Ice Accretion

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Muhammad S. Virk - One of the best experts on this subject based on the ideXlab platform.

  • Study of Ice Accretion along symmetric and asymmetric airfoils
    Journal of Wind Engineering and Industrial Aerodynamics, 2018
    Co-Authors: Jia Yi Jin, Muhammad S. Virk
    Abstract:

    Abstract A parametric numerical study of Ice Accretion along symmetric (NACA-0012) and asymmetric (NACA-23012) airfoils has been carried out at different operating and geometric conditions with the aim to better understand the Ice Accretion along wind turbine blades. The results show that the airfoil geometric shape and size has an effect on the rate and shape of Ice Accretion. Streamline Ice shapes are observed in the case of symmetric airfoil in comparison to the ones found for the asymmetric airfoil. Aerodynamic characteristics of both airfoils for clean and Iced conditions were analyzed at different angles of attack ranging from −16° to +16°. The analysis shows a decrease in the aerodynamic characteristics of the Iced airfoils as compared to the clean airfoil. The parametric analysis of the Ice Accretion at different operating and geometric conditions show an increase in the Ice growth with the increase in air velocity and droplet size, whereas a change in the atmospheric temperature significantly affects the accreted Ice shapes. A decrease in accreted Ice mass and thickness is observed with the increase of airfoil geometric size.

  • On the empirical k-factor in Ice Accretion on wind turbines: A numerical study
    2017 2nd International Conference on Power and Renewable Energy (ICPRE), 2017
    Co-Authors: Pavlo Sokolov, Muhammad S. Virk
    Abstract:

    An investigation of empirical k-factor, describing the ratio of Ice Accretion on reference collector (cylinder) and wind turbine blade has been performed with a series of numerical simulations, and analytical calculations. The results show that k-factor can vary to a degree, depending on a number of different parameters. These include the effect of object's geometry, droplet distribution spectrum on Ice Accretion and collision efficiencies, different ambient conditions, experienced by both the reference collector and wind turbine blade, which can lead to different Ice growth regimes. Further numerical experimentations and actual validation of the concepts is warranted. Considering the complexity of the process in question, there is a significant chance that Ice Accretion on a wind turbine blade, when compared to Ice Accretion of reference cylinder cannot be explained using simple, dimensionless ratio.

  • Ice Accretion on circular cylinder in relation to its diameter
    Wind Engineering, 2016
    Co-Authors: Muhammad S. Virk
    Abstract:

    Numerical study of atmospheric Ice Accretion on circular cylinder is carried out to understand the relation between cylinder diameter and resultant Ice Accretion. To validate the numerical model, r...

  • Multiphase Numerical Study of Ice Accretion on Circular Cylinders in Duplex Configuration
    Applied Mechanics and Materials, 2016
    Co-Authors: Muhammad S. Virk
    Abstract:

    Numerical study of atmospheric Ice Accretion on circular cylinders in duplex configuration has been carried out at different operating and geometric conditions. Analyses showed a difference in Ice Accretion on both cylinders, as streamline accumulated Ice shapes were observed along front cylinder and irregular Ice shapes were found along rear cylinder. Results also showed a change in accreted Ice load and Ice shape along rear cylinder with the change in distance between both cylinders. Parametric study at different droplet sizes and temperatures showed a variation in Ice Accretion. This prelimenary research work provides a useful base for better understanding and further investigation of atmospheric Ice Accretion on circular overhead conductors in duplex configuration, installed in cold climate of high north regions.

  • Atmospheric Ice Accretion on Non-Rotating Vertical Circular Cylinder
    World Journal of Engineering and Technology, 2015
    Co-Authors: Muhammad S. Virk, Umair Najeeb Mughal, Geanette Polanco
    Abstract:

    Study of atmospheric Ice Accretion on a non-rotating vertical circular cylindrical object was carried out at dry and wet Ice conditions. Both numerical and experimental techniques were used during this study. 3D numerical study was carried out using computational fluid dynamics based approach, whereas experimental study was carried out at Cryospheric Environmental Simulator ‘CES’ in Shinjo, Japan. A good agreement was found between experimental and numerical results. The dimensions of the cylindrical object used to measure the atmospheric Ice load on structures along this study, were selected as per the ISO12494 standard. Results provide useful information about Ice growth and intensity along circular cylindrical objects at different atmospheric temperatures. This research work also provides a useful base for further investigation of atmospheric Ice Accretion on structures particularly circular power network cables, & tower masts installed in the cold regions.

Russell Greiner - One of the best experts on this subject based on the ideXlab platform.

