Bodo Reimann

Aerodynamic Design Analysis of the HEXAFLY-INT Hypersonic Glider

This paper deals with the aerodynamic performance analysis of the expendable Experimental Flight Test Vehicle under development in the seventh framework programme, namely HEXAFLY-INT. A mission scenario, the different flight segments and events to which the payload is exposed to are described and justified. This allowed the definition of the aerothermo-mechanical loads required to conceptually design all elements on board of the vehicle. This flying test bed is a self-controlled glider configuration that shall face a hypersonic flight starting at about Mach 8, just after the separation from the experimental support module at about 50 km altitude, up to vehicle loss. During this flight, several experiments shall be carried out. The appraisal of the vehicle aerodynamic performance is needed for Flight Mechanics and Guidance, Navigation and Control analysis. In particular, hinge line moments for the EFTV’s aileron are also addressed to design the actuation line and to select the actuator device itself. The vehicle made maximum use of databases, expertise, technologies and materials elaborated in previously European community co-funded projects ATLLAS I & II, LAPCAT I & II, and HEXAFLY.

Numerical Investigation of Double-Cone and Cylinder Experiments in High Enthalpy Flows using the DLR TAU Code

In the framework of validation and further development of the DLR TAU code for hypersonic applications several laminar calculations were conducted participating in a RTO working group. The enthalpy in the generic test cases ranges from 5 to 22 MJ/kg addressing thermo-chemical relaxation processes in air and pure nitrogen. Strong bow shocks as well as boundary layer separation, shock-shock and shock-boundary layer interactions are present in the flow fields. The applied numerical models are discussed. The comparison with the experimental data shows the current capability of the DLR TAU code to predict the aero-thermodynamic loads and how model improvements can be supported by these experiments.

DLR τ -Code for High Enthalpy Flows

The development of an equilibrium chemistry model for the DLR τ-Code has extended its ability to simulate high enthalpy flows, such as those around reentry vehicles or within high speed test facilities. Details of the development of the chemistry model, and some test cases, are included in this paper. Also presented is an improved axisymmetry treatment for the code, aimed at producing accurate and noise-free solutions for common hypersonic applications such as blunt bodies and shock tunnels.

Computations of shock wave propagation with local mesh adaptation

The numerical simulation of discontinuous flow phenomena results in high demands related to the used computational grids. A high resolution of the grid is required to resolve shock waves and contact surfaces. This leads, especially for unsteady flows with moving structures, to grids with a large number of points. Local mesh adaptation allows to reduce the computational effort by refining the mesh only in regions where it is necessary. In the present paper a numerical simulation of the shock tunnel flow in the High Enthalpy Shock Tunnel G¨ottingen (HEG) is performed. Local grid adaptation is used to capture shocks and contact discontinuities. Of particular interest for the shock tunnel performance and the investigation of driver gas contamination is the shock reflection process and the interaction between the reflected shock, the boundary layer and the contact surface separating the test gas from the driver gas.

Coupled Simulation of CFD and Flight Mechanics with a Two-Species-Gas-Model for the Hot Staging of a Multistage Rocket

The hot staging dynamics of a multistage rocket is studied using the coupled simulation of Computational Fluid Dynamics (CFD) and Flight Mechanics (FM). In the coupled simulations, the free-stream is modeled as “cold air” and the exhausted plume from the continuing-stage-motor is modeled with an equivalent calorically-perfect-gas that approximates the properties of the plume at the nozzle exit. The Navier-Stokes equations in the coupled simulations are time-accurately solved in moving system, with which the Flight Mechanics equations can be fully coupled. The Chimera mesh technique is utilized to deal with the relative motions of the separated stages. A few representative staging cases with different initial flight conditions of the rocket are studied with the coupled simulation. Based on the simulation results, the staging dynamics of the rocket are finally analyzed.