Time-Domain Two-Way Fluid–Structure Interaction Analysis of the HIRENASD Transonic Wing: Static Aeroelastic Response and Flutter Prediction

The aeroelastic behaviour of the High Reynolds Number Aero-Structural Dynamics (HIRENASD) transonic wind tunnel model is investigated through a time-domain, loosely-coupled, two-way Fluid–Structure Interaction (FSI) framework implemented in ANSYS Workbench, coupling ANSYS Fluent (density-based solver, SST k–ω turbulence model) with ANSYS Mechanical (Block-Lanczos modal extraction, Newmark-β transient integration) via ANSYS System Coupling. Steady-state CFD validation at Mach 0.8, Reynolds number 7×10⁶, and angle of attack 1.5° gives C _L = 0.3264, C _D = 0.0140, and C _M  = − 0.2657, agreeing with the NASA FUN3D benchmark within 1.87%, 3.45%, and 3.52%, respectively. Modal analysis predicts the fundamental bending frequency at 26.504 Hz, within 1.94% of the measured 26.0 Hz. Static aeroelastic computations from − 1.5° to + 4.5° angle of attack at Mach 0.7 and 0.8 give a lift-curve slope of approximately 0.107 per degree at M = 0.8 and a maximum wing-tip deflection of 12 mm, in close agreement with FUN3D. Dynamic flutter analysis, conducted at two representative flight conditions (M = 0.8, ρ = 0.2525 kg/m³ and M = 0.7, ρ = 0.50 kg/m³), identifies flutter velocities of 266.56 m/s and 230.46 m/s and flutter dynamic pressures of 8.97 kPa and 13.27 kPa, respectively, with both cases governed by first-bending-mode flutter. Because the two conditions differ in free-stream density as well as Mach number, the 47.9% higher flutter dynamic pressure at the lower Mach number reflects the combined effect of reduced aerodynamic stiffness and lower atmospheric density at altitude, consistent with the scaling q _f ∝ ρV _f ² . The validated framework offers a reproducible, industrially accessible pathway for preliminary flutter boundary assessment of transport-category aircraft wings using exclusively commercial CFD–CSD tools.