Abstract
Advances in additive manufacturing techniques potentially allow researchers to make their own airfoils designs for performance testing in a wind tunnel. Having broader access to physical airfoils creates interesting opportunities for educational purposes, for research on novel geometries and for validation of numerical simulations. This paper is meant to provide useful information for others who are looking to produce their own airfoil models via additive manufacturing. To this end, this study reports on lessons learned when using a 3D printer (Formlabs 3+) to make NACA 0015 models with varying chord lengths ranging from 42 mm to 151 mm. This printer utilizes the process of Stereolithography (SLA) where a UV laser cures resin in a process that is repeated layer by layer to achieve the desired 3D shape. Some of the models produced include pressure ports along the surface which can be connected to a bank of manometers for determining the pressure distribution around the airfoil. Many of the lessons learned pertain to the geometry of these pressure channels. Additionally, this study reports on a technique to minimize any residual surface roughness caused by the printing method. An experimental comparison was made between an airfoil made via an in-house 3D printer and an airfoil that was purchased from a wind tunnel company and made via more traditional manufacturing techniques. Tests were conducted in a subsonic wind tunnel with a test section of 30.5 cm x 30.5 cm cross sectional area. These tests include measurements of the pressure distributions, stall angle and the velocity contours on the upper surface of the airfoil at varying angles of attack and Reynolds numbers (100,000 to 200,000). The efforts made to date have resulted in strong agreement between the 3D printed airfoil and purchased airfoil. Thoughts on potential future improvements are also shared.