Photogrammetry in oil-film interferometry

The application of photogrammetry to the measurement of skin friction using oil-film interferometry is discussed. Oil-film interferometry and photogrammetry are first described to justify the need for photogrammetry, and then the method is applied to two flows. The results indicate that when model curvature is high or the camera-to-model distance is short, large uncertainties (of the order of 10%) in skin friction can be introduced if photogrammetry is not applied. For most applications demanding high-accuracy skin-friction measurements, approaches such as those described in this article should be considered.