| Biodiesel,as one of the renewable resources ,is the focus issue on which many researchers have studied recently. Diesel engines, furnished by this one, are much more powerful, efficient and less carbon exhaust emission than other kinds. Since the size and quantity of spry-drops is the important index to appraise the fuel-spray's quality and characteristic, the measurement of spry-drops has significant meanings. Currently, digital camera method, among of the varied spray-drops measurements, has become much popular than others for its cost saving and operate facility. As a result, this thesis, which based on images that obtained by digital camera, obtained the size and quantity of the spray drops by adopting the digital image processing techniques, esteemed as a great investigation on the study of the spray drops measurement.The comparison of spray characteristic between diesel and diesel-biodiesel blend fuel was made by using high resolving power digital camera. The results showed that, with the increase of biodiesel mixed ratio, the fuel viscosity was increase, the spray angle was decreased, and the Sauter mean diameter was increased. Sauter mean diameter of pure diesel was slight larger than that of MB24 because of pure diesel's larger relative size range and dispersion boundary. Sauter mean diameter of MB24 was the smallest because it was diluted by ethanol, and so spray quality of MB24 was improved evidently. It could be seen by the droplet size number distribution that all fuel curve peak was located at 14, that was so say, the smaller size droplet took a large percentage. All the curve peaks of droplet size number distribution went down evenly and gently with the increase of biodiesel mixing ratio, which indicated that the fuel droplet size number distribution in spray became even with the increase of fuel viscosity. The diameter of the droplet that reached a certain cumulative volume increased with the increase of biodiesel mixing ration, which indicated that the number of large drops increased.This thesis study the complete course of the image processing and analysis based on the characteristic of the fuel spray drops-image. The main algorithm is as follows, to process the integrate image and divided image with threshold method; use the open operation of the morphology method can reduce the noise of the image and also can depart the adhesion drops in the drops-image; use five edge detector to detected the edge of the images, to a certain extent it is advantageous in number counts. Meanwhile, It has realized between the image element unit and unit of length's conversion relations, and has realized the program processing the spray drops image, output statistics diagram of curves, but the diameter of 7 and 14 drops have big inaccuracy between computer processing and manual processing, It Needs to carry on the coefficient adjustment to the program. The results after adjustment is very close to the manual process results. Use computer program to process the image can save much time, has the realistic significance. |
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