Research On Background Schlieren Technique For Aerodynamic Effect Detection

Background oriented schlieren(BOS)is a new type of schlieren imaging technology.Its experimental process is simple and convenient.Just take two pictures with or without refractive index gradient field in the area to be observed,and use image processing software to process it.You can get the schlieren image of the area to be observed.Compared with traditional schlieren technology,it has the advantages of simple structure,light device and low cost,and can realize schlieren imaging under large field of view and complex conditions,which is the current research focus of schlieren imaging technology.This article will use the background oriented schlieren to detect the aerodynamic effects of high-temperature and high-speed airflow,and provide a basis for identifying high-speed targets.The work content of this article has the following two aspects:First,the research background of the background oriented schlieren is elaborated,the basic principle of the background oriented schlieren and the core image processing method—PIV(Particle Image Velocimetry)particle image velocity measurement algorithm are studied,and finally the corresponding research content of this article is improved to make it It can produce better schlieren imaging effect under different background conditions.Second,the background schlieren imaging optical path was built on the optical platform,and the background schlieren technology experiment to detect aerodynamic effects was conducted.In view of the great demand in the field of aeronautics for the detection of aerodynamic optical effects under real flight conditions of aircraft,the system has carried out relevant experimental research.In the background of the scatterplot,the hot air flow above the candle flame is used to pass through the aircraft model to simulate the flight status of the aircraft,detect the movement of the air flow when passing through the aircraft,and obtain its background schlierenimage for analysis.Using a hot air gun and an alcohol blowtorch to simulate the exhaust turbulence of the aircraft during flight,the background texture image was also analyzed to verify whether the background texture technology can be used to capture high-speed targets.Replace the scatterplot background with a natural background,such as grass and branches,and perform the same experiment as above to obtain the background schlieren image for analysis,and explore whether the background oriented schlieren can meet the actual detection needs under different background conditions.Through the experimental exploration in this paper,it is verified that the background oriented schlieren is capable of detecting high-speed moving targets,and in the case where the natural environment is used as the background oriented schlieren,the purpose of detecting high-speed targets can also be achieved,which is a large field of view The background schlieren detection provides a basis.