面向流场密度观测的聚焦纹影参数分析与光学设计OA

Focusing schlieren technique can capture and measure the transverse structure distribution of single-layer flow field,and plays an important role in flow field visualization and flow field parameter mea-surement.In order to ensure the flow field measurement effect of the focusing schlieren system in the ultra-high speed environment,the relationship between the depth of sharp focus and the flow deflection angle was derived from the flow field characteristic parameters,which included Mach number and shock angle,etc.The value ranges of the system sensitivity,depth of sharp focus and other indicators were determined according to system measurement requirements.On the basis of imaging principles and optical path charac-teristics,the optimization of the system parameters was completed,and the system performance was im-proved.The design of the large-aperture focusing schlieren system with a field of view of Φ300 mm was completed.By setting multiple structures,the source grid-knife edge grid imaging and the flow field target imaging under different object distances were realized.The focusing schlieren system was tested.When the ob-ject distance changed within 1 m,the imaging resolution of the system in the test area reached more than 23 lp/mm,and the depth of sharp focus was within 35 mm.The high-speed dynamic flow field was photographed with the system,and the display effect was good.The experimental results show that the designed optical sys-tem can meet the needs of fine observation of flow field density.