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International Conference on Icing of Aircraft, Engines, and Structures
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A Three-Layer Thermodynamic Model for Ice Crystal Accretion on Warm Surfaces: EMM-C

Rolls-Royce Plc-Geoffrey Jones, Benjamin Collier
University of Oxford-Alexander Bucknell, Matthew McGilvray, David Gillespie
Published 2019-06-10 by SAE International in United States
Ingestion of high altitude atmospheric ice particles can be hazardous to gas turbine engines in flight. Ice accretion may occur in the core compression system, leading to blockage of the core gas path, blade damage and/or flameout. Numerous engine powerloss events since 1990 have been attributed to this mechanism. An expansion in engine certification requirements to incorporate ice crystal conditions has spurred efforts to develop analytical models for phenomenon, as a method of demonstrating safe operation. A necessary component of a complete analytical icing model is a thermodynamic accretion model. Continuity and energy balances are performed using the local flow conditions and the mass fluxes of ice and water that are incident on a surface to predict the accretion growth rate. In this paper, a new thermodynamic model for ice crystal accretion is developed through adaptation of the Extended Messinger Model (EMM) from supercooled water conditions to mixed phase conditions (ice crystal and supercooled water). A novel three-layer accretion structure is proposed and the underlying equations described. The EMM improves upon the original model for…
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Semi-Empirical Modelling of Erosion Phenomena for Ice Crystal Icing Numerical Simulation

ONERA-Virgile Charton, Pierre Trontin, Philippe Villedieu
SAFRAN Aircraft Engines-Gilles Aouizerate
Published 2019-06-10 by SAE International in United States
The aim of this work is to develop a semi-empirical model for erosion phenomena under ice crystal condition, which is one of the major phenomena for ice crystal accretion. Such a model would be able to calculate the erosion rate caused by impinging ice crystals on accreted ice layer.This model is based on Finnie [1] and Bitter [2] [3] solid/solid collision theory which assumes that metal erosion due to sand impingement is driven by two phenomena: cutting wear and deformation wear. These two phenomena are strongly dependent on the particle density, velocity and shape, as well as on the surface physical properties such as Young modulus, Poisson ratio, surface yield strength and hardness. Moreover, cutting wear is mostly driven by tangential velocity and is more effective for ductile eroded body, whereas deformation wear is driven by normal velocity and is more effective for brittle eroded body. Several researchers based their erosion modelling on these two phenomena such as Hutchings et al. [4] for deformation erosion, or Huang et al. [5] and Arabnejad et al. [6]…
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Material Properties of Granular Ice Layers Characterized Using a Rigid-Body-Penetration Method: Experiments and Modeling

Technical University of Darmstadt-Markus Schremb, Kenan Malicevic, Louis Reitter, Ilia Roisman, Cameron Tropea
Published 2019-06-10 by SAE International in United States
Accretion and shedding of ice layers is a serious problem for various engineering applications. In particular, ice layers growing due to ice crystal impingement on warm parts of an aircraft jet engine pose a severe hazard since they seriously affect safe operation of an aircraft. The material properties, and in the first place the strength of an ice layer, are crucial for the mechanisms leading to, and taking place during, both accretion and shedding of an ice layer. In the present study, the apparent yield strength of dry granular ice layers is examined employing a novel rigid-body-penetration approach. Dynamic projectile penetration into granular ice layers of varying porosity and ice grain size is experimentally investigated for different projectile impact velocities using a high-speed video system and post-processing of the captured video data. The obtained data for the total penetration depth of the projectile is used to calculate the apparent yield strength of the ice layer based on theoretical modeling of the projectile dynamics during penetration. Finally, the experimental method and theoretical modeling employed in the…
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Experimental Investigations of an Icing Protection System for UAVs

