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2015-06-15
Technical Paper
2015-01-2112
Thomas Schlegl, Michael Moser, Hubert Zangl
Abstract We present a wireless sensor system for temperature measurement and icing detection for the use on aircraft. The sensors are flexible (i.e. bendable), truly wireless, do not require scheduled maintenance, and can be attached easily to almost any point on the aircraft surface (e.g. wings, fuselage, rudder, elevator, etc.). With a sensor thickness of less than two millimeters at the current state of development, they hardly affect the aero dynamical behavior of the structure. In this paper, we report laboratory and field results for temperature measurement and icing detection.
2015-06-15
Technical Paper
2015-01-2082
Andreas Tramposch, Wolfgang Hassler, Reinhard F.A. Puffing
Abstract Certain operating modes of the Environmental Control System (ECS) of passenger aircraft are accompanied with significant ice particle accretion in a number of pivotal parts of the system. Icing conditions particularly prevail downstream of the air conditioning packs and, as a consequence, ice particle accretion takes place in the Pack Discharge Duct (PDD) and in the mixing manifold. For a better understanding of these icing processes, numerical simulations using a multiphase model based on a coupled Eulerian-Lagrangian transport model in a generic PDD were performed. The obstruction of the PDD due to ice growth and the resulting change of the flow geometry were treated by deforming the computational mesh during the CFD simulations. In addition to the numerical investigations, a generic and transparent PDD was studied experimentally under several operating conditions in FH JOANNEUM's icing wind tunnel.
2015-06-15
Technical Paper
2015-01-2081
Hossein Habibi, Graham Edwards, Liang Cheng, Haitao Zheng, Adam Marks, Vassilios Kappatos, Cem Selcuk, Tat-Hean Gan
Abstract Icing conditions in cold regions of the world may cause problems for wind turbine operations, since accreted ice can reduce the efficiency of power generation and create concerns regarding ice-shedding. This paper covers modelling studies and some experimental development for an ongoing ice protection system that provides both deicing and anti-icing actions for wind turbine blades. The modelling process contained two main sections. The first part involved simulation of vibrations with very short wavelength or ultrasonic guided waves (UGW) on the blade to determine optimal excitation frequency and transducer configuration. This excitation creates horizontal shear stress at the interface between ice and blade and focuses energy at the leading edge for de-bonding ice layers.
2015-06-15
Technical Paper
2015-01-2080
Roger J. Aubert
Abstract The entire process from ice accretion to ice impact with ice shedding in between still needs refinement. This paper presents key points illustrating the need for improvements in understanding the mechanical properties of ice accretion on helicopter rotor systems.
2015-06-15
Technical Paper
2015-01-2079
Colin Hatch, Jason Moller, Eleftherios Kalochristianakis, Ian Roberts
Abstract The introduction of ice-phobic coatings promises to allow passive ice protection systems to be developed particularly for rotating systems such as propellers. The centrifugal force field combined with reduced adhesive strength can produce a self-shed capability limiting the amount of ice build-up. The size and shed time of ice shed from a propeller is predicted using a process that determines ice shape, ice growth rate and both internal and ice-structure interface stresses. A simple failure model is used to predict the onset of local failure and to propagate damage in the ice until local ice shedding is obtained. Recommendations are made on developing the model further.
2015-06-15
Technical Paper
2015-01-2078
Alric Rothmayer, Hui Hu
Abstract A strong air/water interaction theory is used to develop a fast simplified model for the trapping of water in a film that flows over sub-grid surface roughness. The sub-grid model is used to compute correction factors that can alter mass transport within the film. The sub-grid model is integrated into a covariant film mass transport model of film flow past three-dimensional surfaces in a form that is suitable for use in aircraft icing codes. Sample calculations are presented to illustrate the application of the model.
