Ice Protection System Research Articles

Cyclic Voltammetry for Accurate Icing Detection on Simulated Aircraft Surfaces.

Icing and ice accretion on aerodynamically critical surfaces of an aircraft increase drag, reduce lift, and raise stalling speed, which pose significant safety hazards to aircraft while in flight. Icephobic coatings have been intensively investigated by the Canadian and global aerospace industries for passive ice protection. Nevertheless, effective icephobic coatings suitable for aerospace applications are far from ideal. Ice protection of an aircraft still relies on active ice protection systems based on heating, mechanical expulsion, and deicing fluids, which are heavy-weight, power-intensive, and unfriendly to the environment. To address these challenges, rapid and accurate detection of icing is highly desirable to activate these ice protection systems only when needed. To this end, cyclic voltammetry was used for the first time to detect the initiation of icing on aircraft surfaces with or without icephobic coatings. In this study, a water droplet was sandwiched between a screen-printed electrode and a simulated aircraft surface. Cyclic voltammograms were then collected as the temperature was slowly decreased until the droplet froze to form ice. A sharp spike in faradaic current was recorded in the voltammograms during the phase transition, suggesting a switch in the mass transfer mechanism from diffusion to a surface-confined pathway. This electrochemical signal could then be used to precisely indicate the onset of icing. The developed sensing method shows potential in icing detection to manage active ice protections and ameliorate icing risks in the aerospace and aviation industries.

Experimental Study on Optimum Design of Aircraft Icing Detection Based on Large-Scale Icing Wind Tunnel

Icing detection is the premise and basis for the operation of aircraft icing protection system, and is the primary issue in flight safety assurance. At present, there is a lack of research methods and design reference for the layout optimization of ice detectors. Therefore, in order to simulate the real icing environment encountered by the aircraft more accurately, a large-scale icing wind tunnel was used to carry out experimental research on the icing characteristics of the sensor probes. A closed-loop experimental method including the typical condition selection, sensor array interference examination and ice shape repeatability verification was initially proposed. A stepwise optimization process and a sensitivity analysis on ambient conditions were combined to determine the optimal distribution for sensor installation. It is found that the water collection coefficient on the cylinder surface of the probe first increases and then decreases along the axial direction, reaching the extreme value at a certain position. The height of this extreme point will gradually increase with the development of the wall boundary layer, showing a variation range of 2~30 mm. Improper design may cause the sensor probe to fail to capture the point with the maximum icing thickness, affecting the sensitivity of icing detection. In addition, each probe position has different sensitivity to changes in flow parameters; the points with larger icing mass and lower sensitivity to changes in attack angle will have better detection effect. The measured data and analysis in the present work can provide a basis for the accurate design of icing sensor probes.

Superhydrophobic Coating Solutions for Deicing Control in Aircraft

The risk of accidents caused by ice adhesion on critical aircraft surfaces is a significant concern. To combat this, active ice protection systems (AIPS) are installed on aircraft, which, while effective, also increase fuel consumption and add complexity to the aircraft systems. Replacing AIPS with Passive Ice Protection Systems (PIPS) or reducing the energy consumption of AIPS could significantly decrease aircraft fuel consumption. Superhydrophobic (SH) coatings have been developed to reduce water adherence to surfaces and have the potential to reduce ice adhesion, commonly referred to as icephobic coatings. The question remains whether such coatings could reduce the cost associated with AIPS and provide durability and performance through suitable tests. In this paper, we then review current knowledge of superhydrophobic and icephobic coatings as potential passive solutions to be utilized alternatively in combination with active systems. We can identify physical parameters, coating composition, structure, roughness, and morphology, durability as properties not to be neglected in the design and development of reliable protection systems in aircraft maintenance.

Integrated composite electrothermal de-icing system based on ultra-thin flexible heating film