Norwegian University of Science and Technology (NTNU)-Richard Hann, Kasper Borup, Artur Zolich, Håvard Vestad, Martin Steinert, Tor Johansen
UBIQ Aerospace-Kim Sorensen
Published 2019-06-10 by SAE International in United States
UAV icing is a severe challenge that has only recently shifted into the focus of research. Today, there are no mature icing mitigation technologies for UAVs, except for the largest fixed-wing drones. We are working on the development of an electro-thermal icing protection technology called D•ICE for medium-sized fixed-wing UAVs. As part of the design process, an experimental test campaign at the Cranfield icing wind tunnel has been conducted. This paper describes the icing protection system and shares experimental results on its capability for icing detection and anti-icing. Icing detection is based on an algorithm evaluating temperature signals that are induced on the leading-edge of the wing. A baseline signal is generated during dry (icing cloud off) conditions and compared to a signal during wet (icing cloud on) conditions. Due to significant differences in the heat transfer regime, the system can differentiate between these two states. The experiments show that our system can reliably detect icing conditions based on this principle. Furthermore, the anti-icing capability of the system is proven for two icing cases. The…
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Microwave Technique for Liquid Water Detection in Icing Applications

University of Oxford-Matthew McGilvray, David Gillespie
University of Southern Queensland-John Leis, David Buttsworth, Ramiz Saeed, Khalid Saleh
Published 2019-06-10 by SAE International in United States
The partial melting of ingested ice crystals can lead to ice accretion in aircraft compressors, but accurately measuring the relatively small fraction of liquid water content in such flows is challenging. Probe-based methods for detecting liquid water content are not suitable for deployment within turbofan engines, and thus alternatives are sought. Recent research has described approaches based on passive microwave sensing. We present here an approach based on active microwave transmission and reflection, employing a vector network analyzer. Utilization of both transmission and reflection provides additional data over and above emission or transmission only, and permits a more controllable environment than passive sensing approaches. The paper specifically addresses the question of whether such an approach is viable within the context of representative icing wind tunnel and engine flow conditions. A quasi-thermal equilibrium approach is presented herein to estimate the melting ratio during microwave analysis of samples at 0 °C. Experimental results using microwaves in the 2.45GHz region are presented, and post-processing methods investigated. This is followed by an investigation of detection limits for ice accretion…
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Focus on Challenges in SLD Regime: Reemitted Droplet Modelling

Dassault Aviation-Francois Caminade, Loïc Frazza
Published 2019-06-10 by SAE International in United States
A lot of studies have been carried out over the last decades on SLD ice accretion challenges. Many of them referred to SLD physics modelling such as break-up, splashing, bouncing, etc… and relied on numerous physics experiments. Different models have been developed in Europe and North-America and have been implemented in several numerical tools, widely in 2D but more and more in 3D. As these tools are intended to be used increasingly among the community, deficiencies have to be deeper investigated. This paper provides some highlights on specific needs linked to SLD impingement and ice accretion, especially for 3D high fidelity computations. Regarding the results, deficiencies on the numerical side and on experimental needs will be highlighted in order to feed brainstorming for ongoing SLD projects such as in European Union H2020 ICE-GENESIS.
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Simulation of Ice Particle Breakup and Ingestion into the Honeywell Uncertified Research Engine (HURE)

NASA Glenn Research Center-Ashlie Flegel, Michael King
Vantage Partners Limited-David L. Rigby, William Wright
Published 2019-06-10 by SAE International in United States
Numerical solutions have been generated which simulate flow inside an aircraft engine flying at altitude through an ice crystal cloud. The geometry used for this study is the Honeywell Uncertified Research Engine (HURE) which was recently tested in the NASA Propulsion Systems Laboratory (PSL) in January 2018. The simulations were carried out at predicted operating points with a potential risk of ice accretion. The extent of the simulation is from upstream of the engine inlet to downstream past the strut in the core and bypass. The flow solution is produced using GlennHT, a NASA in-house code. A mixing plane approximation is used upstream and downstream of the fan. The use of the mixing plane allows for steady state solutions in the relative frame. The flow solution is then passed on to LEWICE3D for particle trajectory, impact and breakup prediction. The LEWICE3D code also uses a mixing plane approximation at the boundaries upstream and downstream of the fan. A distribution of particle sizes is introduced upstream, based on the distribution measured during the test. Predicted collection…
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ICICLE: A Model for Glaciated & Mixed Phase Icing for Application to Aircraft Engines

