SYNCHRONIZED DROPLET SIZE MEASUREMENTS FOR COAL-WATER SLURRY SPRAYS GENERATED FROM A HIGH-PRESSURE DIESEL INJECTION SYSTEM
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An experimental study has investigated intermittent sprays of coal-water slurry (CWS) fuel injected from an electronically controlled accumulator injector system. A laser diffraction particle-analyzing (LDPA) technique was used to measure the Sauter mean diameter (SMD) near the spray-tip region. To ensure accurate synchronization of the measurement with the intermittent sprays, a synchronization technique was developed that uses the light-extinction signal as a trigger for initiating the data-taking. This technique allowed measurement of SMDs near the spray tip, where the light-extinction level was low and the data were free from the multi-scattering bias. Coal-water slurry fuel with 50% coal loading in mass containing 5 μm mass median diameter coal particulate was considered. The studies involved injection pressures ranging from 28 to 110 MPa, nozzle orifice diameters of 0.2 and 0.4 mm, and four axial measurement locations from 60 to 120 mm from the nozzle orifice. Measurements were made for pressurized (2.0 MPa g) and for atmospheric chamber conditions. The spray SMD showed a rise with the distance of the axial measurement location and with the ambient gas density, and a fall with rising injection pressure. An experimental correlation of the Sauter mean diameter with the injection conditions was determined as SMD = 0.279 ΔP-0.702ρa0.285x1.521, showing satisfactory agreement with the measured SMD data. The results were also compared with previous SMD correlations that were available only for diesel-fuel sprays.
author list (cited authors)
KIHM, K. D., TERRACINA, D. P., PAYNE, S. E., & CATON, J. A.