Measurement and validation of hole-to-hole fuel injection rate from a diesel injector

Hole-to-hole fuel injection characteristic differences that occurs during injection, results in non-uniform fuel distribution and compromised combustion and emission in direct injection IC engines. Hence the instantaneous determination of these differences could help in understanding and the improvement of combustion characteristics. In this paper, a hole-to-hole transient measuring method based on the spray momentum flux theorem was developed and used to determine the fuel injection rate from each nozzle hole of a multi-hole diesel injector. The customized measuring method, was further used to study the characteristics of injection from multi-hole nozzle. Injection rates from the multi-hole nozzle, were compared with those measured with an EFS IFR-600 which is widely used to measure the total injection rate of diesel injector. And about 1% discrepancy in terms of cycle fuel injection quantity, was obtained. Additionally, the fuel injection rate from each nozzle hole of a double layered eight-hole diesel injection nozzle were measured and analyzed. It was found that the cycle fuel injection quantities of the lower layered nozzle holes (4 holes) were 5-15% greater than the cycle fuel injection quantities of the upper layered nozzle holes (4 holes). This was attributed to the different degrees of flow resistance encountered by the nozzle holes. The lower layered nozzle holes encountered relatively less flow resistance than the upper layered ones. This result validates the experiment results obtained from the same nozzle, where the mean fuel injection quantities from eight fuel tunnels connected to the holes, showed the same trend.