  • Learning to predict Ice Accretion on electric power lines
    Engineering Applications of Artificial Intelligence, 2012
    Co-Authors: Ashkan Zarnani, Petr Musilek, Xiaoyu Shi, Russell Greiner
    Abstract:

    Ice Accretion on power transmission and distribution lines is one of the major causes of power grid outages in northern regions. While such icing events are rare, they are very costly. Thus, it would be useful to predict how much Ice will accumulate. Many current Ice Accretion forecasting systems use precipitation-type prediction and physical Ice Accretion models. These systems are based on expert knowledge and experimentations. An alternative strategy is to learn the patterns of Ice Accretion based on observations of previous events. This paper presents two different forecasting systems that are obtained by applying the learning algorithm of Support Vector Machines to the outputs of a Numerical Weather Prediction model. The first forecasting system relies on an icing model, just as the previous algorithms do. The second system learns an effective forecasting model directly from meteorological features. We use a rich data set of eight different icing events (from 2002 to 2008) to empirically compare the performance of the various Ice Accretion forecasting systems. Several experiments are conducted to investigate the effectiveness of the forecasting algorithms. Results indicate that the proposed forecasting system is significantly more accurate than other state-of-the-art algorithms.

Emily L. Johnson - One of the best experts on this subject based on the ideXlab platform.

  • Isogeometric analysis of Ice Accretion on wind turbine blades
    Computational Mechanics, 2020
    Co-Authors: Emily L. Johnson
    Abstract:

    For wind turbines operating in cold weather conditions, Ice Accretion is an established issue that remains an obstacle in effective turbine operation. While the aerodynamic performance of wind turbine blades with Ice Accretion has received considerable research attention, few studies have investigated the structural impact of blade Ice Accretion. This work proposes an adaptable projection-based method to superimpose complex Ice configurations onto a baseline structure. The proposed approach provides an efficient methodology to include Ice Accretion in the high-fidelity isogeometric shell analysis of a realistic wind turbine blade. Linear vibration and nonlinear deflection analyses of the blade are performed for various Ice configurations to demonstrate the impact of different Ice Accretion distributions on structural performance. These analyses indicate decreases in the blade natural frequencies and deflection under icing conditions. Such Ice-induced changes clearly reveal the need for structural design consideration for turbines operating under icing conditions.

Petr Musilek - One of the best experts on this subject based on the ideXlab platform.

  • Learning to predict Ice Accretion on electric power lines
    Engineering Applications of Artificial Intelligence, 2012
    Co-Authors: Ashkan Zarnani, Petr Musilek, Xiaoyu Shi, Russell Greiner
    Abstract:

    Ice Accretion on power transmission and distribution lines is one of the major causes of power grid outages in northern regions. While such icing events are rare, they are very costly. Thus, it would be useful to predict how much Ice will accumulate. Many current Ice Accretion forecasting systems use precipitation-type prediction and physical Ice Accretion models. These systems are based on expert knowledge and experimentations. An alternative strategy is to learn the patterns of Ice Accretion based on observations of previous events. This paper presents two different forecasting systems that are obtained by applying the learning algorithm of Support Vector Machines to the outputs of a Numerical Weather Prediction model. The first forecasting system relies on an icing model, just as the previous algorithms do. The second system learns an effective forecasting model directly from meteorological features. We use a rich data set of eight different icing events (from 2002 to 2008) to empirically compare the performance of the various Ice Accretion forecasting systems. Several experiments are conducted to investigate the effectiveness of the forecasting algorithms. Results indicate that the proposed forecasting system is significantly more accurate than other state-of-the-art algorithms.

  • Evolutionary Optimization of an Ice Accretion Forecasting System
    Monthly Weather Review, 2010
    Co-Authors: Pawel Pytlak, Petr Musilek, Edward P. Lozowski, Dan Arnold
    Abstract:

    The ability to model and forecast Accretion of Ice on structures is very important for many industrial sectors. For example, studies conducted by the power transmission industry indicate that the majority of failures are caused by icing on overhead conductors and other components of power networks. This paper presents an extension to the Ice Accretion forecasting system (IAFS) that is comprised of a numerical weather prediction model, a precipitation-type algorithm, and an Ice Accretion model. To optimize the performance of IAFS, the parameters of the precipitation-type algorithm are estimated using a genetic algorithm. The system is developed by hindcasting a well-documented freezing-rain event and calibrated using four additional Ice storms. Subsequently, the system is tested using three independent storms. The results show a significant improvement in consistency, accuracy, and skill of IAFS. The methodology described in this contribution is not limited to Ice Accretion modeling—it provides a general approach for setting operational parameters of data-processing algorithms to achieve interoperability of numerical weather prediction models with add-on applications based on empirical observations.

