PoliMIce: A simulation framework for three-dimensional ice accretion

doi:10.1016/j.amc.2015.05.081

Applied Mathematics and Computation

Volume 267, 15 September 2015, Pages 96-107

https://doi.org/10.1016/j.amc.2015.05.081 Get rights and content

Abstract

A modeling framework is developed to perform two- and three-dimensional simulations of ice accretion over solid bodies in a wet air flow. The PoliMIce (Politecnico di Milano Ice accretion software) library provides a general interface allowing different aerodynamic and ice accretion software to communicate. The built-in ice accretion engine moves from the well-known Myers approach and it includes state-of-the-art ice formation models. The ice accretion engine implements a fully three-dimensional representation of the two-phase flow over the solid body, accounting for both rime and glaze ice formation. As an improvement over the reference model, a parabolic temperature profile is assumed to guarantee the consistency with respect to the wall boundary conditions. Moreover, the mass balance is generalized to conserve the liquid fraction at the interface between the glaze and the rime ice types. Numerical simulations are presented regarding in-flight ice accretion over two-dimensional airfoils and three-dimensional straight- and swept-wings. The CFD open-source software OpenFOAM was used to compute the aerodynamic field and the droplet trajectories. Simulation results compare fairly well with available experiments on ice accretion.

Introduction

A wide number of catastrophic crashes in aviation is directly or indirectly related to the occurrence of ice formation. The icing phenomenon affects aircraft flying in severe conditions, like those that can be encountered in clouds composed by super-cooled droplets, namely, droplets in a state of unstable thermo-mechanical equilibrium that is possibly perturbed upon impact on the surface, generating water freezing [8].

Ice formations are classified as either rime or glaze ice. The former typically occurs at very low temperature: when super-cooled droplets hit the surface of the plane, their unstable equilibrium is perturbed and water instantaneously freezes. This causes small air bubbles to remain trapped within the ice, so the resulting ice is characterized by an opaque aspect. If instead the temperature is closer to the melting point, droplets first impact the surface and flows over it before freezing: the circumstance permits air bubbles to separate from water and hence the resulting ice has an homogeneous structure characterized by a typical transparent look, producing what we usually call glaze ice. This type of ice is always covered by a thin liquid film, giving it a lucid aspect. The density of glaze ice is usually higher than that of rime ice [13], [15], [18].

Ice formation over an aircraft causes a significant increase in weight. It can possibly choke the air manifold of the engine and it may result in the locking of inner mechanisms such as aerodynamic control surfaces or high-lift devices. Moreover, the occurrence of ice can affect aircraft instrumentation in general and measurement instruments in particular, thus presenting misleading information to the pilot. The most prominent effect of ice formation is possibly the change in the airfoil shape, which implies a dramatic loss of aerodynamic performances: a reduction of lift and an increase of drag. The formation of ice over the blades of the first stage of a turbofan compressor can lead to an engine failure due to the ice shedding which causes direct impact damages and indirect damages due to structural unbalancing.

The interest towards ice accretion is not limited to aeronautical applications: a considerable amount of resources is being allocated to the study of ice accretion in nautical and civil applications. As an example, ice accretion produces relevant effects on cables used in energy distribution nets and it affects the efficiency of wind turbines in alpine regions [7], [11].

A deeper knowledge of the icing phenomenon may enable the development of new anti-icing techniques and may guide the future design of innovative de-icing system, leading to more efficient solutions and a significant reduction of costs and environmental impact.

In order to study the ice accretion phenomenon and to develop ice protection on-board systems, different types of approach can be adopted: physical modeling, experiment or Computational Fluid Dynamics (CFD) simulations. The experimental approach includes in-flight tests, where a typical experiment consists of a flying tank that precedes the test aircraft. Ice is produced over the test aircraft by releasing water spray in favorable conditions. Experiments can be also conducted in refrigerated wind tunnels, where water droplets are released in the stream. This kind of experiments usually involve only portions of the entire geometry, such as wing sections or engine nacelles or antennas.

To complement experimental activities, numerical simulations are also carried out and are exstensively used in the design phase. Examples are the LEWICE [4], [23], [22], GlennICE [21], FENSAP-ICE [24] and MULTI-ICE [14], [17] softwares. LEWICE is an ice prediction code developed at NASA since 1983. It is a 2D solver based on the standard Messinger model [13] and it can tackle simple three-dimensional geometries by means of a 2D-strip approach. The flow is solved by means of a potential solver; it is however possible to couple LEWICE with an external flow viscous solver. GlennICE is the LEWICE’s successor and it has been developing at NASA Glenn Research Center since 1999. It is a full three-dimensional solver and it implements the standard Messinger model with slight modifications in the thermal fluxes. A strong limitation of GlennICE code is that it is capable of running only single time-step simulations because of its lack of a full-three dimensional routine for geometry reshaping. FENSAP-ICE is a three-dimensional ice accretion solver [2]. It was initially developed at McGill University and it implements a modified Messinger model. The complete Reynolds-Averaged Navier–Stokes (RANS) equation system is solved to compute the aerodynamic flow field. MULTI-ICE is a software developed by CIRA, the the Italian Aerospace Research Center, which contributes to the EXTICE (EXTreme ICing Environment) international project. MULTI-ICE uses a panel method for the computation of the aerodynamic field and is capable of evaluating the ice accretion on single or multi-element airfoils. This software implements the classical Messinger model and can also be coupled with a RANS solver for the evaluation of the aerodynamic field [14], [17].

