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Brøndbyvester, Denmark

Croce G.,University of Udine | De Candido E.,University of Udine | Habashi W.G.,McGill University | Munzar J.,McGill University | And 4 more authors.
Journal of Aircraft | Year: 2010

Ice roughness, which has a major influence on in-flight icing heat transfer and, hence, ice shapes, is generally input from empirical correlations to numerical simulations. It is given as uniform in space, while sometimes being varied in time. In this paper, a predictive model for roughness evolution in both space and time during in-flight icing is presented. The distribution is determined mathematically via a Lagrangian model that accounts for the stochastic process of bead nucleation, growth, and coalescence into moving droplets and/or rivulets and/or water film. This general model matches well the spatial and temporal roughness distributions observed in icing tunnel experiments and is embedded in FENSAP-ICE, extending its applicability outside the range of airfoil types for which correlations exist. Thus, an additional important step has been taken toward removing another empirical aspect of in-flight icing simulation. Copyright © 2010 by W.G. Habashi. Source

Cinquegrana D.,Centro Italiano Ricerche Aerospaziali | Cinquegrana D.,Computational Fluid Dynamics Laboratory
Journal of Spacecraft and Rockets | Year: 2015

In the early stage of a reentry vehicle design are often necessary tools able to perform mission and trajectory trade studies. Many works in the literature present tools able to interpolate from a numerical database of high-fidelity simulations to a target free-stream condition. In this context, the work explores the capability of a reduced-order model in extending a limited database of computational fluid dynamics simulations to the full coverage of the design space. This results in a fast physic-based tool able to generate load history experienced on a vehicle's surface during the reentry flight. The reduced-order model is based on proper orthogonal decomposition coupled with a Gaussian process for interpolations. Main results are the history of the pressure and skin-friction coefficient of a reference trajectory related to a specific vehicle's control points. This output will be compared with a simple Gaussian metamodel based directly on the computational fluid dynamics data of such control points. A detailed cross-validation analysis of the model that provides a loss function map in the design space can be considered as a guide to in-fill the database with further computational fluid dynamics simulations, keeping the number of computational fluid dynamics runs at a minimum value to limit the computational budget. Copyright © 2015 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. Source

Pellissier M.P.C.,McGill University | Pellissier M.P.C.,Computational Fluid Dynamics Laboratory | Habashi W.G.,McGill University | Habashi W.G.,Bombardier | Pueyo A.,Bombardier
Journal of Aircraft | Year: 2011

This paper presents a methodology for the optimization of hot-bleed-air anti-icing systems, known as Piccolo tubes. Such systems are widely used to anti-ice the wings of many commercial aircrafts, ranging from regional to wide-body jet aircrafts. Having identified the most critical in-flight icing conditions, as well as any anti-icing system constraints as inputs, the ideal aim is to achieve fully-evaporative conditions over the heated surfaces. To do so, an optimization method based on three-dimensional computational fluid dynamics, reduced-order models, and genetic algorithms was constructed to determine the optimal geometric configuration of the Piccolo tube (jet angles, spacing of jets, and distance from leading edge). The external and internal airflows are computed using the finite element Navier-Stokes applications package (FENSAP-ICE). The methodology leads to significantly-improved configurations for three- to five-dimensional design spaces. Copyright © 2010 byWagdi G. Habashi. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. Source

Zhang Y.,McGill University | Zhang Y.,Computational Fluid Dynamics Laboratory | Habashi W.G.,McGill University | Habashi W.G.,Computational Fluid Dynamics Laboratory | And 3 more authors.
Journal of Aircraft | Year: 2016

This paper presentsamultiscale finite-element formulation for the second modeofzonal detached-eddy simulation. The multiscale formulation corrects the lack of stability of the standard Galerkin formulation by incorporating the effect of unresolved scales to the grid (resolved) scales. The stabilization terms arise naturally and are free of userdefined stability parameters. Validation of the method is accomplished via the turbulent flow over tandem cylinders. The boundary-layer separation, free shear-layer rollup, vortex shedding from the upstream cylinder, and interaction with the downstream cylinder are well reproduced. Good agreement with experimental measurements gives credence to the accuracy of zonal detached-eddy simulation in modeling turbulent separated flows. A comprehensive study is then conducted on the performance degradation of ice-contaminated airfoils. NACA 23012 airfoil with a spanwise ice ridge and Gates Learjet Corporation-305 airfoil with a leading-edge horn-shape glaze ice are selected for investigation. Appropriate spanwise domain size and sufficient grid density are determined to enhance the reliability of the simulations. A comparison of lift coefficient and flowfield variables demonstrates the added advantage that the zonal detached-eddy simulation model brings to the Spalart-Allmaras turbulence model. Spectral analysis and instantaneous visualization of turbulent structures are also highlighted via zonal detached-eddy simulation. Copyright © 2015 by the CFD Lab of McGill University. Published by the American Institute of Aeronautics and Astronautics, Inc. Source

Badcock K.J.,University of Liverpool | Badcock K.J.,Computational Fluid Dynamics Laboratory | Woodgate M.A.,University of Liverpool | Woodgate M.A.,Computational Fluid Dynamics Laboratory
AIAA Journal | Year: 2010

Computational aeroelasticity has become an active area of research in the past decade. Effort has been put into coupling between computational fluid dynamic and finite element solvers and into model reduction to make the resulting simulations more useful for practical analysis. This paper is the latest in a series that describe research toward making eigenvalue-based stability analysis routine for large-scale computational-fluid-dynamic-based semidiscrete systems. The particular contribution of this paper is to formulate the problem in a framework that exploits the Schur complement. This effectively allows the different parts of the system Jacobian to be treated in a decoupled way, with the final result being a small nonlinear eigenvalue problem for the stability analysis. The calculation of this small system can be done robustly in parallel. Results to illustrate the performance of the method are presented for model wings and full aircraft test cases. Source

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