Ice Buildup Research Articles

NUMERICAL SIMULATIONS AND SENSITIVITY ANALYSIS OF ICE FORMATION ON FAN BLADES

Abstract In-flight icing, the formation of ice during flight, poses risks to the safety and reliability of aircraft. Due to environmental conditions, ice accumulation occurs on the low-pressure compressor blades of an engine, diminishing aerodynamic performance and potentially causing damage to the engine. Numerical simulations of ice accretion are conducted on the blades of the NASA Rotor 67 utilizing the Computational Fluid Dynamics (CFD) software ANSYS CFX and the in-flight icing software FENSAP-ICE. One-dimensional and two-dimensional sensitivity studies aim to analyze the influences of temperature, droplet diameter and liquid water content (LWC) on the resulting ice build-up on the blade. The analyses reveal that ice accumulates predominantly at the leading edge of the blade, where collection efficiency is maximal. Additionally, an ice layer forms at the blade root on the pressure side. While LWC and temperature exerts a significant influence on the ice mass, only a marginal impact on droplet diameter is observed.

A detailed investigation into the legacy of glacial readvances and ice-dammed lakes around Sellafield, West Cumbria: Implications for 3D modelling, hydrogeology and ground engineering

The glacial evolution of western Cumbria, England is reassessed following a comprehensive review of both published and extensive unpublished records from the Sellafield area, together with targeted fieldwork. The exercise scrutinises evidence for glacial readvances across former ice-dammed lakes, determining their occurrence, relative age, extent and legacy. It is concluded that the area was affected by at least two substantial glacial readvances following the maximum build-up of ice during the last, Late Devensian (Weichselian/Wisconsin) glaciation. The earlier Gosforth Oscillation involved locally sourced ice together with ice that circulated around the north of the Lake District into the Irish Sea basin whilst most of the region was substantially glaciated. The subsequent Fishgarth Wood Readvance involved ice flowing from the north, but when an ice centre positioned over the western Southern Uplands of Scotland had become dominant. Glacial oscillations across the coastal plain have resulted in a complex interdigitating sequence of sediments of contrasting permeability and physical properties, commonly preserved within buried valleys. The genesis of some thin units of clay-rich diamicton and pebbly clay previously interpreted as till is discussed in the light of ongoing debate concerning their possible glaciolacustrine origin.

Альтернативні протиожеледні матеріали для боротьби з утворенням та ліквідації зимової слизькості на автомобільних дорогах

Introduction. The winter season is the most challenging for road maintenance and traffic management. Key factors affecting vehicle movement during winter include the presence of ice and snow-ice buildup, leading to a sharp decline int tyre grip, increased rolling resistance, and deteriorating surface evenness. Problem Statement. Addressing the prevention and elimination of ice on roads is a priority in all countries that experience negative temperatures annually. In our country, the salt from the “Artemsil” plant was traditionally used to combat winter slipperiness. However, the plant was destroyed at the beginning of the war, necessitating the search for alternative de-icing materials for roads and streets. Objective. To study the possibility of using alternative de-icing materials (industrial waste, local materials, etc.) for combating winter slipperiness on roads during the martial law period.

Tracking palaeotemperatures in Coniacian–Maastrichtian seas

In this study the stable isotopes of belemnites, are presented from the Coniacian–Maastrichtian interval (∼76–66 Ma) derived from the chalks of Yorkshire and Norfolk, UK, deposited on the western North Atlantic shelf. Cathodoluminescence and elemental geochemistry of the belemnites reveals that most of the rostra were well preserved. If interpreted in terms of temperature, our oxygen isotope record reveals that during the Coniacian (at ∼43 °N) the climate was relatively warm, with maximum mean temperatures of ∼26 °C, followed by cooling to <∼21 °C during the Campanian and Maastrichtian. This overall stratigraphic trend is similar to other records, suggesting that the cooling pattern was not a regional trend and, therefore, driven predominantly by global mechanisms. Within our belemnite data, we also observe a decline in δ13C at the Campanian- Maastrichtian boundary, again consistent with other records. This trend has been interpreted as a result of an increased ratio of organic to inorganic carbon introduced into the oceans, driven by increased weathering and reworking of organic-rich sediments exposed on continental shelves during a sea-level fall. The latter related to a build-up of polar ice. Although our oxygen isotope data point to a cooling this was not necessarily linked to polar ice formation.

