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A computational model of a wind tunnel (WT) with a special experimental rig has been developed directly for studying unsteady aerodynamic characteristics of a wing section with a helicopter blade profile. The model was constructed using CFD (Computational Fluid Dynamics) methods based on the URANS approach (Unsteady Reynolds Averaged Navier Strokes Equations). Therefore, the aerodynamic characteristics of the airfoil can be determined, taking into account influence of the WT walls such as walls perforation and various configurations of the experimental rig. Simulation of the flow around the wing section with the SC1095 airfoil in steady and unsteady settings is performed. The flow features in the working section of the WT and the experimental rig are analyzed. For a particular case, the calculation method was validated in a 2D formulation on the basis of available experimental data. The developed model can be used to refine the methods of processing experimental data, taking into account the individual characteristics of the WT and the experimental rig configuration.

The paper is focused on numerical modeling of the aerodynamic characteristics of a full-scale coaxial main rotor in hover. The simulation was performed using two approaches of computational fluid dynamics (CFD): the original free wake model (FWM) developed by the authors and the unsteady Reynolds-averaged Navier–Stokes (URANS) equations method based on the Ansys Fluent software. The structure of the rotor vortex wake, flow images, vorticity and induced velocity fields, total and distributed aerodynamic characteristics of the rotor, including the rotor performance and figure of merit diagrams, have been analyzed. A comparison between FWM/URANS based calculations and calculated/experimental data by other authors has been performed. A satisfactory match of these data confirms reliability of used methods when modeling the aerodynamic characteristics of coaxial rotors. The FMW demonstrates a significant advantage in speed and resources intensity when calculating the total aerodynamic characteristics of a coaxial rotor. The URANS method makes it possible to model with significant accuracy the effects associated with the blade vortex interactions and pressure distribution over the blade surface. Finally, conclusions about most effectiveness of joint application of considered methods in solving complex problems of coaxial rotor aerodynamics has been made.

The presented work is dedicated to the numerical study of the aerodynamic characteristics of the helicopter rotor. Two approaches to modeling of the rotor are applied: the free wake model developed by the Authors with using steady airfoil characteristics and the Unsteady RANS method based on the Ansys Fluent software. The modes of hovering and horizontal flight in the range of advancing ratio μ = (0-0.45) are considered. The shapes of the rotor wake, the distributions of the normal force coefficient and the fields of inductive velocities for all considered flight modes are calculated. For a particular case with μ = 0.25 there is a comparison with experimental data. The time needed for calculation of the applied methods is estimated. Accuracy of the used methods in the framework of the solved task is analysed with taking into account used models assumptions. It is shown that in the range of μ = (0-0.25) the free wake model provides a fast and reliable calculation of the aerodynamic characteristics of the helicopter rotor. For values of μ > 0.35 it is necessary to take into account the unsteady characteristics of the airfoil.