A new phenomenological model to predict drop size distribution in Large-Eddy Simulations of airblast atomizers

Chaussonnet, Geoffroy; Vermorel, Olivier; Riber, Éléonore; Cuenot, Bénédicte

doi:10.1016/j.ijmultiphaseflow.2015.10.014

Cited by 39 publications

(30 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The whole time scale of the breakup process is the sum of the Rayleigh-Taylor instability time scale τ RT and the breakup time scale τ bu . Both time scales are found to be proportional to the capillarity time as τ RT ≈ 10 τ c and τ bu ≈ 1.8 τ c [22] so that:…”

Section: Modelmentioning

confidence: 95%

“…Model 3, named PAMELA which stands for Primary Atomization Model for prEfiling airbLAst injectors, was developed by Chaussonnet et al [21,22] and calibrated by the experiments of Gepperth et al [7,8] described previously. The proposed mechanism is depicted in Fig.…”

Section: Modelmentioning

confidence: 99%

“…The inputs of the model are the geometric features of the injector as well as fluid properties. Concerning the dependency on the gas velocity, the model exists in a global and in a local form [22]. The global form takes the bulk velocity U g as an input and estimates u g and δ by:…”

Section: Modelmentioning

confidence: 99%

See 2 more Smart Citations

Time-Response of Recent Prefilming Airblast Atomization Models in an Oscillating Air Flow Field

Chaussonnet

Müller

Holz

et al. 2017

Journal of Engineering for Gas Turbines and Power

Self Cite

View full text Add to dashboard Cite

The present study investigates the response of recent primary breakup models in the presence of an oscillating air flow, and compares them to an experiment realized by Müller and coworkers in 2008. The experiment showed that the oscillating flow field has a significant influence on the Sauter Mean Diameter (SMD) up to a given frequency. This observation highlights the low-pass filter character of the prefilming airblast atomization phenomenon, which also introduces a significant phase shift on the dynamics of SMD of the generated spray. The models are tested in their original formulations without any calibration in order to assess their robustness versus different experiments in terms of SMD and time-response to an oscillating flow field. Special emphasis is put to identify the advantages and weaknesses of theses models, in order to facilitate their future implementation in CFD codes. It is observed that some models need an additional calibration of the time constant in order to match the time shift observed in the experiment, whereas some others show a good agreement with the experiment without any modification. Finally, it is demonstrated that the low-pass filter character of the breakup phenomenon can be retrieved by considering the history of the local gas velocity, instead of the instantaneous velocity. This might result in a higher simulation fidelity within CFD codes. * geoffroy.chaussonnet@kit.edu † Dr. A. Müller is currently Team leader for sensor systems at JENOPTIK Robot GmbH

show abstract

Section: Modelmentioning

confidence: 95%

Section: Modelmentioning

confidence: 99%

See 1 more Smart Citation

Time-Response of Recent Prefilming Airblast Atomization Models in an Oscillating Air Flow Field

Chaussonnet

Müller

Holz

et al. 2017

Journal of Engineering for Gas Turbines and Power

Self Cite

View full text Add to dashboard Cite

show abstract

“…In addition to the papers cited in the introduction (Rizkalla & Lefebvre 1975;El-Shanawany & Lefebvre 1980;Aigner & Wittig 1988;Gepperth et al 2013), correlations of Inamura et al (2012), Eckel et al (2013), Chaussonnet et al (2016) and Shanmugadas & Chakravarthy (2017) have been published. They are all listed in Table 7.…”

Section: Literature Surveymentioning

confidence: 99%

Influence of the ambient pressure on the liquid accumulation and on the primary spray in prefilming airblast atomization

Chaussonnet

Gepperth

Holz

et al. 2020

International Journal of Multiphase Flow

Self Cite

View full text Add to dashboard Cite

The influence of the ambient pressure on the breakup process is investigated by means of PIV and shadowgraphy in the configuration of a planar prefilming airblast atomizer. The ambient pressure is varied from 1 to 8 bar. Other investigated parameters are the gas velocity and the film loading. From single-phase PIV measurements, it is found that the gas velocity in the vicinity of the prefilmer partly matches the analytical profile from the near-wake theory. The shadowgraphy images of the liquid phase directly downstream of the prefilmer allow to extract characteristic quantities of the liquid accumulation at the atomizing edge. Two different characteristic lengths, as well as the ligament velocity and a breakup frequency are determined. In addition, the droplets generated directly downstream of the liquid accumulation are captured. Hence, the spray Sauter Mean Diameter (SMD) and the mean droplet velocity are given for each operating point. A scaling law of these quantities with regard to ambient pressure is derived. A correlation is observed between the characteristic length of the accumulation and the SMD, thus promoting the idea that the liquid accumulation determines the primary spray characteristics. An threshold to distinguish the zones between primary and secondary breakup is proposed based on an objective criterion. It is also shown that taking non-spherical droplets into account significantly modifies the shape of the dropsize distribution, thus stressing the need to use shadowgraphy when investigating primary breakup. The ambient pressure and the velocity are varied accordingly to keep the aerodynamic stress ρ g U 2 g constant. This leads to almost identical liquid accumulation and spray characteristics. Hence, it is confirmed that the aerodynamic stress is a more appropriate parameter than the gas velocity or the ambient pressure to characterize prefilming airblast breakup. Finally, SMD correlations from the literature are compared to the present experiment. Most of the correlations calibrated with LDA/LDT measurement underestimate the SMD. This highlights the need to use shadrowgraphy for calibrating primary breakup models.

