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Unsteady euler and detached-eddy simulations of vortex breakdown over a full-span delta wing
KTH, Superseded Departments, Aeronautical and Vehicle Engineering.
2004 (English)In: ECCOMAS 2004 - European Congress on Computational Methods in Applied Sciences and Engineering, 2004, 1-20 p.Conference paper (Refereed)
Abstract [en]

The inherently unsteady flow field over a stationary, full-span delta wing at high incidence is simulated time-accurately using the structured Navier-Stokes Multi Block (NSMB) code. Inviscid calculations are performed on an Euler-type grid using explicit global Runge-Kutta time stepping. Detached-Eddy Simulations (DES) are done on a Navier-Stokes grid using implicit dual time stepping. The full-span model Euler simulations capture vortex interactions - the numerical solutions exhibit asymmetry as well as streamwise fluctuations in the port and starboard vortex breakdown locations, despite symmetric boundary conditions and a symmetric computational grid. Flow visualization reveals that spiral-type breakdown is predicted over both sides of the wing for the predominant part of the simulations. The rotation of the port and starboard post-breakdown helical structures is shown to be out of phase at certain times. Intermittent bubble-type breakdown is also observed to occur periodically over one side or the other of the wing and related to the occurrence of asymmetry in the vortex breakdown location. For DES, a time step study and a grid sensitivity study are conducted on semi-span grids to verify time accuracy and grid resolution. The full-span DES results are compared to detailed LDV and pressure measurements for the same geometry. The breakdown location is shown to be grid sensitive. Agreement between the measured and computed breakdown locations is shown to be good on the refined grid. The surface pressure distribution is underestimated, even on the refined grid, maybe due to excessive wind-tunnel blockage effects.

Place, publisher, year, edition, pages
2004. 1-20 p.
Keyword [en]
CFD, Delta wing, Detached-eddy simulation, Unsteady aerodynamics, Vortex breakdown
National Category
Engineering and Technology
URN: urn:nbn:se:kth:diva-144463ScopusID: 2-s2.0-84893462115OAI: diva2:713520
European Congress on Computational Methods in Applied Sciences and Engineering, ECCOMAS 2004; Jyväskylä; Finland; 24-28 July 2004

QC 20141210

Available from: 2014-04-23 Created: 2014-04-23 Last updated: 2014-12-10Bibliographically approved

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