Icing is a serious threat to the flight safety of aircraft. Lightweight and efficient electrothermal de-icing systems for carbon fiber reinforced polymer components are expected to contribute to the lightweighting and electrification of aircraft. This study presents the development and test of a novel, integrated, multifunctional composite electrothermal ice protection system. The system achieves this by incorporating a carbon-based ultra-thin flexible heating film into a carbon fiber-reinforced polymer composite laminate. T700 and M40 carbon fiber prepregs were used. The system composition and configuration were designed based on the anisotropic mechanical and thermal properties of the carbon fiber-reinforced polymer composite. The effects of ply stacking sequence, presence of insulation layer, ply angle, heating area, and prepreg type on thermal response and de-icing performance were investigated. Thermal response experiments were carried out in both room temperature and low temperature environments. A one-dimensional thermal response analysis model was developed for a representative heating structure. Comparative de-icing experiments were conducted on different samples in a low-temperature test chamber. A numerical model, based on the modified enthalpy-porosity method, was developed to simulate the de-icing process, and showed good agreement with the experimental results. Experiments and numerical calculations show that the arrangement of the heater close to the deicing surface improves the performance of the electrothermal deicing system while maintaining the overall mechanical properties of the multi-layer structure. While the insulation layer helps marginally with heat loss during de-icing, it significantly increases the system’s thermal inertia, which delays the de-icing’s start. It is recommended to minimize or eliminate insulation layer thickness. Rapid de-icing effects, combined with energy conservation, can be achieved through a short-term, high-power heating strategy.

Integrating Ice Protection and Noise Abatement Systems for Aircraft Application: A Review

Aircraft icing remains a key aviation hazard as the global fleet of aircraft in various sectors continues to expand, posing a serious threat to flight safety. As previously stated, the growth of this type of aircraft has been accompanied by an increase in noise levels, and aircraft is reportedly the second most bothersome noise source after traffic. However, integrating an acoustic liner with anti-icing techniques on the leading edge of a nacelle would not efficiently eliminate forward radiated noise and improve the thermal performance of the anti-icing system. Hence, it is of the utmost importance to research the integration of ice protection and noise abatement systems for aircraft applications. This review discusses the integration of ice accretion and noise abatement systems in aircraft applications. The prominence of this review is to explain significant features such as ice protection systems, Computational Fluid Dynamics in ice protection, noise abatement systems, and the integration of ice protection systems and noise abatement systems wherever they are described.

A framework for simulating snow accumulation and ice accretion on high-speed trains

A simulation framework for three-dimensional particle trajectory tracking, snow accumulation and ice accretion modelling on solid bodies in high-speed air flow is presented. The framework, named HADICE, solves the aerodynamic flow field as Reynolds averaged Navier-Stokes (RANS), with optional hybrid RANS/LES capabilities for modelling complex turbulent flows. Particle trajectory tracking is performed in an Eulerian-Lagrangian approach and wall collision is modelled using a hard collision model with reflect condition and a momentum based trap condition. A novel accurate and robust iterative evaluation method for the local collection efficiency is proposed for arbitrary 3D geometry and flow. Ice accretion is modelled in a multi-step approach and iced geometry is updated through mesh deformation using a radial basis function (RBF) interpolation method. Snow accumulation and ice accretion predictions based on the framework are validated against climatic wind tunnel experimental measurements. A full 3D simulation is demonstrated for snow accumulation and ice accretion on a 1:8 scaled high-speed train model. Using the presented framework, snow accumulation and icing simulation for high-speed trains can be conducted in an accurate and efficient manner, which is of great importance for physical investigations and the design of anti-snow and ice protection systems.

Experimental assessment of the ice protection effectiveness of electrothermal heating for a hovering drone rotor

Drones and UAVs are gaining worldwide popularity and are now considered a popular choice for both military and commercial applications. Icing poses tremendous safety and performance concerns for the operation of all types of drones. This paper is part of a project that studies icing effects on the hovering 0.66 m diameter Bell APT70 drone rotor and the development of potential ice protection systems. The objective of this paper is to investigate the use of electrothermal heaters with severe icing conditions and to characterize the energy efficiency of anti-icing or de-icing regimes. Rotor speeds of 3880, 4440 and 4950 RPM were used while two air temperatures, −5 and −12 °C, were also tested. The heat transfer profile on the blade was studied using dry run tests where the rotor operated with heating but without water spray. Anti-icing tests with variable heating power were tested to determine the location of the initial ice accumulation as well as the minimum heating power requirement to protect the leading edge. Moreover, anti-icing tests with constant heating rates were done and compared to previous tests of unprotected blades, under similar condition. On the other hand, de-icing tests with various heating cycles were also carried out. Results indicate that although de-icing requires significantly less heating energy compared to anti-icing, there is clear trade-off on rotor stable aerodynamic output, electrical power consumption and vibration levels, depending on the adopted de-icing mode. Future work is about investigating the rise of secondary effects, such as shed ice impact due to de-icing. Work is also planned for a hybrid ice protection system that combines electro-thermal heaters with icophobic or superhydrophobic coatings.

