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Bom Bombardier Con Contribution on t to t o the rd AIAA Hi 3 rd AIAA High gh-Lif Lift t Wo Workshop Marc Langlois Hong Yang Kurt Sermeus Advanced Aerodynamics Bombardier AIAA SciTech 2018 Forum Applied Aerodynamics Orlando,

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SLIDE 1

Bom Bombardier Con Contribution

  • n t

to t

  • the

3rd

rd AIAA Hi

AIAA High gh-Lif Lift t Wo Workshop

Marc Langlois Hong Yang Kurt Sermeus Advanced Aerodynamics Bombardier

AIAA SciTech 2018 Forum Applied Aerodynamics Orlando, Florida January 10, 2018

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SLIDE 2

Overview

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 2

  • Objectives
  • Test Cases
  • Flow solver Dragon
  • Grids
  • Results on JAXA JSM configuration
  • Convergence
  • Impact of curvature correction in turbulence model
  • Impact of laminar-turbulent transition
  • Nacelle installation
  • Conclusions
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SLIDE 3

Objectives

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 3

  • Assess the performance of our high-lift CFD

prediction tools:

  • Pointwise for unstructured mesh generation
  • Dragon for flow solution
  • Compare results obtained on different grids, in-house

generated and supplied by the Workshop committee

  • Evaluate impact of turbulence and transition

modelling on solution accuracy

  • Compare our prediction capabilities to what is

assumed to be the best in industry/academia

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SLIDE 4

Test Cases

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 4

3 test cases / 5 geometries were to be analyzed:

  • Cases 1a/c:

NASA High-lift Common Model (HL-CRM)

  • Simple WB landing configuration w/o slat tracks or FTFs
  • Full-span slats with slat cuts
  • 2-segment (IB/OB) flaps
  • Case 1a: gapped flaps (between IB/OB and fuselage/IB)
  • Case 2a: partially-sealed flaps
  • Cases 2a/c: JAXA High-lift Standard Model (JSM)
  • More complex WB/WBN landing configuration with slat tracks and FTFs
  • Full-span slats with slat cuts
  • 2-segment (IB/OB) flaps, sealed
  • Case 2a: WB
  • Case 2c: WBN (underwing nacelle)
  • Wind-tunnel data available
  • Case 3: 2D validation/verification study
  • Many participants submitted data for only some of these cases
  • Bombardier submitted data for all cases, on multiple grids
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SLIDE 5

Cases 2a/c – JSM WB & WBN – WT overview

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 5

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SLIDE 6

Dragon Flow Solver

§ Bombardier in-house 3D unstructured RANS solver

  • Cell-centered, coupled solver

§ Implicit time integration with LU-SGS approach

  • 1st-order accurate in time for steady simulations

§ 2nd-order accurate Roe’s upwind scheme for convective flux and central differencing scheme for viscous flux discretization § Turbulence modelling:

§ Standard Spalart-Allmaras § Wilcox k-w 1988 and 1998 § SST § Bardina-type streamline curvature correction § Fully-turbulent or imposed transition location

§ Parallel large-scale simulation capability with non-blocking MPI § Interfaced with CGNS data produced by main-stream commercial grid generators

  • Ref.: Yang, H. and Langlois, M. “Towards Accurate Simulation of Aircraft

High-Lift Flows with One- and Two-Equations Turbulence Models”, 62nd CASI Aeronautics Conference, May 2015.

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 6

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SLIDE 7

JAXA JSM – Cases 2a/2c – Bombardier grids

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 7

Case 2a Case 2c Nodes 17 708 448 21 720 656 Cells 41 695 790 50 488 218 Fuselage 35 826 35 826 Wing 224 280 233 538 Slats 289 914 247 623 Flaps 253 048 253 048 Nacelle

  • 174 472

Generated with Pointwise Medium grid guidelines

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SLIDE 8

Convergence history

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 8

All forces and moment converged to engineering accuracy

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SLIDE 9

Early results: forces & moments

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 9

Lift underpredicted Early stall Shift in pitching moment and drag Pitch-up at stall

