Imaging and Scattering Measurements for Diesel Spray Combustion: Optical Development and Phenomenological Studies
Final rept. 1 Apr 2007-30 Jun 2012
COLORADO SCHOOL OF MINES GOLDEN
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The first successful demonstration of picosecond ballistic imaging using a greater-than-10 picosecond-pulse-duration laser in diesel sprays is reported. This technique uses an optical Kerr effect shutter constructed from a CS2 liquid cell and a 15 picosecond pulse at 532 nm. The optical shutter can be adjusted to produce effective imaging pulses between 7 and 16 picoseconds. This technique is used to image the near-orifice region first 3mm of diesel sprays from a high-pressure single-hole fuel injector. Ballistic imaging of dodecane and methyl oleate sprays are reported. The first known ballistic images of diesel injection at pre-ignition engine-like conditions are reported. Dodecane was injected into air heated to 600 deg C and pressurized to 20 atm. The resulting ballistic images of the near-orifice region at these diesel-engine-like conditions reveal dramatic shedding of the liquid near the nozzle, an effect which has been predicted, but to our knowledge never before imaged. Several parameters are explored including injection pressure, liquid fuel temperature, air temperature and pressure, and fuel type. Resulting trends are summarized with accompanying images. Finally, the beginnings of a new ballistic scattering technique is presented with preliminary results.
- Fluid Mechanics
- Reciprocating and Rotating Engines