Boundary Layer Wind Tunnel (BLWT)
 
Power: 2 x 90 kW electric motors
Working section: 3.6m x 2.5m
Maximum speed: 20m/s (72 km/hr)
Features:
-3.6m diameter turntable
-Bike rig force balance
-Rolling road

The BLWT is a closed loop circuit wind tunnel. Wind is blown by two 1.8m fans down a diffusion section and passed through two mesh screens to remove turbulence before being sped up by a contraction for the test section. Large steel turning vanes are installed at each corner to increase the efficiency of the tunnel.

The test section is broken into three sections; a bike rig for measuring drag on cyclists and athletes, a rolling road for testing model car bodies and a large turntable for testing a variety of building scenarios.

As athletes typically see a uniform, low turbulence flow, such tests are conducted at the start of the section. The resisting drag force can be found over a 60 degree angle range. Motion capture is also available in this test area.

In comparison, boundary layer effects are very important for building testing, hence it is setup at the end of the test section. The 20-meter-long test section allows the target atmospheric boundary layer to be simulated by adding roughness features or various shapes and sizes. This controls both velocity profile and turbulence levels.