References of "Terrapon, Vincent"
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See detailUsing Proper Orthogonal Decomposition Methods for Comparing CFD Results to Experimental Measurements
Andrianne, Thomas ULg; Guissart, Amandine ULg; Terrapon, Vincent ULg et al

in Proceedings of the 5th Symposium on Integrating CFD and Experiments in Aerodynamics (Integration 2012) (2012, October 03)

This work presents a method for quantitative comparison of numerical results to experimental measurements. It is based on the concept of Proper Orthogonal Decomposition. This technique is selected in ... [more ▼]

This work presents a method for quantitative comparison of numerical results to experimental measurements. It is based on the concept of Proper Orthogonal Decomposition. This technique is selected in order to compare the unsteady aerodynamic flows around static and oscillating bodies obtained from wind tunnel testing and numerical simulations. Two dimensional Time-resolved Particle Image Velocimetry measurements are carried out on the upper surface a 4:1 rectangular cylinder. Simulations are performed using unsteady Reynolds-Averaged Navier-Stokes and an unsteady Discrete Vortex Method. It is demonstrated that the proposed technique is a good preliminary step for comparing the main characteristics of unsteady aerodynamic data. [less ▲]

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See detailReynolds-Averaged Navier-Stokes Simulations of the HyShot II Scramjet
Pecnik, Rene; Terrapon, Vincent ULg; Ham, Frank et al

in AIAA Journal (2012), 50(8), 1717-1732

The internal flow in the HyShot II scramjet is investigated through numerical simulations. A computational infrastructure to solve the compressible Reynolds-Averaged Navier-Stokes equations on ... [more ▼]

The internal flow in the HyShot II scramjet is investigated through numerical simulations. A computational infrastructure to solve the compressible Reynolds-Averaged Navier-Stokes equations on unstructured meshes is introduced. A combustion model based on tabulated chemistry is considered to incorporate a detailed chemical kinetics mechanics while retaining a low computational cost. Both non-reactive and reactive simulations have been performed and results are compared with ground test measurements obtained at DLR. Different turbulence models were tested and the dependence on the mesh is assessed through grid refinement. The comparison with experimental data shows good agreement, although for the reactive case the computed heat fluxes at the wall are higher than measurements. A sensitivity analysis on the turbulent Schmidt and Prandtl numbers shows that the choice of these parameters has a strong influence on the results. In particular, variations of the turbulent Prandtl number lead to large changes in the heat flux at the walls. Finally, the inception of thermal choking is investigated by increasing the equivalence ratio, whereby a normal shock is created locally and moves upstream leading to a large increase in the maximum pressure. Nevertheless a large portion of the flow is still supersonic. [less ▲]

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See detailComputational Fluid Mechanics for Civil Engineering Applications
Terrapon, Vincent ULg

Scientific conference (2012, May 23)

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See detailAnalysis of transitional polymeric flows and elastic instabilities
Dubief, Yves; Terrapon, Vincent ULg; Soria, Julio

in Center for Turbulence Research, Proceedings of the Summer Program (2012)

The dynamics of turbulence generated and controlled by polymer additives is investigated from the perspective of the coupling between polymer dynamics and flow structures. Direct numerical simulations of ... [more ▼]

The dynamics of turbulence generated and controlled by polymer additives is investigated from the perspective of the coupling between polymer dynamics and flow structures. Direct numerical simulations of channel flow with Reynolds numbers ranging from 1,000 to 10,000 (based on the bulk and the channel height) are used to study the formation and dynamics of elastic instabilities and their effects on the flow. The resulting mechanism of interactions between polymer dynamics and the flow helps resolve a long-standing controversy in the understanding of polymer drag reduction and explains the phenomenon of early turbulence, or onset of turbulence at lower Reynolds numbers than for Newtonian flows, previously observed in polymeric flows. [less ▲]

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See detailA flamelet-based combustion model for high-speed flows!
Terrapon, Vincent ULg

Scientific conference (2011, December 13)

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See detailTowards a better understanding of polymer drag reduction in turbulent wall-bounded flows
Terrapon, Vincent ULg; Dubief, Yves; White, Chris et al

Scientific conference (2011, November 14)

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See detailPolymer Maximum Drag Reduction: A Unique Transitional State
Dubief, Yves; White, Christopher M.; Shaqfeh, Eric S.G. et al

E-print/Working paper (2011)

The upper bound of polymer drag reduction is identified as a unique transitional state between laminar and turbulent flow corresponding to the onset of the nonlinear breakdown of flow instabilities.

