Research On Calculation Method Of High-speed Airflow Imaging In Double Vertical Wedge

The intake duct is one of the most important parts of a hypersonic aircraft.When the aircraft is flying at high speed,the air interacts with the wall surface,and a complicated flow field is generated in the intake duct.The shock wave and its reflection wave,vortex flow field,etc.,lead to the aircraft.Performance drops.The dual vertical wedges simulate the shock wave of the inlet boundary layer,explore the influence of different forms of boundary layer on the inlet,and provide support for the design of the inlet.Relying only on wind tunnel test results,the test cost is high.When the model changes,it needs to be re-tested for verification.The use of computational optics method is not only efficient,fast,and cost-saving,but also verifies the flow field calculation method.This article first introduces the research methods of hypersonic gas flow mechanism and the function,advantages and disadvantages of computational optics in hypersonic flow field.Then it introduces the two test methods used in this paper to verify the calculation method,nanoparticle scattering technology and focused schlieren technology,which are used in the research of shock wave interference and eddy current control in double vertical wedge.In the research of computational optical image processing methods,the optical physical model is transformed into a mathematical model,and two image processing methods are designed: the shortest distance method and the circumscribed cuboid method.The accuracy of the image adopts the direct assignment method and the first-order precision method.The first-order precision method has higher precision than the direct assignment method.For the verification of calculated images,a focused schlieren system was established.First,use a cross pressure gauge to verify the focusing ability of the constructed optical system.In the experimental verification of the double vertical wedges,two placement methods,horizontal placement and vertical placement,were used.The horizontal placement method focuses on the thickness of the boundary layer at the bottom of the model.The thickness of the calculated image boundary layer is 4?6mm,and the thickness of the test image is 4?5mm.The calculation result has certain reliability.The vertical placement method mainly observes the shock wave and its reflected wave position in the double vertical wedges.The quantitative analysis of the vertical placement method shows that the relative error between the horizontal and vertical directions is less than 3%.Comparing the calculated image with the test image in this state verifies the correctness of the theoretical calculation.