Study of the influence of the inlet boundary conditions in a LES simulation of internal flow in a diesel injector

Payri, Raúl; Martí-Aldaraví, Pedro; Bracho, Gabriela

doi:10.1016/j.mcm.2011.11.019

Cited by 6 publications

(8 citation statements)

References 15 publications

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“…This maximum value is reached towards the inlet and also next to the wall orifice instead of right at the orifice restriction like with standard and high density ratio k − models. This distribution is similar to the one obtained with Large Eddy Simulation (LES) by Payri et al (2013), a numerical technique which is supposed to be more accurate than RANS. The fifth model, Realizable k − , generates a turbulent viscosity pattern which is a mixture of the other contours, high turbulence levels in the middle of the orifice but also towards the fuel inlet.…”

Section: Turbulence Modelsupporting

confidence: 80%

“…Although it clearly overestimates mass flow rate and momentum flux, the velocity profile at the exit of the orifice fits better with the theoretical one assumed by Payri et al (2012) and also with the one obtained with LES simulations by Payri et al (2010). Furthermore, turbulent viscosity contours are more accurate when compared also with LES simulations of Payri et al (2013). Mismatch in mass flow rate and momentum flux (and their coefficients) when compared to the experiments are probably due to the pressure value at the nozzle inlet which actually has to be lower than in the common-rail due to losses in all conducts and volumes that connect both parts of the injection system, the rail and the injector nozzle.…”

Section: Turbulence Modelsupporting

confidence: 73%

“…These velocity profiles explain why SST k − ω and Realizable k − models give higher mass flow rate and momentum flux for the same inlet pressure value. At this point it is worthy to mention that LES models could improve the accuracy on the prediction of the velocity coefficient up to 0.6% (Payri et al (2013)). LES models have also been successful in improving primary atomization predictions, Chesnel et al (2011) evaluated the different available sub-grid models and showed that the scale similarity assumption provides better estimation of the sub-grid terms than the Smagorinsky formulation; however the presence of a constant that needs to be estimated and the various values that are found depending on the filter size are the main drawbacks of this approach.…”

Section: Turbulence Modelmentioning

confidence: 96%

“…When simulating internal flows of diesel injectors, the common choice for the inlet boundary condition is to fix the injection pressure, as Battistoni et al (2012); Som et al (2010) and Payri et al (2013) do. An alternative to avoid pressure wave reflexions that take place in compressible fluids and still being able to fix the pressure is to use a non-reflexive constant pressure boundary condition, often found as outlet boundary condition.…”

Section: Inlet Boundary Conditionmentioning

confidence: 99%

See 3 more Smart Citations

Effect of turbulence model and inlet boundary condition on the Diesel spray behavior simulated by an Eulerian Spray Atomization (ESA) model

Salvador

Gimeno

Pastor

et al. 2014

International Journal of Multiphase Flow

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Simulating liquid spray first and second atomization is not an easy task. Many models have been developed over the past years, but Eulerian ones have proved their better performance for the dense zone of the spray. In this work a new compressible Eulerian model is used to compute the internal flow together with the spray. Up to five two-equation turbulence models have been tested and its influence is remarkable in terms of spray behavior, but also greatly affects the mass flow rate and the momentum flux. At the end, SST k − ω model proves to be best than the others. Additionally, different types of inlet boundary conditions have been also tested and analyzed. Results when compared with previously obtained experimental data show that the commonly used for external flow time-varying velocity boundary condition gives also good performance for the internal flow.

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Section: Turbulence Modelsupporting

confidence: 80%

Section: Turbulence Modelsupporting

confidence: 73%

Section: Turbulence Modelmentioning

confidence: 96%

Section: Inlet Boundary Conditionmentioning

confidence: 99%

See 2 more Smart Citations

Effect of turbulence model and inlet boundary condition on the Diesel spray behavior simulated by an Eulerian Spray Atomization (ESA) model

Salvador

Gimeno

Pastor

et al. 2014

International Journal of Multiphase Flow

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, in some cases the turbulence inlet does not have important effects on the turbulence developed downstream. That is the case of the geometries simulated in the current investigation, where three different inlet conditions have been tested: a fixed pressure value, an inlet with a random noise and a mapped inlet, which uses a precursor calculation to generate inflow conditions and a library of turbulent data which can be introduced into the main domain at the real inlet [49].…”

Section: Boundary Conditionsmentioning

confidence: 99%

Large-eddy simulation analysis of the influence of the needle lift on the cavitation in diesel injector nozzles

Desantes

Salvador

Carreres

et al. 2014

Proceedings of the Institution of Mechanical Engineers, Part D:

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Cavitation phenomenon has a strong influence on the internal flow and spray development in diesel injector nozzles. Despite its importance, there are lots of aspects which remain still unclear, especially at partial needle lifts when the injector is in the opening and closing phases. For that reason, the current paper is focused on the influence of the needle lift on the internal flow in a diesel nozzle. This study has been carried out with 3D simulations at high injection pressure (160 MPa) using a homogeneous equilibrium model implemented in OpenFOAM to model cavitation phenomenon.The nozzle has been simulated with LES methods at six different needle lifts (10, 30, 50, 75, 100 and 250 μm), providing relevant information about the evolution of the internal flow, the turbulence development (vorticity, turbulence-cavitation interaction and turbulent structures) and the flow characteristics in the nozzle outlet (mass flow, momentum flux and effective velocity) with the needle position.

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Effect of turbulent model closure and type of inlet boundary condition on a Large Eddy Simulation of a non-reacting jet with co-flow stream

Payri

López

Martí-Aldaraví

et al. 2016

International Journal of Heat and Fluid Flow

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In this paper, the behavior and turbulence structure of a non-reacting jet with a coflow stream is described by means of Large Eddy Simulations (LES) carried out with the computational tool OpenFoam. In order to study the influence of the sub-grid scale (SGS) model on the main flow statistics, Smagorinsky (SMAG) and One Equation Eddy (OEE) approaches are used to model the smallest scales involved in the turbulence of the jet. The impact of cell size and turbulent inlet boundary condition in resulting velocity profiles is analyzed as well. Four different tasks have been performed to accomplish these objectives. Firstly, the simulation of a turbulent pipe, which is necessary to generate and map coherent turbulence structure into the inlet of the non-reacting jet domain. Secondly, a structured mesh based on hexahedrons has been built for the jet and its coflow. The third task consists on performing four different simulations. In those, mapping statistics from the turbulent pipe is compared with the use of fluctuating inlet boundary condition available in OpenFoam; OEE and SMAG approaches are contrasted; and the effect of changing cell size is investigated. Finally, as forth task, the obtained results are compared with experimental data. As main conclusions of this comparison, it has been proved that the fluctuating boundary condition requires much less computational cost, but some inaccuracies were found close to the nozzle. Also, both SGS models are capable to simulate this kind of jets with a co-flow stream with exactitude.

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Study of the influence of the inlet boundary conditions in a LES simulation of internal flow in a diesel injector

Cited by 6 publications

References 15 publications

Effect of turbulence model and inlet boundary condition on the Diesel spray behavior simulated by an Eulerian Spray Atomization (ESA) model

Effect of turbulence model and inlet boundary condition on the Diesel spray behavior simulated by an Eulerian Spray Atomization (ESA) model

Large-eddy simulation analysis of the influence of the needle lift on the cavitation in diesel injector nozzles

Effect of turbulent model closure and type of inlet boundary condition on a Large Eddy Simulation of a non-reacting jet with co-flow stream

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