Theoretical Calculation of Spray Deflection Angle of Direct-Injected Sprays from a Multiple-Orifice Nozzle

A theoretical calculation method for determining the deflection angle of direct-injection sprays injected from a multiple-orifice nozzle is developed by applying the extended spray momentum theory which takes the backward-flow surrounding sprays into account. The imbalance of the momentum of the backward gas flow causes a deflection of the sprays. The effect of the nozzle tip protrusion on the engine-out emissions of a diesel engine can be theoretically explained by the calculated deflection angles. Small variations in the nozzle tip protrusion are amplified at the rim of the piston cavity according to the spray deflection angle in the vicinity of the nozzle tip.