Experimental Visualization And Measurement Of Shock Reflection Structure

Shock reflection is a common phenomenon in high-speed flow,and it is also a typical structure of the interaction between shock wave and boundary layer.It has very important significance in the aerodynamic design of aircraft.Shock reflection phenomenon can be divided into regular reflection and mach reflection according to the type of flow field,where regular reflection is composed of incident shock and reflected shock;Mach reflection is composed of incident shock,reflected shock,mach rod and slip line.When the flow field conditions change,the shock reflection structure transitions between regular reflection and mach reflection,and the shock reflection hysteresis will occur.Combining with the present research status at home and abroad,this paper uses experimental methods to display and measure the flow field structure of shock wave reflection.First,based on the shear-sensitive liquid crystal coating measurement technology,this paper displays and measures the high-speed flat-plate jet structure and wall friction.By comparing with oil flow technology,it demonstrates the ability of shear-sensitive liquid crystal coating technology in supersonic flow field structure characterization and friction field visualization.In the same flow field structure,the results of the shear-sensitive liquid crystal coating are calibrated by Preston tube technology,and the fitted curve of the wall friction force and the image color value is given.The more accurate calibration results in the high-speed measurement experiment are obtained.Secondly,based on high-speed schlieren measurement,shear sensitive liquid crystal and CFD numerical simulation,the structure of supersonic internal shock wave reflection was experimentally displayed and measured.The conversion of cross-shock reflection and incident shock reflection was obtained respectively.In the incident shock reflection flow field,the shear sensitive liquid crystal is used to obtain the separation flow field structure and friction force changes of regular reflection and mach reflection under the influence of strong incident shock wave,and the measured results are in good agreement with schlieren image.