Anti-icing System Research Articles

Fabrication of a durable anti-icing composite coating based on polyurethane elastomer and silica nanoparticles

In order to design and fabricate hydrophobic, durable and anti-icing coating for aircraft, a polyurethane elastomer matrix was hydrophobically modified and incorporated with fluorinated SiO2 nanoparticles to prepare a micro/nanostructured coating. The micro/nanostructured coating with low surface energy displayed significantly improved mechanical properties and hydrophobicity, which exhibited the water contact angle of 162° as well as the sliding angle of 2°. The coating is highly stretchable, which could sustain large-scale extension, and exhibits tensile strength and elongation at break up to 16.22 MPa and 385%, respectively. Furthermore, the coating exhibited a remarkably weak ice adhesion strength of 14.33 kPa, on which the accumulative ice is prone to fall off under natural wind and its own weight. The coating sustained long-term superhydrophobic properties and anti-icing performance even after 1000 abrasion cycles. The proposed method for the production of scalable superhydrophobic coating is cost-effective and can be applied in aerospace and automotive anti-icing systems.

Numerical procedure for the simulation of an electro-thermal anti-icing system

PurposeThis study aims to couple two codes, one able to perform icing simulations and another one capable to simulate the performance of an electrothermal anti-icing system in an integrated fashion.Design/methodology/approachThe classical tool chain of icing simulation (aerodynamics, water catch and impact, mass and energy surface balance) is coupled to the thermal analysis through the surface substrate and the ice thickness. In the present approach, the ice protection simulation is not decoupled from the ice accretion simulation, but a single computational workflow is considered.FindingsA fast approach to simulate advanced anti-icing systems is found in this study.Originality/valueThis study shows the validation of present procedure against literature data, both experimental and numerical.

Anti-icing systems based on elastomers modified with carbon nanostructures with the effect of temperature self-regulation

Anti-icing systems based on elastomers modified with carbon nanostructures with the effect of temperature self-regulation

High-Speed Erosion Behavior of Hydrophobic Micro/Nanostructured Titanium Surfaces.

Ice accretion on aircrafts or their engines can cause serious problems and even accidents. Traditional anti-icing and de-icing systems reduce engine efficiency, which can be improved by the use of hydrophobic/icephobic coatings or surfaces that reduce the amount of bleed air or electric power needed. These hydrophobic/icephobic coatings or surfaces are eroded by high-speed air flow, water droplets, ice crystals, sand, and volcanic ash, resulting in the degradation, material loss, or deterioration of the coating’s waterproof and anti-icing properties. Thus, the durability of hydrophobic micro/nanostructured surfaces is a major concern in aircraft applications. However, the mechanism responsible for material loss in hydrophobic micro/nanostructured surfaces resulting from high-speed erosion remains unclear. In this paper, hydrophobic titanium alloy surfaces with cubic pit arrays are fabricated by photoetching and tested using a high-speed sand erosion rig. Under the same impact conditions, the erosion rates of the micro/nanostructured titanium surfaces were similar to those of smooth titanium alloy, implying that the hydrophobic surface fabricated on the bulk material had erosion-resistant capabilities. The material loss mechanisms of the micro/nanostructures under different impact angles were compared, providing useful information for the future optimization of micro/nanostructures with the goal of improved erosion resistance.

Numerical Simulation of Aircraft Icing under Local Thermal Protection State

The icing phenomenon seriously threatens flight safety, and, therefore, the aircraft needs to be equipped with an icing protection system. Icing may still occur when the anti-icing system is in operation when the protection range or protection power is too small. Given this state, the ice shapes of the airfoil under local thermal protection states are studied in this paper. A numerical simulation method for icing considering water film flow is demonstrated. The solution methods for the governing equations and convective heat transfer coefficient are given. The calculation results were compared with experimental data and a LEWICE calculation to verify the validity of the method. Different protection ranges and protection powers were designed, and the ice shapes under different conditions were simulated. The calculation results show that when the protection range is large, but the protection power is low, icing will still occur in the protection range. Alternatively, when the protection range is small, icing may form outside the protection area. When the combination of protection range and protection power is inappropriate, the critical ice ridge phenomenon will occur. Ice ridges cause the degradation of aerodynamic characteristics and are more dangerous than icing.

