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Beitrag in Sammelwerk/Tagungsband

  • Tobias Strobl
  • S. Storm
  • S. Ameduri

Synergic Effects of Passive and Active Ice Protection Systems

pg. 841-864.

Oxford, United Kingdom

  • (2017)
  • Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen
  • DIGITAL
Beitrag in Sammelwerk/Tagungsband

  • Tobias Strobl
  • R. Adam
  • R. Entz
  • M. Hornung

A Hybrid System for Ice Protection and Detection

  • (2015)
Aircraft icing is considered a serious weather hazard during flight. Even slight deposits of ice on the wing, empennage, or control surfaces, can adversely affect the aerodynamic performance of an aircraft, and, in a worst case scenario, control of the aircraft may be entirely lost leading to fatal accidents. Hence, ice protection systems, IPS, are essential for aircraft operating in icing conditions. Against the background of a more-electric aircraft, thermoelectric and electro-mechanical systems for ice protection are well-suited to remove in-flight ice accretions from aircraft components.
  • Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen
  • DIGITAL
Zeitschriftenartikel

  • Tobias Strobl
  • S. Storm
  • D. Thompson
  • M. Hornung
  • F. Thielecke

Feasibility Study of a Hybrid Ice Protection System

In: Journal of Aircraft vol. 52 pg. 2064-2076.

  • (2015)

DOI: 10.2514/1.C033161

A key design factor impacting the use of electrical power to drive aircraft systems and subsystems is energy efficiency. With the design of an all-electric, hybrid ice protection system, energy consumption can be reduced to a large extent. The hybridization is achieved through an intentional partitioning of the ice at the stagnation line by melting via surface heating and ice shedding in the unheated regions of the airfoil surface via an electromechanical deicing system based on piezoelectric multilayer actuators. To further reduce energy consumption, the adhesion forces between the ice and the airfoil surface can be reduced using an ultrasmooth, nanostructured surface with water- and ice-repellent properties that encourages ice shedding. Experimental investigations, performed in a laboratory-scale icing wind tunnel for a small-scale configuration, reveal that the hybrid approach for ice protection reliably sheds the ice accreted on the airfoil surface. Compared with an all-thermoelectric system for ice protection investigated in the same icing wind tunnel facility using identical test conditions, the hybrid approach was demonstrated to reduce power consumption up to 91%. Beyond the laboratory tests, numerical simulations of the hybrid strategy analogous to the one used for the experiments are performed. The time history of the residual ice shapes aft of the heated region is simulated using the ice accretion prediction software LEWICE2D for a wet-running anti-icing subsystem. Finite element analyses of the effects of the piezoelectric actuators are then performed using Abaqus to investigate the ice-shedding capability in the unheated regions of the airfoil surface. The numerical results show that the variation in the different ice shapes affects the stiffness of the model. It becomes obvious that the critical threshold for ice shedding, that is, the stiffness that determines whether residual ice delaminates from the airfoil surface, is affected to a minor extent by the interfacial area and predominantly by the thickness of the ice layer. Further, the simulation results correlate well with experimental results obtained in the icing wind tunnel. It can be concluded that reliable operation of the hybrid system for ice shedding can be guaranteed when using a harmonic sweep excitation able to excite the structure at its resonance.
  • Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen
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Beitrag in Sammelwerk/Tagungsband

  • Tobias Strobl
  • D. Thompson
  • M. Hornung

Feasibility Study of a Hybrid Ice Protection System Based on Passive Removal of Residual Ice

  • (2015)

DOI: 10.2514/6.2015-0032

  • Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen
  • DIGITAL
Beitrag in Sammelwerk/Tagungsband

  • J. Blake
  • D. Thompson
  • D. Raps
  • Tobias Strobl
  • E. Bonaccurso

Effects of Surface Characteristics and Droplet Diameter on the Freezing of Supercooled Water Droplets Impacting a Cooled Substrate

Reston, Virginia

  • (2014)

DOI: 10.2514/6.2014-2328

Reducing the accretion ofice on aerodynamic surfaces remains a challenge. Certain surface types have been hypothesized to reduce ice buildup. In this paper, a previously developed numerical method is employed to investigate the effects of droplet size and surface characteristics on the solidification of a supercooled water droplet as it impacts a cooled surface at high speed. Upon impact, nucleation is assumed to occur instantaneously, and properties of the droplet are chosen to account for the nucleation process. Simulations are performed in ANSYS Fluent using a coupled Volume of Fluid and Level-Set method to capture the air-water interface and an Enthalpy-Porosity method to capture the liquid- solid interface. We consider high-speed Supercooled Large Droplet impacts on hydrophilic, hydrophobic, and superhydrophobic surfaces. Results show that superhydrophobic surfaces may not be icephobic for larger diameter droplets.
  • Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen
  • DIGITAL
Beitrag in Sammelwerk/Tagungsband

  • Tobias Strobl
  • S. Storm
  • D. Thompson
  • M. Hornung

Feasibility Study of a Hybrid Ice Protection System

Reston, Virginia

  • (2014)

