Atomization quality in the cylinder of a port-injected spark-ignition engine

The atomization quality of liquid fuel entering the cylinder of a port-injected, spark-ignition engine was measured and the effects of the air velocity in the port, the injection timing, the injector spray quality, and the amount of injected fuel are discussed. From an analysis of the data rates, estimates of the relative rates of fuel accumulation in the port were made. The Sauter mean diameter (SMD) of the incoming droplets and the rate of fuel accumulation in the port may be reduced significantly by increasing the air velocity in the intake port. Injector spray quality affects the sizes of droplets entering the cylinder for open-valve injection timing but not for closed-valve timing. Doubling the amount of injected fuel results in a modest increase in SMD of the spray entering the cylinder.