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See detailRadiation Modeling of a Hydrogen-Fueled Scramjet
Crow, Andrew J.; Boyd, Iain D.; Terrapon, Vincent ULg

in 42nd AIAA Thermophysics Conference 2011, Vol. 3; No AIAA 2011-3769 (2011, June)

With the difficulty and cost of full-scale flight experiments, the design of scramjet engines relies heavily on computational simulations. Radiation may play an important role in wall heating and flow ... [more ▼]

With the difficulty and cost of full-scale flight experiments, the design of scramjet engines relies heavily on computational simulations. Radiation may play an important role in wall heating and flow cooling of scramjets. However, very few studies have focused on such. The present analysis is based on three-dimensional turbulent reacting flow simulations of the HyShot II hydrogen fueled scramjet engine running at flight conditions of Mach 7.4. A one-dimensional Discrete Ordinates Method analysis with a narrow band averaged spectral model is employed to determine wall heating and flow cooling from thermal radiation. The one-dimensional Discrete Ordinates Method is verifi ed against a three-dimensional ray tracing method. The radiative species considered are H2O and OH. The radiative heat flux is on the order of 10 kW/m2, which is 0.1-0.2% of the total convective wall heat flux. Flow cooling due to radiation is found to be on the order of 2 K. Sensitivity analysis shows that radiation is highly dependent on chamber size, temperature, pressure and radiative species mole fraction. Variations in these factors can explain the differences between previous analyses in the literature that studied hypothetical engines and the current work that models an existing scramjet. [less ▲]

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See detailIntroduction to uncertainty analysis and uncertainty representations
Terrapon, Vincent ULg; Iaccarino, Gianluca

Scientific conference (2011, May 13)

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See detailFull-system simulation of the HyShot II scramjet
Terrapon, Vincent ULg

Scientific conference (2011, May)

The renewed interest in high-speed flight has recently demonstrated the need for the development of hypersonic air-breathing propulsion systems, i.e., in which the ambient air is used as oxidizer. Because ... [more ▼]

The renewed interest in high-speed flight has recently demonstrated the need for the development of hypersonic air-breathing propulsion systems, i.e., in which the ambient air is used as oxidizer. Because the internal flow in a scramjet is supersonic, it has a very short residence time during which air and fuel must mix on a molecular level, and chemical reactions have to be completed before leaving the engine. Moreover, the kinetic energy of the free stream of air entering the propulsion engine is of the same order of magnitude as the combustion heat re- lease. This results in a small net thrust compared to the aerodynamic drag. On the other hand, an excessive heat release can lead to the unstart phenomenon, i.e., the choking of the engine, that causes a sudden drop in thrust and large mechanical loads on the structure. Performance optimization requires thus maximizing thrust without crossing the unstart bound. To achieve predictive computations, the quantification of margins and uncertainties (QMU) with respect to this unstart bound is critical. Recent advances within the PSAAP program at Stanford University to develop computational tools to study the unstart phenomenon will be presented. In the first part, an overview of the program will be given. The second part will focus on the combustion model. Since heat release is at the heart of a scramjet operation and the main contributor to unstart, it is also the major source of uncertainties. A novel model for supersonic combustion based on a flamelet/progress variable approach has been developed. This approach allows the use of com- plex chemistry with only 2 or 3 additional scalar transport equations. The model is applied in a RANS computation of the hydrogen fueled HyShot II scramjet and simulation results are compared with experimental data. LES results for a jet in a supersonic crossflow will also be presented. [less ▲]

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See detailCharacterizing the operability limits of the HyShot II scramjet through RANS simulations
Emory, Michael; Terrapon, Vincent ULg; Pecnik, René et al

in 17th AIAA International Space Planes and Hypersonic Systems and Technologies Conference 2011, Vol. 2; No AIAA 2011-2282 (2011, April)

Experimental and flight data for hypersonic air-breathing vehicles are both difficult and extremely expensive to obtain, motivating the use of computational tools to enhance our understanding of the ... [more ▼]