Rolls-Royce Plc-Geoffrey Jones, Benjamin Collier
University of Oxford-Alexander Bucknell, Matthew McGilvray, David Gillespie, Xin Yang
Published 2019-06-10 by SAE International in United States
High altitude ice crystals can pose a threat to aircraft engine compression and combustion systems. Cases of engine damage, surge and rollback have been recorded in recent years, believed due to ice crystals partially melting and accreting on static surfaces (stators, endwalls and ducting). The increased awareness and understanding of this phenomenon has resulted in the extension of icing certification requirements to include glaciated and mixed phase conditions. Developing semi-empirical models is a cost effective way of enabling certification, and providing simple design rules for next generation engines. A comprehensive ice crystal icing model is presented in this paper, the Ice Crystal Icing ComputationaL Environment (ICICLE). It is modular in design, comprising a baseline code consisting of an axisymmetric or 2D planar flowfield solution, Lagrangian particle tracking, air-particle heat transfer and phase change, and surface interactions (bouncing, fragmentation, sticking). In addition, an efficient particle tracking method has been developed into the code, which employs the representative particle size distribution at each injection location and a deterministic particle sticking method by using an in-situ particle based…
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Heat Transfer Enhancement in Stagnation Region of Aero-Engine Inlet Vanes due to Ejection Slot and Anisotropic Heat Conduction

AECC Commercial Aircraft Engine Co., Ltd-Kun Yang, Hongkui Zhou
Beihang University-Peng Ke, Jie Liu, Lukas Schaeflein
Published 2019-06-10 by SAE International in United States
Ice protection is important for aero-engine induction system, such as the inlet vanes. For the ice protection of such parts manufactured with low thermal conductivity polymer-based composite material, the combined heating method using interior jet impingement and exterior ejection film has certain advantages. The simulation model coupling CFD with solid heat conduction was developed and solved with the anisotropic thermal conductivities model to investigate the heat transfer enhancement in the stagnation region of aero-engine inlet vanes due to ejection slot and anisotropic heat conduction, which is related to the curved geometry, ejection slots and anisotropic heat conduction.The temperature distribution and heat flux ratio between the stagnation region on outside surface and the impingement region inside were calculated and analyzed for the configuration with different ejection angle and different materials. The results show that ejection slots and anisotropic heat conduction plays important roles of the heat transfer process. For the same ejection angles, the larger the thermal conductivity, the higher the temperature at stagnation point and the better ice protection. For the same material property, the…
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The Cloud Detectability Conundrum

Collins Aerospace-Darren Glenn Jackson
Published 2019-06-10 by SAE International in United States
Since the beginning of aviation, aircraft designers, researchers, and pilots have monitored the skies looking for clouds to determine when and where to fly as well as when to deice aircraft surfaces. Seeing a cloud has generally consisted of looking for a white / grey puffy orb floating in the sky, indicating the presence of moisture. A simple monitoring of a temperature gauge or dew point sensor was used to help determine if precipitation was likely or accumulation of ice / snow on the airframe could occur.Various instruments have been introduced over the years to identify the presence of clouds and characterize them for the purposes of air traffic control weather awareness, icing flight test measurements, and production aircraft ice detection. These instruments have included oil slides, illuminated rods, vibrating probes, hot wires, LIDAR, RADAR, and several other measurement techniques. Each technology has its own strength and weakness including the particle size range and water content that can be measured and its ability (or lack thereof) to discriminate different types of icing conditions.The FAA release…
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