DOI: 10.2514/6.2014-2060

A key design factor impacting the utilization of electrical power to drive aircraft systems and subsystems is energy efficiency. With the design of an all-electric, hybrid ice protection system, energy consumption can be reduced to a large extent. The hybridization is achieved through an intentional partitioning of the ice at the stagnation line by melting via surface heating and ice shedding in the unheated regions of the airfoil surface via an electro-mechanical deicing system based on piezoelectric multilayer actuators. In addition, to reduce energy consumption, the adhesion forces between the ice and the airfoil surface can be reduced using an ultrasmooth, nanostructured surface with water and ice repellent properties that encourages ice shedding. Experimental investigations, performed in a laboratory-scale icing wind tunnel for a small-scale system configuration, reveal that the hybrid approach for ice protection reliably sheds the ice accreted on the airfoil surface. Compared to conventional state-of-the-art systems for ice protection, the hybrid approach is able to reduce power consumption up to 95 %. Beyond the laboratory tests, numerical simulations of the hybrid strategy analogous to the one used for the experiments are performed. The time history of the residual ice shapes aft of the heated region are simulated using the ice accretion prediction software LEWICE2D for a wet-running anti-icing subsystem. Finite element analyses of the effects of the piezoelectric actuators are then performed using Abaqus to investigate the ice shedding capability in the unheated regions of airfoil surface. It is shown that the variation in the thickness of the different ice shapes affects the stiffness of the model, and the ice shedding capability, respectively. Simulation results correlate well with experimental results obtained with the icing wind tunnel. It can be concluded that reliable operation of the hybrid system for ice shedding can be guaranteed when using a harmonic sweep excitation able to excite the structure at its resonance.
  • Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen
  • DIGITAL
Beitrag in Sammelwerk/Tagungsband

  • Tobias Strobl
  • M. Kolb
  • J. Haag
  • M. Hornung

Development of a Hybrid Ice Protection System Based on Nanostructured Hydrophobic Surfaces

  • (2014)
Eliminating the hazard of aircraft icing still remains a challenge. Thermal-based ice protection systems are widely used to remove in-flight ice accretions. For reasons of power consumption, coatings that reduce the adhesion of the ice represent suitable approaches to protect aircraft surfaces susceptible to ice accretion. This effort intends to tailor an ultrasmooth surface with hydrophobic and icephobic properties, respectively, which are obtained by nanostructuring and subsequent surface hydrophobizing. A hybrid method of ice protection is presented in this study, where the ultrasmooth hydrophobic surface is applied on the surface of a small-scale NACA 0012 airfoil. The hybrid system further consists of a thermo-electric heater element for ice partitioning at the stagnation line by melting. Ice shedding in the unheated portion of the airfoil surface is performed by piezoelectric multilayer actuators. System performance is studied in a laboratory icing wind tunnel where it becomes evident that using the ultrasmooth, nanostructured hydrophobic surface encourages ice shedding from the airfoil surface. Measurement results also reveal that the hybrid system reduces the amount of power consumption by up to 95 % compared to state-of-the-art ice protection systems.
  • Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen
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Beitrag in Sammelwerk/Tagungsband

  • J. Blake
  • D. Thompson
  • D. Raps
  • Tobias Strobl

Simulating the Freezing of Supercooled Water Droplets Impacting a Cooled Substrate

Reston, Virginia

  • (2014)

DOI: 10.2514/6.2014-0928

To study ice adhesion at the droplet scale, a strategy is presented to simulate the impact and solidification of a supercooled water droplet on a cooled substrate. Upon impact, nucleation is assumed to occur instantaneously, and properties of the droplet are chosen to account for the nucleation process. Simulations are performed in ANSYS Fluent using a coupled volume-of-fluid and level-set method to capture the air-water interface, and an enthalpy-porosity method is used to capture the liquid-solid interface. Calibration of a simulation parameter Amush is performed in order to match experimental data for different ideal surface types and surface temperatures. The simulation strategy successfully predicts the overall droplet response for several droplet impact conditions. Copyright © 2015 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
  • Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen
  • DIGITAL
Beitrag in Sammelwerk/Tagungsband

  • Tobias Strobl
  • D. Raps
  • M. Hornung

Evaluation of Roughness Effects on Ice Adhesion

Reston, Virginia

  • (2013)

DOI: 10.2514/6.2013-2547

In this study, the adhesion strength of ice to bare aluminum substrates with different values of surface roughness is investigated. A thin glaze ice accumulation is formed on the substrate surface within an icing wind tunnel facility. The adhesion strength between the ice and the metal samples is measured by means of a permanent magnet shaker. Ice de-bonding occurs in the interface between the ice and the aluminum. The experimental results reveal that the ice adhesion strength is significantly dependent on the degree of surface roughness of the respective aluminum substrate.
  • Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen
  • DIGITAL
Beitrag in Sammelwerk/Tagungsband

  • Tobias Strobl
  • D. Raps
  • M. Hornung

Comparative Evaluation of Ice Adhesion Behavior

vol. 68 pg. 1676-1681.

  • (2012)
  • Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen
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Beitrag in Sammelwerk/Tagungsband

  • D. Raps
  • S. Jung
  • Tobias Strobl

Comparative Evaluation of Icing on Aerodynamic Surfaces

  • (2012)
In this study, the formation and adhesion of ice to solid substrates with different surface properties is compared. It provides an overview of icing test methods to analyze the freezing delay, droplet impact, runback icing and ice adhesion on aerodynamic surfaces. The investigations have shown the feasiblity of a smooth hydrophobic and nano-textured super hydrophobic coating configuration to fulfill a passive ice resistance on aerodynamic surfaces. For achieving anti-icing properties at the impact area of supercooled water droplets (e.g. leading edge), smooth coatings with low surface free energy (e.g. hydrophobicity) achieved by an appropriate chemical composition seem to be the most promising approach. In contrast super hydrophobic coatings with low water contact angle hysteresis performed best to carry the accumulated water within the aerodynamic boundary layer away from the body-surface. The affinity for ice adhesion is significantly influenced by the water contact angle of the respective sample.
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