Anti-Icing Engine Damage Analysis Boeing 737 - 800 Ng With Fault Tree Analysis Method

An Anti-icing system is a system that aims to prevent the formation of ice when the plane is in the air. The formation of ice in aircraft is of great concern because an airplane flight will pass through the atmosphere, which will experience the formation of the ice at a certain altitude. The formation of such ice will cause a hazard to the aircraft. So that the ice protection system, namely the anti-icing system, is very concerned so that it is always in a serviceable condition. In this study, direct observation and fault tree analysis were used to determine the cause of failure of the Boeing 737-800 NG anti-ice system engine and anti-icing cowl inlet. The results of the analysis using the fault tree analysis method obtained essential events, namely: actuator fails, electrical connector disconnected, Control Selenoid Trouble, Regulator Trouble, Sense Line Connector Trouble, Engine Fault, Engine Control Trouble, Engine Duct Trouble, Panel Buttom Problem, EICAS Module Problem, No Source Electricity, Negative Electrical Source, Wiring Problem.

Anti-Icing Engine Damage Analysis Boeing 737 - 800 Ng With Fault Tree Analysis Method

An Anti-icing system is a system that aims to prevent the formation of ice when the plane is in the air. The formation of ice in aircraft is of great concern because an airplane flight will pass through the atmosphere, which will experience the formation of the ice at a certain altitude. The formation of such ice will cause a hazard to the aircraft. So that the ice protection system, namely the anti-icing system, is very concerned so that it is always in a serviceable condition. In this study, direct observation and fault tree analysis were used to determine the cause of failure of the Boeing 737-800 NG anti-ice system engine and anti-icing cowl inlet. The results of the analysis using the fault tree analysis method obtained essential events, namely: actuator fails, electrical connector disconnected, Control Selenoid Trouble, Regulator Trouble, Sense Line Connector Trouble, Engine Fault, Engine Control Trouble, Engine Duct Trouble, Panel Buttom Problem, EICAS Module Problem, No Source Electricity, Negative Electrical Source, Wiring Problem.

On a reduced-order model-based optimization of rotor electro-thermal anti-icing systems

PurposeResponsible for lift generation, the helicopter rotor is an essential component to protect against ice accretion. As rotorcraft present a smaller wing cross-section and a lower available onboard power compared to aircraft, electro-thermal heating pads are favored as they conform to the blades’ slender profile and limited volume. Their optimization is carried out here taking into account, for the first time, the highly three-dimensional (3D) nature of the flow and ice accretion, in contrast to the current state-of-the-art that is limited to two-dimensional (2D) airfoils.Design/methodology/approachConjugate heat transfer simulation results are provided by the truly 3D finite element Navier–Stokes analysis package-ICE code, embedded in a proprietary rotorcraft simulation toolkit, with reduced-order modeling providing a time-efficient evaluation of the objective and constraint functions at every iteration. The proposed methodology optimizes heating pads extent and power usage and is versatile enough to address in a computationally efficient manner a wide variety of optimization formulations.FindingsLow-error reduced-order modeling strategies are introduced to make the tackling of complex 3D geometries feasible in todays’ computers, with the developed framework applied to four problem formulations, demonstrating marked reductions to power consumption along with improved aerodynamics.Originality/valueThe present paper proposes a 3D framework for the optimization of electro-thermal rotorcraft ice protection systems, in hover and forward flight. The current state-of-the-art is limited to 2D airfoils.

