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In this paper, the complex flows around forward-flying helicopter blades are numerically investigated. Both the Reynolds-averaged Navier–Stokes (RANS) and the Detached Eddy Simulation (DES) methods are used for the analysis of characteristics like local dynamic flow separation, effects of radial sweeping and reversed flow. The flow was solved by a highly efficient finite volume solver with multi-block structured grids. Focusing upon the complexity of the advance ratio effects, above properties are fully recognized. The current results showed significant agreements between both RANS and DES methods at phases with attached flow phases. Detailed information of separating flow near the withdrawal phases are given by DES results. The flow analysis of these blades under reversed flow reveals a significant interaction between the reversed flow and the span-wise sweeping.

This paper presents the dynamic response of a rotating beam with elastic restraints in forward flight. The motion equations of the system are established by Hamilton’s principle. The structure model is established by Euler-Bernoulli beam theory. The influence of elastic restraints and centrifugal force is considered in the form of potential energy. The aerodynamic model is established by Greenberg theory and considered in the form of an external force. A modified Fourier series method is used to expand the displacement field. The stiffness intervals of boundary springs corresponding to the elastic restraints are determined by natural frequencies. The effects of advance ratios on the dynamic response of the system are studied. Then, the effects of spring stiffness in different directions are compared. The results show that the displacements and velocities of the rotating beam increase with the advance ratio. The displacement amplitudes of the rotating beam increase as the stiffness of boundary springs decrease.