2015-06-15
Technical Paper
2015-01-2076
Caroline Laforte, Neal Wesley, Marc Mario Tremblay
Abstract This study presents a new method to evaluate and compare the anti-icing performance, i.e., the ability to delay the reformation of ice, of runways and taxiways deicing/anti-icing fluids (RDF) under icing precipitation, based on the skid resistance values, obtained with the Portable Skid Resistance Tester (PSRT). In summary, the test consists of applying, on a standardized concrete pavement sample, a given quantity of de-icing fluid. Following this application, the concrete sample is submitted to low freezing drizzle intensities, in a cold chamber at −5.0 ± 0.3°C. The skid resistance of concrete is measured at 5 minute intervals, until the concrete becomes completely iced. The anti-icing performance of 5 different fluids, both experimental and commercial, was assessed in comparison with a reference solution of 50% w/w K-formate. The anti-icing performance is analyzed based on two parameters: the duration (Icing Protection Time, IPT) and the effectiveness of this protection.
2015-06-15
Technical Paper
2015-01-2095
Wolfgang Hassler, Reinhard F.A. Puffing, Andreas Tramposch
Abstract This paper deals with thermal ice protection of electrically heated restraining grids designed for applications in the environmental control system (ECS) of passenger aircraft. The restraining grids described in the paper consist of strung, electrically insulated wire and are - in certain operation modes of the ECS - exposed to an airstream containing supercooled water droplets and/or ice particles. Heat is generated in the wire by an electric current, and the temperature of the wire is controlled with the aid of an electronic control system. A substantial question for laying out the controller and for operating the grids is the following: What minimum heating power is required to prevent ice accretion on the surface of the wire, i.e., what is the least heating power that is necessary to keep a grid being exposed to specific icing conditions devoid of ice? This problem is studied for a simple model system first and is then examined for restraining grids.
2015-06-15
Technical Paper
2015-01-2094
William B. Wright, Peter Struk, Tadas Bartkus, Gene Addy
Abstract This paper will describe two recent modifications to the LEWICE software. The version described is under development and not ready for release. First, a capability for modeling ice crystals and mixed phase icing has been modified based on recent experimental data. Modifications have been made to the ice particle bouncing and erosion model. This capability has been added as part of a larger effort to model ice crystal ingestion in aircraft engines. Comparisons have been made to ice crystal ice accretions performed in the NRC Research Altitude Test Facility (RATFac). Second, modifications were made to the runback model based on data and observations from thermal scaling tests performed in the NRC Altitude Icing Tunnel. The runback model was modified to match film models used in the open literature. An empirical water shedding was also implemented. Comparisons were made to thermal deicing data taken at the NRC Altitude Icing Tunnel.
2015-06-15
Technical Paper
2015-01-2097
Timothy A. Shannon, Stephen T. McClain
Abstract Changes in convection coefficient caused by the changes in surface roughness characteristics along an iced NACA 0012 airfoil were investigated in the 61-cm by 61-cm (24 in. by 24 in.) Baylor Subsonic Wind Tunnel using a 91.4-cm (36-in.) long heated aerodynamic test plate and infrared thermometry. A foam insert was constructed and installed on the wind tunnel ceiling to create flow acceleration along the test plate replicating the scaled flow acceleration the along the leading 17.1% (3.6 in.) of a 53.3-cm (21-in.) NACA 0012 airfoil. Two sets of rough surface panels were constructed for the study, and each surface used the same basic random droplet pattern created using the Lagrangian droplet simulator of Tecson and McClain (2013). For the first surface, the roughness pattern was replicated with the same geometry over the plate following a smooth-to-rough transition location noted in historical literature for the case being replicated.
2015-06-15
Technical Paper
2015-01-2096
Philippe Reulet, Bertrand Aupoix, David Donjat, Francis Micheli
Abstract Numerical simulation of ice accretion on aircraft surfaces necessitates a good prediction of wall friction coefficient and wall heat transfer coefficient. After the icing process begins, surface roughness induces a high increase of friction and heat transfer, but simple Reynolds analogy is no longer valid. An experimental campaign is conducted to provide a database for numerical model development in the simple configuration of a heated flat plate under turbulent cold airflow conditions. The flat plate model is placed in the centre of the test section of a wind tunnel. The test model is designed according to constraints for the identification of friction and heat transfer coefficients. It includes three identical resin plates which are moulded to obtain a specified roughness on the upper surface exposed to the flow. Only the 3rd resin plate is heated on its lower face by an electrical heater connected to a temperature regulator.