Experimental and flight data for hypersonic air-breathing vehicles are both difficult and extremely expensive to obtain, motivating the use of computational tools to enhance our understanding of the complex physics involved. One of the major difficulties in simulating this regime is the interaction between combustion and turbulence, both of which are intrinsically complex processes. This work represents a first attempt at addressing assumptions introduced by physical models representing the turbulent reacting flow on the resulting predictions of the scramjet performance. A combustion model for high-speed flows is introduced and tested for the HyShot II vehicle. A reduced order chemistry model is then derived to investigate the effect of certain chemistry modeling assumptions within the combustion model. These models are used to investigate the unstart of the engine due to thermal choking by increasing the fuel flow rate. It is shown that an abrupt change occurs where a normal shock forms and moves upstream accompanied by a large region of subsonic flow. Additionally scalar metrics are described which are used as early indicators of unstart, to formulate safe operating limits for the scramjet engine. [less ▲]

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See detailAn Efficient Flamelet-based Combustion Model for Supersonic Flows
Saghafian, Amirreza; Terrapon, Vincent ULg; Ham, Frank et al

in 17th AIAA International Space Planes and Hypersonic Systems and Technologies Conference 2011, Vol. 2; No AIAA 2011-2267 (2011, April)

A combustion model based on a Flamelet/Progress Variable approach for high-speed flows is introduced. In the proposed formulation, the temperature is computed from the transported total energy and ... [more ▼]

A combustion model based on a Flamelet/Progress Variable approach for high-speed flows is introduced. In the proposed formulation, the temperature is computed from the transported total energy and tabulated species mass fractions. The combustion is thus modeled by 3 additional scalar equations and a chemistry table that is computed in a pre-processing step. This approach is very efficient and allows the use of complex chemical mechanisms. An approximation is also introduced to eliminate costly iteration steps during the temperature calculation. To better account for compressibility e ects, the source term for the progress variable is rescaled with the pressure. The model is tested in both RANS and LES computations of a hydrogen jet in a supersonic transverse flow. Comparison with experimental measurements shows good agreement, particularly in the LES case. It is also found that the disagreement between RANS results and experimental data is mostly due to the mixing model de ciencies used in RANS. [less ▲]

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See detailAssessment of the combustion characteristics of hydrogen transverse jets in supersonic crossflow
Gamba, Mirko; Terrapon, Vincent ULg; Saghafian, Amirreza et al

in Annual Research Briefs (2011)

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See detailNumerical predictions of the performance in flight of an air-breathing hypersonic vehicle: HyShot II
Iaccarino, Gianluca; Pecnik, Rene; Terrapon, Vincent ULg et al

in Proceedings of the ASME 2010 International Mechanical Engineering Congress & Exposition; No IMECE2010-40186 (2010, November)

The uncertainties inherent to the operating conditions of the Hyshot II scramjet flight test are assessed. In particular, the variability of the pressure prediction in the combustor due to uncertain free ... [more ▼]

The uncertainties inherent to the operating conditions of the Hyshot II scramjet flight test are assessed. In particular, the variability of the pressure prediction in the combustor due to uncertain free stream conditions is investigated using a probabilistic methodology based on stochastic collocation. The uncertainties in Mach number, angle of attack and flight altitude are inferred from pressure measurements in the unfueled combustor using a Bayesian inversion approach. The forward computation relies on a reduced order model that represents the combustion processes in the scramjet combustor. A ground based experimental data set obtained from 1-to-1 model of the HyShot II vehicle with well defined operating conditions is used to validate the non-reacting solver and to calibrate the heat release model for the reacting combustor. The model prediction agrees well with the experimentally acquired flight data. On the other hand, our estimated flight free stream conditions differ from previously published results. [less ▲]

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See detailRANS Simulations of Supersonic Combustion using a Flamelet-based Model
Terrapon, Vincent ULg

Conference (2010, November)

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See detailMulti-physics modeling
Terrapon, Vincent ULg

Scientific conference (2010, February)

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See detailFlamelet-based combustion model for supersonic combustion
Terrapon, Vincent ULg

Scientific conference (2010, February)

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See detailFull-system RANS of the HyShot II scramjet Part 2: Reactive cases
Terrapon, Vincent ULg; Pecnik, Rene; Ham, Frank et al

in Annual Research Briefs (2010)

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See detailFull-system RANS of the HyShot II scramjet Part 1: Numerics and non-reactive simulations
Pecnik, Rene; Terrapon, Vincent ULg; Ham, Frank et al

in Annual Research Briefs (2010)

Detailed reference viewed: 29 (0 ULg)