Simulation of a Complete Helicopter: a CFD Approach to the Study of Interference Effects

Computations performed with the RANS solver ROSITA are compared with the experimental data gathered for the GOAHEAD full helicopter model. The tested configuration is made of a scaled NH90 fuselage, the ONERA 7AD rotor with a simplified rotor hub and a scaled BO105 tail rotor. The model is mounted on a support to match the wind tunnel conditions of the experiments. The considered flow conditions correspond to a cruise level flight. The general agreement between numerical and experimental results can be judged satisfactory, such as to validate the use of the ROSITA code for aerodynamic interference studies. In the second part of the study, numerical simulations of the 7AD isolated rotor, the NH90 isolated fuselage and the full GOAHEAD helicopter configuration are compared to analyze the interference effects between the rotor wakes and the fixed components of the fuselage and the influence of the fuselage on the rotor loads. The unsteadiness of the fuselage loads, especially on the tail boom and vertical fin, due to a highly turbulent wake is put in evidence, as well as the average incidence variation experimented by the horizontal tail plane. The influence of the fuselage on the main rotor loads appears to be localized.