Shock-wave control by permeable wake generators

Kurzfassung

Feasibility experiments for shock-wave control by small permeable wake generators were performed in the supersonic Ludwieg Tube Facility at DLR Göttingen. In order to improve the shock-control effectiveness novel micro-perforated or porous PWG devices shaped similar to a wind-cone are investigated in the present work. In the first part, the working principle and the induced wake-flow peculiarities are discussed. A simplified gas-dynamic model of the flow around an isolated permeable device is applied for wake-flow calculation at different generator geometries and porosities. The preliminary validation of this model was made by the cross-sectional wake extension obtained in the wind-tunnel tests. In the main part, effects of PWG-devices attached to a rod in front of a blunt body on its drag and heating rates at Mach numbers of 2, 3 and 5 are analyzed. Flow-field shadowgrams, drag-force and heat-flux measurements are used to quantify these effects. The results show clear advantages of the investigated permeable flow-control devices in comparison to the solid aero-discs and aero-spikes.