UAV icing: Development of an ice protection system for the propeller of a small UAV

Atmospheric icing, also called in-flight icing, is a common hazard for the operation of uncrewed aerial vehicles (UAVs). With the background of a growing commercial and military market of small and medium-sized drones and the developments in the urban air mobility markets, protecting the propellers of UAVs against icing has become a pivotal technology to unlock the potential of these markets. The propellers and rotors accumulate ice faster than the UAVs’ wings and airframe. This ice accumulation leads to aerodynamic degradation, making the protection of the propeller key for the operation of UAVs in conditions with potential icing. In this work, an electro-thermal ice protection system is developed for a propeller of a small UAV, with a propeller diameter of 53 cm or 21 inch. For the design of the system, the required anti-icing heat fluxes were calculated using icing computational fluid dynamics (CFD) analysis. Carbon fibre-based heating elements were integrated into the structure of the propeller. This propeller was tested in an icing wind tunnel at −5 °C, −10 °C, and −15 °C. The tests were performed with a rotation rate representative for a medium-sized UAV of 4200 rpm. The liquid water content of the wind tunnel was 0.44 g/m3. It prevented the performance penalties from ice accretion at temperatures of −5 °C. At lower temperatures, the propeller IPS could limit the ice accretion on the propeller, thus allowing it to retain its ability to create thrust. The results showed a requirement for a significantly higher heat flux than predicted by the CFD analysis. This work is the first step in developing a mature ice protection system for the propellers and rotors of medium-sized UAVs and to enable all-weather operations.

Robust Optimization of a Thermal Anti-Ice Protection System in Uncertain Cloud Conditions

This paper presents a framework for the robust optimization of the heat flux distribution for an anti-ice electrothermal ice protection system under uncertain conditions. The considered uncertainty regards a lack of knowledge concerning the characteristics of the cloud, i.e., the liquid water content and the median volume diameter of water droplets, and the accuracy of measuring devices, i.e., the static temperature probe. Uncertain parameters are modeled as random variables, and two sets of bounds are investigated. A forward uncertainty propagation analysis is carried out using a Monte Carlo approach exploiting a surrogate models. The optimization framework relies on a gradient-free algorithm (mesh adaptive direct search), and two different objective functions are considered, namely, the 95 quantile of the freezing mass rate and the statistical frequency of the fully evaporative operating regime. The framework is applied to a reference test case, revealing a potential to improve the heat flux distribution of the baseline design. A new heat flux distribution is proposed, and it presents a more efficient use of the thermal power, increasing flight safety even at nonnominal environmental conditions.

A Study on the Sensitivities of an Ice Protection System Combining Thermoelectric and Superhydrophobic Coating to Icing Environment Parameters

The hybrid Ice Protection System combining thermoelectric and superhydrophobic coating is efficient and benefits from low-energy consumption. In order to explore the application details of superhydrophobic coating, this paper investigated the sensitivities of the Ice Protection System parameters including the range of the superhydrophobic coating, heating range and power to icing environmental parameters. In this paper, an icing wind tunnel test was adopted to study the performance of this Ice Protection System under different icing conditions, as well as the influence of the superhydrophobic coating range, heating range and power variation on ice protection. The results showed that the superhydrophobic coating is effective only when it covers the droplet impingement area, with the heating power requirement emerging as a critical design consideration that is extremely sensitive to environmental temperature changes. Additionally, median volumetric diameter determines the protection area to be protected, while liquid water content variation has little effect on the designed Ice Protection System in contrast.

Ice Accretion: Image Post-Processing Measurement Techniques for 2D Ice Shapes

Ice accretion poses substantial safety hazards for the manned and unmanned aviation industries. Its study is essential for icing events risk assessment and for the development of efficient ice protection systems. The existing ice accretion measurement techniques—casting, molding, and laser-scanning—are time-consuming, sometimes cumbersome to use, and highly expensive, while hand tracing is inexpensive, but has lower accuracy and time-consuming post-processing. This work presents two low-cost, fast, and easy-to-use measurement techniques for 2D ice accretion profiles. Both employ algorithms of automatic ice shape detection, one based on unmediated image-processing, another based on the processing of manual ice tracings. The techniques are applied to ice accretion experiments conducted in an icing wind tunnel at low Reynolds numbers, and their results are validated against ice thickness caliper measurements. A comparison of the results shows that both techniques accurately measure the leading-edge ice thickness and the 2D shape of the ice accretion profiles. One technique is faster, with higher measurement accuracy, but produces interrupted-line 2D ice profiles and requires good lighting conditions, while the other generates continuous-line 2D profiles and has no application restriction, but it is slower, with lower accuracy. A discussion is conducted, aiming to help one determine the best applications for each ice accretion measurement technique presented.

