Research

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24 pages, 18418 KiB

Open AccessArticle

Investigation on Phase Transition and Collection Characteristics of Non-Spherical Ice Crystals with Eulerian and Lagrangian Methods

by Shengfang Lu, Weijian Chen, Dalin Zhang, Zihao Zhang and Guangya Zhu

Aerospace 2024, 11(4), 299; https://doi.org/10.3390/aerospace11040299 - 11 Apr 2024

Viewed by 395

Abstract

Ice crystal icing occurs in jet engine compressors, which can severely degrade jet engine performance. In this paper, two different numerical calculation methods, the Eulerian method and the Lagrangian method, were used to evaluate the dynamics, mass transfer, heat transfer, phase transition and [...] Read more.

Ice crystal icing occurs in jet engine compressors, which can severely degrade jet engine performance. In this paper, two different numerical calculation methods, the Eulerian method and the Lagrangian method, were used to evaluate the dynamics, mass transfer, heat transfer, phase transition and trajectory of ice crystals. Then, we studied the effects of initial diameter, initial sphericity, initial temperature of ice crystal, and relative humidity of airflow on the phase transition and collection characteristics of ice crystal particles. Results indicate that the non-spherical characteristics of ice crystals have a significant impact on their impingement limits and collection characteristics. The collection coefficient of unmelted ice crystals is positively correlated with the initial particle diameter and sphericity, and negatively correlated with the initial particle temperature and the relative humidity of airflow. The melting rate of ice crystal particles on the impact surface increases exponentially with the initial diameter of the particles, linearly increases with the relative humidity of the airflow and initial temperature of the particles, and exponentially decreases with the sphericity of the particles. Full article

(This article belongs to the Special Issue Deicing and Anti-Icing of Aircraft (Volume III))

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17 pages, 18023 KiB

Open AccessArticle

Research on the Methods for Obtaining Droplet Impingement Characteristics in the Lagrangian Framework

by Xiaobin Shen, Chunhua Xiao, Yijun Ning, Huanfa Wang, Guiping Lin and Liangquan Wang

Aerospace 2024, 11(3), 172; https://doi.org/10.3390/aerospace11030172 - 21 Feb 2024

Viewed by 733

Abstract

The impact of supercooled water droplets is the cause of aircraft icing, and the acquisition of impingement characteristics is the key to icing prediction and the design of ice protection systems. The introduction of water droplet collection efficiency is required to obtain the [...] Read more.

The impact of supercooled water droplets is the cause of aircraft icing, and the acquisition of impingement characteristics is the key to icing prediction and the design of ice protection systems. The introduction of water droplet collection efficiency is required to obtain the characteristics for the Lagrangian method. In this work, a traditional flow tube method, a local flow tube method, and a statistical method are established to calculate the local collection efficiency, based on Lagrangian droplet trajectories. Through the numerical simulations of the air–droplet flow field around an NACA 0012 airfoil, the accuracies of the three methods in regard to collection efficiency are verified. Then, these three methods are applied to obtain the results for water droplet trajectories and the collection efficiency of an S-shaped duct, a 2D engine cone section and an icing wind tunnel. The results show that the distributions of water droplet collection efficiency obtained by the three methods are consistent and the three methods are all feasible when the water droplets do not overlap or cross before hitting the aircraft surfaces. When the water droplets are shadowed by upstream surfaces or blown by air injection, the droplet trajectories might overlap or even cross, and the local collection efficiencies obtained by the traditional flow tube method, local flow tube method, and statistical method might differ. The statistical method is relatively accurate. However, not all the droplet impingement characteristics obtained by the three methods are different due to these effects, and the non-crossing of the droplet trajectories is not a necessary condition for the use of the flow tube method. The effects of trajectory crossings are analyzed and discussed in detail in different situations for the three methods. This work is helpful for understanding and accurately calculating the droplet impingement characteristics and is of great significance for simulations of the aircraft icing process and anti/de-icing range. Full article

(This article belongs to the Special Issue Deicing and Anti-Icing of Aircraft (Volume III))

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12 pages, 3762 KiB

Open AccessArticle

Experimental Investigation on Ice–Aluminum Interface Adhesion Strength under Heating Conditions

by Yusong Wang, Chengxiang Zhu, Ke Xiong and Chunling Zhu

Aerospace 2024, 11(2), 152; https://doi.org/10.3390/aerospace11020152 - 14 Feb 2024

Viewed by 726

Abstract

Ice accumulation on airfoils and engines seriously endangers fight safety. The design of anti-icing/de-icing systems calls for an accurate measurement of the adhesion strength between ice and substrates. In this research, a test bench for adhesion strength measurement is designed and built. Its [...] Read more.

