Flutter Based Aeroelastic Optimization of an Aircraft Wing with Analytical Approach

Abstract

We present an analytical flutter prediction methodology employing assumed mode technique for three dimensional wing and wing/store configurations. The flutter solution makes use of Lagrange formulation for aeroelastic modeling and Theodorsen function for aerodynamic load calculation. An in-house flutter code is developed and validated by using benchmark problems, next applied to Goland and AGARD 445.6 wing models. Flutter results in all cases are in excellent agreement with the reference data. The flutter code is further enhanced to enable aeroelastic optimization and uncertainty based flutter analysis of AGARD 445.6 wing/store configurations. Firstly, aeroelastic optimization study varying input parameters such as taper ratio, sweep angle, spanwise elasticity and shear modulus is performed to maximize flutter boundary of AGARD 445.6 wing and an optimum clean wing model is ascertained. Next, the structural effects of designated external masses are investigated for flutter of initial and optimized AGARD 445.6 wing models and optimum configurations of store placement are determined. Finally, structural randomness such as in spanwise elasticity and shear modulus of the wing are propagated through flutter analyses and this uncertainty quantification is applied to initial and optimum AGARD 445.6 clean wing models. Finally, for wing/store models, random parameters relevant to store masses, store load placements are added to material property uncertainties and similarly flutter boundary uncertainty is examined. In all analyses, uncertainty quantification is accomplished by Monte Carlo Simulation method with various Coefficient of Variation estimates.

Optimization of Control Surface Parameters with Augmented Flutter Boundary Constraints

“…For example, aeroelastic design optimization of AGARD Wing is shown to enhance the flutter boundary and optimal structural parameters such as taper ratio, sweep angle, elasticity and shear modulus etc. are obtained in [27]. For active aeroservoelastic control the optimization process may involve the sensor data and actuator performance.…”

Multi-objective robust design optimization (MORDO) of an aeroelastic high-aspect-ratio wing

“…Ultimately, the achievement of this paper was that robust aerodynamic shape design of an airfoil based on six-σ could improve the performance of air-vehicles in transonic regime. Nikbay and Acar [32] investigated flutter velocity optimization of a tapered-wing with an engine attached to it in 2012. They used the v-g method to calculate the flutter velocity.…”