Rainbow Schlieren Deflectometry Apparatus for Diagnostics in Micro-Scale Flow Systems

摘要

A miniature rainbow schlieren deflectometry (RSD) system for non-intrusive diagnostics in micro-scale flows has been developed. The optical layout of the miniature schlieren system is similar to that of a macro-scale system, although the field of view is smaller by an order of magnitude. The system employs collimating and decollimating lenses of 6.35 mm diameter. The rainbow schlieren images are obtained at spatial resolution of 3.2 to 12μm. Helium jets and hydrogen jet diffusion flames from injectors of inside diameter ranging from 50 to 1100μm are investigated. The capability of the system is further explored by visualizing under-expanded nitrogen jets revealing details of the shock structures existing downstream of the jet exit.