Schlieren Imaging and Flow Analysis on a Cone/Flare Model in the AFRL Mach 6 Ludwieg Tube Facility
Abstract
High-speed Schlieren photography was utilized to visualize flow over a cone/flare model with variable geometry in the AFRL Mach 6 Ludwieg tube facility. Testing was performed at freestream Reynolds numbers of 10.0E6 and 19.8E6 per meter. The variable-angle flare portion of the model provided a method for adjusting the intensity of the adverse pressure gradient at the cone/flare junction. As expected from existing literature, boundary layer separation along the cone frustum occurred further upstream as adverse pressure gradient intensity increased. Imaging of the four cone tip radii revealed a slightly positive angle of attack for the model. This conclusion was supported by asymmetrical heating contours observed in a prior infrared thermography study on the same model. Measurements of the bow shock angles downstream of the cone tip verified Mach 6 flow from the Ludwieg tube nozzle when analyzed using Taylor-Maccoll theory. Blunt cone tips generated laminar boundary layers along the cone frustum. These laminar boundary layers led to unstable behavior in the recirculation region at the cone/flare junction. Analysis of the instability revealed loosely cyclical behavior. Future hypersonic vehicles will inevitably include numerous adverse pressure gradients. A full understanding of these regions is imperative to successful design and flight testing.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 08, 2019
- Accession Number
- AD1073757
Entities
People
- David A. Labuda
Organizations
- Air Force Institute of Technology