GM Wind Tunnel
The basic research wind tunnel at Western Michigan University's applied aerodynamics laboratory is shown schematically in Figure 1. It was donated by General Motors. This tunnel will be set up as long as the lab space is available. It is particularly suitable for ground vehicle testing.
This is a closed-circuit, closed test section wind tunnel with a rectangular test section that is 711 mm wide and 507 mm high at the entry. The test section is 2285 mm long and the side walls have a small divergence angle of 0.35 degrees to account for the growth of the wall boundary layers. The tunnel in its present configuration has a contraction ratio of 10.67. Immediately upstream of the contraction, a flow straightener and two wire-mesh anti-turbulence screens are installed. The return path is of the diffuser type and the corners were constructed to be diffusion free. The turning vanes were made of circular arc sections with straight trailing-edge extension. A Westinghouse Class III 1370 mm centrifugal-type fan with a side discharge is used to create the air flow. The fan is driven by a 18 kW Reliance Max Pak DC variable-speed motor which is controlled by a potentiometer. The test section is equipped with a six-component strain gauge balance unit by Microcraft, Inc.
Figures 2 and 3 show the test section and force balance, respectively.