Effect of phase change materials on thermophysical properties of asphalt mixtures and snow melting performance

The increased Thermal Conductivity and Thermal Diffusion Coefficient of asphalt mixtures means that the material is able to conduct and disperse heat more efficiently. In winter, this property can be used to accelerate the melting process of snow and ice, reducing the risk of road sliding due to snow and ice build-up. In this study, the thermal conductivity, thermal diffusion coefficient, and specific heat capacity of phase change asphalt (PCA) mixtures were investigated using a transient flat-plate heat source method. Analysis was performed with a thermal constant analyzer, a custom-designed thermal conductivity experiment, and a differential scanning calorimeter. Additionally, a phase change asphalt mixture thermoregulation rutting plate was prepared to evaluate its thermoregulation and snow and ice resistance under actual winter and indoor conditions. Results indicated that the thermal conductivity and thermal diffusion coefficient of PCA mixtures were superior to those of conventional asphalt mixtures. Notably, the specific heat capacity of these mixtures increased significantly within the phase change temperature range. The integration of phase change materials enhanced heat transfer within the asphalt mixtures, allowing for a delayed cooling process when temperatures decreased, with the maximum cooling range observed to be 2.8°C. Snow melting tests confirmed the early snowfall efficacy of the phase change asphalt mixture rutting plate, effectively achieving minimal snow accumulation and demonstrating the capability of 'melting light snow.'

Icing Wind Tunnel and Erosion Field Tests of Superhydrophobic Surfaces Caused by Femtosecond Laser Processing

Ice accumulation on lift-generating surfaces, such as rotor blades or wings, degrades aerodynamic performance and increases various risks. Active measures to counteract surface icing are energy-consuming and should be replaced by passive anti-icing surfaces. Two major categories of surface treatments—coating and structuring—already show promising results in the laboratory, but none fulfill the current industry requirements for performance and durability. In this paper, we show how femtosecond laser structuring of stainless steel (1.4301) combined with a hydrocarbon surface treatment or a vacuum treatment leads to superhydrophobic properties. The anti-ice performance was investigated in an icing wind tunnel under glaze ice conditions. Therefore, flexible steel foils were laser-structured, wettability treated and attached to NACA 0012 air foil sections. In the icing wind tunnel, hydrocarbon treated surfaces showed a 50 s ice build-up delay on the leading edge as well as a smoother ice surface compared to the reference. To demonstrate the erosion resistance of these surfaces, long-term field tests on a small-scale wind turbine were performed under alpine operating conditions. The results showed only minor erosion wear of micro- and nano-structures after a period of six winter months.

Target temperature-based simulation method for predicting performance and designing aircraft thermal anti-icing systems

The prevention of ice build-up on aircraft surfaces is crucial for safe operations. Thermal ice protection systems, particularly electro-thermal systems, are commonly employed to mitigate ice formation. However, the weight of electric batteries used in these systems significantly impacts aircraft performance, necessitating the minimization of power load during design. Despite this requirement, effective anti-icing operation mandates a sufficient heat flux to maintain surface temperature above the freezing point and evaporate any runback water film. Previous research has utilized numerical simulation analysis to predict the performance of electro-thermal anti-icing systems. The conjugate heat transfer method has been commonly employed to predict temperature distribution on the protected surface. However, non-isothermal surfaces exhibit distinct local convective heat transfer coefficients that influence local thermal balance, unlike isothermal surfaces that adopt the loosely-coupled method for computational efficiency. In this study, we present a novel target temperature-based anti-icing simulation method that predicts the required heat flux for thermal ice protection systems without employing the conjugate heat transfer method. Our objective was to calculate the necessary heat flux to achieve the desired non-isothermal surface temperature for effective anti-icing. By eliminating the excessive iteration process associated with the coupling method for conjugate heat transfer, we have streamlined the simulation procedure. Through validation, target temperature-based anti-icing simulation method, when compared to the tight coupling method, demonstrated the ability to predict the same surface water flow rates while reducing computation time by up to 90 %. Furthermore, when applied to design problems, our method achieved approximately a 10 % reduction in the required heat capacity for anti-icing compared to experimental values. As a result, target temperature-based anti-icing simulation method offers a more efficient alternative to traditional conjugate heat transfer methods, providing valuable insights for both predicting anti-icing system performance and optimizing aircraft design.