2015-06-15
Technical Paper
2015-01-2099
Mario Vargas, Charles Ruggeri, Peter Struk, Mike Pereira, Duane Revilock, Richard Kreeger
This work presents the results of an experimental study of ice particle impacts on a flat plate made of glass. The experiment was conducted at the Ballistics Impact Laboratory of NASA Glenn Research Center in 2014 and is part of the NASA fundamental research efforts to study physics of ice particles impact on a surface, in order to improve understanding of ice crystal ingestion and ice accretion inside jet engines. The ice particles, which were nominally spherical ranging in initial diameter between 1 and 3.5 millimeters, were accelerated to velocities from 20 to 130 m/s using a pressure gun. High speed cameras captured the pre-impact particle diameter and velocity data as well as the post-impact fragment data. The initial stages of ice particle breakup were captured and studied at 1,000,000 frames per second with a high speed camera imaging at a plane normal to the impact surface.
2015-06-15
Technical Paper
2015-01-2098
Stephen T. McClain, Mario Vargas, Richard E. Kreeger, Jenching Tsao
Abstract Many studies have been performed to quantify the formation and evolution of roughness on ice shapes created in Appendix C icing conditions, which exhibits supercooled liquid droplets ranging from 1-50 µm. For example Anderson and Shin (1997), Anderson et al. (1998), and Shin (1994) represent early studies of ice roughness during short-duration icing events measured in the Icing Research Tunnel at the NASA Glenn Research Center. In the historical literature, image analysis techniques were employed to characterize the roughness. Using multiple images of the roughness elements, these studies of roughness focused on extracting parametric representations of ice roughness elements. While the image analysis approach enabled many insights into icing physics, recent improvements in laser scanning approaches have revolutionized the process of ice accretion shape characterization.
2015-06-15
Technical Paper
2015-01-2101
Hai Li, Ilia Roisman, Cameron Tropea
Abstract Airframe icing caused by supercooled large droplets (SLD) has been identified as a severe hazard in aviation. This study presents an investigation of impact of a supercooled drop onto superhydrophobic and partially wettable substrates. Drop impact, spreading and rebound were observed using a high-speed video system. The maximum spreading diameter of an impacting drop on partially wettable surfaces was measured. The temperature effect on this parameter was only minor for a wide range of the drop and substrate temperatures. However solidification hindered receding when both the drop and substrate temperatures were below 0°C. The minimum receding diameter and the speed of ice accretion on the substrate were measured for various wall and drop temperatures. The two parameters increased almost linearly with the decrease of the wall temperature, but eventually leveled off beyond a certain substrate temperature.
2015-06-15
Technical Paper
2015-01-2084
Benedikt König, Ehab Fares, Andy P. Broeren
Abstract A Lattice-Boltzmann approach is used to simulate the aerodynamics of complex three-dimensional ice shapes on a NACA 23012 airfoil. The digitally produced high fidelity geometrical ice shapes were created using a novel laser scanning technique in the NASA Icing Research Tunnel. The geometrically fully resolved unsteady simulations are conducted on two ice shapes representing a roughness type and a horn type icing on the leading edge of the airfoil. Comparisons between simulation and experiment of lift, drag, and pitching moment as well as pressure distributions indicate overall a good qualitative agreement in capturing the aerodynamic degradation. Especially for the horn-type ice shape, the quantitative agreement is also mostly very good. Analysis of the flow structures indicates furthermore a good capturing of the three-dimensional separation behavior of the flow.
2015-06-15
Technical Paper
2015-01-2100
Yongsheng Lian, Yisen Guo
Abstract In this paper we numerically investigated the impact of large droplets on smooth solid surfaces to understand the splashing mechanism involved in ice accretion due to supercooled large droplets. A Navier-Stokes solver was used to describe the flow field, the moment-of-fluid (MOF) method was used to capture the droplet interface evolution, and the adaptive mesh refinement technique was employed to refine the mesh near the region of interest. We investigated the effect of air on splashing mechanism and confirmed that a low pressure can suppress the droplet splashing. The size distribution of splashed secondary droplets was studied and showed good agreement with experimental results. The effect of surface curvature on the splashing phenomenon was highlighted. Finally, the droplet impact on a NACA 23012 airfoil was studied and the water collection efficiency was investigated.
