Wind-tunnel interference effects on a 70° delta wing

2004 ◽  
Vol 108 (1088) ◽  
pp. 505-513 ◽  
Author(s):  
M. R. Allan ◽  
K. J. Badcock ◽  
G. N. Barakos ◽  
B. E. Richards
Keyword(s):  
Wind Tunnel ◽  
Boundary Conditions ◽  
Vortex Breakdown ◽  
Delta Wing ◽  
Reynolds Numbers ◽  
Helix Angle ◽  
Wind Tunnels ◽  
Wall Boundary Conditions ◽  
All Solutions ◽  
High Reynolds

Abstract This paper considers the effects of both wind-tunnel walls and a downstream support structure, on the aerodynamics of a 70° delta wing. A RANS model of the flow was used with the wind-tunnel walls and supports being modelled with inviscid wall boundary conditions. A consistent discretisation of the domain was employed such that grid dependence effects were consistent in all solutions, thus any differences occurring were due to varying boundary conditions (wall and support locations). Comparing solutions from wind-tunnel simulations and simulations with farfield conditions, it has been shown that the presence of tunnel walls moves the vortex breakdown location upstream. It has also been seen that vortex strength, helix angle, and mean incidence also increase, leading to a more upstream breakdown location in wind-tunnels. The secondary separation line was also observed to move outboards. It was observed that for high Reynolds numbers, with a support downstream of the wing, vortex breakdown can be delayed due to blockage effects providing the vortices do not impinge on the support This was observed to be the case for smaller supports also.

Detached-Eddy Simulations and Reynolds-Averaged Navier-Stokes Simulations of Delta Wing Vortical Flowfields

2002 ◽  
Vol 124 (4) ◽  
pp. 924-932 ◽  
Author(s):  
Scott Morton ◽  
James Forsythe ◽  
Anthony Mitchell ◽  
David Hajek
Keyword(s):  
Vortex Breakdown ◽  
Delta Wing ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Fighter Aircraft ◽  
Eddy Simulation ◽  
Reynolds Averaged Navier Stokes ◽  
High Reynolds

An understanding of vortical structures and vortex breakdown is essential for the development of highly maneuverable vehicles and high angle of attack flight. This is primarily due to the physical limits these phenomena impose on aircraft and missiles at extreme flight conditions. Demands for more maneuverable air vehicles have pushed the limits of current CFD methods in the high Reynolds number regime. Simulation methods must be able to accurately describe the unsteady, vortical flowfields associated with fighter aircraft at Reynolds numbers more representative of full-scale vehicles. It is the goal of this paper to demonstrate the ability of detached-eddy Simulation (DES), a hybrid Reynolds-averaged Navier-Stokes (RANS)/large-eddy Simulation (LES) method, to accurately predict vortex breakdown at Reynolds numbers above 1×106. Detailed experiments performed at Onera are used to compare simulations utilizing both RANS and DES turbulence models.

Turbulent vortex breakdown at high Reynolds numbers

AIAA Journal ◽  
2000 ◽  
Vol 38 ◽  
pp. 825-834
Author(s):  
F. Novak ◽  
T. Sarpkaya
Keyword(s):  
Vortex Breakdown ◽  
Reynolds Numbers ◽  
Turbulent Vortex ◽  
High Reynolds Numbers ◽  
High Reynolds

Wind-tunnel experiments and separation control of a NACA4412 with 25○sweep at high Reynolds numbers

2022 ◽  
Author(s):  
Pierre-Yves Passaggia ◽  
Guillermo Lopez Quesada ◽  
Stéphane Loyer ◽  
Lucien Baldas ◽  
Jean-Christophe Robinet ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Reynolds Numbers ◽  
Separation Control ◽  
Wind Tunnel Experiments ◽  
High Reynolds Numbers ◽  
High Reynolds

The Effect of Condensation on Hypersonic Laminar Heat Transfer to Cones

1968 ◽  
Vol 72 (690) ◽  
pp. 520-521
Author(s):  
N. B. Wood
Keyword(s):  
Unsaturated Flow ◽  
Reynolds Numbers ◽  
Wind Tunnels ◽  
Condensed State ◽  
Focused Attention ◽  
Stagnation Temperature ◽  
Operating Limits ◽  
High Reynolds ◽  
Increasing Temperature ◽  
Working Section

The investigation of Daum focused attention on the problem of condensation in hypersonic wind tunnels. In such tunnels there is often a conflict between the desire to obtain the maximum Reynolds number and the necessity of operating with a sufficiently high stagnation temperature to avoid liquefaction of the working gas. The hypersonic gun tunnel, in which the present tests were made, is capable of running at relatively high Reynolds numbers and to define the operating limits of the RARDE gun tunnel, Bowman made measurements similar to those of Daum, but using nitrogen as the working gas. It will be recalled that Daum made measurements of static and pitot pressures at varying temperatures. He deduced from these measurements that below a certain working section pressure significant degrees of supersaturation could be tolerated before breakdown to the condensed state. Thus three regions can be defined; in order of increasing temperature these are: (i) condensing flow; (ii) supersaturated uncondensed flow; and (iii)unsaturated flow (see Fig. 1).

