Effects of Nozzle-Lip Length on Reduction of Transonic Resonance in 2D Supersonic Nozzle

摘要

It is known that the transonic resonance takes place, in divergent section of supersonic nozzle, similarly to the longitudinal acoustic resonance of a conical section with one end closed and the other end open. And the “conical section” is similar to the separation zone between shock wave and nozzle exit in divergent part of supersonic nozzle. The present paper describes an experimental work to investigate a reduction of transonic resonance by change the lip length of 2-Dimensional converging-diverging nozzle. In this study, the nozzle pressure ratio varied in the range between 1.4 and 2.2 as shock-containing flow conditions. And a Schlieren optical system was used to visualize the flow fields. Especially, by using a high-speed video camera, we obtained the shock position at that moment. And acoustic measurements were employed to compare the sound spectra level of each experimental case. And it was found that the transonic resonance was decreased when a large separation zone located at the side, where a nozzle-lip attached to nozzle exit additionally. In this case, the amplitude of shock oscillation and wall static pressure oscillation were also decreased. ?