Nozzle Flow and Spray Characteristics from VCO Diesel Injector Nozzles

Gavaises, Manolis; Arcoumanis, C.; Roth, H.; Choi, Young-Pil; Theodorakakos, A.

doi:10.1007/978-3-662-10502-3_3

Cited by 7 publications

(3 citation statements)

References 9 publications

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“…Currently, the data of the ECN represent the most comprehensive database for fuel sprays; relevant predictions have been recently reported; 60 still, effects occurring upon the needle valve closing and the dwelt time between injections have not been studied, while the flow in the single-nozzle considered is a simplification compared to the complex flow distribution in the VCO nozzle studied here. Finally, the recent work 14,39,60,61 provides qualitative validation of a barotropic model against images obtained inside a transparent real-size sac-type nozzle operating at pressures similar to those tested here; this study provides further confidence that the model can capture the co-existence of cavitation vapour and air entrainment during the closing phase of the needle valve and during the dwelt time. As already mentioned, the present manuscript includes further qualitative comparison of the model predictions against the experimental data reported recently by the authors in Gold et al 5 and also the work of Manin et al 53…”

Section: Limitations Link To Previous Work and Present Contributionsupporting

confidence: 64%

“…These comparisons give confidence that the barotropic model is performing relatively well for similar cases as those studied here. With regards to validation of the models for realistic nozzle geometries, past studies exist for VCO nozzles; 2,14,60,61 still focus was placed on sprays using a Lagrangian methodology, which cannot predict fuel dribbling. Currently, the data of the ECN represent the most comprehensive database for fuel sprays; relevant predictions have been recently reported; 60 still, effects occurring upon the needle valve closing and the dwelt time between injections have not been studied, while the flow in the single-nozzle considered is a simplification compared to the complex flow distribution in the VCO nozzle studied here.…”

Section: Limitations Link To Previous Work and Present Contributionmentioning

confidence: 99%

See 1 more Smart Citation

Numerical simulation of fuel dribbling and nozzle wall wetting

Gavaises

Murali-Girija

Rodríguez

et al. 2021

International Journal of Engine Research

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The present work describes a numerical methodology and its experimental validation of the flow development inside and outside of the orifices during a pilot injection, dwelt time and the subsequent start of injection cycle. The compressible Navier-Stokes equations are numerically solved in a six-hole injector imposing realistic conditions of the needle valve movement and considering in addition a time-dependent eccentric motion. The valve motion is simulated using the immersed boundary method; this allows for simulations to be performed at zero lift during the dwelt time between successive injections, where the needle remains closed. Moreover, the numerical model utilises a fully compressible two-phase (liquid, vapour) two-component (fuel, air) barotropic model. The air’s motion is simulated with an additional transport equation coupled with the VOF interface capturing method able to resolve the near-nozzle atomisation and the resulting impact of the injected liquid on the oleophilic nozzle wall surfaces. The eccentric needle motion is found to be responsible for the formation of strong swirling flows inside the orifices, which not only contributes to the breakup of the injected liquid jet into ligaments but also to their backwards motion towards the external wall surface of the injector. Model predictions suggest that such nozzle wall wetting phenomena are more pronounced during the closing period of the valve and the re-opening of the nozzle, due to the residual gases trapped inside the nozzle, and which contribute to the poor atomisation of the injected fluid upon re-opening of the needle valve in subsequent injection events.

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Section: Limitations Link To Previous Work and Present Contributionsupporting

confidence: 64%

Section: Limitations Link To Previous Work and Present Contributionmentioning

confidence: 99%

Numerical simulation of fuel dribbling and nozzle wall wetting

Gavaises

Murali-Girija

Rodríguez

et al. 2021

International Journal of Engine Research

View full text Add to dashboard Cite

show abstract

“…In Mitroglou et al 21,22 the eccentric movement of the needle valve was visually observed in transparent real-size nozzles operating at pressures up to 60 MPa, while the compressibility effects inducing air flow back into the nozzle have been simulated in recent studies. 23 In Ohnishi et al, 24 Gavaises et al, 25 Gavaises, 26 Gavaises et al, 27 Mitroglou et al, 28 they studied the behavior of fuel spray in a multi-hole VCO nozzle experimentally and computationally. Specifically in 24 they found that the maximum eccentric needle radial displacements are 60 mm inside a VCO nozzle and 24 mm inside a micro-SAC nozzle.…”

Section: Introductionmentioning

confidence: 99%

An analytical model of diesel injector’s needle valve eccentric motion

Wang

Moro

Jin

et al. 2021

International Journal of Engine Research

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Past experimental studies have shown that the needle valve of high-pressure diesel injectors undergoes lateral movement and deformation, while the continuous increase in injection pressure enlarges the gap of the needle valve assembly. Two different analytical models, considering or omitting this change are presented here, linking the geometries of the needle valve assembly with the magnitude of needle valve tip lateral movement. It is found that the physical dimensions of the needle valve assembly and the injection pressure have a significant impact on the radial displacement of the needle. For example, for nominal clearances between the needle guidance and the needle valve of about 1–3 μm, the magnitude of the radial movement of the needle tip could reach tens of microns. The model that takes into account the variation of the gap between the needle guide and needle valve is found to give predictions closer to the experimental results.

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Interaction of Cavitation with Sprays in High-Pressure Diesel Injection Systems

Hwang

2021

Cavitation and Bubble Dynamics

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Nozzle Flow and Spray Characteristics from VCO Diesel Injector Nozzles

Cited by 7 publications

References 9 publications

Numerical simulation of fuel dribbling and nozzle wall wetting

Numerical simulation of fuel dribbling and nozzle wall wetting

An analytical model of diesel injector’s needle valve eccentric motion

Interaction of Cavitation with Sprays in High-Pressure Diesel Injection Systems

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