Research and Development of Three-Dimensional Controll Diffusion Airfoil

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To develop an advanced technology of highly loaded axial compressor stage with high efficiency and sufficient surge margin, end-bend/swept blades for both rotor and stator, which aim to improve endwall boundary layr flows, were designed and tested, and its effectiveness was verified by low-speed model testing of a stage, internal flow survey and a flow diagnosis by 3D Navier-Sotkes simulation.Test section consists of four cascades, i.e., inlet guide vane-stator-rotor-stator in order to simulate the development of endwall boundary layr. For both rotor and stator, the baseline blades which has slightly high loading and end-bend/swept blades which has the same loading as the baseline blades are designed and tested. Internal flow survey were made by traversing a 5-hole pitot tube in the radial and circumferential direction. Further, the flow field relative to the rotor was measured with a hot wire.Concluded remarks are as follows : Firstly, the efficiency at design flow rate with the use of end-bend/swept blades for both rotor and stator was 1.1 percent higher than with the use of baseline blades. Secondly, the surge margin defined at the rotor stall inception point was 19 percent larger with the use of end-bend/swept blades. Thirdly, from the internal flow survey, it was found that the improvement of stage performance resulted from the activation of endwall boundary layr with the use of end-bend/swept blades.Further, from the 3D Navier-Stokes analysis, it was found that the calculated results explained an effect of the end-bend/swept blades for suppressing a secondary flow and a flow separation.