Numerical Assessment of the airfoils EDI-M109 and EDI-M112 by 3D CFD calculations of the 5-bladed INROS rotor in Hover and Forward Flight

Numerical investigations of a helicopter rotor in hover and forward flight are presented to evaluate the benefit of the new rotor airfoils EDI-M109 and EDI-M112. In order to minimize the impact of numerical uncertainties the results are compared with computations of a reference rotor using rotor blades with the identical planform and twist, but different airfoils of the OA-series. In all cases investigated the power requirements of the rotor with EDI-airfoils are lower than for the reference rotor with OA-airfoils. Comparisons of fully turbulent calculations and calculations including transition prediction indicate that the performance enhancements of the new EDI-airfoils are based only to a lesser extent on the enlargement of the laminar zones. For the hover calculations a RANS method was applied. The forward flight calculations are computed with coupled approach of an URANS method and a comprehensive rotor simulation code in order to trim the rotors to identical flight conditions and to consider the elastic deformations of the blades. For high accurate numerical results the laminar-turbulent transition is considered by empirical criteria and the influence of the laminar areas are investigated by comparisons with fully turbulent computations