Electrothermal Ice Protection Systems De-Icing: An Experimentally Validated Idealized Ice Shedding Model

The increased use of electrothermal ice protection systems (ETIPSs) in various industries (manned and unmanned aviation, energy production) requires improvements to de-icing efficiency, ice shedding predictability, and energy consumption. To achieve these, a coupled numerical and experimental investigation of ETIPS’s ice removal (ice shedding) mechanism is presented in this paper. Idealized ETIPS de-icing experiments performed in the icing wind tunnel of the von Karman Institute show several ice shedding mechanisms. A one-dimensional phase change solver developed for ice melting simulations highlights the water layer thickness influence over the ice shedding process. Coupled numerical–experimental results are employed to develop an idealized ice shedding model. The model is validated in realistic de-icing experiments in a second experimental campaign in the icing wind tunnel of the LeClerc Icing Research Laboratory.

Multi-physics simulation of 3D in-flight ice-shedding

In-flight ice accretion may possibly jeopardize the safety of fixed- and rotary-wing aircraft. Icing can possibly occur if supercooled water droplets in clouds impinge on the aircraft surfaces and freeze upon impact. It may result in instrument failures and degradation of the aerodynamic performances. A major problem related to ice accretion is the possibility of ice shedding from the main body and impacting other parts of the aircraft or being ingested by the engines. In fixed-wing aircraft, shedding is caused by the action of the aerodynamic forces or the activation of an Ice Protection System. In the present work, a multi-physics framework is presented to simulate ice accretion and shedding from wings and engine nacelles. The aerodynamics is computed using the open-source toolkit SU2 (Economon et al., 2015)[1] . Cloud droplet trajectories are computed using the arbitrary-precision Lagrangian in-house solver PoliDrop. Then, the in-house ice accretion toolkit PoliMIce (Gori et al., 2015) is used to determine the ice layer. An algebraic level-set approach with iterative volume mesh refinement has been developed to extract the ice shape from the iced wing geometry. A FEM structural analysis is performed on the accreted ice shape by means of the open-source code MoFEM (Kaczmarczyk et al., 2014, 2020) [2]. Internal stresses within the ice geometry due to aerodynamic forces are computed. Three-dimensional ice accretion simulations are performed to check the validity of the present approach.

Experimental assessment of the ice protection effectiveness of icephobic coatings for a hovering drone rotor

A new installation at the Anti-Icing Materials International Laboratory was developed to study the effects of icing on the degradation of a hovering drone rotor aerodynamic performance and to test different potential ice protection solutions. Following a study on icing parameters effects on aerodynamic performance, this paper studies a methodology developed to assess the performances of coatings as a potential ice protection system under severe icing conditions and rotor speeds up to 4950 RPM. Four different coatings, commercial or under development, were applied to the rotor blades and their effect on the resulting ice accumulation and aerodynamic degradation were measured and compared to those previously obtained on similar, uncoated blades. Results show that passive icephobic coatings in general are a promising solution to limit the negative effect of icing conditions for drone applications, without any additional energy consumption from the system. Moreover, the repeatability assessment of tests under similar conditions and for the same coating showed agreement within ±5% between repetitions, showing no signs of ice protection efficiency degradation for any of the tested coatings.

Understanding ice accretion on wind turbines with field data

With the abundance of wind resources in cold climates, a significant share of the worldwide wind energy installed capacity is located in those areas. However, the advantages of cold climate operation comes with challenges associated with ice accretion. Throughout the years, alternative operational strategies have been developed to cope with these challenges. Although many strategies, such as blade heating, have been commercially available for a long time, few field studies have investigated their performance. Evaluating the performance of wind turbines in cold climates is a hard task due to the lack standards and the variability of external factors influencing turbine behaviour. In this paper, a methodology to assess the performance of wind turbines in cold climates is illustrated with a case study. This methodology aims to provide a better understanding of how ice accretion impacts wind turbine performance. This methodology was exemplified with a case study where the performance of a turbine equipped with a retrofit hot air ice protection system was analyzed over a 9-day icing event. It was found that the usage of the cold climate solution yielded an average energy gain of 159 MWh and an average potential recovery of 62%.

