The schlieren interferograms used to be analyzed in a qualitative way. In this paper, by meansof the powerful computational ability and the large memory of computer; the image processing method isinvestigated for the ...The schlieren interferograms used to be analyzed in a qualitative way. In this paper, by meansof the powerful computational ability and the large memory of computer; the image processing method isinvestigated for the digitalization of an axisymmetric schlieren interferogram and the determination of thedensity field. This method includes the 2-D low-pass filtering, the thinning of interferometric fringes, theextraction of physical information and the numerical integration of the density field. The image processingresults show that the accuracy of the quantitative analysis of the schlieren interferogram can be improved anda lot of time can be saved in dealing with optical experimental results. Therefore, the algorithm used here isuseful and efficient.展开更多
Flows around rectangular cylinders with a series of width-to-heightratios are calculated by means of the Improved Finite Analytic Method (IFAM) andthe formation, development and shedding of vortices from the cylinders...Flows around rectangular cylinders with a series of width-to-heightratios are calculated by means of the Improved Finite Analytic Method (IFAM) andthe formation, development and shedding of vortices from the cylinders are simulatedsuccessfully. According to these results of time-dependent processes the physicalphenomena in the flows are investigated in detail, and the discontinuity of Strouhalnumber is explained in the case of the width-to-height ratio equal to 3.0. The numer-ical solutions here show good agreement with the experimental results. In addition,based on several hundreds of the calculated flow patterns a moving picture is madeby the computer image processing technology and recorded on a video tape, and thenthe vivid pictures of the physical process of vortex-shedding can be replayed later andanalysed in detail.展开更多
In the framework of the finite element method (FEM), a predictionmethod for the heating rate and the skin friction on a body surface is presented byusing the energy and momentum conservation equations respectively. Me...In the framework of the finite element method (FEM), a predictionmethod for the heating rate and the skin friction on a body surface is presented byusing the energy and momentum conservation equations respectively. Meanwhile, abrief analysis is made of the role the weighted functions play in the present work.展开更多
In this paper,analyzing the experiment data of multiple scanning probes in the arc wind-driven hypersonic plasma flows with the chaos dynamics method,we have obtained the power spectrum,the frequency wavenumber spectr...In this paper,analyzing the experiment data of multiple scanning probes in the arc wind-driven hypersonic plasma flows with the chaos dynamics method,we have obtained the power spectrum,the frequency wavenumber spectral density,the correlation dimension and Kolmogorov entropy of the flows,respectively.The distribution of correlation dimension and Kolmogorov entropy of the blunt cone wakes along the axis and the radius of the flows are presented successfully in the flows.The distributions clearly show the structure of turbulence and lamination in blunt cone wakes.Using the method of minimum Kolmogorov entropy,we observed the structure of the bow shock at far wake region in the blunt cone wakes.展开更多
文摘The schlieren interferograms used to be analyzed in a qualitative way. In this paper, by meansof the powerful computational ability and the large memory of computer; the image processing method isinvestigated for the digitalization of an axisymmetric schlieren interferogram and the determination of thedensity field. This method includes the 2-D low-pass filtering, the thinning of interferometric fringes, theextraction of physical information and the numerical integration of the density field. The image processingresults show that the accuracy of the quantitative analysis of the schlieren interferogram can be improved anda lot of time can be saved in dealing with optical experimental results. Therefore, the algorithm used here isuseful and efficient.
基金The project supported by the National Natural Science Foundation of China
文摘Flows around rectangular cylinders with a series of width-to-heightratios are calculated by means of the Improved Finite Analytic Method (IFAM) andthe formation, development and shedding of vortices from the cylinders are simulatedsuccessfully. According to these results of time-dependent processes the physicalphenomena in the flows are investigated in detail, and the discontinuity of Strouhalnumber is explained in the case of the width-to-height ratio equal to 3.0. The numer-ical solutions here show good agreement with the experimental results. In addition,based on several hundreds of the calculated flow patterns a moving picture is madeby the computer image processing technology and recorded on a video tape, and thenthe vivid pictures of the physical process of vortex-shedding can be replayed later andanalysed in detail.
基金The project supported by the National Natural Science Foundation of China (19889210)
文摘In the framework of the finite element method (FEM), a predictionmethod for the heating rate and the skin friction on a body surface is presented byusing the energy and momentum conservation equations respectively. Meanwhile, abrief analysis is made of the role the weighted functions play in the present work.
文摘In this paper,analyzing the experiment data of multiple scanning probes in the arc wind-driven hypersonic plasma flows with the chaos dynamics method,we have obtained the power spectrum,the frequency wavenumber spectral density,the correlation dimension and Kolmogorov entropy of the flows,respectively.The distribution of correlation dimension and Kolmogorov entropy of the blunt cone wakes along the axis and the radius of the flows are presented successfully in the flows.The distributions clearly show the structure of turbulence and lamination in blunt cone wakes.Using the method of minimum Kolmogorov entropy,we observed the structure of the bow shock at far wake region in the blunt cone wakes.
