Macroscopic Parameter Analysis And Measurement System Design Of Fuel Spray Image

In order to study the combustion characteristics of dimethyl ether substitute fuel on the engine,this article based on the spray experiment conducted by the team in the early stage,selected a good quality spray image from a large number of spray pictures for research,using image processing and parameter measurement procedures to obtain spray oil The macroscopic characteristic parameters of the beam,providing a theoretical basis for the subsequent research of dimethyl ether substitute fuel.This article focuses on the analysis of image processing algorithms and the study of parameter measurement methods.First,in terms of image enhancement,the objective evaluation index of the image is introduced,and compared with several image enhancement algorithms,this paper chooses the background difference method combined with contrast linear broadening to better enhance the image contrast.Secondly,in terms of noise filtering,four filtering methods such as median and mean filtering are compared respectively,and finally,an improved median filter with better protection for the boundary of the oil bundle is selected for filtering and denoising.Then,in terms of threshold segmentation,according to the actual characteristics of the spray oil bundle,the OTSU method is used for the early spray image,and the partial block threshold score algorithm is used for the late spray image.At the same time,detailed experimental verification of the block method was performed,and the results showed that the effect of threshold segmentation was the best when the image was divided into 4 * 2 small blocks.Then,in terms of measuring the spray cone angle,the advantages and disadvantages of the Hough transform and the least square method are analyzed to design the oil bundle boundary data fitting algorithm in this paper.The results show that the spray cone angle measured by the algorithm in this paper has better symmetry and higher accuracy.Thirdly,the program was used to measure the macro characteristics parameters under different back pressures,different initiation pressures,and different apertures,and the changes were analyzed to obtain the following conclusions:(1)Increase the nozzle diameter,spray cone angle,lateral penetration distance,and The spray area is increased,but it has little effect on the axial penetration distance.In the early stage of spraying,the area of the spray oil bundle and the injection time have a linear relationship.As the injection time advances,the smaller the aperture,the sooner the linear relationship is released.(2)Increasing the back pressure of the constant volume bomb is conducive to the increase of the spray cone angle,but after the environmental back pressure is increased to a certain value,the increase of the spray cone angle will not be significant.At the same time,increasing the back pressure will reduce the development speed of the front of the fuel bundle,and the higher the back pressure,the sooner the front of the fuel bundle reaches the maximum speed.(3)Increasing the injection pressure will promote the development of spray cone angle,penetration distance and spray area,and the spray area will increase approximately linearly with time.Finally,based on the MATLAB / GUI module,a spray macro characteristic parameter measurement system was developed to facilitate users to measure,analyze,and save data,saving a lot of manpower and material resources.