Optimisation of a Nacelle Electro-Thermal Ice Protection System for Icing Wind Tunnel Testing

Abstract Aircraft are equipped with ice protection systems (IPS), to avoid, delay or remove ice accretion. Two widely used technologies are the thermo-pneumatic IPS and the electro-thermal IPS (ETIPS). Thermo-pneumatic IPS requires air extraction from the engine negatively affecting its performances. Moreover, in the context of green aviation, aircraft manufacturers are moving towards hybrid or fully electric aircraft requiring all electric on-board systems. In this work, an ETIPS has been designed and optimised to replace the nacelle pneumatic-thermal system. The aim is to minimise the power consumption while assuring limited or null ice formation and that the surface temperature remains between acceptable bounds to avoid material degradation. The design parameters were the length and heat flux of each heater. Runback ice formations and surface temperature were assessed by means of the in-house developed PoliMIce framework. The optimisation was performed using a genetic algorithm, and the constraints were handled through a linear penalty method. The optimal configuration required 33% less power with respect to the previously installed thermo-pneumatic IPS. Furthermore, engine performance is not affected in the case of the ETIPS. This energy saving resulted in an estimated reduction of specific fuel consumption of 3%, when operating the IPS in anti-icing mode.

The effect of icing severity on wind turbine ice protection systems efficiency

In the past years, there has been a gain of interest in wind turbine Ice Protection Systems (IPS) as wind farm owners realize the extent of their ice-induced losses. More and more wind turbine manufacturers are now offering IPSs in their cold climate packages. IPS retrofits are now available to minimize icing losses on existing unheated wind turbines. With this growth in interest, questions about the efficiency of those systems arise. Field experience has shown that these systems can be ineffective in certain ambient conditions which led to the concept of IPS performance envelopes. These envelopes lay out on a wind speed vs ambient temperature map the conditions where IPSs are expected to be effective. While these envelopes can give a good overlook of the IPSs efficiency in post-icing conditions, they neglect the effect that icing severity can have on IPS effectiveness. This paper presents a simple 1D model for hot-air IPS able to generate performance envelopes considering the icing severity. This model was validated with the production data of six different icing events. It has been shown to be coherent with the observed efficiency of the hot air IPS.

Numerical Simulation of an Electrothermal Ice Protection System in Anti-Icing and Deicing Mode

The design of efficient thermal ice protection systems is a challenging task as these systems operate in complex environments involving several coupled physical phenomena such as phase change, boundary-layer flow, and heat transfer. Moreover, certification rules are becoming more stringent, and there is a strong incentive for the reduction of fuel consumption. In this context, numerical tools provide a powerful asset during the design phase but also to gain insight into the physical mechanisms at play. This article presents modeling and simulation strategies for thermal ice protection systems. First, the model describing the behavior of the thermal protection system is presented. Second, a model and associated numerical method is presented for unsteady ice accretion. Third, the coupling methodology between the ice accretion solver and the heat conduction solver is described. In the fourth part, different methods to simulate the boundary-layer flow are described. Finally, some relevant examples are presented, both in steady and unsteady configurations.

Computational approach for investigating nanoscale interfacial ice adhesion trends

For developing high performance, low-energy ice protection systems, it is vital to understand the icing physics at the interface of the ice and substrate. This can be achieved by modelling the interface at nanoscale and then studying the adhesion trends.

열전달 결합 기법에 따른 열적 결빙보호장치 수치해석 개발

The numerical analysis of the thermal Ice Protection System(IPS) is conducted by heat transfer analysis between an icing simulation and an internal heat transfer simulation. For accurate heat transfer analysis, the coupling method is required since heat transfer occurs in each region. A loose-coupling method, which is used by most of the prior research, does not take into account the effect of the internal heat transfer on the convection heat of external flow. While the tight-coupling method takes longer to calculate than the loose-coupling method, it can result in high accuracy. In this study, a convective heat transfer coefficient is obtained by the tight-coupling method in dry conditions without water film. A comparative analysis was then performed with experimental results and other numerical analysis studies. The tight-coupling method showed more excellent agreement with the experiments than the loose-coupling method. Furthermore, it is confirmed that the developed numerical method has a great performance.