Turbulent Vortex Breakdown at High Reynolds Numbers

AIAA Journal ◽  
2000 ◽  
Vol 38 (5) ◽  
pp. 825-834 ◽  
Author(s):  
F. Novak ◽  
T. Sarpkaya
Keyword(s):  
Vortex Breakdown ◽  
Reynolds Numbers ◽  
Turbulent Vortex ◽  
High Reynolds Numbers ◽  
High Reynolds

An Intermittent High-Reynolds-Number Wind Tunnel

1977 ◽  
Vol 28 (4) ◽  
pp. 259-264 ◽  
Author(s):  
J L Stollery ◽  
A V Murthy
Keyword(s):  
Reynolds Number ◽  
Wind Tunnel ◽  
High Reynolds Number ◽  
Reynolds Numbers ◽  
Simple Method ◽  
High Reynolds Numbers ◽  
Reservoir Conditions ◽  
High Reynolds ◽  
Cryogenic Wind Tunnel ◽  
Performance Estimates

SummaryThe paper suggests a simple method of generating intermittent reservoir conditions for an intermittent, cryogenic wind tunnel. Approximate performance estimates are given and it is recommended that further studies be made because this type of tunnel could be valuable in increasing the opportunities for research at high Reynolds numbers.

scholarly journals Experimental and Numerical Icing Penalties of an S826 Airfoil at Low Reynolds Numbers

Aerospace ◽  
2020 ◽  
Vol 7 (4) ◽  
pp. 46 ◽  
Author(s):  
Richard Hann ◽  
R. Jason Hearst ◽  
Lars Roar Sætran ◽  
Tania Bracchi
Keyword(s):  
Wind Tunnel ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Low Reynolds Numbers ◽  
3D Printed ◽  
Numerical Tools ◽  
Low Reynolds ◽  
Performance Penalty ◽  
High Reynolds ◽  
Ice Shapes

Most icing research focuses on the high Reynolds number regime and manned aviation. Information on icing at low Reynolds numbers, as it is encountered by wind turbines and unmanned aerial vehicles, is less available, and few experimental datasets exist that can be used for validation of numerical tools. This study investigated the aerodynamic performance degradation on an S826 airfoil with 3D-printed ice shapes at Reynolds numbers Re = 2 × 105, 4 × 105, and 6 × 105. Three ice geometries were obtained from icing wind tunnel experiments, and an additional three geometries were generated with LEWICE. Experimental measurements of lift, drag, and pressure on the clean and iced airfoils have been conducted in the low-speed wind tunnel at the Norwegian University of Science and Technology. The results showed that the icing performance penalty correlated to the complexity of the ice geometry. The experimental data were compared to computational fluid dynamics (CFD) simulations with the RANS solver FENSAP. Simulations were performed with two turbulence models (Spalart Allmaras and Menter’s k-ω SST). The simulation data showed good fidelity for the clean and streamlined icing cases but had limitations for complex ice shapes and stall.

Turbulence reduction by screens

1988 ◽  
Vol 197 ◽  
pp. 139-155 ◽  
Author(s):  
Johan Groth ◽  
Arne V. Johansson
Keyword(s):  
Wind Tunnel ◽  
Reynolds Numbers ◽  
Wind Tunnels ◽  
Small Scale ◽  
Flow Conditions ◽  
Upstream Side ◽  
Turbulence Suppression ◽  
Controlled Flow ◽  
Reduction Effectiveness

Turbulence suppression by use of screens was studied in a small wind tunnel especially designed and built for the purpose. Wide ranges of mesh sizes and wire-diameter Reynolds numbers were covered in the present investigation, enabling the study of sub- and super-critical screens under the same, well-controlled, flow conditions. For the latter type small-scale fluctuations, produced by the screen itself, interact with the incoming turbulence. In the immediate vicinity of the screen the turbulence was found to be highly anisotropic and the intensities were higher than on the upstream side. Downstream of a short initial decay region, where the intensities decrease rapidly, the return to isotropy was found to be much slower than for the unmanipulated turbulence. The latter was generated by a square rod grid, and was shown to become practically isotropic beyond a distance of roughly 20 mesh widths from the grid. The role of the turbulence scales for the overall reduction effectiveness, and for the optimization of screen combinations for application in low-turbulence wind tunnels was studied.

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