Nonlinear aeroelastic response of delta wing to periodic gust

A nonlinear response analysis of a simple delta wing excited by periodic gu st loads in low subsonic flow is presented along with a companion wind-tunn el test program. The analytical model uses a three-dimensional time-domain vortex lattice aerodynamic method and a reduced order aerodynamic technique . Results for a single harmonic gust and a continuous frequency sweep gust have been computed and measured for both flow velocities below and above th e Butter speed. A theoretical jump response phenomenon for the nonlinear st ructural model was observed both for the single harmonic and the continuous frequency sweep gust excitation. Those results further confirm some conclu sions about limit cycle oscillations above the Butter speed and complement our earlier theoretical and experimental studies. Also an experimental inve stigation has been carried out in the Duke wind tunnel using a rotating slo tted cylinder gust generator and an Ometron VPI 4000 scanning laser vibrome ter measurement system. The fair to good quantitative agreement between the ory and experiment verifies that the present analytical approach has reason able accuracy and good computational efficiency for nonlinear gust response analysis in the time domain. Without the use of reduced order models, calc ulations of the gust response for the nonlinear model treated here would be impractical.