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Reid T.,Newmerical Technologies International | Baruzzi G.S.,Newmerical Technologies International | Habashi W.G.,McGill University | Habashi W.G.,CFD Laboratory
Journal of Aircraft | Year: 2012

This paper presents a truly unsteady approach for the numerical simulation of in-flight electrothermal anti-icing or de-icing, using a conjugate heat transfer technique. This numerical approach has been implemented in FENSAPICE to compute the complex heat transfer phenomena occurring during in-flight de-icing with multiple heating elements following independent cycling. At each time step, the energy fluxes through the aircraft's solid skin, the melting ice layer, the liquid water film, and the external fluid are computed. The ice shape is then modified by taking into account the opposing mass balance effects of ice accreting due to the impact of supercooled droplets and/or water runback, and the partial or total melting of the existing ice layer due to heating. The results of the verification of this phase-change conduction code are presented, followed by a study of intercycle de-icing on a wing, showing intercycle ice growth. Copyright © 2011 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

Veillard X.,McGill University | Veillard X.,Imperial College London | Habashi W.G.,McGill University | Habashi W.G.,CFD Laboratory | Baruzzi G.S.,Newmerical Technologies International
Journal of Propulsion and Power | Year: 2011

The present paper develops the particular methodology required to simulate icing not only on the front of a jet engine, but inside multistage ones, to respond to recent safety and performance concerns. When flying in certain weather conditions, engines have been found to ingest a mix of iced and liquid particles that can result in a dangerous buildup onthe internal components of the compressor. The ice can then shed and may cause mechanical damage and performance losses to downstream components. To cost-effectively replicate such an environment, a threedimensional quasi-steady numerical approach is developed to model both rotating and static components and their interaction. An intercomponent mixing-plane approach, along with stagnation and radial equilibrium boundary conditions, has been implemented, allowing the treatment of multistage unequal-pitch blade rows via afinite element interpolation method and proper circumferential averaging. The approach is first validated for the well-documented Aachen turbine, and then used on a NASA compressor stage to highlight impingement locations of supercooled droplets and the corresponding ice shapes. Copyright © 2011 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

Bilodeau D.R.,McGill University | Bilodeau D.R.,CFD Laboratory | Habashi W.G.,McGill University | Habashi W.G.,CFD Laboratory | And 3 more authors.
Journal of Aircraft | Year: 2015

A conservative Eulerian numerical approach for modeling postimpact Supercooled Large Droplets undergoing splashing and bouncing on aircraft surfaces is presented. The approach introduces the effect of the postimpact droplets by successive solutions of the conservation equations. Two models have been selected to identify the droplet splashing and bouncing conditions, and to provide initial conditions for the reinjected water. The method has been applied to droplet impingement in Supercooled Large Droplet conditions on clean and iced NACA 23012 geometries, as well as the MS(1)-0317 airfoil, and the results have been compared to experimental data. Good agreement is observed for both impingement limits and collection efficiency. Additionally, the method has been applied to a threeelement high-lift configuration operating in one of the proposed Appendix O Supercooled Large Droplet environments to demonstrate the danger posed by the re-impingement of splashing and bouncing droplets on complex interacting aerodynamic components. © 2014 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

Aliaga C.N.,Newmerical Technologies International | Aliaga C.N.,CFD Laboratory | Aube M.S.,Newmerical Technologies International | Aube M.S.,CFD Laboratory | And 4 more authors.
Journal of Aircraft | Year: 2011

In-flight ice accretion, even though driven by a steady flow airstream, is an inherently unsteady phenomenon. It is, however, completely ignored in icing simulation codes (one-shot) or, at best approximated via quasi-steady modeling (multishot). The final ice shapes thus depend on the length of the total accretion time (one-shot), or of the arbitrarily prescribed time intervals (multishot), during which the impact of ice growth on both airflow and water impingement is ignored. Such a longstanding heuristic approximation is removed in this paper by coupling in time the dilute two-phase flow (air and water droplets flow) with ice accretion, and is implemented in a new code, FENSAP-ICE-Unsteady. The two-phase flow is solved using the coupled Navier-Stokes and water concentration equations, and the water film characteristics and ice shapes are obtained from laws of conservation of mass and energy within the thin film layer. To continually update the geometry of the iced surface in time, arbitrary Lagrangian-Eulerian terms are added to all governing equations to account for mesh movement in the case of stationary components. In the case of rotating/stationary interacting components, a dynamically stitched grid is used. The numerical results clearly show that unsteady modeling improves the accuracy of both rime and glaze ice shape prediction, compared with the traditional quasi-steady approach with frozen solutions. The unsteady model is shown to open the door for a unified approach to icing on fixed wings, on helicopters with blades/rotors/fuselage systems. Problems of current concern in the icing community such as the ingestion of ice crystals at high altitude become tractable with the new formulation. Copyright © 2010 by W.G. Habashi.

Lawson S.J.,University of Liverpool | Lawson S.J.,CFD Laboratory | Barakos G.N.,University of Liverpool | Barakos G.N.,CFD Laboratory
Aerospace Science and Technology | Year: 2010

This paper demonstrates the Detached Eddy Simulation (DES) approach for the computation of flows around uninhabited combat air vehicles. One of the key features of this new family of aircraft is that weapon bays are used to enhance stealth characteristics and improve aerodynamic performance. The highly energetic flow-field within the weapon bays can change dramatically the aerodynamics of these aircraft and for this reason detailed CFD analyses are needed to provide insight in the change of loads encountered when weapon bays are exposed. In contrast to previous studies where idealised, isolated cavities are used as model problems, a realistic aircraft geometry is used in this work. Computations using DES are presented for the clean aircraft, the idealised cavity and the complete configuration. Advanced multi-block topologies are used which allow for most of the geometric details of the aircraft to be preserved and resolved by the employed CFD solver. For all cases where weapon bays are present, DES is used for the simulation while statistical turbulence models prove to be adequate for the clean aircraft cases. Comparisons against experimental data demonstrate the accuracy of the employed methods and strengthen confidence in the employed DES models. The overall loading of the aircraft is well-predicted even at high angles of attack and DES appears to offer encouraging results at low and high Mach number cases. Experiments conducted by QinetiQ and DSTL are used for validation of the DES method and results indicate that less than 3dB discrepancies in the overall sound pressure level can be obtained in comparison to the tunnel data. © 2010 Elsevier Masson SAS. All rights reserved.

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