Deterministic and Statistical Characterization of the Impact of Control Surface Freeplay on Flutter and Limit -Cycle Oscillation (LCO) using Efficient

Research is proposed for the development and implementation of state of the art computational and experimental tools for the investigation of the impact of control surface freeplay on the flutter and limit cycle oscillation characteristics of two-dimensional and three-dimensional wings in subsonic and transonic flow. Highly efficient and accurate aeroelastic simulation tools will be constructed based upon the following novel concepts 1) reduced order in time models based upon the mathematical formalism of optimal prediction theory 2) high-fidelity aeroelastic simulation based upon the coupling of a particle-method based CFD method to a nonlinear finite element structural dynamics solver and 3) reduced order in spatial models based upon proper orthogonal decomposition (POD) and Volterra theory. In addition, the proposed work will include the use of computational uncertainty quantification which will address, using a probabilistic approach, questions pertaining to the sensitivity of flutter and limit cycle oscillation with respect to possibly uncertain model input parameters such as the amount of freeplay and the freeplay stiffness. Legacy wind tunnel data along with new tests for the transonic regime will be used to validate and improve the computational models and to provide further insight into the complex phenomena of freeplay-induced flutter and limit cycle oscillations.