At Politecnico di Milano, a novel framework for ice accretion simulations is currently under development, with the aim of providing a flexible interface among different CFD and ice-accretion models [5], [9]. The PoliMIce (Politecnico di Milano Ice accretion software) library provides a built-in ice accretion engine which moves from the well-known Myers approach [15] and it includes state-of-the-art ice formation models. It solves the fully three-dimensional two-phase flow equations over the solid body, accounting for both rime and glaze ice formation.

In the present paper, the main features and the organization of the PoliMIce software are presented. Modifications to the original Myers’s model include the assumption of a parabolic temperature profile to guarantee the consistency with respect to the wall boundary conditions. Moreover, the mass balance is generalized to conserve the liquid fraction at the interface between the glaze and the rime ice types. Numerical simulations are presented using the CFD open-source software OpenFOAM regarding in-flight ice accretion over two-dimensional airfoils and three-dimensional straight- and swept-wings.

The first section reports the general structure of the PoliMIce framework. Section 3 provides a brief review of the existing ice accretion models and shortly describes the PoliMIce implementation. Section 4 presents two- and three-dimensional simulations of in-flight icing. Numerical results are compared to simulations results from other software and to available experimental data.

Section snippets

Icing simulation framework

Ice accretion is a time dependent problem: as ice starts to form, the shape of the surface changes and therefore the aerodynamic flow field around the body is altered. Since droplet trajectories strongly depend on the local value of the flow velocity, each trajectory is modified and the impact point is displaced, thus eventually altering the ice accretion rate. Therefore, two different time scales can be singled out: the aerodynamic and the ice formation ones. The former is the time scale

Ice accretion models

The first mathematical formulation of the liquid water–ice two-phase problem was given by J. Stefan in 1889, on the basis of the fundamental formulations proposed by F. Neumann, B.P. Clapeyron and G. Lamé, among others. Starting from the results of Stefan’s work regarding ice formation in the polar sea, the so-called Stefan’s problem was generalized to describe physical systems where phase change can possibly occur, such as e.g. chemical processes, solid/liquid metal interfaces. Messinger in

Numerical results

In the present section numerical results used for assessing the new ice accretion model and the PoliMIce framework are presented.

In two spatial dimensions, predictions from the improved and the standard Myers’ modesl implemented in PoliMIce are compared to experimental results and to numerical results from NASA LEWICE code. Two-dimensional simulations of the symmetric NACA 0012 airfoil are reported in 4.1 NACA 0012 in low temperature conditions, 4.2 NACA 0012 in mild temperature conditions for

Final remarks

The suite PoliMIce, a software environment for simulating fully three-dimensional ice accretion problems, was presented. The PoliMIce environment is intended as a versatile research and design tool, which can be used as a framework for the further development of ice accretion models. According to this idea, the highly modular structure of PoliMIce was designed to easily include different CFD solvers and ice accretion models. The former include the CFD software (OpenFOAM, CFD++ [3]) and

Acknowledgments

The authors would like to thank Gianluca Parma for implementing the new input procedure for defining the case data.

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Citation Excerpt :
An ability to simulate how ice accretes is essential to the prediction of its associated aerodynamic effects and the development of mitigation strategies. Most current numerical ice accretion models used in the aerospace industry are limited in their applicability because of their reliance on solving continuous, partial differential equations for the conservation of energy, momentum, and mass (Gori et al., 2015; Qiu et al., 2022). For structural engineering applications, ice accretion models tend to be based on a simpler set of continuous, governing equations (Fu et al., 2006; Sundin and Makkonen, 1998).
This paper presents a novel mesh-free framework, using the smoothed particle hydrodynamics method (SPH), for the analysis of large drop impingement and ice accretion prediction on land engineering structures. The SPH method is an efficient and effective approach for the analysis of dynamic fluid flow problems involving free-surface interfaces. In this paper, it has been extended to include the thermodynamics of the freezing process. This allows not only the prediction of drop impact, splashing, and retraction, but also drop freezing and the formation of ice accretion. This mesh-free approach solves a set of non-linear transient dynamic continuum equations. The code also employs an enthalpy-based energy evolution algorithm, coupled with a phase transition equation. Surface tension and adhesion are handled with an approach that is shown to provide an accurate prediction of impinging water drop behavior. Numerical results of drop impact and freezing have been validated against a combination of experimental data and simple ice accretion models. In addition, ice accretions resulting from multi-drop impingement and freezing have been predicted. It is also shown that the developed method can simulate the influence of surface wettability on ice accretion shapes. The presented mesh-free formalism provides a next-generation approach to ice accretion prediction.

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PoliMIce: A simulation framework for three-dimensional ice accretion

Abstract

Introduction

Section snippets

Icing simulation framework

Ice accretion models

Numerical results

Final remarks

Acknowledgments

Progr. Aerosp. Sci.

FENSAP-ICE-unsteady: unified in-flight icing simulation methodology for aircraft, rotorcraft, and jet engines

J. Aircraft

Wind turbine performance under icing conditions

Wind Energy

Aircraft icing

Annu. Rev. Fluid Mech.

Aircraft icing

Philos. Trans. R. Soc. Lond. A

Wind turbine performance under icing conditions

J. Solar Energy Eng.

Ice Accretions and Icing Effects for Modern Airfoils