Effects of Localized Flow Heating by DC-Arc Discharge Ahead of Non-Slender Bodies

The influence of steady energy addition into the flow by low-voltage DC-arc discharge located upstream of conically-nosed and spherically-blunted bodies was investigated experimentally in the Ludwieg-Tube Facility at Mach 5. The results include drag force measurements and shadowgraph flow visualizations. The flow-field structure arising due to the bow-shock/heated-wake interaction, as well as the effects of bow-shock intensity and heating power variation on the drag reduction of different non-slender bodies are analyzed in this paper. The results demonstrate the existence of an optimum heating rate providing a maximum effectiveness of energy deposition and show distinct drag reductions up to 70% dependent on the test conditions and model geometry

Flow topology and secondary separation modelling at crossing shock wave/turbulent boundary layer interaction conditions

Steady RANS modelling has been carried out for a symmetrical double-sharp-fin configuration with an inclination angle 15°, Mach 3.92 and Reynolds number Reδ = 3.08 x 105. Grid refinement and turbulence model influences using ω-based Reynolds Stress model (RSM), one-equation Eddy Viscosity Transport and two-equation Shear Stress Transport, have been studied and predicted wall pressure distributions were in good agreement with experiment data. RSM model surface flow topology was found to be in better qualitatively agreement with experimental oil-flow visualization than those from other two models. The secondary separation phenomenon observed in the experiment was successfully reproduced by the RSM model, due to its ability to evaluate correct level of turbulence kinetic energy that is critical in determining pseudo-laminar state of an embedded reversed flow underneath the main cross-flow vortex. Three-dimensional flow structures demonstrated that the initially weak secondary separation has been further strengthened in span-wise direction towards the central separated zone

Experimental and Numerical Study of Shock Wave Transformation by Laser-Induced Energy Deposition

Joint experimental / numerical study is performed to specify influence of the single- and double-pulsed laser-induced energy deposition on the bow shock wave and flow field structure in the vicinity of spherically blunted body with a diameter of 60mm at the Mach number of 2. The optical discharge is induced by a focused laser beam penetrating in the upstream direction in front of the hemisphere. Experimental investigations are conducted in the Ludwieg Tube Facility at DLR Göttingen. The numerical calculations are performed in the framework of the unsteady Euler equations

Experimental and Numerical Investigation of Electric-Arc Airspikes for Blunt and Sharp Bodies at Mach 5

Joint experimental and numerical investigation is performed to analyze effect of a localized DC-arc discharge upstream of blunt and sharp axisymmetric bodies on the flowfield structure and aerodynamic drag at Mach 5. DC arc power of W = 1.5 kW was realized for the flow control using thin tungsten-electrodes. Experimental investigations are conducted in the Ludwieg Tube Facility at DLR Göttingen. The numerical calculations are performed in the framework of the unsteady Euler equations

Study of the Bow Shock Interaction with Laser-Pulse-Heated Air Bubbles

The influence of various parameters characterizing the single- and double-pulse energy deposition (ED) upstream of a blunt body (distance between the deposition point and the body, amount of the energy and time delay between the pulses) on the topology of the supersonic flow at Mach 2 is studied experimentally and numerically. The obtained pressure-time diagram at the upstream stagnation point of the body as well as some significant topological properties of the bow-shock / heated-bubble interaction, like shock deformation and reflection, as well as the evolution of the heated bubble into vortex rings downstream, are analyzed as resulting from the shock-decelerated spherical light-gas inhomogeneity. The evolution and topology of the interfering heated bubbles by double-pulse ED show the significance of vorticity generation initiated by blast-waves coming from the neighboring bubbles

Experimental and Numerical Modeling of the Bow Shock Interaction with Pulse-Heated Air Bubbles

The influence of various parameters characterizing the single- and double-pulse energy deposition (ED) upstream of a blunt body (distance between the deposition point and the body, amount of the energy and time delay between the pulses) on the topology of the supersonic flow at Mach 2 is studied experimentally and numerically. The obtained pressure-time diagram at the upstream stagnation point of the body as well as some significant topological properties of the bow-shock / heated-bubble interaction, like shock deformation and reflection, as well as the evolution of the heated bubble into the vortex ring downstream, are analyzed as resulting from the shock-decelerated spherical light-gas inhomogeneity. The evolution and topology of the interfering heated bubbles by double-pulse ED show the significance of vorticity generation initiated by blast-waves coming from the neighboring bubbles