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SLIDE 10

Early results: surface flow pattern at a = 18.6°

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 10

Excessive separation behind most OB slat track Initial stall caused by massive flow separation behind slat track #6

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SLIDE 11

Early results: surface flow pattern at a = 21.6°

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 11

« Final » stall occurs at wing root Need to prevent flow separation on OB wing Early flow separation linked to excessive turbulence dissipation, w, which can be reduced by introducing curvature correction

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SLIDE 12

Curvature correction: forces & moments

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 12

Lift improved significantly but still sligthly underpredicted Late stall with pitch-up Shift in pitching moment reduced at higher AOAs Drag only slightly improved

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SLIDE 13

Curvature correction: surface flow pattern at a = 18.6°

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 13

With curvature correction: Reduced separation behind most OB slat track Flow remains attached behind slat track #6

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SLIDE 14

Curvature correction: surface flow pattern at a = 21.6°

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 14

Wing root flow remains attached Stall occurs at a = 23° behind slat track #5 Need to increase lift and « trigger » stall at wing root

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SLIDE 15

Impact of laminar-turbulent transition

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 15

WT Reynolds number is low Significant extents of laminar flow are expected Transition imposed in Dragon (not predicted) Based on WT transition detection No transition on slats Inboard WUSS fully-turbulent even w/o nacelle Laminar flow on fixed IB leading edge Transition location on LS same as on US a = 4.4° Used for 0° £ a £ 8° a = 10.5° Used for 10.5° £ a £ 16° a = 18.6° Used for a ³ 17.5°

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SLIDE 16

Transition influence: forces & moments

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 16

Imposing regions of laminar flow results in slightly higher CL and much improved prediction of αstall and CLmax Fully-turbulent flow slightly underpredicts CL and

  • verpredicts αstall and Clmax

Predicts pitch-up at stall Properly predicts pitch- down at stall No real drag improvement Shift in drag and pitching moment is most likely related to half-model effect

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SLIDE 17

Transition influence: surface flow pattern at a = 10.5°

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 17

Flow pattern well predicted overall:

  • Flow separation behind FTFs
  • Flow separation behind most-OB

slat track

  • Wingtip separation
  • Slat tracks vortices (lower y+)
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SLIDE 18

Transition influence: surface flow pattern at a = 18.6°

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 18

FT solution overpredicts extent of flow separation behind most-OB slat track and FTFs

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SLIDE 19

Transition influence: surface flow pattern at a = 21.6°

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 19

FT solution does not predict IB separation Prediction improved with laminar flow on fixed IB LE

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SLIDE 20

JAXA JSM results Transition influence: pressure distributions at a = 4.4°

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 20

Cps closer to WT data with presence of laminar flow

  • n flaps

and on wing

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SLIDE 21

Transition influence: pressure distribution at stall (a = 20.6°)

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 21

Improved IB prediction due to laminar flow on IB fixed LE Much improved Cps on OB WUSS and slat

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SLIDE 22

Transition influence: post-stall pressure dist. (a = 21.6°)

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 22

but OB Cps are still improved IB stall is too abrupt Laminar flow extent

  • n IB fixed LE should

be reduced

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SLIDE 23

Dragon vs. other codes: forces & moment

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 23

Large scatter in lift and pitching moment Solution w/o curvature correction is still within the range of results presented Solutions with curvature correction are among those providing the best agreement with the WT data All solutions overpredict drag

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SLIDE 24

Dragon vs. other codes: lift and drag at a = 18.6°

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 24

Lift predicted by Dragon is very close to average of all CFD data and to WT data Drag is also close to the CFD average and closer to the WT data than most WT data WT data

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Nacelle installation: forces & moments

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 25

Trends are mostly well predicted:

  • Earlier stall
  • Pitching moment shift
  • Drag shift
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SLIDE 26

Nacelle installation: surface flow pattern at a = 10.5°

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 26

Good flow patterns prediction Reduced TE separation behind nacelle Flow separation

  • n nacelle
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SLIDE 27

Nacelle installation: surface flow pattern at a = 18.6°

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 27

IB flow separation predicted Wing area affected by nacelle is not as wide as in WT

