Modeling the LCO of a delta wing with an external store using a high fidelity structural model
The flutter and limit cycle oscillation(LCO) behavior of a 45 degree delta wing-store model, with various store spanwise locations, is studied using an aeroelastic model which includes a high fidelity, nonlinear finite element structural solver and a vortex lattice aerodynamic model. The store aerodynamics are modeled using slender body theory. The computed results are compared to a previous computational model and to experiment. The zero angle of attack flutter behavior of the wing-store configuration is shown to be sensitive to the spanwise store location. This is predicted accurately using the current methodology. LCO results for zero angle of attack are computed for two store spanwise locations and compare favorably with experiment. For a clean wring configuration and a configuration which had the store located at y/c = .291, the flutter results show very little sensitivity to the model angle of attack. This too was predicted accurately using the current model. However when the store is placed at y/c = .545, the experimental flutter data show a large sensitivity to angle of attack with the flutter velocity decreasing by almost 20% when the model is placed at an angle of attack of two degrees. This is not predicted in the current work and it is possible that unmodeled flow physics such as leading edge vortices are the cause of this difference.
