Observations on the applicability of an eddy viscosity formulation to interacting supersonic streamwise vortices
23rd AIAA International Space Planes and Hypersonic Systems and Technologies Conference, 2020
The understanding and modeling of turbulent phenomena in supersonic streamwise vortices enables their application in injection strategies suitable for hypersonic air-breathers. In fact, the combination of total pressure losses introduced by these flow structures and their mixing effectiveness, which is strictly connected to their turbulent characteristics, are fundamental parameters in the performance assessment of an injection system for scramjet engines. This work is focused on the experimental characterization of the flow associated with the vortex merging process in a Mach 2.5 freestream, with the final goal of determining whether or not the use of an eddy viscosity model would be suitable for the description of its highly turbulent nature. Measurements were taken in a cold-flow supersonic wind tunnel by means of in-stream Pitot and total temperature probes at two cross-flow stations located in a shock-free region of the test section. Stereoscopic Particle Image Velocimetry was also used in conjunction with the intrusive measurement techniques to calculate the total pressure and all the related thermodynamic properties of the flow. The mean-flow strain rate tensor components and the corresponding turbulent shear stresses follow very similar trends across the flow structures, thus providing an indication that, despite the known intrinsic and inevitable limitations of every gradient-based method, an eddy-viscosity-type model may be suitable for reduced-order models applied to this specific class of flows.
Eddy Viscosity, Vortex Structure, Particle Image Velocimetry, Shear Stress, Croccos Theorem, Supersonic Wind Tunnels, Strain Rate Tensor, Thermodynamic Properties, Scramjet Engines, Reynolds Averaged Navier Stokes
Fabrizio Vergine and Luca Maddalena. "Observations on the applicability of an eddy viscosity formulation to interacting supersonic streamwise vortices" 23rd AIAA International Space Planes and Hypersonic Systems and Technologies Conference, 2020 (2020). https://doi.org/10.2514/6.2020-2437