Preconditioning of mountain permafrost towards degradation detected by electrical resistivity

Warming permafrost has been detected worldwide and is projected to continue during the next century by many modelling studies. In mountain regions, this can lead to potentially hazardous impacts on short time-scales by an increased tendency for slope instabilities. However, time scales of permafrost thaw and the role of the ice content are less clear, especially in heterogeneous mountain terrain, where ice content can vary between zero and supersaturated conditions over small distances. Warming of permafrost near the freezing point shows therefore complex inter-annual behaviour due to latent heat effects during thawing and the influence of the snow-cover, which is governed by highly non-linear processes itself. Here, we demonstrate a preconditioning effect within near-surface layers in mountain permafrost that causes non-linear degradation and accelerates thaw. We hypothesise that a summer heat wave, as has occurred in the Central European summers 2003, 2015 and 2022, will enhance permafrost degradation if the active layer and the top of the permafrost layer are already preconditioned, i.e. have reduced latent heat content. This preconditioning can already be effectuated by a singular warm year, leading to exceptionally strong melting of the ground ice. On sloping terrain this ice-loss can be considered as irreversible, as large parts of the melted water will drain during the process, and an equivalent build-up of ice in cold years does not happen on similar time-scales as the melting. We propose a simple geophysical approach based on electrical resistivity tomography surveys that can assess the state of preconditioning in the absence of boreholes. In addition, we will show that resistivity data from a total of 124 permafrost sites in the Andes, Europe, and Antarctic adhere to a distinct power law behaviour between unfrozen and frozen states, which confirms the consistent electrical behaviour of permafrost and active layer materials over a wide range of landforms and material composition.

Early-Stage Ice Detection Utilizing High-Order Ultrasonic Guided Waves.

Ice detection poses significant challenges in sectors such as renewable energy and aviation due to its adverse effects on aircraft performance and wind energy production. Ice buildup alters the surface characteristics of aircraft wings or wind turbine blades, inducing airflow separation and diminishing the aerodynamic properties of these structures. While various approaches have been proposed to address icing effects, including chemical solutions, pneumatic systems, and heating systems, these solutions are often costly and limited in scope. To enhance the cost-effectiveness of ice protection systems, reliable information about current icing conditions, particularly in the early stages, is crucial. Ultrasonic guided waves offer a promising solution for ice detection, enabling integration into critical structures and providing coverage over larger areas. However, existing techniques primarily focus on detecting thick ice layers, leaving a gap in early-stage detection. This paper proposes an approach based on high-order symmetric modes to detect thin ice formation with thicknesses up to a few hundred microns. The method involves measuring the group velocity of the S1 mode at different temperatures and correlating velocity changes with ice layer formation. Experimental verification of the proposed approach was conducted using a novel group velocity dispersion curve reconstruction method, allowing for the tracking of propagating modes in the structure. Copper samples without and with special superhydrophobic multiscale coatings designed to prevent ice formation were employed for the experiments. The results demonstrated successful detection of ice formation and enabled differentiation between the coated and uncoated cases. Therefore, the proposed approach can be effectively used for early-stage monitoring of ice growth and evaluating the performance of anti-icing coatings, offering promising advancements in ice detection and prevention for critical applications.

Advanced wind turbine blade inspection with hyperspectral imaging and 3D convolutional neural networks for damage detection

In the context of global efforts to mitigate climate change by pursuing sustainable energy sources, wind energy has emerged as a critical contributor. However, the wind energy industry faces substantial challenges in maintaining and preserving the integrity of wind turbine blades. Timely and accurate detection and classification of blade faults, encompassing issues such as cracks, erosion, and ice buildup, are imperative to uphold wind turbines' ongoing efficiency and safety. This study introduces an inventive approach that amalgamates hyperspectral imaging and 3D Convolutional Neural Networks (CNNs) to augment the precision and efficiency of wind turbine blade fault detection and classification. Hyperspectral imaging is harnessed to capture comprehensive spectral information from blade surfaces, facilitating exact fault identification. The process is streamlined through Incremental Principal Component Analysis (IPCA), reducing data dimensions while maintaining integrity. The 3D CNN model demonstrates remarkable performance, achieving high accuracy in detecting all fault categories in full-band hyperspectral images. The model retains high accuracy even with dimensionality reduction to 20 spectral bands. The reduced processing time of the 20-band image enhances the practicality of real-world applications, thereby reducing downtime and maintenance expenditures. This research represents a significant advancement in wind turbine blade inspection, contributing to the sustainability and dependability of wind energy systems and furthering the cause of a cleaner and more sustainable energy future as part of the broader fight against climate change.

