Computations of Measured Pitot-Probe Spectra using Angled Freestream Disturbances and Comparisons to Experiments

摘要

Laminar-turbulent transition of hypersonic flows is dependent on the freestream disturbance environment, so wind tunnels must be characterized. The transfer function, defined as the relationship between freestream acoustic disturbances and pressure spectra measured with pitot probes, is computed using direct numerical simulation for several incident angles of freestream acoustic disturbances. The observed behavior is found to depend significantly on the incident angle. A framework for comparing simulation to experiment is presented. Several pitot-probe geometries were used to measure pressure spectra in the Purdue BAM6QT facility. Results for some geometries match reasonably well with computations, although there is significant scatter.