Temporal Evolution of Split-Injected Fuel Spray at Elevated Chamber Pressures

Gang Wu,Tie Li,Xinyi Zhou

doi:10.3390/en12224284

Gang Wu, Tie Li + Show 1 more

Open Access

https://doi.org/10.3390/en12224284

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Abstract

For reducing soot and NOx emissions, an effective method is to apply split injection strategies. In this research, characteristics of split injection were investigated by applying the pilot-main injection strategy and main-post injection strategy. The injection mass of fuel with the two strategies was measured by an in-house fuel injection rate test system based on the Bosch method. The development of spray tip and tail penetrations, as well as the evolvement of the spray angle when applying these two injection strategies, were explored by employing the high speed shadowgraphy at various injection pressures and surrounding gas densities. The results indicate the tail penetration rate of spray has no relation to the fuel injection pressure. However, the increased injection pressure causes a faster penetration development in the spray tip position. It was also found that the spray tip penetration rate of the second spray is slightly slower than that of the first spray at the beginning stage of injection, but it was significantly larger than the first one at the later stage.

Highlights

An effective method for reducing soot and NOx emissions of internal combustion engines is applying split injection strategies [1]
The results indicated that the Sauter mean diameter (SMD) in the spray of split injection is larger than that of the single injection
The fuel injection rate can be calculated on the foundation of Bosch’s method that can be expressed as Equation (1): P = a · ρf · u where P is the pressure wave obtained by the piezoelectric sensor, a is the speed of sound in fuel, ρf is the fuel density, and u is the fuel flow rate

Summary

Introduction

An effective method for reducing soot and NOx emissions of internal combustion engines is applying split injection strategies [1]. The split injection strategy can affect the ignition timing. This is essential for improving the combustion process. According to Carlucci [5], the ignition delay was reduced when using split injection strategies, which means more flexible control for the start of ignition and a more effective method to control emissions [6]. Some other studies revealed that split injection strategies can improve the combustion efficiency [7] and reduce engine noise [8]

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