Analysis on the effects of turbulent inflow conditions on spray primary atomization in the near-field by direct numerical simulation

Salvador, F.J.; Ruíz, Santiago; Crialesi-Esposito, Marco; Blanquer, Ignácio

doi:10.1016/j.ijmultiphaseflow.2018.01.019

Cited by 44 publications

(29 citation statements)

References 48 publications

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“…However, the effect appears to be weak. The later DNS study of Salvador et al [38] looks further into the effect of the integral scale. Salvador et al [38, fig.…”

Section: The Effect Of the Integral Scale On Velocity Profile Relaxationmentioning

confidence: 99%

Turbulent theory of velocity-profile-induced jet breakup

Trettel¹

2019

Preprint

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Velocity profile relaxation is commonly believed to be a cause of jet breakup. This claim is critically reevaluated in this work. Contrary to common belief, laminar liquid jets with parabolic velocity profiles are actually more stable than laminar jets with flatter velocity profiles. This is shown using prior theory and experiments. For turbulent jets, the influence of the velocity profile is more difficult to determine. Previous experimentalists claimed to show that the velocity profile has an effect by varying the nozzle length. The claim is that the boundary layer thickness grows with nozzle length, and that the larger the boundary layer, the less stable the jet. In this work, nozzle length is shown to be a poor proxy for velocity profile effects because the turbulence intensity also increases as the nozzle length increases. Studies with this confounding were ignored in this work. Thinner boundary layers have greater shear, yet experiments have shown that if the boundary layer were made thinner (all else constant), the jet often is more stable. This is termed the "shear paradox". A potential resolution to the shear paradox is developed by considering that the area with shear also decreases as the boundary layer thickness is decreased, and by non-dimensionalizing the turbulent production rate by the dissipation. This theory shows an interaction between the integral scale and velocity profile relaxation which has not been previously discussed. The theoretical prediction that a smaller integral scale leads to more stable jets (due to increased turbulent dissipation) is shown to be somewhat consistent with the limited experimental and DNS data available.

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“…However, the effect appears to be weak. The later DNS study of Salvador et al [38] looks further into the effect of the integral scale. Salvador et al [38, fig.…”

Section: The Effect Of the Integral Scale On Velocity Profile Relaxationmentioning

confidence: 99%

Turbulent theory of velocity-profile-induced jet breakup

Trettel¹

2019

Preprint

View full text Add to dashboard Cite

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“…The simulations presented in this paper use the Parallel Robust Interface Simulator (PARIS-Simulator Ling et al, 2015;Malan et al, 2018;Salvador et al, 2018), which is an in-home CFD code developed jointly at Institute ∂'Alembert, University of Notre-Dame and University of Bologna. PARIS-Simulator is a classical, MAC-type solver using uniform, cuboidal meshes.…”

Section: The Paris-simulatormentioning

confidence: 99%

“…More details about the interface tracking and advection methods used here can be found e.g. in comparative work (Aniszewski et al, 2014), comprehensive textbook (Tryggvason et al, 2011) or, in context of PARIS-Simulator (Ling et al, 2015;Salvador et al, 2018).…”

Section: Interface Trackingmentioning

confidence: 99%

Numerical simulations of pore isolation and competition in idealized micro-spall process

Aniszewski

Zaleski

Llor

et al. 2019

International Journal of Multiphase Flow

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The 'micro-spall' phenomenon is a variant of fragmentation processor spall fracture-that is traditionally discussed in context of solid materials (metals). However it concerns situations in which the medium is fully or partially melted-be it due to kinetic impact, detonation or laser loading. The phenomenon takes place at sub-micrometer and sub-microsecond scales making it inaccessible to direct experimental observation; so far, investigations have been restricted to observations of late time "post-mortem" fragments. In this context, it becomes a viable approach to apply analysis using numerical description for fluids. This work presents such an application for an idealized rapid uniaxial (one-dimensional) system expansion. Cavitation in the medium is represented by including vacuous pores or cavities with surface tension whose growth and interaction are traced in time. The simulations reveal two main regimes of pore growth regulated by a characteristic Weber number.

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“…The regression equations between F 1 , F 2 and D, d 2 , P in are, respectively, shown in Eqs. (13) and (14).…”

Section: Response Surface Approximation Modelmentioning

confidence: 99%

“…Considering the technology of self-excited oscillation pulsed cavitation jet nozzle, the atomization process can be divided into the primary atomization and the secondary atomization. The primary atomization is the first disintegration of the coherent liquid into big droplets and ligaments near the outlet of nozzle, which strongly depends on the flow conditions inside the injection holes and the starting conditions for the spray breakup [13]. Tamaki et al [14] and Geng et al [15] pointed out that the cavitation effect and turbulence effect are the incentive of the primary atomization of the jet near the nozzle.…”

Section: Introductionmentioning

confidence: 99%

Multi-objective parameters optimization design of self-excited oscillation pulsed atomizing nozzle

Wang

Sun

Chen

2019

J Braz. Soc. Mech. Sci. Eng.

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The self-excited oscillation pulsed atomizing nozzle can effectively and evenly spray the high-speed solid cone jet without any extra power. The primary atomization of the jet at the outlet of nozzle directly affects the final spray quality, and the turbulence and cavitation at the outlet of the atomizing nozzle are the other two main factors affecting the atomization. In this work, multi-objective optimization depending on nozzle parameters was established by using mathematical optimization techniques and computational fluid dynamics to improve the jet atomization quality at the outlet of the nozzle. The central composite design method and the response surface method were used to obtain the approximate mathematical model of the primary atomization quality of the jet at the outlet of nozzle. Finally, the non-dominated sorting genetic algorithm with elitist strategy (NSGA-II) and the grey theory were used in combination to optimize the nozzle parameters. Through combining with the NSGA-II and the grey theory, the nozzle parameters were optimized in order to obtain the best primary atomization at the outlet area of nozzle. The optimization results verified the nozzle design with multi-objective optimization method. The optimized values of the turbulent kinetic energy F 1 and the vapor volume fraction F 2 increased by 28.26% and 5.56%, respectively, and the corresponding nozzle parameters of the chamber diameter D, the lower nozzle diameter d 2 and the upper nozzle inlet pressure P in were, respectively, optimized to 28.056 mm, 5.472 mm and 3.999 Mpa.

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Analysis on the effects of turbulent inflow conditions on spray primary atomization in the near-field by direct numerical simulation

Cited by 44 publications

References 48 publications

Turbulent theory of velocity-profile-induced jet breakup

Turbulent theory of velocity-profile-induced jet breakup

Numerical simulations of pore isolation and competition in idealized micro-spall process

Multi-objective parameters optimization design of self-excited oscillation pulsed atomizing nozzle

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