Ice accumulation on airfoils and engines seriously endangers fight safety. The design of anti-icing/de-icing systems calls for an accurate measurement of the adhesion strength between ice and substrates. In this research, a test bench for adhesion strength measurement is designed and built. Its reliability and accuracy are verified by the calibration. The adhesion strength is first measured at different loading speeds and freezing times, and the most suitable values are determined based on the results. Then, the variation in adhesion strength with heating temperatures at different initial substrate temperatures and different heating powers is investigated. Parameter AW is defined to evaluate the heating power from the point of view of energy consumption and adhesion strength. As a result, the loading speed and the freezing time are determined to be 0.5 mm/s and 90 min, respectively. The adhesion strength degrades as the heating temperature increases. As the initial temperature drops, the adhesion strength decreases more slowly. Furthermore, the temperature of WAS (Weak Adhesion State) under heating varies with the initial temperature. Heating with a high power will yield more reduction in adhesion strength for the same temperature increase. The values of AW illustrate that a medium power heating is more favorable to reduce the adhesion strength with a low energy consumption. Full article

(This article belongs to the Special Issue Deicing and Anti-Icing of Aircraft (Volume III))

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26 pages, 11701 KiB

Open AccessArticle

Round-Robin Study for Ice Adhesion Tests

by Nadine Rehfeld, Jean-Denis Brassard, Masafumi Yamazaki, Hirotaka Sakaue, Marcella Balordi, Heli Koivuluoto, Julio Mora, Jianying He, Marie-Laure Pervier, Ali Dolatabadi, Emily Asenath-Smith, Mikael Järn, Xianghui Hou and Volkmar Stenzel

Aerospace 2024, 11(2), 106; https://doi.org/10.3390/aerospace11020106 - 24 Jan 2024

Viewed by 1048

Abstract

Ice adhesion tests are widely used to assess the performance of potential icephobic surfaces and coatings. A great variety of test designs have been developed and used over the past decades due to the lack of formal standards for these types of tests. [...] Read more.

Ice adhesion tests are widely used to assess the performance of potential icephobic surfaces and coatings. A great variety of test designs have been developed and used over the past decades due to the lack of formal standards for these types of tests. In many cases, the aim of the research was not only to determine ice adhesion values, but also to understand the key surface properties correlated to low ice adhesion surfaces. Data from different measurement techniques had low correspondence between the results: Values varied by orders of magnitude and showed different relative relationships to one another. This study sought to provide a broad comparison of ice adhesion testing approaches by conducting different ice adhesion tests with identical test surfaces. A total of 15 test facilities participated in this round-robin study, and the results of 13 partners are summarized in this paper. For the test series, ice types (impact and static) as well as test parameters were harmonized to minimize the deviations between the test setups. Our findings are presented in this paper, and the ice- and test-specific results are discussed. This study can improve our understanding of test results and support the standardization process for ice adhesion strength measurements. Full article

(This article belongs to the Special Issue Deicing and Anti-Icing of Aircraft (Volume III))

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18 pages, 1712 KiB

Open AccessArticle

Three-Dimensional Trajectory and Impingement Simulation of Ice Crystals Considering State Changes on the Rotor Blade of an Axial Fan

by Koichiro Hirose, Koji Fukudome, Hiroya Mamori and Makoto Yamamoto

Aerospace 2024, 11(1), 2; https://doi.org/10.3390/aerospace11010002 - 19 Dec 2023

Cited by 1 | Viewed by 860

Abstract

Ice crystal icing occurs in jet engine compressors, which can severely degrade jet engine performance. In this study, we developed an ice crystal trajectory simulation, considering the state changes of ice crystals with a forced convection model, indicating a significant difference in impinging [...] Read more.

Ice crystal icing occurs in jet engine compressors, which can severely degrade jet engine performance. In this study, we developed an ice crystal trajectory simulation, considering the state changes of ice crystals with a forced convection model, indicating a significant difference in impinging ice crystal content on the blade for tiny ice crystals. Then, ice crystal trajectory simulations were performed for the rotor blade of an axial fan to investigate the effects of ice crystal size and relative humidity on collision characteristics. The results indicate that the surrounding air affects the composition of tiny ice crystals before collision, and the flight time until impingement on the rotor blade varies significantly depending on the span position. Among them, ice crystals with a diameter of 50 μm impinge with water content that is most likely to adhere to the blade. Three-dimensional simulation results show that many ice crystals impinge not only on the leading edge, where icing occurs as revealed by the two-dimensional simulations but also on the trailing edge of the hub side. This study emphasizes the importance of evaluating the three-dimensional impingement position and water content in the prediction of ice crystal icing. Full article

