A mesoscopic modelling approach for direct numerical simulations of transition to turbulence in hypersonic flow with transpiration cooling
A mesoscopic modelling approach for direct numerical simulations of transition to turbulence in hypersonic flow with transpiration cooling
A rescaling methodology is developed for high-fidelity, cost-efficient direct numerical simulations (DNS) of flow through porous media, modelled at mesoscopic scale, in a hypersonic freestream. The simulations consider a Mach 5 hypersonic flow over a flat plate with coolant injection from a porous layer with 42 % porosity. The porous layer is designed using a configuration studied in the literature, consisting of a staggered arrangement of cylinder/sphere elements. A characteristic Reynolds number Re
c of the flow in a pore cell unit is first used to impose aerodynamic similarity between different porous layers with the same porosity, ∊, but different pore size. A relation between the pressure drop and the Reynolds number is derived to allow a controlled rescaling of the pore size from the realistic micrometre scales to higher and more affordable scales. Results of simulations carried out for higher cylinder diameters, namely 24 μm, 48 μm and 96 μm, demonstrate that an equivalent Darcy-Forchheimer behaviour to the reference experimental microstructure is obtained at the different pore sizes. The approach of a porous layer with staggered spheres is applied to a 3D domain case of porous injection in the Darcy limit over a flat plate, to study the transition mechanism and the associated cooling performance, in comparison with a reference case of slot injection. Results of the direct numerical simulations show that porous injection in an unstable boundary layer leads to a more rapid transition process, compared to slot injection. On the other hand, the mixing of coolant within the boundary layer is enhanced in the porous injection case, both in the immediate outer region of the porous layer and in the turbulent region. This has the beneficial effect of increasing the cooling performance by reducing the temperature near the wall, which provides a higher cooling effectiveness, compared to the slot injection case, even with an earlier transition to turbulence.
Hypersonic flow, boundary-layer stability, wall cooling
Cerminara, Adriano
6fd11181-c852-4558-82b5-5f7eac291a3f
Deiterding, Ralf
ce02244b-6651-47e3-8325-2c0a0c9c6314
Sandham, Neil
0024d8cd-c788-4811-a470-57934fbdcf97
1 December 2020
Cerminara, Adriano
6fd11181-c852-4558-82b5-5f7eac291a3f
Deiterding, Ralf
ce02244b-6651-47e3-8325-2c0a0c9c6314
Sandham, Neil
0024d8cd-c788-4811-a470-57934fbdcf97
Cerminara, Adriano, Deiterding, Ralf and Sandham, Neil
(2020)
A mesoscopic modelling approach for direct numerical simulations of transition to turbulence in hypersonic flow with transpiration cooling.
International Journal of Heat and Fluid Flow, 86, [108732].
(doi:10.1016/j.ijheatfluidflow.2020.108732).
Abstract
A rescaling methodology is developed for high-fidelity, cost-efficient direct numerical simulations (DNS) of flow through porous media, modelled at mesoscopic scale, in a hypersonic freestream. The simulations consider a Mach 5 hypersonic flow over a flat plate with coolant injection from a porous layer with 42 % porosity. The porous layer is designed using a configuration studied in the literature, consisting of a staggered arrangement of cylinder/sphere elements. A characteristic Reynolds number Re
c of the flow in a pore cell unit is first used to impose aerodynamic similarity between different porous layers with the same porosity, ∊, but different pore size. A relation between the pressure drop and the Reynolds number is derived to allow a controlled rescaling of the pore size from the realistic micrometre scales to higher and more affordable scales. Results of simulations carried out for higher cylinder diameters, namely 24 μm, 48 μm and 96 μm, demonstrate that an equivalent Darcy-Forchheimer behaviour to the reference experimental microstructure is obtained at the different pore sizes. The approach of a porous layer with staggered spheres is applied to a 3D domain case of porous injection in the Darcy limit over a flat plate, to study the transition mechanism and the associated cooling performance, in comparison with a reference case of slot injection. Results of the direct numerical simulations show that porous injection in an unstable boundary layer leads to a more rapid transition process, compared to slot injection. On the other hand, the mixing of coolant within the boundary layer is enhanced in the porous injection case, both in the immediate outer region of the porous layer and in the turbulent region. This has the beneficial effect of increasing the cooling performance by reducing the temperature near the wall, which provides a higher cooling effectiveness, compared to the slot injection case, even with an earlier transition to turbulence.
Text
IJHFF-accepted-paper
- Accepted Manuscript
More information
Accepted/In Press date: 7 October 2020
e-pub ahead of print date: 9 October 2020
Published date: 1 December 2020
Additional Information:
Funding Information:
The authors would like to acknowledge support from EPSRC (Engineering and Physical Sciences Research Council) under the Grant No. EP/P000878/1.
Publisher Copyright:
© 2020 Elsevier Inc.
Keywords:
Hypersonic flow, boundary-layer stability, wall cooling
Identifiers
Local EPrints ID: 444900
URI: http://eprints.soton.ac.uk/id/eprint/444900
ISSN: 0142-727X
PURE UUID: 9d4f506a-9bfc-4c77-b7c3-d216a6bbbede
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Date deposited: 10 Nov 2020 17:33
Last modified: 17 Mar 2024 05:58
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Author:
Adriano Cerminara
Author:
Neil Sandham
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