Study on durable icephobic surfaces modified with phase change oil impregnation

The build-up of ice on critical infrastructure could cause severe disruptions and substantial economic consequences. The application of ice-repellent surfaces has been identified as a promising approach to tackle and mitigate the problem. The main challenge is to ensure they can endure harsh environmental conditions and maintain long-term mechanical durability. This study presents an innovative design concept that incorporates phase change liquids with Ni scaffolds and polydimethylsiloxane (PDMS) in a multi-phase ice-repellent construction. Incorporating phase change liquids within the oil-infused surface construction facilitates the absorption and subsequent release of heat during the icing process. The supercooled droplets took significantly longer (7–8 times) to ice on the sample surfaces compared to aluminum alloy, attributed to the solidification of phase change liquids at low temperatures, resulting in decreased oil depletion during de-icing. Furthermore, the durability enhancement effect was validated by the weight maintenance ratio of samples, which remained almost unchanged after undergoing 50 cycles of icing/de-icing tests, providing a practical solution for addressing concerns on oil depletion in prolonged service conditions.

Modification of gelcoat based unsaturated polyester resin with functionalized octaspherosilicates to reduce the ice adhesion strength

Many composite structures used in various industries, such as wind turbines, aircraft, watercraft, lifeboats and others face the problem of ice build-up in winter seasons. The mechanical, thermal and chemical methods used so far to remove ice are inefficient, uneconomical and hurt the environment. Recently, surfaces have begun to be designed to eliminate or minimize ice accumulation, namely icephobic surfaces. The key parameter of such surfaces is the lowest possible ice adhesion strength (IA). One of the mechanisms for designing icephobic surfaces is a modification with compounds that direct hydrophobic properties. In this work, unsaturated polyester resin gelcoats modified with compounds from the group of octaspherosilicates with alkyl and methacrylic functional groups proposed as fluorine-free additives were investigated in terms of water repellent and ice adhesion. The surface roughness of the tested materials was measured. The surface zeta potential was also determined, which is new compared to available studies of surfaces for icephobic applications. The work also presents microstructure observations of the surface. Almost all of the modifiers increased the water contact angle (WCA), modifying the reference material from hydrophilic to slightly hydrophobic. The highest WCA was equal to 94°. The most important IA parameter was decreased by 56% compared to the unmodified gelcoat, with a value of 152 kPa. In addition, the study observed that the lowest value of IA correlated with the lowest value of CAH. The highest reduction in CAH was 44% compared to the reference sample. The roughness, wettability and IA parameters were determined before and after UV exposure to investigate modified gelcoats durability.

Adhesion of impure ice on surfaces.

The undesirable buildup of ice can compromise the operational safety of ships in the Arctic to high-flying airplanes, thereby having a detrimental impact on modern life in cold climates. The obstinately strong adhesion between ice and most functional surfaces makes ice removal an energetically expensive and dangerous affair. Hence, over the past few decades, substantial efforts have been directed toward the development of passive ice-shedding surfaces. Conventionally, such research on ice adhesion has almost always been based on ice solidified from pure water. However, in all practical situations, freezing water has dissolved contaminants; ice adhesion studies of which have remained elusive thus far. Here, we cast light on the fundamental role played by various impurities (salt, surfactant, and solvent) commonly found in natural water bodies on the adhesion of ice on common structural materials. We elucidate how varying freezing temperature & contaminant concentration can significantly alter the resultant ice adhesion strength making it either super-slippery or fiercely adherent. The entrapment of impurities in ice changes with the rate of freezing and ensuing adhesion strength increases as the cooling temperature decreases. We discuss the possible role played by the in situ generated solute enriched liquid layer and the nanometric water-like disordered ice layer sandwiched between ice and the substrate behind these observations. Our work provides useful insights into the elementary nature of impure water-to-ice transformation and contributes to the knowledge base of various natural phenomena and rational design of a broad spectrum of anti-icing technologies for transportation, infrastructure, and energy systems.

