High-Speed Microscopic Imaging of the Initial Stage of Diesel Spray Formation and Primary Breakup University of Brighton

Format:

Conference/Event

Author/Creator:

Crua, Crua, author.

Contributor:

Gold, Martin

Heikal, Morgan

Higham, Cassandra

Shoba, Tenzin

Conference Name:

SAE 2010 Powertrains Fuels & Lubricants Meeting (2010-10-25 : San Diego, California, United States)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2010

Summary:

The formation and breakup of diesel sprays was investigatedexperimentally on a common rail diesel injector using a long rangemicroscope. The objectives were to further the fundamentalunderstanding of the processes involved in the initial stage ofdiesel spray formation.Tests were conducted at atmospheric conditions and on a rapidcompression machine with motored in-cylinder peak pressures up to 8MPa, and injection pressures up to 160 MPa. The light source andlong range imaging optics were optimized to produce blur-freeshadowgraphic images of sprays with a resolution of 0.6 μm perpixel, and a viewing region of 768x614 μm. Such fine spatial andtemporal resolutions allowed the observation of previouslyunreported shearing instabilities and stagnation point on the tipof diesel jets. The tip of the fuel jet was seen to take the shapeof an oblate spheroidal cap immediately after leaving the nozzle,due to the combination of transverse expansion of the jet and thephysical properties of the fuel. The spheroidal cap was found toconsist of residual fuel trapped in the injector hole after the endof the injection process. The formation of fuel ligaments close tothe orifice was also observed, ligaments which were subsequentlyseen to breakup into droplets through hydrodynamic and capillaryinstabilities.An ultra-high-speed camera was then used to capture the dynamicsof the early spray formation and primary breakup with fine temporaland spatial resolutions. The frame rate was up to 5 million imagesper second and exposure time down to 20 ns, with a fixed resolutionof 1280x960 pixels covering a viewing region of 995x746 μm. Avortex ring motion within the vaporized spheroidal cap wasidentified, and resulted in a slipstream effect which led to acentral ligament being propelled ahead of the liquid jet

Notes:

Vendor supplied data

Publisher Number:

2010-01-2247

Access Restriction:

Restricted for use by site license