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SLIDE 28

Nacelle installation: pressure distributions at a = 4.4°

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 28

Impact of nacelle on Cps is well predicted

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SLIDE 29

Nacelle installation: pressure distributions at a = 18.6°

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 29

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SLIDE 30

Nacelle-on configuration: volume plots

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 30

Main flow features are captured but likely dissipate too quickly Volumic refinement/adaptation would be required

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SLIDE 31

Nacelle-on configuration: volume plots

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 31

Main flow features are captured but likely dissipate too quickly Volumic refinement/adaptation would be required

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SLIDE 32

Conclusions

  • Fully-turbulent flow assumption not valid at low WT

Reynolds number

  • Improvements to initial results come from two factors:
  • Curvature correction in k-w model
  • Imposed laminar-turbulent transition
  • Transition should be predicted rather than imposed
  • Nacelle installation effects properly predicted
  • Main flow features can be captured with a medium grid

but volumic refinement/adaptation could help

  • Free-stream CFD can predict half-model WT data, but

discrepencies in absolute levels of drag and pitching moment remain that can be related to half-model effect

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 32

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SLIDE 33

Thanks Questions?

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 33

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SLIDE 34

Back-up material

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 34

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SLIDE 35

Comparison with NSU3D: forces & moments

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 35

Dragon better predicts lift than NSU3D Both codes predict similar stall incidence Pitching moment at low incidences better predicted by NSU3D NSU3D drag closer to wind-tunnel data

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SLIDE 36

JAXA JSM results Transition influence: surface flow pattern on IB fixed LE

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 36

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SLIDE 37

JAXA JSM results Transition influence: pressure distributions

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 37

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SLIDE 38

JAXA JSM results Transition influence: skin friction (mid a)

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 38

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SLIDE 39

JAXA JSM results Transition influence: skin friction

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 39

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Transition influence: pressure distribution on fuselage

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 40

Better prediction related to separated flow on wing

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SLIDE 41

Turbulence model influence: forces & moment

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 41

FT solutions only SST solution that best matches k-w for stall angle is slightly better at low CL, slightly worse at high CL No drag improvement

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SLIDE 42

Nacelle installation: forces & moment variations

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 42

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SLIDE 43

JAXA JSM results Nacelle installation: surface flow pattern

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 43

Wing stall from IB fixed LE predicted Wingtip flow not as « messy » at in the WT

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SLIDE 44

JAXA JSM results Nacelle installation: pressure distributions

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 44

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SLIDE 45

JAXA JSM results Nacelle installation: pressure distributions

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 45

IB stall is again too abrupt

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SLIDE 46

JAXA JSM results Nacelle installation: skin friction

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 46

Higher Cf with nacelle

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SLIDE 47

JAXA JSM results Nacelle installation: skin friction

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 47

Lower Cf with nacelle

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SLIDE 48

JAXA JSM results – Case 2a Grid influence

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 48

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SLIDE 49

JAXA JSM results – Case 2a Grid influence: forces and moments

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 49

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SLIDE 50

JAXA JSM results – Case 2a Grid influence: pressure distributions

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 50

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SLIDE 51

JAXA JSM results – Case 2a Grid influence: pressure distributions

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 51

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SLIDE 52

JAXA JSM results – Case 2a Grid influence: pressure distributions

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 52

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SLIDE 53

JAXA JSM results Nacelle installation: skin friction

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 53

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SLIDE 54

JAXA JSM results – Case 2a Slat gaps influence: forces and moments

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 54

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SLIDE 55

Nacelle-off configuration: volume plots (post-stall)

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 55

Main flow features are captured but likely dissipate too quickly Volumic refinement/adaptation would be required

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SLIDE 56

JAXA JSM results Nacelle-off configuration: volume plots

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 56

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SLIDE 57

Nacelle-on configuration: volume plots

SciTech 2018 - Orlando, January 2018 Bombardier Contribution to HiLiftPW-3 57

Main flow features are captured but likely dissipate too quickly Volumic refinement/adaptation would be required