Aeroelastic wind tunnel test for aerodynamic uncertainty model validation

A half model of a scaled aircraft is designed and tested in the wind tunnel to validate the uncertainty model for unsteady pressure coefficient in the frequency domain. In the wind tunnel test, a step-swept test was conducted to obtain the model's frequency response function. Then a time-domain response test was performed with turbulence excitation to identify the aircraft's on-line poles. Based on the tested frequency response function or the on-line poles, the structured singular value (μ) method was applied to determine the aerodynamic uncertainty level under the model validation framework. Finally, the widely used μ analysis was again employed to analyze the worst-case flutter boundary, compared with the experimental flutter velocity. The experimental flutter velocity (30.5m/s) is in the range of the predicted robust flutter boundary (28.5m/s), in which parameters' uncertainties were taken into account in the numerical model. Experimental results validate that the uncertainty quantification theoretical frameworks incorporating experimental data can estimate the proper aerodynamic uncertainty level and predict a safe flutter boundary. The present results suggest that the time-response validation theoretical framework is more advantageous in robust stability analysis than the one upon the frequency response function validation.