Visual Analyses of End of Injection Liquid Structures and the Behaviour of Nozzle Surface-Bound Fuel in a Direct Injection Diesel Engine

Sykes, Dan; Sercey, Guillaume De; Gold, Martin; Pearson, Richard; Crua, Cyril

doi:10.4271/2019-01-0059

Cited by 6 publications

(8 citation statements)

References 36 publications

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“…These droplets of small but measurble mass linger and evaporate slowly rather than undergo traditional spray breakup due to aerodynamic effects. An increase in liquid penetration after the injection period can also be seen in the experiments which may be related to post injection nozzle dribble and droplet coalescence [29]. The slow evaporation and late combustion of these trailing droplets is the source of the elevated heat release towards the end of the combustion in Figure 3.…”

Section: Liquid Penetrationmentioning

confidence: 59%

Predictive CFD Auto-Tuning Approach for In-Cylinder Simulations of Two Small-Bore LDD Engines

Nsikane¹,

Vogiatzaki²,

Morgan³

et al. 2019

SAE Technical Paper Series

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Tightening emission regulations and accelerating production cycles force engine developers to shift their attention towards virtual engineering tools. When simulating in-cylinder processes in commercial LDD DI engine development, the trade-off between run time and accuracy is typically tipped towards the former. Highfidelity simulation approaches which require little tuning would be desirable but require excessive computing resources. For this reason, industry still favors low-fidelity simulation approaches and bridges remaining uncertainties with prototyping and testing. The problem with low-fidelity simulations is that simplifications in the form of sub models introduce multi variable tuning parameter dependencies which, if not understood, impair the predictive nature of CFD simulations.In previous work, the authors have successfully developed a boundary condition dependent input parameter table. This parameter table showed outstanding results for lab-scale experiments for over 40 varying operating conditions. The objective in this paper is first to identify the necessary considerations to adjust for the inherent differences between lab-scale and real engine conditions and then implement this parameter table into industry relevant conditions. With this approach the appropriate simulation setup for a real EU6 diesel engine can be predefined by the boundary conditions without previous tuning iterations. The performance of the simulation will be assessed based on its capability to match experimental heat release and chamber pressure data. The approach shown here has the potential to remove the necessity of lengthy tuning iterations and lays the groundwork for novel auto-tuned and predictive in-cylinder simulations.

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Section: Liquid Penetrationmentioning

confidence: 59%

Predictive CFD Auto-Tuning Approach for In-Cylinder Simulations of Two Small-Bore LDD Engines

Nsikane¹,

Vogiatzaki²,

Morgan³

et al. 2019

SAE Technical Paper Series

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“…Injector deposits have been found in a number of locations in the injector, on the nozzle tip and in the spray holes external injector deposits (EDID) and since around 2008 internally on the push rod, the upper and lower springs and the needle. Though investigated for some time, these internal injector deposits (IDID) continue to be studied by groups worldwide because of their importance to the industry and a need to understand fully their nature [25][26][27][28][29][30][31][32][33]. Initial analysis by a number of groups contributed to identifying the deposits formed, leading to their classification in six distinct groups:…”

Section: Excerpts From History: Analytical Testingmentioning

confidence: 99%

“…Thus clearly the polarity and constitution of a fuel is also a fundamental parameter with regard to a fuels ability to solubilize deposit sources [50]. Since these may vary for a base mineral diesel fuel, once the wide variety of biodiesel [26,64] and synthetic diesels and alternative fuels [65] are considered the picture becomes exceptionally complicated.…”

Section: Excerpts From History: Analytical Testingmentioning

confidence: 99%

“…A trend was also noted that the higher the charge on the metal cation the greater the fuel flow loss [25]. Sykes has used visual analysis to understand surface bound fuel in nozzles to inform on control of surface wetting and thus inhibiting nozzle coking [26]. Bernemyr has shown a correlation between low aromatic fuels and an increase in nozzle hole deposits [27].…”

