Nanosecond laser ablation of the trapezoidal structures for turbomachinery applications

Correctly designed nature inspired micrometer size grooves i.e. riblets can be used to reduce drag. There exist several methods to manufacture these structures but all of them have their own problems and disadvantages, wherefore they are not perfectly suitable for all real industrial applications. Aim of this paper is to show how a short nanosecond pulse laser ablation can be applied in a micrometer size trapezoidal shape structures i.e. riblets manufacturing for a turbomachinery applications. It is shown that although the quality of the riblets, fabricated with this method, is not as good as with the best possible manufacturing methods, it is still enhancing the properties. Added to this, the processing speed is fast enough and acquisition costs of the system are economic so that method is suitable for the real industrial application. The wind tunnel studies indicate that the fabricated riblets on an airfoil reduce wall shear stress compared to a smooth airfoil without structuring.