The Transonic Dynamics Tunnel (TDT) is dedicated to identifying, understanding and solving aeroelasticity issues confronting fixed-wing aircraft and helicopter and tiltrotor configurations. Rotary-wing tests at the TDT have investigated performance, loads and stability characteristics, while fixed-wing buffet and divergence have been scrutinized as well. Researchers have also used the TDT to determine the effects of ground-wind loads on launch vehicles, and to provide steady and unsteady aerodynamic pressure data to support computational aeroelasticity and computational fluid dynamics code development and validation.
The TDT is a closed-circuit, continuous flow, variable pressure wind tunnel. Advantages include improved model-to-full-scale similitude, higher Reynolds numbers, easier fabrication of scaled models, reduced tunnel power requirements, and in the case of rotary-wing models, reduced model-power requirements.
There is excellent model visibility from the tunnel control room and safety screens protect the tunnel fan blades from debris in case of a model failure. Particularly useful for flutter tests is a group of four bypass valves that connect the TDT test section area to the opposite leg of the wind-tunnel circuit downstream of the fan motor. In the event of model instability, these quick-actuating valves are opened, causing a rapid reduction in the test section Mach number and dynamic pressure that serves to stabilize the model.
Studies have been conducted at the TDT by the aircraft industry, NASA, the Department of Defense and an array of universities.