Michael B. Bragg - One of the best experts on this subject based on the ideXlab platform.

  • Swept-Wing Ice Accretion Characterization and Aerodynamics
    5th AIAA Atmospheric and Space Environments Conference, 2013
    Co-Authors: Andy P. Broeren, Mark G. Potapczuk, James T. Riley, Philippe Villedieu, Frédéric Moens, Michael B. Bragg
    Abstract:

    NASA, FAA, ONERA, the University of Illinois and Boeing have embarked on a significant, collaborative research effort to address the technical challenges associated with icing on large-scale, three-dimensional swept wings. The overall goal is to improve the fidelity of experimental and computational simulation methods for swept-wing Ice Accretion formation and resulting aerodynamic effect. A seven-phase research effort has been designed that incorporates Ice-Accretion and aerodynamic experiments and computational simulations. As the baseline, full-scale, swept-wing-reference geometry, this research will utilize the 65 percent scale Common Research Model configuration. Ice-Accretion testing will be conducted in the NASA Icing Research Tunnel for three hybrid swept-wing models representing the 20, 64 and 83 percent semispan stations of the baseline-reference wing. Threedimensional measurement techniques are being developed and validated to document the experimental Ice-Accretion geometries. Artificial Ice shapes of varying geometric fidelity will be developed for aerodynamic testing over a large Reynolds number range in the ONERA F1 pressurized wind tunnel and in a smaller-scale atmospheric wind tunnel. Concurrent research will be conducted to explore and further develop the use of computational simulation tools for Ice Accretion and aerodynamics on swept wings. The combined results of this research effort will result in an improved understanding of the Ice formation and aerodynamic effects on swept wings. The purpose of this paper is to describe this research effort in more detail and report on the current results and status to date.

  • aerodynamic simulation of runback Ice Accretion
    Journal of Aircraft, 2010
    Co-Authors: Andy P. Broeren, Edward A Whalen, Greg Busch, Michael B. Bragg
    Abstract:

    This report presents the results of recent investigations into the aerodynamics of simulated runback Ice Accretion on airfoils. Aerodynamic tests were performed on a full-scale model using a high-fidelity, Ice-casting simulation at near-flight Reynolds (Re) number. The Ice-casting simulation was attached to the leading edge of a 72-in. (1828.8-mm ) chord NACA 23012 airfoil model. Aerodynamic performance tests were conducted at the ONERA F1 pressurized wind tunnel over a Reynolds number range of 4.7?10(exp 6) to 16.0?10(exp 6) and a Mach (M) number ran ge of 0.10 to 0.28. For Re = 16.0?10(exp 6) and M = 0.20, the simulated runback Ice Accretion on the airfoil decreased the maximum lift coe fficient from 1.82 to 1.51 and decreased the stalling angle of attack from 18.1deg to 15.0deg. The pitching-moment slope was also increased and the drag coefficient was increased by more than a factor of two. In general, the performance effects were insensitive to Reynolds numb er and Mach number changes over the range tested. Follow-on, subscale aerodynamic tests were conducted on a quarter-scale NACA 23012 model (18-in. (457.2-mm) chord) at Re = 1.8?10(exp 6) and M = 0.18, using low-fidelity, geometrically scaled simulations of the full-scale castin g. It was found that simple, two-dimensional simulations of the upper- and lower-surface runback ridges provided the best representation of the full-scale, high Reynolds number Iced-airfoil aerodynamics, whereas higher-fidelity simulations resulted in larger performance degrada tions. The experimental results were used to define a new subclassification of spanwise ridge Ice that distinguishes between short and tall ridges. This subclassification is based upon the flow field and resulting aerodynamic characteristics, regardless of the physical size of the ridge and the Ice-Accretion mechanism.

  • Aerodynamic Simulation of a Horn-Ice Accretion on a Subscale Model
    Journal of Aircraft, 2008
    Co-Authors: Greg Busch, Andy P. Broeren, Michael B. Bragg
    Abstract:

    The objective of this experimental investigation was to determine the geometric simulation fidelity required to accurately model the aerodynamics of a horn-Ice Accretion in a wind tunnel. A casting and a 2-D smooth simulation with variable horn geometry were constructed to model a horn-Ice Accretion on a NACA 0012 airfoil. Several simulations of differing fidelity, including a casting, were constructed to model a horn-Ice Accretion on a NACA 23012 airfoil. Aerodynamic testing was performed in the University of Illinois 3 x 4 ft wind tunnel at a Reynolds number of 1.8 x 10 6 and a Mach number of 0.18. Minor changes to the upper-horn geometry of the NACA 0012 2-D smooth simulation were found to have notable impacts on drag and maximum lift. Therefore, spanwise variations in the Ice Accretion geometry must be carefully examined so that an appropriate cross section can be chosen from which to generate a tracing for a 2-D simulation. Such a 2-D smooth simulation, as was constructed for the NACA 23012 airfoil, can model maximum lift to within 1 % of that of the casting. This type of simulation can also provide an estimate of drag that is within the uncertainty of the casting due to spanwise variation, although it does not reproduce three dimensionality in the Iced-airfoil flowfield.

