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AePW-3:  High Angle of Attack Working Group AePW-3:  High Angle of Attack Working Group

AePW-3: High Angle of Attack Working Group - PowerPoint Presentation

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AePW-3: High Angle of Attack Working Group - PPT Presentation

POC PawelChwalowskinasagov Objectives Use current state of the art coupled CFD tools in a predictive manner coupled structural dynamics unsteady aerodynamics Apply to configuration and test conditions that challenge the range of application of the modeling ie physics are challengin ID: 933206

aepw flutter separated flow flutter aepw flow separated mach angle attack data transonic conditions axis including points 1992 challenge

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Presentation Transcript

Slide1

AePW-3: High Angle of Attack Working GroupPOC: Pawel.Chwalowski@nasa.gov

Objectives

Use current state of the art coupled CFD tools in a predictive manner (coupled: structural dynamics + unsteady aerodynamics)

Apply to configuration and test conditions that challenge the range of application of the modeling (i.e., physics are challenging) due to separated flow and dynamically separating flowDefine regions of Mach number, angle of attack and structural dynamic characteristics that require different analysis methods, grid resolution and treatment, temporal resolution, etc.Examine the influence on the unsteady characteristics including flutter of in-tunnel effects, including juncture flow

Background

Transonic conditions are particularly challenging for computational tools because strong shocks may introduce separated flow

The equations on which many methods are based fail to include separated flow field physicsFlutter can be introduced into a system due to flow separationThe most critical transonic flutter cases are those in the transonic dip, where the onset condition (dynamic pressure at which flutter occurs) can drop rapidly in terms of Mach number change and angle of attack changeThe transonic dip points are difficult to calculate and difficult to obtain experimentally

Initial Configuration: NASA Benchmark Supercritical Wing

Model planform. Dimensions are in inches.

32

16

Pitch axis, forced oscillations

Pitch axis, flutter cases

AePW-1 and AePW-2 Predictions

AePW-1: separated flow produced a challenge for analyses, even for steady conditions

AePW-2: Very large variation in flutter onset predictions at separated flow conditions

AePW

-1

AePW

-2

Slide2

AePW-3: High Angle of Attack Working GroupPOC: Pawel.Chwalowski@nasa.gov

Mach 0.8,

AoA

= 5° condition

in R-134a has been chosen

for initial analyses challenge

Existing Data

Separated flow assessment, using data from 1992 testing

R-12, Mach 0.8 Flutter Points, 1992

R-12, Flutter Points,

a

=0°, 1992

AePW-3

Predictions to date at Mach 0.8,

AoA

= 5

°

2

Experimental data,

Mach 0.8,

AoA

~ 5◦Current Time-DomainCalculationsCurrent Frequency –Domain Calculations

Computational

and Experimental Plans

Perform input uncertainty analyses (geometry, angle of attack, elastic axis location, analysis method parameters)

Conduct additional wind tunnel testing:

Measure the flutter boundaries including the front, bottom, and backsides of the flutter buckets

Acquire global detailed subcritical data sets:

Digital image correlation measurements for static and time-accurate model motion and deformation

Unsteady pressure sensitive paint for on-surface quantitiesUnsteady particle image velocimetry for off-body velocitiesAcquire repeat data pointsQuantify (measure) the flow environment