Wind Gust Simulation System within Subsonic Wind Tunnel at the University of Arizona

The University of Arizona houses a closed-circuit low turbulence subsonic wind tunnel. A new capability, the wind gust simulation system, has been integrated into the tunnel. Its components are: (i) the wind gust generator featuring two horizontal pitching vanes individually driven by servomotors controlled by user-defined software, and (ii) airflow velocity measurements using constant temperature anemometry with the hot-wire probe along with a two-axes traverse mechanism. This system modifies the test section flow with key wind profiles: discrete gust (1-cos), continuous gust (sinusoidal), and user-defined functions. The structure of the wind gust system and its operation are presented in detail. Preliminary tests revealed negative peaks at the endpoints of the 1-cos wind gust. To improve this profile, a piecewise continuous function was designed removing slope discontinuities for the vane's angular position over time. The match of experimental data to a 1-cos function was determined using the normalized root mean square error method. Experimental plots for several runs using the same vane’s rotation function displayed minimal differences across the runs. A linear correlation between the vane rotation amplitude and pitch angle was observed. A continuous wind gust was produced using a sinusoidal input function for the vane's rotation. For the given parameter ranges, the system generated time plots of the vertical velocity and pitch angle that closely matched the desired sinusoidal functions. The gust parameter space covered by the developed gust generation system was established and analyzed.