(This article belongs to the Special Issue Deicing and Anti-Icing of Aircraft (Volume III))

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33 pages, 15341 KiB

Open AccessArticle

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

by Adriana Enache, Joachim Wallisch, Jeroen van Beeck, Patrick Hendrick and Richard Hann

Aerospace 2023, 10(5), 451; https://doi.org/10.3390/aerospace10050451 - 13 May 2023

Viewed by 1363

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Deicing and Anti-Icing of Aircraft (Volume III))

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29 pages, 2806 KiB

Open AccessArticle

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

by Lokman Bennani, Pierre Trontin and Emmanuel Radenac

Aerospace 2023, 10(1), 75; https://doi.org/10.3390/aerospace10010075 - 11 Jan 2023

Cited by 4 | Viewed by 2367

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Deicing and Anti-Icing of Aircraft (Volume III))

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22 pages, 7321 KiB

Open AccessArticle

Fiber Optic Ice Sensor for Measuring Ice Thickness, Type and the Freezing Fraction on Aircraft Wings

by Aris Ikiades

Aerospace 2023, 10(1), 31; https://doi.org/10.3390/aerospace10010031 - 30 Dec 2022

Cited by 3 | Viewed by 2115

Abstract

Ice accretion on an aircraft affects the aerodynamic performance of the wings by disrupting the airflow, increasing drag, and altering its flight characteristics, leading to a main or tail wing-stall and altimetry to aircraft loss. The current generation of ice-detection systems relies on [...] Read more.

Ice accretion on an aircraft affects the aerodynamic performance of the wings by disrupting the airflow, increasing drag, and altering its flight characteristics, leading to a main or tail wing-stall and altimetry to aircraft loss. The current generation of ice-detection systems relies on environmental parameters to determine icing conditions, with the sensors usually located on the nose of the aircraft, giving no information on the ice accreted on the wings. This work focuses on modeling and developing a fiber-optic-array ice sensor, which illuminates and detects the reflected and scattered light directly from the ice surface and volume, and measures the accretion rate and type of ice on the wings. The ice morphology is influenced by the rate of freezing of the super-cooled droplets impacting the wings, and partially or totally trapping the dissolved gasses. This leads to the formation of rugged surfaces and ice shapes, which can be transparent or opaque, a process which is dependent on the local Freezing Fraction (FF) of the impinging super cooled water. The detection method relies on the optical characteristics of ice, affected by density and the size of micro-cracks and micro-bubbles formed during freezing. By using high Numerical Aperture (NA) fibers, it was possible to accurately measure the ice thickness, and to investigate a proof-of-concept experiment, correlating the optical diffusion to the FF of the ice on a wing. Full article

(This article belongs to the Special Issue Deicing and Anti-Icing of Aircraft (Volume III))

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Review

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26 pages, 3297 KiB

Open AccessReview

Ice Accretion on Rotary-Wing Unmanned Aerial Vehicles—A Review Study

by Manaf Muhammed and Muhammad Shakeel Virk

Aerospace 2023, 10(3), 261; https://doi.org/10.3390/aerospace10030261 - 08 Mar 2023

Cited by 8 | Viewed by 2656

Abstract

Ice accretion on rotary-wing unmanned aerial vehicles (RWUAVs) needs to be studied separately from the fixed-wing UAVs because of the additional flow complexities induced by the propeller rotation. The aerodynamics of rotatory wings are extremely challenging compared to the fixed-wing configuration. Atmospheric icing [...] Read more.

Ice accretion on rotary-wing unmanned aerial vehicles (RWUAVs) needs to be studied separately from the fixed-wing UAVs because of the additional flow complexities induced by the propeller rotation. The aerodynamics of rotatory wings are extremely challenging compared to the fixed-wing configuration. Atmospheric icing can be considered a hazard that can plague the operation of UAVs, especially in the Arctic region, as it can impose severe aerodynamic penalties on the performance of propellers. Rotary-wing structures are more prone to ice accretion and ice shedding because of the centrifugal force due to rotational motion, whereby the shedding of the ice can lead to mass imbalance and vibration. The nature of ice accretion on rotatory wings and associated performance degradation need to be understood in detail to aid in the optimum design of rotary-wing UAVs, as well as to develop adequate ice mitigation techniques. Limited research studies are available about icing on rotary wings, and no mature ice mitigation technique exists. Currently, there is an increasing interest in research on these topics. This paper provides a comprehensive review of studies related to icing on RWUAVs, and potential knowledge gaps are also identified. Full article

(This article belongs to the Special Issue Deicing and Anti-Icing of Aircraft (Volume III))

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