This research laboratory consists of a low-speed low-turbulence-intensity open-loop pressurized wind tunnel and associated equipment and instrumentation. Downstream of the blower a feedback-controlled rotating-blade damper can produce large-amplitude gusts up to 2 Hz, which is useful for simulating unsteady separating turbulent boundary layers in the test section.
bllab1
Photograph of the Boundary Layer Wind Tunnel

The test section is 3 feet wide and 24 feet long, has an adjustable upper wall that permits various streamwise pressure gradients, and has active suction and tangential wall-jet boundary controls on the non-test walls that are used to prevent unwanted stalls in strong adverse-pressure-gradient and unsteady flows.
bllab2
bllab3
Probe mounted on milling machine base under boundary layer wind tunnel test section.
This facility has been used over the past 28 years in a number of experimental studies. Custom-designed and constructed laser-Doppler anemometers have been used. The results have revealed new features of the turbulence structure of turbulent boundary layers and separated flows. Recently Olcmen and Simpson (1995) developed a fiber-optic "5-velocity-component" laser-Doppler velocimeter system for measuring 3 velocity components simultaneously at one point (30 um diameter) and 2 other velocity components at 2 other points. Turbulent convective heat transfer in 3-D and separated flows have also been examined in this facility (Lewis and Simpson, 1996). Currently, this facility and instrumentation are being used to define the second-order turbulence structure of three-dimensional flows around hull/appendage and wing/body junctions.
bllab4
Unshrouded V System Housings
bllab5
Optical Table Equipment Next To Test Section

Kevin T. Crofton Department of Aerospace and Ocean Engineering (MC0203)
Randolph Hall, RM 215,
Virginia Tech
460 Old Turner St.
Blacksburg, VA 24061-0203

Phone: (540) 231-6611
Fax: (540) 231-9632