should be considered

Contribution of Numerical and Experimental Flow Simulations to the Aerodynamic Data Base of the DLR Reusable Flight Experiment ReFEx

ReFEx is a Reusable Flight Experiment of the DLR. For the layout of the aerodynamic shape of the vehicle, the identification of a flight trajectory and finally the control systems, extensive data sets are necessary. The focus of this paper lays on the comparison of calculated versus measured aerodynamic coefficients. All simulations were carried out with the DRL TAU Code. The measurements were performed in the trisonic wind tunnel (TMK) of the DLR. One aerodynamic flight control element of ReFEx are the canards. The here presented analysis delivers a good agreement comparing the calculated and measured coefficients, looking at the symmetrical canard deflections. The occurred differences of the asymmetrical canard deflection are discussed in detail, including the numerical as well as experimental uncertainties