Limit cycle oscillations of delta wing models in low subsonic flow

A nonlinear, aeroelastic analysis of a low-aspect delta wing modeled as a plate of constant thickness demonstrates that limit cycle oscillations (LCOs) of the order of the plate thickness are possible. The structural nonlinearity arises from double bending in both the chordwise and the spanwise directions. The results using a vortex lattice aerodynamic model for a low-Mach-number how complement earlier studies for rectangular wing platforms that showed similar qualitative results. The theoretical results for the flutter boundary (beyond which LCO occurs) have been validated by comparison to the experimental data reported by other investigators for low aspect-ratio delta wings. Also, the LCOs found experimentally by previous investigators (but not previously quantified prior to the present work) are consistent with the theoretical results reported here. Reduced-order aerodynamic and structural models are used to substantially decrease computational cost with no loss in accuracy. Without the use of reduced-order models, calculations of the LCO would be impractical. A wind-tunnel model is tested to provide a quantitative experimental correlation with the theoretical results for the LCO response itself.