Twelve different hole shapes for diesel injector tips were characterized with DF-2 diesel fuel for spray cone angle over a range of injection pressures from 21 MPa (3 kpsi) to 69 MPa (10 kpsi). A baseline and two of the most radical designs were also tested for drop-size distribution and liquid volume fraction (liquid fuel-air ratio) over a range of pressures from 41 MPa (6 kpsi) to 103 MPa (15 kpsi). All hole shapes were circular in cross-section with minimum diameters of 0.4 mm (0.016 in.), and included converging and diverging hole shapes. Overall hole lengths were constant at 2.5 mm (0.098 in.), for an L/d of 6.2. However, the effective L/d may have been less for some of the convergent and divergent shapes. For the cone angle measurements, the injector was operated as a single hole injector spraying continuously into ambient temperature air at a pressure of 0.86 MPa (125 psia) at an air density of 9.7 kg/m3, or about one-half the density of a typical engine at injection conditions. The drop-size measurements were made with the injectors spraying into air at 0.55 MPa (80 psia) at an air density of 6.2 kg/m3. The results showed little effect of hole shape on the fully developed downstream spray cone angle or drop-size distribution. Injection pressure had little effect on the spray shape, while increasing injection pressure reduced drop sizes modestly.
Effects of Different Injector Hole Shapes on Diesel Sprays
Sae Technical Papers
International Congress & Exposition ; 1992
1992-02-01
Conference paper
English
Effects of different injector hole shapes on diesel sprays
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