A New Validation Experiment for Smooth-Body Separation

An experimental test campaign to characterize a Gaussian-shaped bump model for CFD validation of smooth-body separation is underway. Empty tunnel characterization shows excellent uniformity, low turbulence levels, and low angularity in the test section. Boundary layer profiles taken without a test model installed show excellent agreement with CFD analysis. A test entry to investigate the flat plate turbulent boundary layer leading up to the bump model was conducted before the bump was installed. Hot-wire anemometry and oil film interferometry were employed on the splitter plate. Integral parameters from the profiles indicate that the boundary layer acts like a classic zero pressure gradient, turbulent boundary layer. Skin-friction values from both the oil-flow technique and the Clauser method on the boundary layer surveys show good agreement. The bump model was installed in multiple streamwise positions and was tested over a range of Mach numbers using the same oil-flow techniques done on the flat plate, and time-mean surface streamlines were determined using a fluorescent oil mixture. Some disagreement between the oil flows and the CFD streamlines have motivated further investigation at larger Mach numbers due to some asymmetries that were unexpectedly discovered in the simulations. Future work to resolve time-mean and fluctuating velocity in the wake region is being done experimentally to verify the time-accurate simulations that have been completed.