Search

In the present work, the supersonic flow past an axisymmetric cylinder and over a three-dimensional cavity are investigated using detached-eddy simulation to evaluate the predictive capabilities of this simulation technique. The numerical predictions are compared with experimental data of Herrin and Dutton (1994) for the base flow and of Zhuang (2007) for the cavity flow. In the case of base flow, the mean velocity field and pressure along the base are well reproduced. In the cavity flow case, the predictions follow the trends of the measurement concerning the mean velocity field. Pertaining to the sound pressure level along the cavity floor, slightly higher pressure levels are predicted and the reasons are discussed. [ABSTRACT FROM AUTHOR]

The electromagnetic railgun technology appears to be an interesting alternative to launch small payloads into Low Earth Orbit (LEO), as this may introduce lower launch costs. A high-end solution, based upon present state of the art technology, has been investigated to derive the technical boundary conditions for the application of such a new system. This paper presents the main concept and the design aspects of such propelled projectiles with special emphasis on flight mechanics, aero-/thermodynamics, materials and propulsion characteristics. Launch angles and trajectory optimisation analyses are carried out by means of 3 degree of freedom simulations (3DOF). The aerodynamic form of the projectile is optimised to provoke minimum drag and low heat loads. The surface temperature distribution for critical zones is calculated with DLR developed Navier-Stokes codes TAU, HOTSOSE, whereas the engineering tool HF3T is used for time dependent calculations of heat loads and temperatures on project surface and inner structures. Furthermore, competing propulsions systems are considered for the rocket engines of both stages. The structural mass is analysed mostly on the basis of carbon fibre reinforced materials as well as classical aerospace metallic materials. Finally, this paper gives a critical overview of the technical feasibility and cost of small rockets for such missions. [ABSTRACT FROM AUTHOR]

The paper present a numerical/experimental investigation of the flow field resulting around a generic vehiole controlled by means of a lateral jet in supersonic motion. The experimental data are acquired in the DLR wind tunnel TMK in Cologne. To obtain the numerical results, the 3-D viscous, turbulent, Reynolds-averaged hybrid Navier-Stokes Code TAU of DLR is used. Caloulations are made for free stream Maeh number of M∞=2.8 and various angles of attack. Several grids of varied density and structure and different Inrbulenee models are investigated. The CFD results in terms of surface pressure, normal force coefficients, and jet interaction are in good agreement with the results from wind-tunnel tests. On hand the numerical results it is shown important features of the interaction mechanisms between the lateral jet and the flow field originated by the motion of the vehicle. [ABSTRACT FROM AUTHOR]