The Effect of Conductivity on Surface Leakage Currents on Iced-Covered Insulators

Insulators on power transmission systems today are vital to ensuring the reliable and effective operation of high-voltage lines. However, it is inevitable that insulators will encounter problems such as contamination and icing due to natural environmental conditions and environmental factors. Pollution layers and ice buildup that have developed on insulator surfaces have a detrimental impact on insulation performance, increase surface leakage currents, and result in power line failures or interruptions. This article focuses on understanding the phenomena of contamination and icing in insulators, evaluating their effects, and investigating methods that can be taken to prevent or reduce these problems. For this purpose, solutions with different conductivity values were sprayed on the insulators in the laboratory environment, and ice covering the insulator surface was provided. Leakage currents were investigated by applying an alternating voltage with mains frequency to the insulators. Data were obtained with the help of the LabVIEW program, and the relationship of leakage currents of porcelain, glass, and silicone insulators with conductivity was compared.

Shape and temperature dependence on the directional velocity change in a freezing water droplet

Freezing of water droplets are of interest in areas such as de-icing and anti-icing of wind turbine blades, aircrafts and cars. On part of the ice build-up that has been less studied is the internal flow in water droplets and how it affects the freezing process. In this paper the aim is to investigate how the contact angle, substrate composition and temperature influences the internal flow. Particle Image Velocimetry (PIV) is used to determine the magnitude and direction of the internal flow, with specific emphasis on directional changes. Results show that a larger contact angle will increase the internal velocity, freezing time and time until the directional change. Cooler substrate temperature increase the internal velocity while reducing the freezing time, but the dependence on the time until the directional change is not as pronounced. The result thus indicate differences in the driving forces between freezing time, internal velocity and directional velocity change. Difference due to substrate composition, i.e. mixture of ice and metal versus only metal is furthermore compared.

Graphite-epoxy composite systems for Joule heating based de-icing

Ice accretion and build-up in low temperature environments are issues plaguing many different branches of the industry. Recently much work has been done into the development of active de-icing systems based on carbon materials and their composites. The following research presents an investigation into graphite/epoxy composite materials made by a simple casting method with cheap materials and scalability potential, intended for de-icing applications based on Joule heating. The examination has been carried out for samples with different amounts of carbon filler using IR thermal imaging to measure sample heating under the influence of electrical current under constant voltage. Measured electrical currents were then analyzed to examine changes in samples' electrical resistance dependent on temperature. Results provide a positive outlook for further experiments and development for this type of material toward its potential application.

Ice Adhesion Characterization Using Mode-I and Mode-II Fracture Configurations

Abstract The ice buildup on airborne structures operating in cold weather conditions has detrimental impacts on their safety and performance. Due to practical applications, there has been a significant interest in ice removal strategies. However, the current body of literature lacks comprehensive insights into the mechanistic aspects of the ice adhesion/breakage process, resulting in a wide range of reported adhesion strengths that differ by two orders of magnitude. To address this gap, we employed a fracture mechanics-based approach to investigate the fracture behavior of a typical ice/aluminum interface in terms of mode-I and mode-II fractures. We examine a range of surface roughness values spanning from 0.05 to 5 micrometers. An experimental framework employing a single cantilever beam and direct shear tests were developed. The near mode-I and mode-II interfacial fracture toughness and strength values were extracted from the experimentally measured force and displacement by both analytical and numerical models employing cohesive surfaces. The combined experimental and numerical results show that ice adhesion is primarily driven by cohesive interfacial failure, which exhibits almost mode-independent fracture behavior. Mode-I fracture shows directional instability of crack propagation, which is attributed to thermally induced residual tensile stress at the ice layer-substrate interface. The fractographic inspection reveals similar ice-grain size over the examined range of substrate roughness values. For the examined range of surface roughness and temperature, which induces the Wenzel state with full surface wetting at the interface, the ice adhesion is insensitive to the interfacial roughness in both mode-I and mode-II fracture.

Elite skiers'experiences of heat- and moisture-exchanging devices and training and competition in the cold: A qualitative survey.

