Close Nozzle Spray Characteristics of a Prefilming Airblast Atomizer

Holz, Simon; Braun, Samuel; Chaussonnet, Geoffroy; Koch, Rainer; Bauer, Hans‐Jörg

doi:10.3390/en12142835

Cited by 23 publications

(10 citation statements)

References 29 publications

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“…To this end, different numerical approaches have been employed. Using the Smoothed Particle Hydrodynamics (SPH) method, characteristic breakup phenomena known from experimental findings of Gepperth et al [6] like liquid accumulation, ligament flapping and bag breakup are captured well numerically [8,9]. In simulations based on the Volume of Fluid method [10,11] and the Level Set method [12] the same good agreement with experimental observations is achieved.…”

Section: Introductionmentioning

confidence: 72%

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Euler–Lagrangian simulation of the fuel spray of a planar prefilming airblast atomizer

et al. 2021

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The pollutant emissions of aircraft engines are strongly affected by the fuel injection into the combustion chamber. Hence, the precise description of the fuel spray is required in order to predict these emissions more reliably. The characteristics of a spray is determined during the atomization process, especially during primary breakup in the vicinity of the atomizer nozzle. Currently, Euler-Lagrangian approaches are used to predict the droplet trajectories in combustor simulations along with reaction and pollutant formation models. To be able to reliably predict pollutant emissions in the future, well-defined starting conditions of the liquid fuel droplets close to the atomizer nozzle are necessary. In the present work, Euler-Lagrangian simulations of a generic airblast atomizer are presented. The starting conditions of the droplets are varied in the simulations by means of a primary breakup model, which takes into account the local gas velocity when predicting the droplet diameter. The objective of this work is to determine the optimal parameters of the probability density functions for the starting position and the starting velocity of the droplets. Spray properties observed in the simulations are used to qualitatively evaluate the major effects of the distribution parameters on the spray and the suitability of the primary breakup model being applied. Hence, the spatial distribution of an experimental spray can be reproduced using a statistical model for the droplet starting conditions.

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Section: Introductionmentioning

confidence: 72%

“…Holz et al [9] discuss different methodologies for the definition of droplet starting conditions in Euler-Lagrangian simulations of aero-engine combustors. In most cases, drop size distributions are used to determine initial diameters.…”

Section: Introductionmentioning

confidence: 99%

Euler–Lagrangian simulation of the fuel spray of a planar prefilming airblast atomizer

et al. 2021

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“…Therefore, the Lagrangian solvers are often coupled with other models, which are used for the evaluation of the near-nozzle region. Another approach, which recently gained popularity due to constant improvement in available computational resources is the Direct Numerical Simulation (DNS) approach [18][19][20][21]. This approach does not require any sub-model to capture the complex spray physics, e.g., primary and secondary breakup.…”

Section: Introductionmentioning

confidence: 99%

Development of a Eulerian Multi-Fluid Solver for Dense Spray Applications in OpenFOAM

et al. 2020

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The new generation of internal combustion engines is facing various research challenges which often include modern fuels and different operating modes. A robust modeling framework is essential for predicting the dynamic behavior of such complex phenomena. In this article, the implementation, verification, and validation of a Eulerian multi-fluid model for spray applications within the OpenFOAM toolbox are presented. Due to its open-source nature and broad-spectrum of available libraries and solvers, OpenFOAM is an ideal platform for academic research. The proposed work utilizes advanced interfacial momentum transfer models to capture the behavior of deforming droplets at a high phase fraction. Furthermore, the WAVE breakup model is employed for the transfer of mass from larger to smaller droplet classes. The work gives detailed instructions regarding the numerical implementation, with a dedicated section dealing with the implementation of the breakup model within the Eulerian multi-fluid formulation. During the verification analysis, the model proved to give stable and consistent results in terms of the selected number of droplet classes and the selected spatial and temporal resolution. In the validation section, the capability of the developed model to predict the dynamic behavior of non-evaporating sprays is presented. It was confirmed that the developed framework could be used as a stable foundation for future fuel spray modeling.

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“…The gas-liquid mixing can be carried out internally or externally. Internal-mixing twin-fluid (IMTF) nozzles feature lower atomizing gas consumption and higher energy transfer compared to their external-mixing twin-fluid (EMTF) counterparts (e.g., airblast atomizers [20]) [5,[21][22][23], which reduce operating costs.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Geometrical, Operational, Mixing Methods, and Rheological Parameters on Discharge Coefficients of Internal-Mixing Twin-Fluid Atomizers

et al. 2020

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Accurate prediction of the discharge coefficient (CD) for internal-mixing twin-fluid (IMTF) atomizers is challenging, the effect of control factors remains inadequately understood, and comparative data on the CD of IMTF atomizers are unavailable. This work presents an experimental study on CD for different IMTF atomizers with a wide range of factors, including the gas-to-liquid ratio (GLR), the inlet-overpressure ratio (∆pmix/pamb), the orifice length-to-diameter ratio (Lo/do), and the liquid viscosity (µL). Five atomizers with different internal-mixing principles were probed on a cold test rig, including the frequently studied outside-in-gas (OIG) and inside-out-gas (IOG) effervescent types, the recently-introduced outside-in-liquid (OIL) and air-core-liquid-ring (ACLR) atomizers, and our new design named the swirling-air-core-liquid-ring (SACLR) atomizer. The results demonstrate that CD is governed mainly by GLR, and reduces if GLR, Lo/do, or µL is increased. An increase in ∆pmix/pamb causes a CD reduction up to ∆pmix/pamb = 0.98, and CD increases for a higher ∆pmix/pamb. Surprisingly, differences in CD amid examined atomizers were found negligible, although the flow visualization inside the orifice showed a significantly different flow character for each one of the atomizers. Finally, a general CD correlation fitting with an R2 ≥0.99 for all the tested nozzles was proposed. The results amend the present knowledge, allow design optimization, and provide flow rate prediction for a variety of IMTF atomizers.

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Close Nozzle Spray Characteristics of a Prefilming Airblast Atomizer

Cited by 23 publications

References 29 publications

Euler–Lagrangian simulation of the fuel spray of a planar prefilming airblast atomizer

Euler–Lagrangian simulation of the fuel spray of a planar prefilming airblast atomizer

Development of a Eulerian Multi-Fluid Solver for Dense Spray Applications in OpenFOAM

The Effect of Geometrical, Operational, Mixing Methods, and Rheological Parameters on Discharge Coefficients of Internal-Mixing Twin-Fluid Atomizers

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