Non-Intrusive, Time-Resolved Turbulence Measurements in Large-Scale Hypersonic Wind Tunnels

The long-term objective of the proposed work is to provide the DoD and related customers with a viable set of products that will non-intrusively measure the currently uncharacterized high-speed density and velocity fluctuations in our nation’s largest supersonic and hypersonic wind tunnels, and within turbulent boundary layers on wind tunnel models. To achieve this objective of time-resolved measurement, we plan to develop high-speed Krypton Tagging Velocimetry (KTV) for planar measurement of velocity fluctuations in the hypersonic regime, and Dual-Focused Laser Differential Interferometry (D-FLDI) for high-speed (>10 MHz), high-vertical resolution measurement of localized density fluctuations. The key pieces of technology that this team is uniquely qualified to develop are a tunable, pulsed-burst laser for KTV (greatly improving repetition rate) and a data-reduction procedure for D-FLDI (greatly reducing measurement uncertainty). If successful, the impact of our efforts will be a game-changing understanding of the dynamics of turbulence in supersonic and hypersonic flows through access to flow regimes which were previously inaccessible, and greatly reduced uncertainty in hypersonic testing. These new measurements will reduce programmatic risk for the high-speed Test and Evaluation (T&E) community by enabling new means of wind-tunnel characterization and computational fluid dynamics (CFD) code validation via experimental/computational comparison.