2015-06-15
Technical Paper
2015-01-2083
Daniel Silva, Thais Bortholin, J Allan Lyrio, Luis Santos
Abstract An important issue regarding landing performance is the reference speed which determines the approved fields lengths in which a landing can take place. A critical scenario is the accumulation of ice during the holding phase followed by descent, approach and landing. The effect of icing in the landing configuration, with the high-lift devices deployed, is relevant and should be anticipated during the early design phases by simulation. Due to the complex behaviour of the flowfield, 3D CFD methods has been used by several manufacturers but that leads to a high computational cost which might be too intensive for the preliminary design phase.
2015-06-15
Technical Paper
2015-01-2087
Delphine Leroy, Emmanuel Fontaine, Alfons Schwarzenboeck, J. Walter Strapp, Lyle Lilie, Julien Delanoe, Alain Protat, Fabien Dezitter, Alice Grandin
Abstract Despite past research programs focusing on tropical convection, the explicit studies of high ice water content (IWC) regions in Mesoscale Convective Systems (MCS) are rare, although high IWC conditions are potentially encountered by commercial aircraft during multiple in-service engine powerloss and airdata probe events. To gather quantitative data in high IWC regions, a multi-year international HAIC/HIWC (High Altitude Ice Crystals / High Ice Water Content) field project has been designed including a first field campaign conducted out of Darwin (Australia) in 2014. The airborne instrumentation included a new reference bulk water content measurement probe and optical array probes (OAP) recording 2D images of encountered ice crystals. The study herein focuses on ice crystal size properties in high IWC regions, analyzing in detail the 2D image data from the particle measuring probes.
2015-06-15
Technical Paper
2015-01-2091
Ryosuke Hayashi, Makoto Yamamoto
Abstract In a jet engine, ice accreted on a fan rotor can be shed from the blade surface due to centrifugal force, and the shed ice can damage compressor components. This phenomenon, which is referred to as ice shedding, threatens safe flight. However, there have been few studies on ice shedding because ice has numerous unknown physical parameters. Although existing icing models can simulate ice growth, these models do not have the capability to reproduce ice shedding. As such, in a previous study, we developed an icing model that takes into account both ice growth and ice shedding. In the present study, we apply the proposed icing model to a jet engine fan in order to investigate the effect of ice growth and shedding on the flow field. The computational targets of the present study are the engine fan and the fan exit guide vane (FEGV); thus, we simultaneously deal with the rotor-stator interaction problem.
2015-06-15
Technical Paper
2015-01-2086
Matthew Grzych, Terrance Tritz, Jeanne Mason, Melissa Bravin, Anna Sharpsten
Abstract The significant problem of engine power-loss and damage associated with ice crystal icing (ICI) was first formally recognized by the industry in a 2006 publication [1]. Engine events described by the study included: engine surge, stall, flameout, rollback, and compressor damage; which were triggered by the ingestion of ice crystals in high concentrations generated by deep, moist convection. Since 2003, when ICI engine events were first identified, Boeing has carefully analyzed event conditions documenting detailed pilot reports and compiling weather analyses into a database. The database provides valuable information to characterize environments associated with engine events. It provides boundary conditions, exposure times, and severity to researchers investigating the ICI phenomenon. Ultimately, this research will aid in the development of engine tests and ICI detection/avoidance devices or techniques.
