Abstract
An underexpanded jet is well-known as one of supersonic jets and widely utilized in industlies, such as an assist gas for laser machining and a cooling jet in glass-tempering process. In these processes, the underexpanded jet impinges on the work piece and the jet violently oscillates, which leads to a complex flow field with a noise of high sound pressure level. The oscillation of jet and the noise are critical problems concerning manufacturing efficiency. So this paper focuses on the relation between the jet oscillation and the location of the work piece and especially discusses strength of shock formed in jet. The flow field is visualized using shadowgraphy and the pictures are analyzed. The feature of the jet structure is measured, such as locations of plate shock and oblique shock and strengths of shocks.
