Aerodynamic efficiency inspection of micro-structured functional surfaces

The reduction in aerodynamic drag leads to reduced fuel consumption and, therefore, a reduced CO2 usage. This can be achieved by applying micro-structured functional surfaces, like riblets, on e.g., aircraft wings. The fuel reduction efficiency depends on the structural integrity of the riblets and has to be assessed regularly. For this purpose, we propose a portable photometric inspection tool that detects defects and infers the remaining aerodynamic efficiency. The acquired foils are inspected with a tailored statistical data processing method, which provides defect percentages. We implement a percentages-to-efficiency mapping based on measurements performed with an efficiency test bench and riblet foils with known defect percentages. The approach is tested on foils with known defect percentages that were not used before. These tests show that it is possible to assess aerodynamic efficiency with a purely optical inspection tool.