We present an improved digital image processing(DIP)method to calculate the widths of single slits.Different from the traditional laser Fraunhofer diffraction experiment in college physical experiments,by performing f...We present an improved digital image processing(DIP)method to calculate the widths of single slits.Different from the traditional laser Fraunhofer diffraction experiment in college physical experiments,by performing fast Fourier transform,inverse fast Fourier transform and the nonlinear leastsquare fitting on the diffraction pattern taken by a camera,the DIP method can quickly return an analytic expression,whose period is used to calculate widths of single slits.By comparing the measured results by the DIP method and the successional difference(SD)method,we find that for a single slit whose width is 60372μm,the DIP method is more accurate.Experimental results show that for single slits with widths between 40μm and 160μm,the relative error of the DIP method is less than 2.78%.Also,the DIP method can be used to measure the diameter of filament and fibres online in real time.展开更多
As the width-thickness ratio of the discrete nozzle atomizer’s discrete hole greatly influences the loss of atomizing gas flow rate,the discrete nozzle atomizer was transformed into an annular slit atomizer with the ...As the width-thickness ratio of the discrete nozzle atomizer’s discrete hole greatly influences the loss of atomizing gas flow rate,the discrete nozzle atomizer was transformed into an annular slit atomizer with the same total nozzle outlet area.A numerical simulation study on the effect of various parameters on the atomization in the annular slit atomizer was carried out by coupling both the large eddy simulation(LES)and volume of fluid(VOF)model,which is based on the applicability of LES in capturing the breakup behavior of transient liquid droplets and the advantage of VOF method in directly capturing the phase interface.The simulation results showed that the increase in the atomization pressure makes the gas gain higher momentum,while the increase in the nozzle intersection angle decreases the distance between the nozzle exit and the computational domain axis.The increase in these two variables results in enhancing the gas-liquid interaction in the primary atomization zone and the formation of more aluminum droplets simultaneously.It is considered that the atomization effect becomes better when atomization pressure is 2.5 MPa,and the nozzle intersection angle is 60°.Industrial tests showed that the aluminum powder prepared by the optimized annular slit atomizer has a finer mean particle size and a higher yield of fine powder.The numerical simulation results agree well with the industrial test data of the powder particle size.展开更多
基金National Natural Science Foundtion of China(No.11435011)Young Teachers Fund of Nanjing Institute of Technology,China(Nos.QKJ201907 and QKJ201908)+2 种基金China Scholarship Council(No.201708320319)Postgraduate Research and Practice Innovation Program of Jiangsu Province,China(No.KYZZ16-0349)Qing Lan Project of Jiangsu Province,China。
文摘We present an improved digital image processing(DIP)method to calculate the widths of single slits.Different from the traditional laser Fraunhofer diffraction experiment in college physical experiments,by performing fast Fourier transform,inverse fast Fourier transform and the nonlinear leastsquare fitting on the diffraction pattern taken by a camera,the DIP method can quickly return an analytic expression,whose period is used to calculate widths of single slits.By comparing the measured results by the DIP method and the successional difference(SD)method,we find that for a single slit whose width is 60372μm,the DIP method is more accurate.Experimental results show that for single slits with widths between 40μm and 160μm,the relative error of the DIP method is less than 2.78%.Also,the DIP method can be used to measure the diameter of filament and fibres online in real time.
基金the financial support provided by the National Natural Science Foundation of China(U21A20317)supported by High-Performance Computing Center of Wuhan University of Science and Technology.
文摘As the width-thickness ratio of the discrete nozzle atomizer’s discrete hole greatly influences the loss of atomizing gas flow rate,the discrete nozzle atomizer was transformed into an annular slit atomizer with the same total nozzle outlet area.A numerical simulation study on the effect of various parameters on the atomization in the annular slit atomizer was carried out by coupling both the large eddy simulation(LES)and volume of fluid(VOF)model,which is based on the applicability of LES in capturing the breakup behavior of transient liquid droplets and the advantage of VOF method in directly capturing the phase interface.The simulation results showed that the increase in the atomization pressure makes the gas gain higher momentum,while the increase in the nozzle intersection angle decreases the distance between the nozzle exit and the computational domain axis.The increase in these two variables results in enhancing the gas-liquid interaction in the primary atomization zone and the formation of more aluminum droplets simultaneously.It is considered that the atomization effect becomes better when atomization pressure is 2.5 MPa,and the nozzle intersection angle is 60°.Industrial tests showed that the aluminum powder prepared by the optimized annular slit atomizer has a finer mean particle size and a higher yield of fine powder.The numerical simulation results agree well with the industrial test data of the powder particle size.
