In my experimental setup, fuel is sprayed in CVCC by a single-hole injector & images are captured with shadowgraphy technique. Now to determine spray penetration length, spray cone angle, spray velocity, spray area & spray volume, I would like to know the most suitable MATLAB codes to determine the early mentioned spray characteristics from my images?
I am not familiar with image processing in Matlab. So it will be much pleasure if I can get some hints or direction regarding this particular problem in Matlab.
Thanks in advance.
Today I will use our new software MIPAR (http://MIPAR.us), actually written in MATLAB (but does not need MATLAB to be installed to run), to devise an image processing recipe to find your features or interest, and determine which metrics of those found features would be most helpful in determining your traits of interest. Even if you don't end up using MIPAR long term, it could be very valuable in helping you determine the correct processing sequence for writing your own code.
Cheers,
John
For your basic image processing of spray images, you can try using imageJ code (https://imagej.nih.gov/ij/). This code also has an ability to measure spray characteristics but involves some manual work. However since it is a open source code written in JAVA platform, you can write your own code to make the batch process automated.
If you decide to use Matlab for this task, you can take the "Image Processing" Library - A very powerful tool for image postprocessing and also to get the penetration lenghts. What the image processing library does, when reading in an image is to create a data touple for every pixel. You end up with an RGB value for each pixel or a greyscale value for each pixel. You can then check this data touple for e.g.: penetration lengths.
The workflow for you would be something like:
1) Determine a certain threshold value (can be a color coding or a greyscale) that you still consider as spray --> This gives you the general separation of the background and the spray.
2) For the penetration length you could then check for the furthest point away from the nozzle where you still have that certain margin value defined in stage 1) --> Codewise this would mean to get the pixels that fulfill this requirement and then calculate a certain distance of this pixel to the nozzle origin. An even better idea is to use on of the evaluation standards of the Engine Combustion Network (ECN). They have standardised procedures of how to evaluate the penetration length of a Shadowgraph or Schlieren image. That would make your penetration lengths more standardized.
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