Speed Detection in Wind-tunnels by Processing Schlieren Images

Schlieren imaging in wind-tunnels is extensively utilized to study the effects of air on an airplane surface. One of the interesting subjects for research is to study the effects of speed change on the airplane surface. Speed change results in occurrence of shock waves, which are visualized as lines on Schlieren images. In this paper, we study the problem of detecting speed of after occurrence of a shock wave. For this, a two-level scheme is proposed which involves Schlieren image processing and classification. In the first stage, favorite features are extracted from a Schlieren image, which are represented as a feature vector. These features are related to the power and impact of the shock wave and are extracted through the proposed image processing schemes. In the second stage, a classification system is proposed, which categorizes Schlieren images according to their features. Each class represents one specific case of speed change. Experimental results are conducted in Wind-Tunnel laboratory of the Malek Ashater University of Technology. For evaluation, we have taken images, which lie in five classes. The results of applying the proposed system to the test images show a perfect accuracy rate.

کلیدواژه ها:

Classification ، Schlieren Imaging ، Image Processing ، Feature Vector ، Wind-tunnel