Effect of Nozzle Orifice Diameter

High-Speed Schlieren Movies of Diesel Sprays
Parameter Small Orifice Diameter Large Orifice Diameter
Ambient O2 [%] 21 21
Ambient Temperature [K] 1000 1000
Ambient Density [kg/m3] 28 28
ΔPinj [MPa] 136 137
Orifice Diameter [mm] 0.200 0.260
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Fuel is #2 diesel fuel. Injector tip to wall is 109 mm.

The penetration rate decreases with decreasing orifice diameter (Naber, 1996). The momentum of the spray scales with nozzle area for sprays with the same injection pressure above ambient.