Aerodynamic simulation strategies assessment for a fenestron in hover flight

¹ Airbus Helicopters SAS Marignane 13725, France
² CERFACS Toulouse 31057, France
³ Department of Aerodynamics, Energetics and Propulsion ISAE Sup'Aero, Toulouse 31400, France
⁴ Aerodynamics Department, Airbus Helicopters SAS Marignane 13725, France

Abstract

The Fenestron® has a crucial antitorque function and its sizing is a key point of the Helicopter design, especially regarding thrust and power predictions. This paper reports the investigations done on a full scale Dauphin Fenestron®. The objectives are, first, to evaluate the in§uence of some numerical parameters on the performance of the Fenestron®; and then, the flow is analyzed for a high incidence pitch, for which the rotor blade can experience massive boundary layer separations. Simulations are carried out on a single blade passage model. Several parameters are benched such as grid quality, numerical schemes, and turbulence modeling. A comparison with test bench measurements is carried out to evaluate the capability of the numerical simulations to predict both global performance (thrust and power) and local flows (static pressure at the shroud and radial profiles inside the vein). The analysis demonstrates the capability of numerical simulations to accurately estimate the global performance of the Fenestron®, including at high pitch angles. However, some discrepancies remain on the local flow, especially in the vicinity of the rotor shroud. A more detailed analysis of the local flow is performed at a blade pitch angle of 35^◦, with a particular interest for the blade tip region.