Manufacturing of functional riblet structures by profile grinding

In contrast to smooth surfaces, microstructured riblet surfaces can reduce the near-wall shear stresses of a turbulent flow by up to 10%. In the case of compressor blades, riblet structures with a width between 20 and 120 μm and a profile aspect ratio of 0.5 are required, which have to be machined directly onto the metal surface. In this paper, a profile grinding process with multiple V-shaped microprofiles has been applied for the manufacturing of such riblet structures on extensive surfaces. In fluid dynamic investigations in the oil channel and in the cascade wind tunnel, the ground riblet structures have proven their ability to reduce skin friction by up to 4%.