2015-06-15
Technical Paper
2015-01-2088
Richard E. Kreeger, Lakshmi Sankar, Robert Narducci, Robert Kunz
Abstract The formation of ice over lifting surfaces can affect aerodynamic performance. In the case of helicopters, this loss in lift and the increase in sectional drag forces will have a dramatic effect on vehicle performance. The ability to predict ice accumulation and the resulting degradation in rotor performance is essential to determine the limitations of rotorcraft in icing encounters. The consequences of underestimating performance degradation can be serious and so it is important to produce accurate predictions, particularly for severe icing conditions. The simulation of rotorcraft ice accretion is a challenging multidisciplinary problem that until recently has lagged in development over its counterparts in the fixed wing community. But now, several approaches for the robust coupling of a computational fluid dynamics code, a rotorcraft structural dynamics code and an ice accretion code have been demonstrated.
2015-06-15
Technical Paper
2015-01-2093
Maxime Henno
Abstract Advanced sizing of the thermal wing ice protection system (WIPS) requires an improved and a robust manner to simulate the system operation in unsteady phases and particularly in de-icing operations. A two dimensional numerical tool has been developed to enable the simulation of unsteady anti-icing and de-icing operations. For example, the WIPS may be activated with delay after entering into the icing conditions. In this case, ice starts to accrete on the leading edge before the WIPS heats up the skin. Another example is the ground activation of the WIPS for several seconds to check its functionality: low external cooling may cause high thermal constraints that must be estimated with accuracy to avoid adverse effects on the structure. Thermal de-icing WIPS integrated in composite structures intrinsically have unsteady behaviors; the tool enables the computation of the skin temperature evolution with the time.
2015-06-15
Technical Paper
2015-01-2092
David M. Orchard, Catherine Clark, Myron Oleskiw
Abstract Simulations of supercooled large droplet (SLD) icing environments within the NRC's Altitude Icing Wind Tunnel (AIWT) have been performed in which broad band mass distribution spectra are achieved that include a distinct pattern of liquid water content (LWC) over a range of droplet sizes (i.e., bi-modal distribution). The mass distribution is achieved through modification of the existing spray system of the AIWT to allow two spray profiles with differing LWC and median volumetric diameter (MVD) to be simultaneously injected into the flow. Results of spray profile distributions measured in the test section have demonstrated that freezing drizzle conditions, where MVD is either less than or greater than 40 μm, can be achieved.
2015-06-15
Technical Paper
2015-01-2115
Antonio Criscione, Suad Jakirlic, Zeljko Tukovic, Ilia Roisman, Cameron Tropea
Abstract Numerical experiments have been presently conducted aiming at studying the influence of the surface energy on the crystallization process of supercooled water in terms of the supercooling degrees. The mathematical model consists primarily of the equation governing the thermal energy field solved independently in both phases in accordance with the two-scalar approach by utilizing the Stefan condition at the interface to couple both temperature fields. The computational algorithm relying on the level-set method for solid-liquid interface capturing has been appropriately upgraded aiming at accuracy level increase with respect to the discretization of the thermal energy equation and the normal-to-interface derivative of the temperature field. The model describes the freezing mechanism under supercooled conditions, relying on the physical and mathematical description of the two-phase moving-boundary approach.
2015-06-15
Technical Paper
2015-01-2113
Ismail Gultepe, Michael Pavolonis, Binbin Zhou, Randolph Ware, Robert Rabin, William Burrows, Jason Milbrandt, Louis Garand
Abstract Fog and drizzle observations collected during the arctic weather and SAR (Search and Rescue) operations (SAAWSO) project at sub-freezing temperatures (T) are analyzed in this study to identify icing conditions, improve ground-based in-situ and remote sensing observations, and develop icing parameterizations for numerical weather prediction (NWP) models. The SAAWSO project took place during the 2012-2013 winter conditions that occurred over St. John's, NFL, Canada. Observations were obtained by a Droplet Measuring Technologies Fog Measuring Device (FMD), a ground cloud imaging probe (GCIP), a Radiometrics Profiling Microwave Radiometer (PMWR), a Rosemount icing detector, a laser disdrometer, and surface meteorological sensors. Precipitation, wind, and radiation data were also collected. Results suggest that observations obtained from integrated in-situ and remote sensors can be used to characterize icing conditions.