Section: Excerpts From History: Analytical Testingmentioning

confidence: 99%

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Investigations of Diesel Injector Deposits Characterization and Testing

Barker¹,

Reid²,

Wilmot³

et al. 2020

SAE Technical Paper Series

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Over the last decade, there has been an impetus in the automobile industry to develop new diesel injector systems, driven by a desire to reduce fuel consumption and proscribed by the requirement to fulfil legislation emissions. The modern common-rail diesel injector system has been developed by the industry to fulfil these aspirations, designed with ever-higher tolerances pressures, which have led to concomitant increases in fuel temperatures after compression with reports of fuel temperatures of ~150°C at 1500-2500 bar. This engineering solution in combination with the introduction of Ultra Low Sulphur diesel fuel (ULSD) has been found to be highly sensitive to deposit formation both external injector deposits (EDID) and internal (IDID). The deposits have caused concerns for customers with poor spray patterns misfiring injector malfunction and failure producing increased fuel consumption and emissions. The importance to the industry of understanding the nature of diesel injector deposits has led to significant research in this area with a number of industry tests being developed. However, the introduction of new generation fuels e.g. hydrogenated vegetable Oil (HVO) and the reports of injector problems such as "abrasive particles" in Europe continue to stimulate investigation. The interest in characterizing diesel injector deposits has also seen a number of recent contributions being published. Many of these reports describe analyses that either consider only the surface of deposits or use methods which destroy any provenance. In this paper, we will describe the latest data from the deployment of modern analytical techniques to characterize these deposits. As a further contribution to the understanding of diesel injector deposits, this paper will describe the use of Principal Component Analysis (PCA) in conjunction with Time of Flight Secondary Ion Mass spectrometry (ToF-SIMS) to determine trends in IDID chemistries worldwide. The application of the ToF-SIMS technique to EIDS will be described. The latest industry standard engine tests will be discussed with regard to the chemistries involved and the latest advances in the application of a new generation of deposit control additives (DCA) will be described.

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“…The volume of deposited fuel is strongly dependent on the physical properties of the fuel (particularly surface tension and viscosity), which are in turn a function of the fuel temperature [10,15,16]. The unavailability of high-speed fuel and nozzle temperature measurements also impedes the interpretation of phenomena such as the bubbling and evaporation of nozzle-bound films late in the cycle, which are known to be affected by the surrounding gas and surface temperatures [17].…”

Section: Introductionmentioning

confidence: 99%

High-Speed Infrared Measurement of Injector Tip Temperature during Diesel Engine Operation

et al. 2021

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Pre-catalyst engine emissions and detrimental injector deposits have been widely associated with the near-nozzle fluid dynamics during and after the injection events. Although the heating and evaporation of fuel films on the nozzle surface directly affects some of these processes, there are no experimental data for the transient evolution of nozzle surface temperature during typical engine conditions. In order to address this gap in knowledge, we present a non-intrusive approach for the full-cycle time resolved measurement of the surface temperature of production nozzles in an optical engine. A mid-wave infrared high-speed camera was calibrated against controlled conditions, both out of engine and in-engine to account for non-ideal in surface emissivity and optical transmissivity. A custom-modified injector with a thermocouple embedded below the nozzle surface was used to validate the approach under running engine conditions. Calibrated infrared thermography was then applied to characterise the nozzle temperature at 1200 frames per second, during motored and fired engine operation, thus revealing for the first time the effect of transient operating conditions on the temperature of the injector nozzle’s surface.

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Visual Analyses of End of Injection Liquid Structures and the Behaviour of Nozzle Surface-Bound Fuel in a Direct Injection Diesel Engine

Cited by 6 publications

References 36 publications

Predictive CFD Auto-Tuning Approach for In-Cylinder Simulations of Two Small-Bore LDD Engines

Predictive CFD Auto-Tuning Approach for In-Cylinder Simulations of Two Small-Bore LDD Engines

Investigations of Diesel Injector Deposits Characterization and Testing

High-Speed Infrared Measurement of Injector Tip Temperature during Diesel Engine Operation

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