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A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > 30.04.2010 Transition locations on the LEISA high lift airfoil S.Reuß.

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Presentation on theme: "A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > 30.04.2010 Transition locations on the LEISA high lift airfoil S.Reuß."— Presentation transcript:

1 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Transition locations on the LEISA high lift airfoil S.Reuß

2 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 2 Available experimental data  Two different settings were measured:  3eOptV1 which was measured in the slotted test section of the low speed wind tunnel NWB. From this measurement infra red pictures as well as pressure distributions are available.  3eOptV2 which was measured in the closed test section of the NWB. From this measurement pressure distributions as well as accoustical measurements are available.  All grids are for the OptV2 geometry, but the difference between those two is minimal:

3 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 3 Available experimental data  First we got the infrared measurement for the 3eOptV1 and the pressure distribution of the 3eOptV2 both for α=7° angle of attack. A comparison of the pressure distributions for the two different test sections (slotted/closed) revealed strong deviations (see next 3 slides)  After consultation with the experimentalists it was clear, that we needed a different angle of attack for comparison with the data from the slotted test section. The suggestion was to use the α=8° case. Also the suspicion arouse, that there might occur transition on the slat for this angle of attack.  Now that we received the infrared pictures for the other incidence angles, it is clear, that no transition should be found on the slat.  Since no evaluated data is available, we conclude by simple optical judgment, that the transition locations for the α= 7° and α=8° case do not change significantly

4 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 4 Available experimental data Pressure distribution slat Pressure distributions OptV2 (closed section) OptV1 (slotted section) Data is measured in three sections

5 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 5 Available experimental data Pressure distribution wing Pressure distributions OptV2 (closed section) OptV1 (slotted section) Data is measured in three sections

6 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 6 Available experimental data Pressure distribution flap Pressure distributions OptV2 (closed section) OptV1 (slotted section) Data is measured in three sections Here the influence of the wind tunnel side walls can be clearly seen. The curves with the most points are the measurements at the mid section

7 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 7 Flow Available experimental data IR slat and main wing upper side, α=7°

8 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 8 Available experimental data IR slat and main wing upper side, α=8° Flow

9 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 9 Available experimental data IR slat and main wing upper side, α=9° Flow

10 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 10 Available experimental data IR slat and main wing upper side, α=10° Flow

11 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 11 Available experimental data IR slat and main wing upper side, α=11° Flow

12 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 12 Available experimental data IR slat and main wing upper side, α=12° Flow

13 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 13 Available experimental data IR wing and flap upper side, α=7° Flow

14 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 14 Available experimental data IR wing and flap upper side, α=8° Flow

15 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 15 Available experimental data IR wing and flap upper side, α=9° Flow

16 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 16 Available experimental data IR wing and flap upper side, α=10° Flow

17 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 17 Available experimental data IR wing and flap upper side, α=11° Flow

18 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 18 Available experimental data IR wing and flap upper side, α=12° Flow

19 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 19 New numerical results Spalart Allmaras Model  A new grid was built with some modifications:  The farfield distance was increased to 100c  The resolution of the three element noses was reduced a bit  The resolution of the slat wake and above the flap was increased  The resulting grid has again about points per layer  Calculations with this new grid showed a clear difference compared to those on the old grid (2d/3d hybrid grid that can be found on the ATAAC site)  These differences are due to the small farfield distance! Calculations with farfield vortical correction show a clear trend towards the new results  New calculations use a critical N-factor of 7.18, where the theoretically expected value is in the range of 7.18 to 7.3. Originally this value should be calibrated using the experimentally given transition locations, but since all calculations showed earlier transition, this procedure was not successful.

20 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 20 Pressure distribution comparison old/new grid SA model

21 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 21 Pressure distribution new grid SA model  With the new grid a corrected angle of attack of α=5° is needed when the Spalar- Allmaras model is used  Even though the pressure distribution does not show the plateau on the flap the flow seperates

22 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 22 Skin friction new grid SA model  With the new grid a corrected angle of attack of α=5° is needed when the Spalar- Allmaras model is used  Even though the pressure distribution does not show the plateau on the flap the flow seperates

23 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 23 Convergence new grid SA model  The RANS calculations with the SA model converge, but slower as with the old grid, where about iterations were sufficient

24 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 24 Pressure distribution new grid SST model  With the new grid a corrected angle of attack of α=6° is needed when the Menter-SST model is used

25 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 25 Skin friction new grid SST model  With the new grid a corrected angle of attack of α=6° is needed when the Menter-SST model is used

26 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 26 Convergence new grid SST model  The RANS calculations with the SST model do not converge in steady calculations

27 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 27 Convergence new grid SST model  An unsteady restart from the steady solution yields a converged solution (time step is scaled for better presentability)

28 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 28 Transition locations on new grid The black lines indicate the old suggested transition locations. With the new grid and N crit =7.18 the SA model yields transition on the slat. 4° and 5° transition lines coincide

29 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 29 New recommendations  We recommend to use the new grid, to prevent wrong results because of the small farfield distance (Can be found on the ATAAC site as hybrid_mandatory)  We recommend to use the SA model with a corrected angle of attack of α=5° and following transition locations:  We recommend to use the SST model with a corrected angle of attack of α=6° and following transition locations:  Since the SST model shows a much better agreement with the experimental data, DLR is considering to use SST based DES.  *) The transition location on the lower side of the wing did not converge completely, but is considered to have small influence. No experimental data is available for the lower side. SlatWingFlap Upper sideLaminarx tr =0.189x tr =0.953 Lower sideLaminarx tr = *Laminar Upper sideLaminarx tr =0.1815x tr =0.949 Lower sideLaminarx tr = *Laminar

30 A320 DDES on 2048 cores > Silvia Reuß, Dieter Schamborn > Slide 30 Wiggles in Pressure distribution  At several point some wiggles in the pressure distribution could be observed. A close look to the surfaces built by centaur reveals the reason: The surface normals at some cells deviate noticeably from the neighboring ones  I do not have an idea how to prevent centaur from producing such bad cells


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