2015-06-15
Technical Paper
2015-01-2117
Miki Shimura, Makoto Yamamoto
Abstract It is well known that SLD (Supercooled Large Droplets) icing is very dangerous because it is more unpredictable than general icing caused by smaller droplets. In SLD conditions, a droplet deforms largely. Vargas et al. (2011) performed the experiments about the droplet deformation and they confirmed that the droplet deforms to an oblate spheroid, as the droplet approaches the leading edge of an airfoil. Therefore, the assumption that a droplet behaves as a sphere might be no longer valid. There are many models to predict the droplet deformation in which the deformation is described with the change of drag coefficient. For example, Hospers (2013) summarized the linear relations between the Reynolds number and the drag coefficient. Wiegand (1987) developed a model which uses a quasi-steady normal mode analysis of droplet deformation. However, the effect of the droplet deformation models on SLD icing simulations has not been completely clarified yet.
2015-06-15
Technical Paper
2015-01-2116
Peter Struk, Tadas Bartkus, Jen-Ching Tsao, Tom Currie, Dan Fuleki
Abstract This paper presents measurements of ice accretion shape and surface temperature from ice-crystal icing experiments conducted jointly by the National Aeronautics and Space Administration (NASA) and the National Research Council (NRC) of Canada. The data comes from experiments performed at NRC's Research Altitude Test Facility (RATFac) in 2012. The measurements are intended to help develop models of the ice-crystal icing phenomenon associated with engine ice-crystal icing. Ice accretion tests were conducted using two different airfoil models (a NACA 0012 and wedge) at different velocities, temperatures, and pressures although only a limited set of permutations were tested. The wedge airfoil had several tests during which its surface was actively cooled. The ice accretion measurements included leading-edge thickness for both airfoils. The wedge and one case from the NACA 0012 model also included 2D cross-section profile shapes.
2015-06-15
Technical Paper
2015-01-2119
Shinan Chang, Chao Wang, Mengyao Leng
Abstract Droplet deformation and breakup is an important issue that involved in the aircraft and engine icing field especially in the case of the Supercooled Large Droplets (SLD). In this paper, the modes of SLD breakup were discussed in detail based upon the classical theories of droplet breakup and typical icing conditions. It was found that the breakup modes involved in SLD are mainly vibration breakup, bag-type breakup, multimode breakup and shear breakup. A breakup model composed of the typical SLD breakup types was proposed.
2015-06-15
Technical Paper
2015-01-2118
Sergey Alekseyenko, Michael Sinapius, Martin Schulz, Oleksandr Prykhodko
Abstract The results of experimental investigation of the icing processes of NACA 0015 airfoil are presented. The experiments have been carried out with the help of a high-speed camera at the icing/deicing facility at the Institute of Adaptronic and Functional Integration of the Technical University of Braunschweig. The investigation objective is the study of interaction between supercooled large droplets and the icing airfoil surface as well as physical phenomena occurring during the icing process. Evolution of the initial phase of ice growth process over time is observed, the general structure of ice accretion and its alteration along the airfoil is examined. Experiments have been carried out within a wide temperature range. Photos of the specific moments of the icing process have been analyzed. Splashing events and water movement on the icing surface have been observed.
2015-06-15
Technical Paper
2015-01-2120
Yong Han Yeong, Eric Loth, Jack Sokhey, Alexis Lambourne
Researchers have recently focused on superhydrophobic coatings as an ice-mitigation tool. These surfaces have a high degree of water-repellency and were shown in previous low-speed droplet studies to reduce surface ice adhesion strength. However, there is little research regarding testing in aerospace icing conditions, i.e. high-speed super-cooled droplet impact (> 50 m/s) on a freezing substrate and air temperature. A detailed set of experiments were conducted in an icing wind tunnel to measure the ice adhesion strength of various superhydrophobic coatings by subjecting the surfaces to a super-cooled icing cloud consisting of 20 μm droplets and at a constant LWC of 0.4 g/m3. Test conditions include air speeds of 50 m/s and 70 m/s and in glaze (−5°C) and rime ice regimes (−15°C). The accreted ice was then removed by pressurized nitrogen in a mode 1 (tensile) adhesion test.
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