Analyzing low-speed rotor-fuselage interactions: a comparative study of simulations and flight-test data on H175

Abstract In this work, comparisons between simulations and measurements in flight are proposed across a range of low-speed flight conditions out of ground effect (true airspeed between 0 and 60\,kt) on an Airbus Helicopters H175 PT1 rotorcraft equipped with a 5-bladed Spheriflex\textregistered\rotor. Numerical results have been obtained by full-helicopter unsteady simulations relying on a single-rotor loose coupling approach between the Computational Structure Dynamics and Computational Fluid Dynamics parts, assuming blade elasticity and six degrees-of-freedom trim. One flight condition is tackled with both rigid-blade and elastic-blade modelling so as to highlight the influence of the blade softness on the results.\\The paper showcases good agreement between the simulation results and flight-test measurements regarding variations of main-rotor collective pitch, airframe attitude angles, rotor power and rotor loads with true airspeed. Airframe download is also numerically analysed. This work validates the simulation methodology and provides valuable data for improving helicopter performance prediction and design.