FENSAP-ICE: Numerical Prediction of Ice Roughness Evolution, and its Effects on Ice Shapes

Ozcer, Isik; Baruzzi, Guido S.; Reid, Thomas; Habashi, Wagdi G.; Fossati, Marco; Croce, Giulio

doi:10.4271/2011-38-0024

Cited by 25 publications

(8 citation statements)

References 4 publications

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“…The one-equation Spalart-Allmaras turbulence model was chosen for its stability and computational efficiency to provide the spatial distribution of the eddy viscosity needed for the momentum equations. A rough-wall treatment (Ozcer et al , 2011) has been included within the turbulence model in FENSAP to accurately calculate the convective heat transfer and shear stress on the surface (Figure 7).…”

Section: Results: Hovermentioning

confidence: 99%

Modeling of iced rotor dynamics via CFD/CSD coupling

Habashi

Yassin

2022

HFF

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Purpose The purpose of this paper is to advance the multiphysics analysis of helicopter rotors under icing conditions by coupling the iced rotor’s aerodynamics, analyzed by CFD, with the rotor’s structural characteristics, analyzed by CSD. Design/methodology/approach The current work introduces supercomputer-based computational approaches capable of assessing the impact of ice accretion on the aerodynamics, blade dynamics, vibrations and loading of a rotorcraft. The rigid and elastic motions of the blades are accounted for through a loose coupling of the flow solver to a multibody dynamics solver. The coupling framework allows for comprehensive aeroelastic simulations of iced rotors in hover and in forward flight. Findings The flow and structural modules were validated on a full helicopter configuration in forward flight using the ROBIN experimental model. The tip structural deflections were in very close agreement with the experimental measurements. Research limitations/implications The results of the CFD analyses are limited by the available experimental results they can be compared to. In dry air CFD, three-dimensional (3D) experiments occur first and CFD is then compared to them; in icing, the opposite is true: 3D experiments (if they are ever done, as they are very expensive) chase CFD and sometimes never occur. Practical implications This paper presents an outline of how CFD and computational stress dynamics (CSD) analyses can be linked and provides a toolbox for deeper investigation of the complex flows over helicopters operating under difficult in-flight icing conditions. Social implications More and more helicopters are designed to be able to operate in hostile environments such as rescuing and saving lives over the oceans or mountains, conditions under which icing encounters cannot be avoided. Originality/value A loosely coupled CFD/CSD framework that accounts for the rotor blades structural response to aerodynamic loading and ice accretion in hover and forward flight has been presented. This versatile and cost-effective framework provides a more accurate estimation of the helicopter rotor performance and its degradation due to icing encounters during the early design stages than traditional CFD tools.

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Section: Results: Hovermentioning

confidence: 99%

Modeling of iced rotor dynamics via CFD/CSD coupling

Habashi

Yassin

2022

HFF

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“…Therefore, the effect of surface roughness on the resultant ice shapes has been investigated first. In this manner, different constant sand-grain roughnesses (0, 0.5, 1, and 2 mm) and a variable roughness model, based on beads 11 , have been tested. The results of this first study allow the calibration of the icing model by defining the appropriate sand-grain roughness to employ.…”

Section: B Ice Shape Analysismentioning

confidence: 99%

“…Figure 10 shows the intermediate ice shapes of the quasi-unsteady approach; 11 shots were considered for Run 61, and 7 shots for Run 36. Since ice formation is a cumulative process, the final ice shape is sensitive to the accuracy of the initial ice shape predictions 11 . In this manner, the duration of the first two shots (30 seconds each) is shorter than the duration of the remaining shots (60 seconds each).…”

mentioning

confidence: 99%

Quasi-Unsteady Icing Simulation of an Oscillating Airfoil

Fouladi

Aliaga²,

Habashi

2015

7th AIAA Atmospheric and Space Environments Conference

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Over the last two decades, steady-state and quasi-steady computational techniques have been proposed and used to model ice accretion on helicopter rotors in both hover and forward flight. These methods cannot accurately predict ice shapes or their aerodynamic impact on rotor performance, particularly in forward flight due to its unsteady nature. The current study proposes a methodology to predict ice accretion on oscillating airfoils with varying angles of attack. The computation of the airflow, droplet impingement, and ice accretion is carried out in an unsteady framework that preserves the characteristics of air, water droplets and ice accretion with respect to time. Application of this approach to an oscillating airfoil shows good agreement with experiments. Nomenclature l C = lift coefficient d C = drag coefficient f = oscillation frequency ( Hz ) i = time step number k = the total number of icing time step at each shot ( * k n m  ) LWC = liquid water content ( 3 / g m ) m = total number of saved multiphase solutions of a cycle MVD = droplet mean volumetric diameter ( m  ) n = total number of cycles of a shot h Q  = convective heat flux ( / j s ) T = oscillation period ( s ) T  = air temperature at infinity ( C  ) . total t = total exposure time to icing condition ( s ) U  = air speed at infinity ( / m s ) u a = air velocity vector ( / m s ) u d = droplet velocity vector ( / m s )  = pitching angle ( deg ) . ave  = average pitching angle ( deg ) . osc  = oscillating pitching angle ( deg )  = collection efficiency 1 Ph.D. Candidate, Member AIAA. 2 total  = total collection efficiency t  = prescribed time step of ice accretion (s) a  = air density ( 3 / kg m ) wall  = air wall shear stress tensor ( 2 / N m )  = azimuthal angle ( rad )

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“…The initial sand grain roughness height for the surface was assumed to be 0.5 mm and also a variable surface roughness model of FENSAP-ICE based on the beads was used. 26 The two-phase flow was solved using Eulerian-Eulerian approach in FENSAP-ICE. The main advantage of using Eulerian-Eulerian approach is that the same mesh can be used for multiphase flow calculations and ice geometry.…”

Section: Numerical Approachmentioning

confidence: 99%

“…Different geometric surface roughness distributions can result in different ice shapes, due to their influence on water runback characteristics and the resultant ice coverage. 26 Along different areas of real iced surface, the roughness should behave as different patterns or texture, according to the geometric configuration and atmospheric conditions. The surface roughness is known to make an important contribution to the convective heat transfer and surface water mass flow.…”

Section: Study Of Geometric Parameters Variationmentioning

confidence: 99%

Numerical study of atmospheric ice accretion on rotating geometric cross sections with fins

Mughal

Virk

2016

The Journal of Computational Multiphase Flows

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This paper describes the numerical study of atmospheric ice accretion on rotating geometric cross sections, circular, hexagon and square, all having fins, to select an optimum geometric cross section for use as a rotating part of a newlyproposed designed icing sensor. Computational fluid dynamics-based numerical analyses were carried out in this research work to understand and analyse the atmospheric ice growth on these rotating cross sections at varying operating and geometric parameters. A comparison of accreted ice profile shapes from numerical analysis was also made with the experiments, carried out at cryospheric environment simulator (CES), Shinjo Japan. A good agreement was found between numerical and experimental results.

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FENSAP-ICE: Numerical Prediction of Ice Roughness Evolution, and its Effects on Ice Shapes

Cited by 25 publications

References 4 publications

Modeling of iced rotor dynamics via CFD/CSD coupling

Modeling of iced rotor dynamics via CFD/CSD coupling

Quasi-Unsteady Icing Simulation of an Oscillating Airfoil

Numerical study of atmospheric ice accretion on rotating geometric cross sections with fins

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