Flow Visualization of Jet Test Using Background Oriented Schlieren in Altitude Test Facility

摘要

The Background Oriented Schlieren (BOS) method requires only a digital still camera with adequate resolution and a background pattern. It holds substantial potential as a practical engineering and scientific research tool. The present work is a application of the BOS technique to a more complex flow. For the supersonic flow, the application of non-intrusive and quantitative techniques is necessary to probe the locations of shock waves, expansion fans and shear layers in order to determine the flow properties. Three tests were carried out in the test chamber equipped with a Laval nozzle designed with a Mach number of 3.0, and the test articles are a five-hole probe, a wedge and an intake. A multi-step vector-analysis code (written in MATLAB) was used to analyze the image pairs (no-flow and flow). Through contrasting the results of three tests which are from BOS and other methods (flow field calibration, surface static pressure measuring and CFD), it is proved that the BOS technique can be used for the visualization of supersonic jet flows in altitude test facility.