On the Evaluation Methods for Systematic Further Development of Direct-Injection Nozzles

Knorsch, Tobias; Rogler, Philipp; Miller, Maximilian; Wiese, Wolfram

doi:10.4271/2016-01-2200

Cited by 12 publications

(7 citation statements)

References 2 publications

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“…The cavitation phenomenon easily occurs in the injector nozzle once pressure is lower than the saturated vapor pressure [2]. Hence, cavitation could strengthen the turbulent flow and improve spray characteristics [3,4]. However, it may also affect the mass flow of the injector nozzle significantly [5].…”

Section: Introductionmentioning

confidence: 99%

Sensitivity Analysis of Fuel Injection Characteristics of GDI Injector to Injector Nozzle Diameter

Cheng

et al. 2019

Energies

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The accuracy of a nozzle diameter directly affects the difference of the injection characteristics between the holes and productions of a GDI (gasoline direct injection) injector. In order to reduce the difference and guarantee uniform injection characteristics, this paper carried out a CFD simulation of the effect of nozzle diameter which fluctuated in a small range on single-cycle fuel mass. The sensitivity of the fuel injection quantity to the injector nozzle diameter was obtained. The results showed that the liquid phase ratio at the nozzle outlet decreased and the velocity of the outlet increased with the increase of the nozzle diameter. When fluctuating in a small range of nozzle diameters, the sensitivity of the single-hole fuel mass to the nozzle diameter remained constant. The increase of the injection pressure lead to the increase of the sensitivity coefficient of the single-hole fuel mass to the nozzle diameter. The development of cavitation in the nozzle and the deviation of the fuel jet from the axis were aggravated with the increase of the injection pressure. However, the fluctuation in a small range of nozzles had little effect on the near-nozzle flow.

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Section: Introductionmentioning

confidence: 99%

Sensitivity Analysis of Fuel Injection Characteristics of GDI Injector to Injector Nozzle Diameter

Cheng

et al. 2019

Energies

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“…[11][12][13] Some operating strategies and design criteria 14 can help reduce and sometimes eliminate fuel-rich zones, such as late fuel injection or multiple fuel injection events. 12,15,16 However, one surface wetting mechanism that cannot be avoided by injection strategy and is not well understood is injector tip wetting. Injector tip wetting occurs when the fuel injection event creates liquidphase fuel films or droplets on the tip of the fuel injector.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of fuel injector tip wetting and tip drying based on experimental measurements of engine-out particulate emissions from gasoline direct-injection engines

Medina

Alzahrani

Fatouraie

et al. 2020

International Journal of Engine Research

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Gasoline fuel deposited on the fuel injector tip has been identified as a significant source of particulate emissions at some operating conditions of gasoline direct-injection engines. This work proposes simplified conceptual understanding for mechanisms controlling injector tip wetting and tip drying in gasoline direct-injection engines. The objective of the work was to identify which physical mechanisms of tip wetting and drying were most important for the operating conditions and hardware considered and to relate the mechanisms to measurements of particulate number emissions. Trends for each of the physical processes were evaluated as a function of engine operating conditions such as engine speed, start of injection timing, engine load, fuel rail pressure, and coolant temperature. The effects of fuel injector geometries on the tip wetting and drying mechanisms were also considered. Several mechanisms of injector tip wetting were represented with the conceptual understanding including wide plume wetting, vortex droplet wetting, fuel dribble wetting, and fuel condensation wetting. The main tip drying mechanism considered was single-phase evaporation. Using the conceptual understanding for tip wetting and drying mechanisms that were created in this work, the effects of engine operating conditions and fuel injector geometries on the mechanisms were compared with experimental results for particulate number. The results indicate that measured particulate number was increased by increasing injected fuel mass. Increasing injected fuel mass was suspected to increase tip wetting via wide plume wetting and vortex droplet wetting mechanisms. Particulate number was also observed to increase with hole length. Longer hole length was suspected to result in higher tip wetting via vortex droplet and fuel dribble wetting mechanisms. Longer timescale was found to decrease particulate number emissions. Lower speeds and early injection timings increased the timescale. Similarly, higher coolant temperature decreased particulate number. The coolant temperature influenced tip temperature resulting in higher tip drying.

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“…There is an increasing interest in gasoline direct-injection (GDI) engines, as they showed potential to be more efficient than the conventional port fuel injection (PFI) engines. 1,2 However, the direct fuel injection process leads to more particulate emissions in this kind of engine. 3 For this reason, particulate emissions standards for GDI engines are becoming more stringent around the globe, and the regulations that included particulate mass (PM) limits, are now including particulate number (PN) limits.…”

Section: Introductionmentioning

confidence: 99%

Analytical model for liquid film evaporation on fuel injector tip for the mitigation of injector tip wetting and the resulting particulate emissions in gasoline direct-injection engines

Alzahrani

Fatouraie

Sick

2020

International Journal of Engine Research

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Unevaporated fuel films forming on the fuel injector tip of gasoline direct-injection engines burn in a diffusion flame at the time of spark, producing particulates and at some operating conditions, these films have been identified as the dominating source of particulate emissions. This work developed an analytical model for liquid film evaporation on the injector tip, that is, injector tip drying, for the mitigation of injector tip wetting and the resulting particulate emissions. The model explains theoretically how fuel films on the injector tip evaporate with time from the end of injection to the spark. The model takes into consideration engine operating conditions, including engine load and speed, tip and fuel temperatures, gas temperature and pressure, and fuel properties. The model explains the observed trends in particulate number (PN) emissions due to injector tip wetting. Engine experiments were used to validate the model by correlating the predicted film mass at the time of spark to measurements of PN emissions at different conditions. A tip drying time constant was also defined and was found to correlate well with the measured PN for all conditions tested. This time constant is a deterministic factor for mitigating tip wetting. In general, the results indicate that the liquid film evaporation on the injector tip follows a first order, asymptotic behavior. Furthermore, the tip drying physics causes the observed increasing and decreasing non-linear trends in PN emissions with the engine load and the available time for tip drying, respectively. Additionally, the liquid film evaporation on the injector tip is highly sensitive to most of the injector initial and boundary conditions, including the initial film mass after the end of injection, the wetted surface area, the available time for tip drying and the injector tip temperature. The initial film temperature has the least effect on film mass evaporation.

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On the Evaluation Methods for Systematic Further Development of Direct-Injection Nozzles

Cited by 12 publications

References 2 publications

Sensitivity Analysis of Fuel Injection Characteristics of GDI Injector to Injector Nozzle Diameter

Sensitivity Analysis of Fuel Injection Characteristics of GDI Injector to Injector Nozzle Diameter

Mechanisms of fuel injector tip wetting and tip drying based on experimental measurements of engine-out particulate emissions from gasoline direct-injection engines

Analytical model for liquid film evaporation on fuel injector tip for the mitigation of injector tip wetting and the resulting particulate emissions in gasoline direct-injection engines

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