Transition effects on heating in the wake of a blunt body

Hollis, Brian R.; Perkins, John N.

doi:10.2514/6.1997-2569

Cited by 10 publications

(7 citation statements)

References 20 publications

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“…This is caused by the formation of two counter-rotating vortices in the ake. The formation of several vortices in the wake is often observed for high values of the Reynolds number [5,14]. In the present cases, the complexity of the flow in the recirculation and of the wall distributions makes it difficult to quantify the effect of L and α on the heat flux and C p .…”

Section: Heat Flux and C P Distributions On The Aft Of Cylindersmentioning

confidence: 84%

“…Detached flow with solid reattachment is mainly observed behind backward facing steps, where the boundary layer detaches at the edge of the step and reattaches on the wall downwind (figure 6). The recompression caused by the reattachment results in a heat flux peak near the reattachment point R S that can reach up to 18 % of the stagnation point heat flux [6,13,14].…”

Section: Wall Heat Flux and Pressure Coefficient In The Shadow Region Of Space Debrismentioning

confidence: 99%

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Reduced order models for heat flux and pressure distributions on space debris afterbodies

et al. 2021

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The prediction of the on-ground risk caused by re-entering space debris requires accurate and computationally affordable models to compute wall heat flux and pressure coefficient C p at every stage of the reentry. Such models already exist for the wind area of the debris, i.e. the area directly impinged upon by fictitious lines parallel to the incoming flow. But the heat flux and C p are often neglected in the shadow area, even though they can be relatively high for certain shapes of debris. The present work focuses on developing reduced order models for heat flux and C p distributions in the shadow area of space debris, for hypersonic continuous flow conditions. We identified four phenomena which appear in the shadow area and cause relatively high levels of these aerodynamic quantities (attached flow, detached flow with fluid reattachment, detached flow with solid reattachment and shock-shock interactions). Models were developed for the heat flux and C p distributions caused by attached flows on the lee side of cylindrical geometries using the Proper Orthogonal Decomposition (POD) and interpolation method. Using this method, it is possible to reduce the number of required data by efficiently exploring the parameters domain of variation. The sample points were chosen thanks to an adaptive design of experiments, and the input data for the models were obtained by 3D Navier-Stokes computations of the flow around cylinders at incidence. The analysis of the computational results highlighted the influence of the Reynolds number based on the cylinder diameter Re D,∞ on the heat flux and pressure distributions. Reduced-order models were created for three input parameters (length L, diameter D and angle of attack α) and fixed incoming flow conditions, using the POD and interpolation method, and then were extended to other upstream hypersonic continuous flow conditions by more classical approaches based on non-dimensional quantities. Finally, the reentry trajectories of two different cylindrical debris were computed with and without the new models developed, to demonstrate their influence

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Section: Heat Flux and C P Distributions On The Aft Of Cylindersmentioning

confidence: 84%

Section: Wall Heat Flux and Pressure Coefficient In The Shadow Region Of Space Debrismentioning

confidence: 99%

Reduced order models for heat flux and pressure distributions on space debris afterbodies

et al. 2021

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“…Finally, the non-dimensional heat flux along the vehicle surface is shown in Figure 44. With comparisons to numerical results obtained by Scalabrin (2007) and the NEQ2D code (Hollis and Perkins, 1997) and experimental results from the HYPULSE experiments (Hollis, 1996). A small oscillation in the heat flux is present at the location corresponding to the change in the blocking structure of the mesh, but the predicted distribution agrees much better with the experimental results than the other numerical references, in particular, at the extremity of the heat shield.…”

Section: Resultsmentioning

confidence: 99%

A finite element solver for hypersonic flows in thermo-chemical non-equilibrium, Part I

Seguin

Gao

Habashi

et al. 2019

HFF

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Purpose This paper aims to describe the physical and numerical modeling of a new computational fluid dynamics solver for hypersonic flows in thermo-chemical non-equilibrium. The code uses a blend of numerical techniques to ensure accuracy and robustness and to provide scalability for advanced hypersonic physics and complex three-dimensional (3D) flows. Design/methodology/approach The solver is based on an edge-based stabilized finite element method (FEM). The chemical and thermal non-equilibrium systems are loosely-coupled to provide flexibility and ease of implementation. Chemical non-equilibrium is modeled using a laminar finite-rate chemical kinetics model while a two-temperature model is used to account for thermodynamic non-equilibrium. The systems are solved implicitly in time to relax numerical stiffness. Investigations are performed on various canonical hypersonic geometries in two-dimensional and 3D. Findings The comparisons with numerical and experimental results demonstrate the suitability of the code for hypersonic non-equilibrium flows. Although convergence is shown to suffer to some extent from the loosely-coupled implementation, trading a fully-coupled system for a number of smaller ones improves computational time. Furthermore, the specialized numerical discretization offers a great deal of flexibility in the implementation of numerical flux functions and boundary conditions. Originality/value The FEM is often disregarded in hypersonics. This paper demonstrates that this method can be used successfully for these types of flows. The present findings will be built upon in a later paper to demonstrate the powerful numerical ability of this type of solver, particularly with respect to robustness on highly stretched unstructured anisotropic grids.

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“…The Reynolds number at these flow conditions was low enough for the flow along the wedge to be considered laminar according to the criterion of Lees [4], although several previous studies on hypersonic laminar separated flows [5][6][7] have indicated that laminar separated flows readily transition in the free shear layer. The visualisations presented later in the paper showed no evidence of large-scale turbulent structures in the free shear layer.…”

Section: Experiments 21 Facility Flow Conditions and Modelmentioning

confidence: 99%

Development, Uniformity and Peak Heating of a Hypersonic Laminar Near-Wake Flow

O’Byrne¹,

Danehy²

2012

International Journal of Aerospace Innovations

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This paper describes visualisation experiments performed using the planar laser-induced fluorescence of nitric oxide. The focus was to investigate the establishment and crossstream uniformity of the hypersonic separated flow generated in a pulsed free-piston shock tunnel facility. In particular, the laminar Mach 7.5 flow over a step downstream of a wedge was investigated. The ratio of wedge width to total horizontal distance downstream of the leading edge was 0.71 at the furthest downstream measurement point, and model side plates were not used. Flow images were obtained on successive tunnel runs with different delays after flow onset, to identify the nominal flow establishment time. Furthermore, images were obtained at the nominal facility test time using a laser sheet oriented perpendicular to the step, propagating in the spanwise direction at a height equal to half the step height. These images are compared with thermocouple heat flux measurements obtained both with and without the step and show that while the flow downstream of reattachment is uniform in the middle of the model, the separated flow immediately downstream of the step is non-uniform. NOMENCLATURE

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Transition effects on heating in the wake of a blunt body

Cited by 10 publications

References 20 publications

Reduced order models for heat flux and pressure distributions on space debris afterbodies

Reduced order models for heat flux and pressure distributions on space debris afterbodies

A finite element solver for hypersonic flows in thermo-chemical non-equilibrium, Part I

Development, Uniformity and Peak Heating of a Hypersonic Laminar Near-Wake Flow

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