Experimental and simulation research on the interface instability in gas jet forming

Abstract

The phenomenon of interface instability occurred in the gas jet forming of mirror blank has been analysed in this research. Through numerical simulation and the theoretical calculation, the critical velocity of interface instability between epoxy resin and gas jet is 4.855 m/s. Through experiments and surface morphology tests, the influence of interface instability on mirror blank forming is analysed. It is concluded that the interface instability at a low gas flow rate will lead to the increase of the surface roughness of mirror blank, while the interface instability formed at a high gas flow rate will bring a periodic surface wave of epoxy resin, which makes it difficult for the mirror blank to form an expected curved surface. By calculating the gas jet rate when the interface instability occurs, this research aims to examine the causes and critical conditions of interface instability, to prevent it from happening in the process of gas jet forming.