1.2 m large-field focusing schlieren technique

In the conventional “Z” structure schlieren technique, due to the limitation of large-size optical element materials and processing technology, the size of the test field is usually less than 1 meter. In order to show the flow field of a large-scale model in a wind tunnel, the focusing schlieren technique is proposed to show the flow field in the 1.2 m test area. According to the imaging principle, the large size Fresnel lens are replaced by a matrix light source. After solving the key technologies such as the engineering design of large-size light source splicing, the development of large-diameter focusing lens and the production of high-definition imaging screen, two sets of focusing schlieren systems with the test field of view of 1.2 m × 1.2 m were established, and the schlieren images of the hypervelocity flow field with high sensitivity were obtained in the wind tunnel. The flow visualization with larger field is expected to be realized through the splicing of larger size light sources.