  • A Study of Ice Accretion Physics to Improve the Ice Accretion on Airfoils
    2001
    Co-Authors: Michael B. Bragg
    Abstract:

    Final ReportNASA Grant NAG3-1988A Study of Ice Accretion Physics to Improve the Ice Accretion on Airfoils"Michael B. BraggUniversity of Illinois at Urbana-ChampaignJuly 2001IntroductionThis three-year grant began on November 7, 1996 and was no-cost extended to end onOctober 30, 2000. The objectives of the grant were: 1) To examine the effect of windtunnel turbulence on Ice Accretion, 2) To determine the relationship between Ice Accretiongeometry and airfoil performance, and 3)To determine if the wake-survey method was anappropriate experimental technique for Iced-airfoil drag measurement. As specified inthe grant the primary deliverables for-this research were annual reports in the form ofAIAA papers presented at national meetings each year. MS theses and annual oralreports to be given at NASA Lewis (now Glenn) were also deliverables. Six AIAApapers documented the research findings fi'om this study (Refs. 1 - 6), Mr. Chad Henze'sMS thesis describes the wind tunnel turbulence work in detail (Ref. 7), and a summary ofthe icing wind tunnel turbulence work was published in the archival AIAA Journal ofAircraft (Ref. 8). A brief summary of the findings is given below. Please refer to thereports for the details of the studies and findings.Icing Wind Tunnel TurbulenceCurrent understanding of the Ice Accretion process is based largely on icing wind tunneltests. Wind tunnel turbulence has been identified as having potentially important effectson the results of tests performed in icing tunnels. The turbulence intensity level in icingtunnels in the absence of the spray cloud had been previously measured and found to bequite high due to the lack of turbulence reducing screens, and to the presence of the spraysystem in the settling chamber. However, the turbulence intensity level in the presence ofthe spray cloud had not been measured. In this study, a method for making suchmeasurements was developed and a limited set of turbulence measurements was taken inthe NASA Lewis Icing Research Tunnel. Turbulent velocity fluctuations were measuredusing hot-wire sensors. Droplets striking the wire resulted in distinct spikes in the hot-wire voltage that were removed using a digital acceleration threshold filter. Theremaining data were used to calculate the turbulence intensity. Using this method, theturbulence intensity level in the Icing Research Tunnel was found to be highly dependent

  • Hybrid Airfoil Design Procedure Validation for Full-Scale Ice Accretion Simulation
    Journal of Aircraft, 1999
    Co-Authors: Farooq Saeed, Michael S. Selig, Michael B. Bragg
    Abstract:

    This paper presents results of the Ice Accretion tests performed to validate the hybrid airfoil design method. The hybrid airfoil design method was developed to facilitate the design of hybrid airfoils with full-scale leading edges and redesigned aft sections that simulate full-scale Ice Accretion simulation for a given ® range. Icing tests in the NASA Lewis Icing Research Tunnel were conducted with test conditions representative of e ight. A twodimensional half-scale hybrid airfoil was designed and built with a 20% plain e ap and a 5% upper and 20% lower full-scale leading-edge surface of a modern business jet wing section. This paper presents a comparison between the Ice shapes accreted on the business jet and hybrid airfoil models during the tests. The test results show that Ice Accretion simulation could be predicted in terms of the droplet-impingement simulation alone and cone rm the assumption that the leading-edge Ice Accretion will be the same for the full-scale and hybrid airfoils if icing cloud properties, droplet impingement, local leading-edge e owe eld, model surface characteristics, and geometry are held constant. This assumption was found to be valid when tested under the most severe conditions of glaze Ice Accretion over a large time interval. A comparison between the actual Ice shapes and those predicted by LEWIce 1.6 under similar conditions is also shown. The results suggest that the hybrid airfoil design method has signie cant application potential for tests where leading-edge Ice Accretion is desired because it provides an alternative to the myriad of issues related to Ice Accretion scaling.