Improved rotor aeromechanics predictions using a fluid structure interaction approach

The measured HART (Higher harmonic control Aeroacoustic Rotor Test) I data in a descending flight condition is validated using various numerical approaches including CFD (Computational Fluid Dynamics)-CSD (Computational Structural Dynamics) coupled analyses with isolated rotor model and rotor-fuselage model. A CSD-alone approach is also conducted for reference purpose. A three-dimensional (3D) compressible RANS (Reynolds Averaged Navier Stokes) flow solver is employed for the CFD code. Good convergence behavior is found for both coupling analyses. It is observed that the rotor-fuselage model improves the correlation significantly as compared with the measured data. Specifically, the highly oscillating section normal forces signals marked in the advancing and retreating sides of the rotor are captured accurately. Detailed harmonic analysis and the gradient of the airloads signals are observed to prove the validity of the prediction model. The upwash induced due to a fuselage as well as the increased vorticity over the rotor flow fields are attributed to the enhanced correlation. The predicted blade elastic motions and structural moments also indicate improvements with the present rotor-fuselage model.