Test And Reconstruction Of Metal Bridge Foil Ignition Temperature Field Based On Schlieren Method

This paper mainly introduces the optical experimental system needed to test the temperature field of the object to be measured.Through the combination of schlieren and interference method,the temperature change of the same flow field is synchronically collected.The basic principle of schlieren quantitative measurement technology and the basic principle of interference measurement are used to test and reconstruct the detonation temperature field of metal bridge foil.In order to reconstruct the temperature field,the first object to be measured in this topic is a candle,and the temperature change of the candle flame temperature field is measured.The method used in the schlieren system in this paper is to combine the change of the gray value of the schlieren image with the offset of the knife edge through the calibration schlieren method,which is actually equivalent to combining the size of the area of the unblocked light source image with the size of the gray value of the image.Then the distribution of temperature field is calculated according to the derived formula between Gladstone-Dale law and gas state equation.The method used in the interference system is to multiply the obtained flow field picture by the reference light and then do Fourier transform to get the spectrum diagram,and then filter the +1level spectrum through the window filter to get the +1 level spectrum diagram,and then carry out two-dimensional Fourier inversion transformation to get the wrapped phase diagram,and unwrap it to get the original phase distribution.The distribution of refractive index is obtained by Abel inverse transformation,and the temperature field distribution of flame is derived.By comparing the measurement of candle flame temperature in a reference paper of North University of China,the temperature measured by Schlieren system and interferometric system agree with each other,so the algorithm is feasible.The Schlieren + interference optical experiment system,the combination of two high-speed cameras and the high-voltage initiation system of metal bridge foil were used to test the ignition temperature field of metal bridge foil,and the schlieren image and interference image containing the temperature field information of metal bridge foil were obtained simultaneously by the two optical paths to complete the test and reconstruction of the temperature field.Based on the test theory of candle flame temperature field and the image processing method of the obtained experiment,the detonation temperature field information of metal bridge foil is calculated,and the test result of temperature field is obtained.The results are as follows: Under the condition of room temperature of 20℃,schlieren quantitative measurement technology and interferometry technology are combined to measure the temperature field of the measured object at the same time.Through analysis,when the excitation voltage of the high-voltage priming system reaches 1500 v and the high-voltage current reaches 2k A,The temperature field after the diffusion of plasma produced by the detonation of metal bridge foil is basically in the range of 1000K～2500K.