NUMERICAL SIMULATION OF PARALLEL AIRFOIL/VORTEX INTERACTION USING A ZONAL HYBRID RANS/LES METHOD

Helicopter Blade-Vortex Interaction (BVI) generally occurs under certain conditions of powered descent or during extreme manoeuvring. The vibration and acoustic problems associated with the interaction of rotor tip vortices and the following blades is a major aerodynamic concern for the helicopter community. Numerous experimental and computational studies have been performed over the last two decades in order to gain a better understanding of the physical mechanisms involved in BVI. The most severe interaction, in term of generated noise, happens when the vortex fllament is parallel to the blade, thus afiecting a great portion of it. The majority of the previous numerical studies of parallel BVI fall within a potential ∞ow framework therefore precluding vortex-induced ∞ow separation. Some Navier-Stokes approaches using dissipative numerical methods in conjunction with RANS-type turbulence models have also been attempted, but with limited success. In this work, the situation is improved by increasing the fldelity of both the numerical method and the turbulence model. A kineticenergy conserving flnite-volume scheme using a collocated-mesh arrangement, specially designed for simulation of turbulence in complex geometries, was implemented. For the turbulence model, a costefiective zonal hybrid RANS/LES technique is used. The concentrated tip vortex is not attenuated as it is convected downstream and over a NACA-0012 airfoil. The lift, drag, moment coe‐cients induced by the passage of the vortex are monitored in time and compared with available experimental data.