Development of Aeroelastic Analysis Code for Rotor Blade of Medium-Class Utility Helicopter in Forward Flight

Rotorcraft are susceptible to vibration and aeroelastic instability due to the characteristics of their rotor systems, potentially causing structural damage and loss of control. While comprehensive analysis codes exist, they often rely on Lifting-Line Theory(LLT) and free-wake models, limiting their ability to account for complex blade geometries. To address these challenges, this study developed the aeroelastic analysis code for the rotor blade by loosely coupling an aerodynamic model based on the Nonlinear Vortex Lattice Method(NVLM) and Vortex Particle Method(VPM) with a structural model utilizing Geometrically Exact Beam Theory(GEBT). The aerodynamic and structural model of the developed code was validated using the HART II rotor model in forward-flight conditions. Using the rotor blades of medium-class utility helicopter, aeroelastic analysis was conducted at forward flight speeds of 40, 100, 140 knots. The mode analysis results and the tip deformation were examined, and aerodynamic and wake analysis were conducted depending on structural deformation. The results demonstrated the capability of the aeroelastic analysis code to perform coupled aerodynamic-structural analysis, accounting for elastic deformation and its effects on rotor performance in forward flight for the medium-class utility helicopter.