Penetration and combustion characterization of cavitating and non-cavitating fuel injectors under diesel engine conditions

Westlye, Fredrik Ree; Battistoni, Michele; Skeen, Scott A.; Manin, Julien; Pickett, Lyle M.; Ivarsson, Anders

doi:10.4271/2016-01-0860

Cited by 43 publications

(28 citation statements)

References 37 publications

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“…cavitation is promoting rapid mixing and jet growth, but it occurs preferentially along the spray periphery and it is particularly aligned with the sharp inlet of the nozzle. A wider spreading angle for Spray C in comparison to Spray D at View 1 has been previously reported at ECN (900 K) conditions, including an impact on spray combustion processes [33].…”

Section: Cav18-05098supporting

confidence: 62%

Fuel Nozzle Geometry Effects on Cavitation and Spray Behavior at Diesel Engine Conditions

Sforzo

Matusik

Powell

et al. 2018

Proceedings of the 10th International Symposium on Cavitation (CAV2018)

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Cavitation dynamics of diesel and gasoline injection nozzles has been a topic of ongoing research due to the effect of cavitation on the characteristics of the fuel spray, including the discharge coefficient, outlet velocity, spray angle, and atomization process. Additionally, repeated collapse of vapor cavities can damage nozzle surfaces, permanently changing the boundary conditions of the fluid flow field. Understanding the evolution and behavior of cavitation can therefore allow more precise control over its presence, as well as improved predictability of the corresponding fuel spray distribution. Studies have shown that the inception and persistence of fuel vapor inside the spray hole is sensitive to geometric features of the injection nozzle, such as the degree of taper and inlet corner radius of curvature. For example, a hole with a cylindrical profile and sharp inlet corner more readily supports cavitation formation as compared to a monotonically converging hole with a rounded inlet. To better understand the effect of these geometric features on cavitation formation, and by extension, on the associated fuel spray, we compare the nozzle geometry and spray characteristics of two single-hole diesel injectors procured through collaboration with the Engine Combustion Network (ECN). The Spray C injector, specifically designed by the ECN for the express purpose of studying cavitating flows, features a cylindrical hole with a slight divergence near the outlet and a relatively sharp inlet corner. Its non-cavitating analog, the Spray D injector, contains a rounded inlet corner and a gently converging hole profile. High-resolution x-ray tomography measurements coupled with optical microscopy images of both injectors provide the nozzle geometry with O(1) µm spatial resolution. Analysis of the measured geometries reveal that the radius of curvature of the hole inlet varies azimuthally for the modestly hydroground Spray C injector. To elucidate the effect that this asymmetric inlet condition has on cavitation formation during operando conditions, the fuel flow inside the nozzle hole was recorded using high-speed x-ray phase contrast imaging. These images reveal the formation of an asymmetric sheath of fuel vapor that persists throughout the injection event. Complementary x-ray and optical diagnostics of the downstream fuel spray further highlight the effect that this cavitation layer has on the spreading angle of the spray in comparison to the non-cavitating Spray D injector.

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Section: Cav18-05098supporting

confidence: 62%

Fuel Nozzle Geometry Effects on Cavitation and Spray Behavior at Diesel Engine Conditions

Sforzo

Matusik

Powell

et al. 2018

Proceedings of the 10th International Symposium on Cavitation (CAV2018)

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“…Certainly, these engines will profit from, and will be required to achieve, a reduction in fuel consumption and harmful emissions, illustrating the need for detailed understanding of the in-cylinder processes. Studies that combine experimental and numerical approaches have been shown to provide additional insights into such processes [1,2,3,4,5]. Data that is either difficult or impossible to probe by experiments can often be obtained from simulations, which may expose underlying mechanisms after validation of the numerical models using reliable experimental reference from attainable markers.…”

mentioning

confidence: 99%

Heavy-Duty Diesel Engine Spray Combustion Processes: Experiments and Numerical Simulations