show abstract

“…It might provide transient droplet initial conditions, which can be used as input for subsequent Euler-Lagrangian predictions. Even if SPH computations are too costly for every day design studies, they can help deriving simplified primary breakup models such as presented by Chausonnet et al [7], that are efficient and accurate enough to be integrated in conventional CFD-codes. The current study demonstrates, how SPH predictions can be used to investigate the details of primary breakup at fuel spray nozzles typically utilized in aero-engines at realistic operating conditions.…”

mentioning

confidence: 99%

Computational Prediction of Primary Breakup in Fuel Spray Nozzles for Aero-Engine Combustors

Dauch

Braun

Wieth

et al. 2017

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

View full text Add to dashboard Cite

Primary breakup of liquid fuel in the vicinity of fuel spray nozzles as utilized in aero-engine combustors is numerically investigated. As grid based methods exhibit a variety of disadvantages when it comes to the prediction of multiphase flows, the "Smoothed Particle Hydrodynamics" (SPH)-method is employed. The eligibility of the method to analyze breakup of fuel has been demonstrated in recent publications by Braun et al, Dauch et al and Koch et al [1,2,3,4]. In the current paper a methodology for the investigation of the two-phase flow in the vicinity of fuel spray nozzles at typical operating conditions is proposed. Due to lower costs in terms of computing time, 2D predictions are desired. However, atomization of fluids is inherently three dimensional. Hence, differences between 2D and 3D predictions are to be expected. In course of this study, predictions in 2D and based on a 3D sector are presented. Differences in terms of gaseous flow, ligament shape and mixing are assessed. Keywords Multiphase Flows -Fuel Atomization -Smoothed Particle Hydrodynamics -Aero-Engine -Combustor IntroductionAiming at a reduction of pollutant emissions of air-traffic, academia and industry both invest in research to investigate processes causing the formation of pollutants of aero-engine combustors. One aspect influencing the formation of pollutants is the quality of the injected fuel spray and its placement within the gaseous flow field of the combustion chamber. Because of limited optical access and challenging thermodynamic conditions, experimental studies are costly and cannot provide detailed information about breakup of the fuel in the close vicinity of fuel injectors. Hence, numerical investigations analyzing the local two-phase flow are desired. At the "Institut für Thermische Strömungsmaschinen" (ITS) a numerical code based on the Lagrangian "Smoothed Particle Hydrodynamics" (SPH)-method has been developed by Koch, Hoefler and Braun [5,4]. The objective is to predict the liquid fuel breakup in the close vicinity of the fuel spray nozzle. Conventional grid based methods exhibit a variety of inherent shortcomings, which can be overcome by a fully Lagrangian approach. In recent publications the potential of the code in terms of two-phase flow predictions has been demonstrated successfully by Braun et al, Dauch et al and Keller et al [1,3,6]. Current state-of-the art methods for combustor design do not take into account the details of primary breakup. Correlations based on empirical studies are employed to impose droplet initial conditions for subsequent EulerLagrangian CFD predictions. These correlations must be tuned to each individual setup and need to be calibrated. Most of the correlations are valid only for low pressures and temperatures. A detailed simulation of primary breakup can overcome these shortcomings. It might provide transient droplet initial conditions, which can be used as input for subsequent Euler-Lagrangian predictions. Even if SPH computations are too costly for every day design studies, the...

show abstract

A new phenomenological model to predict drop size distribution in Large-Eddy Simulations of airblast atomizers

Cited by 39 publications

References 19 publications

Time-Response of Recent Prefilming Airblast Atomization Models in an Oscillating Air Flow Field

Time-Response of Recent Prefilming Airblast Atomization Models in an Oscillating Air Flow Field

Influence of the ambient pressure on the liquid accumulation and on the primary spray in prefilming airblast atomization

Computational Prediction of Primary Breakup in Fuel Spray Nozzles for Aero-Engine Combustors

Contact Info

Product

Resources

About