X-ray Imaging of Cavitation in Diesel Injectors

Duke, Daniel J.; Swantek, Andrew; Tilocco, Zak; Kastengren, Alan L.; Fezzaa, Kamel; Neroorkar, Kshitij; Moulai, Maryam; Powell, Christopher F.; Schmidt, David P.

doi:10.4271/2014-01-1404

Cited by 65 publications

(45 citation statements)

References 32 publications

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“…A detailed 125 explanation of the setup and methodology can be found in prior work [51,66,67]. In brief, the injector was mounted in a pressurized spray chamber at the Argonne conditions listed in Table 1.…”

Section: Hydraulic and Mechanical Charaterizationmentioning

confidence: 99%

Internal and near nozzle measurements of Engine Combustion Network “Spray G” gasoline direct injectors

Duke

Kastengren

Matusik

et al. 2017

Experimental Thermal and Fluid Science

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Gasoline direct injection (GDI) sprays are complex multiphase flows. When compared to multi-hole diesel sprays, the plumes are closely spaced, and the sprays are more likely to interact. The effects of multi-jet interaction on entrainment and spray targeting can be influenced by small variations in the mass fluxes from the holes, which in turn depend on transients in the needle movement and small-scale details of the internal geometry. In this paper, we present a comprehensive overview of a multi-institutional effort to experimentally characterize the internal geometry and near-nozzle flow of the Engine Combustion Network (ECN) Spray G gasoline injector. In order to develop a complete picture of the near-nozzle flow, a standardized setup was shared between facilities. A wide range of techniques were employed, including both x-ray and visible-light diagnostics. The novel aspects of this work include both new experimental measurements, and a comparison of the results across different techniques and facilities. The breadth and depth of the data reveal phenomena which were not apparent from analysis of the individual data sets. We show that plume-to-plume variations in the mass fluxes from the holes can cause large-scale asymmetries in the entrainment field and spray structure.Both internal flow transients and small-scale geometric features can have an effect on the external flow. The sharp turning angle of the flow into the holes also causes an inward vectoring of the plumes relative to the hole drill angle, which increases with time due to entrainment of gas into a low-pressure region between the plumes. These factors increase the likelihood of spray collapse with longer injection durations.

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Section: Hydraulic and Mechanical Charaterizationmentioning

confidence: 99%

Internal and near nozzle measurements of Engine Combustion Network “Spray G” gasoline direct injectors

Duke

Kastengren

Matusik

et al. 2017

Experimental Thermal and Fluid Science

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“…Both experimental techniques were already reported extensively [9,10,11,21,22,24,33], hence for conciseness the technical details of the experimental setup will not be repeated here. The main experimental parameters relevant to the study of the fuel dribble process are listed in Table 2.…”

Section: Resultsmentioning

confidence: 99%

“…Three different edge detection methods were used to remove background and noise from experimental images: Canny algorithm [20], wavelet filter and morphological opening. A choice of the Canny edge detector is motivated by its excellent performance in the presence of flickering background and boundaries which are caused by a combination of X-ray absorption and phase contrast effects [21,22]. Since detected edges usually have breaks, a Delaunay triangulation algorithm [23] was applied for twodimensional reconstruction of contours of multiple objects.…”

mentioning

confidence: 99%

Quantification of diesel injector dribble using 3D reconstruction from x-ray and DBI imaging

