Multi-Shot Icing Simulations with Automatic Re-Meshing

Ozcer, Isik; Switchenko, David; Baruzzi, Guido S.; Chen, Jian

doi:10.4271/2019-01-1956

Cited by 20 publications

(3 citation statements)

References 10 publications

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“…All numerical simulations used meshes that were generated using the meshing tool of ANSYS Fluent version 2022 R2. This tool was selected because it is also implemented for remeshing of multi-shot simulations with ANSYS FENSAP-ICE [20]. Hence, the mesh settings can be kept the same for all meshes that are used during a multi-shot icing simulation.…”

Section: The Numerical Methodsmentioning

confidence: 99%

UAV Icing: Intercycle Ice Effects on Aerodynamic Performance

Wallisch¹,

Hann²

2023

SAE Technical Paper Series

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<div class="section abstract"><div class="htmlview paragraph">Atmospheric in-flight icing poses a challenge to all aircraft including unmanned aerial vehicles (UAVs). Aircraft should avoid icing conditions unless they have ways of mitigating the negative effects of icing, e.g., if they are equipped with an ice protection system (IPS). When de-icing systems are used, a certain amount of ice is allowed to accumulate before it is removed. This intercycle ice deteriorates the aerodynamics by reducing the lift, adding mass, and increasing the drag. This study combines the energy that is required to compensate for the added drag of intercycle ice shapes with the energy required for a wing IPS and compares the energy needs for different IPS operations. Two different kinds of intercycle ice shapes are simulated numerically using FENSAP-ICE, one ice shape that would accrete on an unprotected wing and one ice shape that would accrete when using a parting strip, a continuously heated element at the leading edge. The results show that both intercycle ice shapes deteriorate the aerodynamic performance of the airfoil significantly compared to a clean airfoil. Additionally, the results show that the aerodynamics deteriorate fastest in the initial stages of ice accretion, likely caused by fast horn growth and a fast transition from laminar to turbulent flow. The aerodynamic performance is combined with energy requirements of electrothermal de-icing tests in an icing wind tunnel. The results show that de-icing with a parting strip is more energy-efficient than de-icing without a parting strip and anti-icing. In addition, it is found that the energy required for the IPS on a wing is significantly larger than the energy required to compensate for the added intercycle drag. Considering these results during the development and operation of an IPS will help to improve the range and endurance of UAVs in icing conditions.</div></div>

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Section: The Numerical Methodsmentioning

confidence: 99%

UAV Icing: Intercycle Ice Effects on Aerodynamic Performance

Wallisch¹,

Hann²

2023

SAE Technical Paper Series

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“…An example of the icing grid is given in Figure 1 and an example for the performance grid in Figure 2. Icing simulations were carried out as FENSAP-ICE multi-shot runs with automatic Fluent remeshing (Ozcer et al, 2019). Each ice accretion run was simulated with ten shots, monodisperse droplet distribution and a constant ice density of r ice = 917kg/m 3 .…”

Section: Methodsmentioning

confidence: 99%

UAV icing: the influence of airspeed and chord length on performance degradation

Hann

Johansen

2021

AEAT

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Purpose The main purpose of this paper is to investigate the effects of icing on unmanned aerial vehicles (UAVs) at low Reynolds numbers and to highlight the differences to icing on manned aircraft at high Reynolds numbers. This paper follows existing research on low Reynolds number effects on ice accretion. This study extends the focus to how variations of airspeed and chord length affect the ice accretions, and aerodynamic performance degradation is investigated. Design/methodology/approach A parametric study with independent variations of airspeed and chord lengths was conducted on a typical UAV airfoil (RG-15) using icing computational fluid dynamic methods. FENSAP-ICE was used to simulate ice shapes and aerodynamic performance penalties. Validation was performed with two experimental ice shapes obtained from a low-speed icing wind tunnel. Three meteorological conditions were chosen to represent the icing typologies of rime, glaze and mixed ice. A parameter study with different chord lengths and airspeeds was then conducted for rime, glaze and mixed icing conditions. Findings The simulation results showed that the effect of airspeed variation depended on the ice accretion regime. For rime, it led to a minor increase in ice accretion. For mixed and glaze, the impact on ice geometry and penalties was substantially larger. The variation of chord length had a substantial impact on relative ice thicknesses, ice area, ice limits and performance degradation, independent from the icing regime. Research limitations/implications The implications of this manuscript are relevant for highlighting the differences between icing on manned and unmanned aircraft. Unmanned aircraft are typically smaller and fly slower than manned aircraft. Although previous research has documented the influence of this on the ice accretions, this paper investigates the effect on aerodynamic performance degradation. The findings in this work show that UAVs are more sensitive to icing conditions compared to larger and faster manned aircraft. By consequence, icing conditions are more severe for UAVs. Practical implications Atmospheric in-flight icing is a severe risk for fixed-wing UAVs and significantly limits their operational envelope. As UAVs are typically smaller and operate at lower airspeeds compared to manned aircraft, it is important to understand how the differences in airspeed and size affect ice accretion and aerodynamic performance penalties. Originality/value Earlier work has described the effect of Reynolds number variations on the ice accretion characteristics for UAVs. This work is expanding on those findings by investigating the effect of airspeed and chord length on ice accretion shapes separately. In addition, this study also investigates how these parameters affect aerodynamic performance penalties (lift, drag and stall).

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“…The first concerns the choice of the duration of the various time steps, especially when no experimental data is available, and preliminary guesses about the ice shape must heavily rely on the user's experience. The second one regards the formation of the oscillations mentioned above and the importance of highly robust methods based, for instance, on remeshing techiniques [11,12], level-set methods [13,14], or immersed boundary methods [15,16] capable of overcoming mesh entanglement and grid intersections, which typically occur with standard deformation techniques when dealing with these complex ice shapes. Remeshing is also unavoidable to preserve the mesh quality even if no grid intersections occur.…”

Section: Introductionmentioning

confidence: 99%

Ice Shape Convergence in Multi-Step Ice Accretion Simulations over Straight Wings

Donizetti,

Bellosta,

Guardone

2024

AIAA SCITECH 2024 Forum

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Local errors in the geometrical description of the ice front are amplified in multi-step simulations over conformal meshes due to the coupling of aerodynamics, water impingement, ice accretion, and grid deformation. Small perturbations in the initial phase of ice formation possibly result in dramatically different ice shapes which can hinder the stability of the multi-step procedure. This problem is analyzed by investigating the combined effects of space and time discretization on the ice growth over airfoils and three-dimensional wings. We propose an automatic procedure for selecting the time interval for the update of the aerodynamics and particle impingement. A local growth limiter 𝜆 is introduced here to bound the local ice thickness growth to be comparable to the local grid spacing on the surface, resulting in an automatic adaptive time-step to be used in the multi-step simulation. Examples are provided for three-dimensional cases under both rime and glaze conditions over straight wings. These examples highlight the different accretion mechanisms of the two ice regimes and preliminary indicate that ice-shape convergence can be achieved for low values of 𝜆.

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Multi-Shot Icing Simulations with Automatic Re-Meshing

Cited by 20 publications

References 10 publications

UAV Icing: Intercycle Ice Effects on Aerodynamic Performance

UAV Icing: Intercycle Ice Effects on Aerodynamic Performance

UAV icing: the influence of airspeed and chord length on performance degradation

Ice Shape Convergence in Multi-Step Ice Accretion Simulations over Straight Wings

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