Maes¹,

Dam²,

Somers³

et al. 2018

SAE Technical Paper Series

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A contemporary approach for improving and developing the understanding of heavy-duty Diesel engine combustion processes is to use a concerted effort between experiments at well-characterized boundary conditions and detailed, high-fidelity models. In this paper, combustion processes of n-dodecane fuel sprays under heavy-duty Diesel engine conditions are investigated using this approach. Reacting fuel sprays are studied in a constant-volume pre-burn vessel at an ambient temperature of 900 K with three reference cases having specific combinations of injection pressure, ambient density and ambient oxygen concentration (80, 150 & 160 MPa-22.8 & 40 kg/m 3-15 & 20.5% O 2). In addition to a free jet, two different walls were placed inside the combustion vessel to study flame-wall interaction. Experimentally, low-and high-temperature reaction product distributions are imaged simultaneously using single-shot planar laser-induced fluorescence (PLIF) of formaldehyde and high-speed line-ofsight imaging of the chemically-excited hydroxyl radical (OH*). Interference of soot incandescence in experimental OH* recordings is assessed to improve interpretation of the results. Interference by poly-cyclic aromatic hydrocarbon (PAH) LIF and soot radiation is mostly evaded by evaluating flame structures shortly after ignition for one of the studied cases, but presumably included in others. Simulations were performed using a recently developed computational fluid dynamics (CFD) methodology with detailed chemistry and turbulence-chemistry interaction. Apart from the capability to model flame structures and combustion indicators based on optical diagnostics, heat-release rate trends are predicted accurately at varying boundary conditions. Significant variation in the distribution of low-temperature combustion products under heavy-duty operating conditions are explained using both CFD simulations and a one-dimensional jet model. Fuel pump Resato P16-400-2 Fuel injector Bosch CRI2 solenoid (0.205 mm) Injector driver EFS IPoD 8532 Fuel pressure sensor Kistler 4067E3000 Vessel pressure sensor Kistler 6041 AU20 Burst disk rupture pressure 35 MPa Vessel volume 1260 cc Mixing fan motor Maxon motor (custom) Inlet and exhaust valves Sitec 710.3124-D

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“…However, that study did not provide information on the breakup structure. A common way to present averaged images is to make averages of single shot images at a single time step of individual conditions (Mitroglou et al 2014;Purwar et al 2015;Westlye et al 2016). However, to investigate the time evolution one then needs to examine and compare series of averaged images for different operation conditions.…”

Section: A Statistical Methods To Describe Breakupmentioning

confidence: 99%

An analysis of surface breakup induced by laser-generated cavitation bubbles in a turbulent liquid jet

Zhou

Andersson

2020

Exp Fluids

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The breakup of turbulent liquid jets by cavitation bubbles was investigated by artificially introducing them by focusing laser light into the jet. The induced surface deformations and ejected liquid structures were characterized using shadowgraphy with a high-speed video camera. The flow velocity of the liquid jets, which were ejected from a 6 mm nozzle, was varied by adjusting the injection pressure from 1 to 5 bar. Deionized water and a dipropylene glycol–water mixture were used to compare the breakup of liquid jets with different surface tension and viscosity. Surface deformation and breakup were found to occur in two stages. One was early breakup of liquid strings into tiny droplets. This was followed by the formation of a larger structure separating into ligaments and larger drops. Averaged time-resolved one-dimensional plots were introduced and implemented to analyze breakup statistically, to address the problem of shot-to-shot variations in the breakup due to the turbulent condition of the jets. Bubble-induced breakup could easily be distinguished from spontaneous breakup with this method. Both the position of bubble formation and the injection pressure had an influence on the scale of the breakup. The deformation of the jet surface was highly affected by shear. The structure of the deformation became less intact when the surface tension was lower. The sizes of the drops produced during the second stage of breakup were analyzed. The bubble-induced breakup produced smaller drops than the spontaneous breakup at lower injection pressure. As expected, lower surface tension favored droplet detachment and smaller sized drops. Graphic abstract

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Penetration and combustion characterization of cavitating and non-cavitating fuel injectors under diesel engine conditions

Cited by 43 publications

References 37 publications

Fuel Nozzle Geometry Effects on Cavitation and Spray Behavior at Diesel Engine Conditions

Fuel Nozzle Geometry Effects on Cavitation and Spray Behavior at Diesel Engine Conditions

Heavy-Duty Diesel Engine Spray Combustion Processes: Experiments and Numerical Simulations

An analysis of surface breakup induced by laser-generated cavitation bubbles in a turbulent liquid jet

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