Graphene for Anti-icing

Aeronautical sector, like many others, is trying to benefit from exceptional properties of graphene as soon as possible (low density, unique electrical, thermal, optical, mechanical properties…). In fact composite airframe enhancement by graphene related materials is part of the biggest European research project, the Graphene Flagship, which is trying to bring graphene from lab to society. Then, within this context, a first high potential application of graphene in aeronautical composite structure has been selected by Airbus: de- / anti-icing system. The graphene concept studied for anti-icing application is an electro-thermal system, where heat is generated by applying electrical voltage by Joule effect. Key work performed in this study was focused on following aspects: identification of use cases and requirements, selection of graphene based related material, integration concepts within carbon fiber reinforced polymers (CFRP), demonstration or proof of concept through manufacturing and functionality tests, and, finally, preliminary value and risk assessment of solution. As per work performed, it can be concluded that the potential of proposed innovative graphene based electro-thermal system for composite aeronautical part anti-icing function has been preliminary proven and demonstrated. However, there is still a long way to increase the maturity, scale-up the concept, demonstrate cost saving and benefits versus other solutions, as well as to overcome the identified risks.

Optimization of Power Distribution for Electrothermal Anti-Icing Systems by Differential Evolution Algorithm

Optimization of Power Distribution for Electrothermal Anti-Icing Systems by Differential Evolution Algorithm

항공기 대기자료 시스템의 방빙 소요전력량 산정을 위한 다물리 전산해석

Aircraft air data systems provide important information necessary for the operation and control of aircraft, such as speed, altitude, and temperature. Air data probes are mainly located in front of aircraft or outside such as nose and wing and are directly affected by icing. Therefore, it is important to design an anti-icing system to prevent icing in the air data probe. Compared to costly icing tests, icing and anti-icing simulations using computational fluid dynamics are very effective. In this study, the most critical icing condition was selected by performing ice accretion simulations for various icing conditions experienced by the aircraft air data system. In addition, the amount of power required for anti-icing was calculated under various icing conditions through multiphysics computational simulation, and the tendency of the amount of power required was analyzed.

Computational simulation of water removal from a flat plate, using surface acoustic waves

Minimization of drop contact time is so important and critical for applications such as self-cleaning and anti-corrosion. In recent years, surface acoustic waves are presented as a powerful method for the manipulation of the drops. In this manuscript, a numerical study of drop shedding under the effect of acoustic waves is presented, which may have potential use in the anti-icing systems. Therefore, the effects of different parameters, such as acoustic wave frequency, amplitude, and direction of the wave on the water removal, are investigated. For this purpose, a color gradient lattice Boltzmann method (LBM) is developed and used in these simulations. The acoustic actuator effect is added as a source term in the LBM governing equation. The obtained results showed, when wave amplitude was increased by about 50%, contact time was reduced by about 47%. Also, the dynamical behaviors of drop in the situations of single right-running and single left-running waves were similar. The dynamical behaviors were investigated based on vortical structures which were performed because of the interaction of waves and drop. Our results showed the most effective situation happened when a pair of SAWs with the same amplitudes and frequencies were applied. In this condition, the contact time decreased by a factor of 3.

Anti-icing hot air jet heat transfer augmentation employing inner channels

Many approaches exist today that employ hot-air from aircraft compressor bleed for anti-icing critical aircraft surfaces. This paper introduces and numerically analyzes the novel application of an inner or etched channel to augment heat transfer from a hot-air jet impinging on a curved surface representing the inner surface of an aircraft wing’s leading edge or slat. The study shows that proper positioning, geometry, and flow characteristics of a channel along the inner surface of the leading edge can significantly enhance heat transfer, boost the anti-icing system performance, and greatly enhance flight safety during critical icing weather conditions. Commercially available CFD software, ANSYS Fluent is used to model and analyze the effect of different geometric and flow parameters typical of those found in small to medium category commercial transport aircraft to help determine the optimum arrangement. These parameters include: (1) jet nozzle height-to-slot diameter ratios from 4 to 8, (2) channel width-to-slot diameter ratios from 0.4 to 1.8, and (3) inner-channel inlet location angles from 10° to 60°. Each configuration resulting from a combination of the above parameters was simulated at Reynolds numbers based on jet-slot diameter of 30,000, 60,000, and 90,000. Empirical relations based on available experimental data are used to validate the results. The main findings of the study reveal that the jet height-to-slot diameter ratio of 6, inner channel height-to-slot diameter ratios of 1.8, and inner-channel inlet angular locations of 10° combination resulted in the highest heat transfer at all Reynolds number as well as higher at increased Reynold numbers.

