In the three-dimensional(3D) contour measurement,the phase shift profilometry(PSP) method is the most widely used one.However,the measurement speed of PSP is very low because of the multiple projections.In order to im...In the three-dimensional(3D) contour measurement,the phase shift profilometry(PSP) method is the most widely used one.However,the measurement speed of PSP is very low because of the multiple projections.In order to improve the measurement speed,color grating stripes are used for measurement in this paper.During the measurement,only one color sinusoidal fringe is projected on the measured object.Therefore,the measurement speed is greatly improved.Since there is coupling or interference phenomenon between the adjacent color grating stripes,a color correction method is used to improve the measurement results.A method for correcting nonlinear error of measurement system is proposed in this paper,and the sinusoidal property of acquired image after correction is better than that before correction.Experimental results show that with these correction methods,the measurement errors can be reduced.Therefore,it can support a good foundation for the high-precision 3D reconstruction.展开更多
This paper analyzes the correctly-expanded supersonic jet from a convergent-divergent axisymmetric nozzle by using numerical simulation of turbulent flow.And the calculated density distributions in this flow are compa...This paper analyzes the correctly-expanded supersonic jet from a convergent-divergent axisymmetric nozzle by using numerical simulation of turbulent flow.And the calculated density distributions in this flow are compared with the present experimental data using rainbow schlieren deflectometry.The value of the density from the experimental data agrees well with the results calculated by this simulation.Therefore,the present method of the measurement using rainbow schlieren deflectometry is useful for the measurement of the density of the correctly-expanded supersonic jet.展开更多
基金supported by the National Natural Science Foundation of China(Nos.60808020 and 61078041)the National Science and Technology Support(No.2014BAH03F01)+1 种基金the Tianjin Research Program of Application Foundation and Advanced Technology(No.10JCYBJC07200)the Technology Program of Tianjin Municipal Education Commission(No.20130324)
文摘In the three-dimensional(3D) contour measurement,the phase shift profilometry(PSP) method is the most widely used one.However,the measurement speed of PSP is very low because of the multiple projections.In order to improve the measurement speed,color grating stripes are used for measurement in this paper.During the measurement,only one color sinusoidal fringe is projected on the measured object.Therefore,the measurement speed is greatly improved.Since there is coupling or interference phenomenon between the adjacent color grating stripes,a color correction method is used to improve the measurement results.A method for correcting nonlinear error of measurement system is proposed in this paper,and the sinusoidal property of acquired image after correction is better than that before correction.Experimental results show that with these correction methods,the measurement errors can be reduced.Therefore,it can support a good foundation for the high-precision 3D reconstruction.
文摘This paper analyzes the correctly-expanded supersonic jet from a convergent-divergent axisymmetric nozzle by using numerical simulation of turbulent flow.And the calculated density distributions in this flow are compared with the present experimental data using rainbow schlieren deflectometry.The value of the density from the experimental data agrees well with the results calculated by this simulation.Therefore,the present method of the measurement using rainbow schlieren deflectometry is useful for the measurement of the density of the correctly-expanded supersonic jet.