Winter endurance athletes have a high prevalence of exercise-induced bronchoconstriction (EIB) and asthma, probably due to repeated and prolonged inhalation of cold and dry air. Heat- and moisture-exchanging devices (HME) warm and humidify inhaled air and prevent EIB. The aimof this study was to share cross-country skiers and biathletes'experiences of training and competition in low temperatures, views on temperature limits, usage of HME, and consequences of cold exposure on their health. Eleven Swedish World Championship or Olympic medalists in cross-country skiing and biathlon were interviewed and transcripts were analyzed using qualitative content analysis. Participants described how cold temperatures predominantly affected the airways, face, and extremities. During training, extreme cold was managed by choosing warmer clothing, modification of planned sessions, use of HME, delaying training, or changing location. In competition, participants described limited possibility for such choices and would prefer adjustment of existing rules (i.e., more conservative temperature limits), especially since they understood elite skiing in low temperatures to present an occupational hazard to their health. Participants had at times used HMEs during training in cold environments but described mixed motives for their use-that HMEs warm and humidify cold inhaled air but introduce additional resistance to breathing and can cause problems due to mucus and ice build-up. Skiers also perceived that they had become more sensitive to cold during the latter part of their careers. The present study gives a unique insight into the "cold" reality of being an elite athlete in skiing and biathlon. Cold exposure results in negative health consequences that are preventable, which means that rules must be followed, and organizers should acknowledge responsibility in protecting athletes from occupational hazards. Development of evidence-based guidelines for protection of athletes'respiratory health should be a focus for future translational research.

Determination of the most dangerous flight modes of aircraft in icing conditions

In this paper, the object of research is the icing of aircraft surfaces during flight in the atmosphere. On many light aircraft, as well as on unmanned aircraft weighing less than 30 kg, there are no on-board de-icing systems. Nevertheless, aviation events occur with these aircraft, which are a consequence of their icing. Therefore, determining the most dangerous flight modes of aircraft in icing conditions is an urgent task. In view of the high cost of conducting flight tests and the impossibility of covering all possible events due to their potential danger, the complexity of creating flight conditions for aircraft in icing conditions on the ground, the mathematical modeling method was used in this study. To solve this problem, the analysis of the airworthiness standards of civil light aircraft, transport category aircraft, rotorcraft of normal and transport category was carried out within the framework of the work, the influence of various parameters on the thickness of ice build-up was investigated using a computational experiment conducted on the software developed by the authors of the article. On the basis of the results of the computational experiment, the dependences of the ice thickness on various icing parameters were obtained, a method was developed for determining the combination of heights and flight speeds of an aircraft, at which ice of the greatest thickness is formed on the surface of aircraft, other things being equal. Possession of this information will allow the aircraft crew and air traffic control specialists to avoid the most dangerous flight modes in terms of icing.

Photothermal superhydrophobic copper nanowire assemblies: fabrication and deicing/defrosting applications

Ice and frost buildup continuously pose significant challenges to multiple fields. As a promising de-icing/defrosting alternative, designing photothermal coatings that leverage on the abundant sunlight source on the earth to facilitate ice/frost melting has attracted tremendous attention recently. However, previous designs suffered from either localized surface heating owing to the limited thermal conductivity or unsatisfied meltwater removal rate due to strong water/substrate interaction. Herein, we developed a facile approach to fabricate surfaces that combine photothermal, heat-conducting, and superhydrophobic properties into one to achieve efficient de-icing and defrosting. Featuring copper nanowire assemblies, such surfaces were fabricated via the simple template-assisted electrodeposition method, allowing us to tune the nanowire assembly geometry by adjusting the template dimensions and electrodeposition time. The highly ordered copper nanowire assemblies facilitated efficient sunlight absorption and lateral heat spreading, resulting in a fast overall temperature rise to enable the thawing of ice and frost. Further promoted by the excellent water repellency of the surface, the thawed ice and frost could be spontaneously and promptly removed. In this way, the all-in-one design enabled highly enhanced de-icing and defrosting performance compared to other nanostructured surfaces merely with superhydrophobicity, photothermal effect, or the combination of both. In particular, the defrosting efficiency could approach ∼100%, which was the highest compared to previous studies. Overall, our approach demonstrates a promising path toward designing highly effective artificial deicing/defrosting surfaces.