Freezing of few nanometers water droplets

Water-ice transformation of few nm nanodroplets plays a critical role in nature including climate change, microphysics of clouds, survival mechanism of animals in cold environments, and a broad spectrum of technologies. In most of these scenarios, water-ice transformation occurs in a heterogenous mode where nanodroplets are in contact with another medium. Despite computational efforts, experimental probing of this transformation at few nm scales remains unresolved. Here, we report direct probing of water-ice transformation down to 2 nm scale and the length-scale dependence of transformation temperature through two independent metrologies. The transformation temperature shows a sharp length dependence in nanodroplets smaller than 10 nm and for 2 nm droplet, this temperature falls below the homogenous bulk nucleation limit. Contrary to nucleation on curved rigid solid surfaces, ice formation on soft interfaces (omnipresent in nature) can deform the interface leading to suppression of ice nucleation. For soft interfaces, ice nucleation temperature depends on surface modulus. Considering the interfacial deformation, the findings are in good agreement with predictions of classical nucleation theory. This understanding contributes to a greater knowledge of natural phenomena and rational design of anti-icing systems for aviation, wind energy and infrastructures and even cryopreservation systems.

Numerical simulation of melting of ice accreted on an airfoil

This article presents an innovative concept of de-/anti-icing of the airplane, which is actually a process of utilization of the de-/anti-icing system and of natural melting of ice. We imagine that the airplane with ice accreted on the wings is instantaneously exposed to the airspace with relative high ambient temperature, without considering the process of gradual change in ambient temperature during flight, so as to discuss this concept theoretically and to further explore the natural melting behavior quickly through numerical simulations. The effects of the heat transfer of the wing skin and different Mach numbers on the melting of ice are analyzed with main conclusions that the heat transfer of the wing skin can accelerate the natural melting of ice although the de-/anti-icing system is closed, and that the larger the Mach number the larger the ice melting area and rate and thus the more significant the ice shape changes in the same ice melting time.

Modeling and Analysis of Anti-Icing Power of Aircraft Engine Inlet Based on Symmetric Algorithms

To evaluate the capability of engine inlet, inlet components and power plant anti ICER under low temperature, this paper introduces the evaluation method of anti icing system for civil aviation engine room, and analyzes the anti icing power of the aircraft intake based on the symmetric algorithm. The realizable k-cube model and wall function method are used to analyze the flow field in the inlet of an aircraft engine. Based on the analysis of the flow field of the intake port of an aircraft engine, the anti ice power of the intake port is calculated according to the heat balance relationship of the intake port surface. The symmetrical particle swarm algorithm is adopted to optimize the calculation process of inlet anti-ice power, and the particle wide area learning strategy is used to promote the calculation of inlet anti-ice power. In this way, the computational complexity is significantly reduce and the accuracy of the power analysis of the inlet anti-ice is enhanced. The simulation results show that the absolute error of the proposed method is less than 1% in 1000 iterations. Through the analysis of the surface temperature changes of the inlet deflector under different experimental conditions, it can be known that the method can effectively analyze the anti-icing power of aircraft engine inlet.

Experimental Analysis of Heat Transfer on the Tubular Tube Heater with a Variable of Twisted Tape Inserts and Wire Coil to Prevent the Icing Contaminated Tailplane Stall

An anti-icing system has the purpose of protecting the leading edge of the tailplane from contamination during aircraft flight. An anti-icing system in a turboprop aircraft employs heaters that use electrical energy as their power source or heat generated by the bleed air. Protecting the tailplane from contamination is preventing the aircraft stall from occurring that triggers dangerous flight conditions. The aluminum prototype tailplane is assembled with a variable of twisted tape insert and wire coil. The twisted tape insert comes in three different geometries with twist ratio T3 = 9.3; T4 = 7; and T5 = 5.6, as well as a wire coil with fixed geometry. This study shows the best heat transfer rate occurs in T3 with a value of 33.90 W. The consequence of this condition is an decrease in pressure drop that occurs. Twisted 3 has the greatest pressure drop when compared to other geometry, with an average value of 4.72 Pa.