Sechenyh

Turner

Sykes

et al. 2017

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems

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Post-injection dribble is known to lead to incomplete atomisation and combustion due to the release of slow moving, and often surface-bound, liquid fuel after the end of the injection event. This can have a negative effect on engine emissions, performance, and injector durability. To better quantify this phenomenon we present a new image processing approach to quantify the volume and surface area of ligaments produced during the end of injection, for an ECN 'Spray B' 3-hole injector. Circular approximation for cross-sections was used to estimate three-dimensional parameters of droplets and ligaments. The image processing consisted in three stages: edge detection, morphological reconstruction, and 3D reconstruction. For the last stage of 3D reconstruction, smooth surfaces were obtained by computation of the alpha shape which represents a bounding volume enveloping a set of 3D points. The object model was verified by calculation of surface area and volume from 2D images of figures with well-known shapes. We show that the object model fits non-spherical droplets and pseudo-cylindrical ligaments reasonably well. We applied our processing approach to datasets generated by different research groups to decouple the effect of gas temperature and pressure on the fuel dribble process. High-speed X-ray phase-contrast images obtained at room temperature conditions (297 K) at the 7-ID beamline of the Advanced Photon Source at Argonne National Laboratory, together with diffused back-illumination (DBI) images captured at a wide range of temperature conditions (293-900 K) by CMT Motores Térmicos, were analysed and compared quantitatively. KeywordsDiesel injector; dribble; ligament; droplet shape; atomisation. IntroductionThe end-of-injection (EOI) fuel dribble causes a formation of unburned hydrocarbons and decreases the performance of internal combustion engines in a variety of ways. For example, deposits lead to an increase in air pollutant emissions [1, 2], a decrease in quality of injection [2,3,4] and further coking of the nozzle [5]. Understanding of the fuel dribbling process is particularly important for the development of a strategy for optimal use of fuels. However, observing the transient end-of-injection processes is particularly challenging due to the extreme operating conditions and the microscopic scales involved. Consequently, there is a lack of quantitative information on the fuel dribble events and the parameters that affect them. Recently published studies [6][7][8][9][10] demonstrate different aspects of the EOI fuel dribble based on a qualitative and quantitative analysis of experimental images of the injection process. The following important factors affecting the mechanism of the fuel dribble were studied: peak injection velocity [7], needle closing speed [7], in-cylinder pressure [6,7], injection pressure [6], fuel mass expulsion [9], bubble ingestion at the EOI [10], liquid length recession at the EOI [8] and different flow characteristics at the EOI [11]. The present study is dedicated to a qua...

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“…The measurements were performed at the 7-BM beamline of the APS using a polychromatic beam [42]. A scintillator converted the X-ray images to visible light, which was recorded using a CMOS camera [30]. Each nozzle was rotated through 180°, and images were recorded at 2400 angles.…”

Section: Nozzle Characterisationmentioning

confidence: 99%

“…Factors which could influence spray dominance are hole geometry [23,24], injector needle movement [25], needle eccentricity [26], and cavitation [22,27]. Cavitation either in the nozzle sac (string cavitation), or on entry to nozzle hole (geometric induced cavitation) could be expected to alter mass discharge and its distribution across the nozzle exit thus altering spray characteristics [22,24,[28][29][30][31][32]. Knowledge of the vapour distribution across the nozzle exit could yield detail on the type of cavitation present.…”

Section: Introductionmentioning

confidence: 98%

Spray flow structure from twin-hole diesel injector nozzles

Nguyen

Duke

Kastengren

et al. 2017

Experimental Thermal and Fluid Science

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a b s t r a c tTwo techniques were used to study non-evaporating diesel sprays from common rail injectors which were equipped with twin-hole and single-hole nozzles for comparison. To characterise the sprays, high speed optical imaging and X-ray radiography were used. The former was performed at the Laboratory for Turbulence Research in Aerospace and Combustion (LTRAC) at Monash University, while the latter was performed at the 7-BM beamline of the Advanced Photon Source (APS) at Argonne National Laboratory. The optical imaging made use of high temporal, high spatial resolution spray recordings on a digital camera from which peripheral parameters in the initial injection phase were investigated based on edge detection. The X-ray radiography was used to explore quantitative mass distributions, which were measured on a point-wise basis at roughly similar sampling rate. Three twin-hole nozzles of different subtended angles and a single-hole nozzle were investigated at injection pressure of 1000 bar in environments of 20 bar back pressure. Evidence of strong cavitation was found for all nozzles examined with their C D ranging from 0.62 to 0.69. Penetration of the twin-hole nozzles was found to lag the single-hole nozzle, before the sprays merged. Switching in hole dominance was observed from one twin-hole nozzle, and this was accompanied by greater instability in mass flow during the transient opening phase of the injectors.

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X-ray Imaging of Cavitation in Diesel Injectors

Cited by 65 publications

References 32 publications

Internal and near nozzle measurements of Engine Combustion Network “Spray G” gasoline direct injectors

Internal and near nozzle measurements of Engine Combustion Network “Spray G” gasoline direct injectors

Quantification of diesel injector dribble using 3D reconstruction from x-ray and DBI imaging

Spray flow structure from twin-hole diesel injector nozzles

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