Study on drag reduction performance of blade milling surface pit topography

Abstract This paper proposes a drag model and a numerical simulation model of turbulent boundary layers , focusing on a single surface topography unit designed for flow control and drag reduction. Using the shape and depth of the topographic unit as variables, the flow characteristics around the unit at different flow velocities are analyzed. By examining flow-field parameters such as total pressure loss and turbulent kinetic energy variation, the effect of the unit’s placement on a blade structure on boundary-layer loss characteristics is investigated. Furthermore, by varying the spanwise and streamwise spacing of the topographic units on the blade surface, the influence of their arrangement on aerodynamic parameters—including the axial distribution of blade loss and the total pressure loss at the outlet section—is studied. The results show that the flow state within the turbulent boundary layer is directly affected by the milling parameters. A quadrilateral topographic unit with a depth of h = 0.2 mm delivers the best drag reduction performance, with a maximum drag reduction rate of 7.9%. Arranging units with a spanwise spacing of 1.2 mm over the range of 0% to 25% of the axial chord length on the blade suction side minimizes the blade capacity loss and achieves the optimal drag reduction effect.