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Development of radial velocity measurements for high pressure fuel injection

Konstantinos Ntatsis
Göteborg : Chalmers tekniska högskola, 2017. Examensarbete - Institutionen för mekanik och maritima vetenskaper; 2017:57, 2017.
[Examensarbete på avancerad nivå]

There is ongoing research on the spray fundamentals in high pressure fuel injection. A basic understanding of the physical aspects of spray formation enables improvements of the injector designs and enhances combustion optimization. High-pressure sprays are complex flows and involve phenomena and physical mechanisms that often require further research before becoming integrated part of the existing spray models. One such phenomenon is the existence of low-level rotational movement (swirl) in the near-field of common production injectors. This aim of this work is to investigate swirl and quantify the degree of radial motion along the centerline of the spray. A new measurement approach is employed in order to overcome the difficulty resolving liquid structures in this region due to its high optical density. Here, dodecane is doped with a long-lived phosphorescent tracer, consisting of Eu-TTA-TOPO. A thin laser-light sheet excites the centerline of the quasi-steady spray, leaving a distinct mark on it. A high-speed CCD camera coupled with an intensifier is used to capture a pair of images shortly after the initial fluorescence has faded away. The light intensity of the signal is tracked between the two images allowing calculation of the radial shift of the signal. Two single-hole injectors with different orifice hole geometries were tested; one with conical orifice and one with cylindrical. Two different sets of data are analyzed. The first consists of single pairs of images with varying timesteps between the two images for 600, 1000 and 1600 bar. The second is a statistical analysis of 50 images for a constant timestep of 6μs and for 600, 800, 1000 and 1200bar. The results show that the light-shift increases in a linear fashion by increasing the timestep, the cylindrical hole injector results in higher calculated light-shift than the conical injector and there is not a clear relation between the shift of light and the injection pressure. This work also discusses the sensitivity of the results to parameters of the analysis.

Nyckelord: diesel injection, high pressure, swirl, phosphorescent tracer, experimental, image analysis, spray fundamentals, single hole , cavitation, near-field

Publikationen registrerades 2018-08-14. Den ändrades senast 2018-09-20

CPL ID: 255696

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