The University of Michigan Department of Aerospace Engineering can boast among its many resources ten wind tunnels for instructional and research work. These tunnels are run by the Gas Dynamics Laboratories (GDL), which consists of a closely integrated group of professors, technicians and students within the Aerospace Department. The function of this group is to conduct experimental and theoretical research, teach lecture and lab courses, and to guide PhD theses. The research interests of the group include a wide range of fluid dynamic, combustion and propulsion problems, much of which is based on wind tunnel experimentation. Below is a list of the wind tunnel facilities that the department offers.
(The University of Michigan Aerospace Engineering Wind tunnel was featured in a special report by WNEM.com on May 15, 2012. The wind tunnel was used to demonstrate the powerful winds you find in tornadoes and the dangers that go along with them. Watch the video above or read the story at WNEM.com.)
The subsonic tunnel was built in 1956 in a joint effort with the US Air Force. It was initially designed to study the effects of gusts on aircraft but has since been upgraded to suit a variety of applications. It is now fully owned by the University and is used for education, research and to serve local industry as a well equipped, affordable subsonic wind tunnel resource.
The facility is a closed circuit, single return tunnel with a 7 ft wide by 5 ft high by 25 ft long test section. With a contraction ratio of 15:1 and the use of multiple diffusion screens, very low turbulence is achievable. The tunnel is capable of continuous operation at velocities of over 150 mph. Large windows on the side and top of the test section allow for excellent model viewing.
Force and moment data are obtained from a below-floor balance system capable of supporting models having gross weights of over 300 pounds. It resolves all six force and moment components to an accuracy of one part in 3,000, with less than 0.1 percent interaction error.
The wind tunnel facility also has instrumentation for the measurement and recording of operating pressures, the angle of attack or angle of yaw, tunnel static pressure, dynamic pressure and temperatures. A computer/data acquisition system is used to average and record the results. Boundary layer velocity profiles on the tunnel walls or on the model can be obtained via Pitot tubes or hot wire probes.
The laboratory has extensive facilities for flow visualization. The introduction of helium-filled bubbles or smoke into the flow, small vanes mounted on a given surface to show flow direction, coating the model with oil and the use of tufts are some of those methods. Photographic systems from still to motion (5 frames/sec up to 1 million frames/sec) are available. Video cameras and recorders are also available.
This tunnel was designed under an Air Force contract to study variable Mach number nozzle contours. The facility continues to be used for instructional and research purposes.
A Schlieren optical system is mounted on an overhead boom which in turn is mounted on a rail system. With this arrangement, schlieren photographs can be made at any position along the window areas.