Robust epoxy-modified superhydrophobic coating for aircraft anti-icing systems

To meet the requirements of hydrophobicity, durability, and anti-icing properties for aircraft coatings, a hydrophobic modified epoxy matrix was incorporated with micro-nano fluoropolymer particles to prepare a superhydrophobic coating. This composite coating exhibited decreased surface energy and significantly improved hydrophobicity and mechanical properties. The coating exhibited the maximum contact angle and the minimum sliding angle of 160° and 2°, respectively, and maintained its superhydrophobic properties even after 240 abrasion cycles and 360 s of sand blasting. Moreover, the coating exhibited good adhesion, corrosion and ageing resistance, and self-cleaning properties. Furthermore, water droplets rapidly bounced off the superhydrophobic coating and the freezing time was effectively extended. The coating exhibited long-term, stable anti-icing performance and, thus, was found to be applicable in aircraft anti-icing systems. • The modification reduces the particle content required for hydrophobicity, showing excellent mechanical properties. • Maintaining good superhydrophobic state after a series of mechanochemical durability tests, showing a long service life. • Accelerating droplet rebound and delaying icing to achieve anti-icing.

Crosstalk-Free, Stretching-Insensitive Sensor Based on Arch-Bridge Architecture for Tactile Mapping with Parallel Addressing Strategy toward Million-Scale-Pixels Processing.

In the field of biomimetic electronics, flexible sensors with both high resolution and large size are attracting a lot of attention. However, attempts to increase the number of sensor pixels have been thwarted by the need for complex inner circuits and the resulting interferences with the output. Technological challenges, such as real‐time spatiotemporal mapping and long‐time reliability, must be resolved for large‐scale sensor matrices. This paper reports a simple and robust sensor with an arch‐bridge architecture (ABA) to address these challenges. The device, which consists of an anti‐icing all‐transparent material system, is fabricated by immobilizing ABA ionic arrays on predefined grooves on the substrate. It systematically integrates ABA structure‐designing, resistance‐position‐sensing, and parallel‐addressing logic, allowing for an improvement of three orders of magnitude in the scanning speed (million‐scale pixels) without logical “diagnose confusion.” In addition, it can withstand 100 000 stretching cycles without functional failure. It is also resistant to interferences from stretching. humidity, wet surfaces, and power lines. The proposed strategy is envisaged to serve as a general solution for high‐density, large‐area tactile sensors in various applications.

Investigation of fluid flow and heat transfer characteristics for a thermal anti-icing system of a high-altitude and long-endurance UAV

ABSTRACT This research performs a three-dimensional simulation to investigate the fluid flow and heat transfer characteristics for hot-air jets impinging on the wing leading-edge surface. Both the periodic model and the whole model are proposed to examine the thermal anti-icing performance for hot air ejecting from a piccolo tube onto the impinging surface. The results show that, for the periodic model, the enhancement of the average Nusselt number can be up to 94.4%, and the enhancement of the average heat flux is up to 29.7% for 100 ≦ uj ≦ 350 m/s and 300 ≦ Tj ≦ 550 K when compared with the results of the basic case of uj = 200 m/s and Tj = 450 K. The maximum enhancement of the $\overline {Nu} $ is 62.3% as the spacing decreases from Sn = 8 to Sn = 4 and the optimum Numax and $\overline {Nu} $ occur at Si = 5 and Si = 6 for the single-array holes with 3 ≦ Si ≦ 7 and 4 ≦ Sn ≦ 8. In addition, the θh for maximum $\overline {{{Nu}}} $ is 10° and the maximum enhancement of the $\overline {{{Nu}}} $ is ∼15.7% for double-array holes and staggered-array holes as compared with single-array holes. In addition, the nonuniformity of Nusselt number and heat flux distributions are significantly improved. For the whole model, the maximum enhancement of the average Nusselt number is ∼7.5% and the optimum configuration is θh = 40°, for cases with La = 60, Dp = 8, $\dot{m}$ = 0.15 kg/s, Si = 6, 1 ≦ Nh ≦ 5, 10 ≦ Sn ≦ 30 and 10° ≦ θh ≦ 60°.