Droplet Breakup, Splashing and Re-Impingement on an Iced Airfoil

Tan, Chiong; Papadakis, Michael

doi:10.2514/6.2005-5185

Cited by 14 publications

(10 citation statements)

References 11 publications

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“…The SLD phenomena are basically Lagrangian in nature and, hence, the corresponding modelization has been traditionally presented in such way. 8 So, a proper formulation of the modeling to the new field approach has been necessary and, together with literature review, represents the core of the research work. Within the splashing/bouncing dynamics, another classification has to be made between direct and indirect impact effects: when a SLD droplet impacts on a surface or a water film, part of the incoming mass remains and deposits on it, part is ejected away in the form of child droplets whose size is usually much smaller than the incoming one.…”

Section: Eulerian Sld Physics Modelingmentioning

confidence: 99%

Eulerian Modeling of SLD Physics Towards More Realistic Aircraft Icing Simulation

Iuliano

Mingione

Petrosino

et al. 2010

AIAA Atmospheric and Space Environments Conference

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The Supercooled Large Droplet (SLD) problem in aircraft icing has gained more and more importance during last years. Several experimental, numerical and regulation efforts have been spent to bridge the knowledge gap. New phenomena have been unveiled and studied to address and explain the peculiar features which characterizes the dynamics of a SLD water cloud. With reference to the impact behaviour of a SLD cloud onto an aircraft surface, the authors present a numerical method to model the basic impact phenomena and effects at aircraft component level. Several semi-empirical models drawn by literature findings are presented and implemented in a software code to evaluate the water droplet impingement sensitivity in the SLD regime. The computational framework is Eulerian, thus a PDE problem is solved for the water droplet field in a specified space domain. As a consequence, the new SLD modeling does not act on the single particle when it hits the surface but it has to be formulated as a wall sink/source in the water flow field. To this aim, a new approach is presented, discussed and compared to existing data. Results show that, even if physics understanding and modeling must be still carefully considered and further developed, the presented approach shows a big potential towards a more realistic prediction of SLD icing. Nomenclatureα Phase volume fraction ρ Phase mass density, kg/m 3 m Phase mass, kg V Phase volume, m 3 V Phase velocity, m/s V n,p Droplet normal to wall velocity component, m/s β Collection efficiency γ Mass loading δ Phase mass density ratio e Droplet eccentricity θ Impact angle, measured from the wall normal θ Impact angle, measured from the wall tangent LW C Liquid water content, kg/m 3 M V D Mean Volumetric Diameter, µ D p Droplet diameter, m f * Dimensionless droplet frequency = 3 2 LW C Dp 1/3 µ Dynamic viscosity, kg/(m s)

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Section: Eulerian Sld Physics Modelingmentioning

confidence: 99%

Eulerian Modeling of SLD Physics Towards More Realistic Aircraft Icing Simulation

Iuliano

Mingione

Petrosino

et al. 2010

AIAA Atmospheric and Space Environments Conference

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“…(1) and (2). The SLD phenomena are basically Lagrangian in nature, and, hence, the corresponding modelization has been traditionally presented in such a way [8]. So, a proper formulation of the modeling to the new field approach has been necessary, and, together with the literature review, represents the core of the research work.…”

Section: Eulerian Supercooled Large Droplet Physics Modelingmentioning

confidence: 99%

Eulerian Modeling of Large Droplet Physics Toward Realistic Aircraft Icing Simulation

Iuliano

Mingione

Petrosino

et al. 2011

Journal of Aircraft

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The supercooled large droplet problem in aircraft icing has gained more and more importance in recent years. Several experimental, numerical, and regulation efforts have been spent to bridge the knowledge gap. New phenomena have been unveiled and studied, to address and explain the peculiar features that characterize the dynamics of a supercooled large droplet water cloud. With reference to the impact behavior of a supercooled large droplet cloud onto an aircraft surface, a numerical method is presented to model the basic impact phenomena and effects at an aircraft component level. Several semi-empirical models, drawn by literature findings, are presented and implemented in a software code to evaluate the water droplet impingement sensitivity in the supercooled large droplet regime. The computational framework is Eulerian; thus, a partial differential equation problem is solved for the water droplet field in a specified space domain. As a consequence, the new supercooled large droplet modeling does not act on the single particle when it hits the surface, but it has to be formulated as a wall sink/source in the water flowfield. To this aim, a new approach is presented, discussed, and compared with existing data. Results show that, even if physics understanding and modeling must be still carefully considered and further developed, the presented approach shows a big potential toward a more realistic prediction of supercooled large droplet icing.

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“…In many cases air or another surrounding medium is also present, yielding possible interactions of at least two fluids in the gap between the bodies. Successive impacts and re-impingements of water droplets combined with air effects in particular have crucial effects on icing of aircraft wings (Purvis & Smith 2004a, b, 2005a, as seen most recently in the experimental and computational works of Tan & Papadakis (2005) and Quero et al (2006). Our principal concern here is with air and water as the two fluids involved between the two solid bodies.…”

Section: Introductionmentioning

confidence: 97%

“…The approach of one solid body towards another solid body with liquid between them, and the subsequent squeezing and impact, has diverse applications and interest not only in droplet impact concerned with aircraft or rotorcraft icing (Gent, Dart & Cansdale 2001, Tan & Papadakis 2005, Quero et al 2006) but also in food manufacture, composites manufacture, coating problems, squeeze films, sport-related impacts and meteor cratering. In many cases air or another surrounding medium is also present, yielding possible interactions of at least two fluids in the gap between the bodies.…”

Section: Introductionmentioning

confidence: 99%

Trapping of air in impact between a body and shallow water

2008

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Near-impact behaviour is investigated for a solid body approaching another solid body with two immiscible incompressible viscous fluids occupying the gap in between. The fluids have viscosity and density ratios which are extreme, the most notable combination being water and air, such that either or both of the bodies are covered by a thin film of water. Air–water interaction and the commonly observed phenomenon of air trapping are of concern in the presence of the two or three thin layers and one or two interfaces. The subcritical regime is of most practical significance here and it leads physically to the effect of inviscid water dynamics coupling with a viscous-dominated air response locally. This physical mechanism induces touchdown (or an approach to touchdown), which is found to occur in the sense that the scaled air-gap thickness shrinks towards zero within a finite scaled time according to analysis performed hand in hand with computation. A global influence on the local touchdown properties is also identified. Comparisons with computations prove favourable. Air trapping is produced between two touchdown positions, at each of which there is a pressure peak; an oblique approach would not affect the finding unless the approach itself is extremely shallow. The mechanism of air–water interaction leading to air trapping is suggested as a quite wide-ranging result.

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Droplet Breakup, Splashing and Re-Impingement on an Iced Airfoil

Cited by 14 publications

References 11 publications

Eulerian Modeling of SLD Physics Towards More Realistic Aircraft Icing Simulation

Eulerian Modeling of SLD Physics Towards More Realistic Aircraft Icing Simulation

Eulerian Modeling of Large Droplet Physics Toward Realistic Aircraft Icing Simulation

Trapping of air in impact between a body and shallow water

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