Inverse Design of Airfoil using Elastic Surface Method in Viscous Subsonic and Transonic Flow

In this research, a new method called elastic surface algorithm is presented for inverse design of 2-D airfoil in a viscous flow regime. In this method as an iterative one, airfoil walls are considered as flexible curved beams. The difference between the target and the current pressure distribution causes the flexible beams to deflect at each shape modification step. In modification shape algorithm, the finite element equations of two-node Timoshenko beam are solved to calculate the deflection of the beams. In order to validate the proposed method, various airfoils in subsonic and transonic regimes are studied, which show the robustness of the method in the viscous flow regime with separation and normal shock. Also, three design examples are presented here, which show the capability of the proposed method

Micro-dimple rolling operation of metallic surfaces

The presence of micro-dimples on the surface of workpieces has long been known to have a positive impact on the friction control and wear resistance at the sliding surfaces. Several manufacturing processes have been used to generate micro-dimples on the surfaces of parts subjected to mechanical contact. Among those methods, metal forming-based techniques have received little attention in the literature mainly due to the challenges present in formation of sub-millimetre dimples using these processes. In this study, a micro-dimple rolling apparatus was developed to rapidly generate dimples with square cross-sections and side dimensions of smaller than 200 μm. The dimples were formed on the surface of a low-carbon structural steel and the effect of generated texture on friction and wear was studied through pin-on-disc test. In comparison with untextured surfaces, the results proved that the dimples formed by the proposed system could effectively reduce the friction coefficient by up to 23% and weight loss due to wear by up to 50%