Interactions between the jets in a multi-hole injector and between the jet and the wall may affect the fuel-air mixing processes in a direct-injection Diesel engine. These interactions are the subject of the investigation in this work. It is known that in the case of free jets, for a given total mass and momentum flow rate, increasing the number of holes would result in an increase in the mixing rate. In the case of a multi-hole injector in an engine, however, if the number of holes are increased beyond an optimum value, the interaction between the jets themselves may result in a reduced mixing. In the limit of increasing the number of holes, a hollow-cone jet would result. The fuel-air mixing in the hollow-cone jet is shown to be slower than in a multi-hole injector with an optimum number of holes. It is also shown that the walls do not appear to have a significant direct effect on the mixing rate as the characteristic time associated with mixing appears to be much shorter than that associated with momentum loss to the walls.
Jet-Jet and Jet-Wall Interactions of Transient Jets from Multi-Hole Injectors
MAGI, Vinicio
1999-01-01
Abstract
Interactions between the jets in a multi-hole injector and between the jet and the wall may affect the fuel-air mixing processes in a direct-injection Diesel engine. These interactions are the subject of the investigation in this work. It is known that in the case of free jets, for a given total mass and momentum flow rate, increasing the number of holes would result in an increase in the mixing rate. In the case of a multi-hole injector in an engine, however, if the number of holes are increased beyond an optimum value, the interaction between the jets themselves may result in a reduced mixing. In the limit of increasing the number of holes, a hollow-cone jet would result. The fuel-air mixing in the hollow-cone jet is shown to be slower than in a multi-hole injector with an optimum number of holes. It is also shown that the walls do not appear to have a significant direct effect on the mixing rate as the characteristic time associated with mixing appears to be much shorter than that associated with momentum loss to the walls.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
