comparisons of experimental and computational results from

June 2014

Atlanta Georgia

Timothy Wadhams

Michael S. Holden

Matthew MacLean

Comparisons of Experimental and Computational Results from “Blind” Turbulent Shock Wave

Interaction Study Over Cone Flare and Hollow Cylinder Flare Configurations

Sponsored by CUBRC Internal Research, NSSEFF grant with

University of Minnesota, and AFOSR

Outline of Presentation

• Comparison between Earlier Measurements for High Reynolds

Number Hypersonic Regions of Shock Wave/Turbulent Interaction

Over HIFiRE 1 and Flat Plate/Wedge/Shock Generator Configurations

(Open Test Cases)

• Program Objectives and Review of Model Geometries: Large Cone

Flare and Hollow Cylinder Flare

• Presentation of Comparison Results from Large Cone Flare

• Review of Case with Submission of Different Codes, Grid Resolution

and Models

• Presentation of Comparison Results from Large Hollow Cylinder

Flare

• Summary and Discussion Results

Program Objectives and Experimental Program Design

• Obtain Detailed Heat Transfer and Pressure Measurements in

Regions of Shock Wave/ Fully Turbulent Boundary Layer

Interactions to Evaluate Models of Turbulence Employed in Codes.

• Conduct Program at Duplicated Mach 5, 6, 7 and 8 Flight Velocities

and in Cold Flows on Models the Size of Typical Flight Vehicles.

• Employ Axisymmetric Models and Flow Conditions to Obtain

Well-Defined Interaction Regions and Well Defined Boundary

Conditions Upstream and Downstream of the Interactions [laminar

heat flux and cone/cylinder pressure upstream and attached, post

peak pressure downstream].

• Distribute Model Geometries and Measured Freestream

Conditions in Invite Letter in March 2014 to 15 Perspective

Participants, 4 of which presented today and will be compared to

experimental results.

• Locations of Boundary Layer Transition on Cone and Cylinder

given in San Diego 2014 AIAA Paper by Holden

Earlier Results from Open Code Validation Cases – Available from AIAA and CUBRC

7° HIFiRE Cone Large 7° Cone/

Flare

Flat Plate / Wedge

Configuration

Flat Plate / Shock Generator

Configuration

AIAA Paper Listings Available in 2013 San Diego Paper and from CUBRC Directly

Heat Transfer Measurements in Transitional and Turbulent Flows Over HIFiRE 7° Cone at Duplicated Mach 6.5 and 7.2 Flight Conditions

Run 4 (M=6.5) Run 6 (M=7.2)

Run Mach U

(m/s)

(kg/m3)

T

(K)

Nose radius

(mm)

4 6.5 1925 0.125 213 2.5

5 7.2 2185 0.070 232 2.5

6 7.2 2185 0.071 231 5.0

8 6.5 1930 0.126 214 5.0

Flux Limiter Modifications to Turbulent Models Required to Match Experimental Data [33 deg. HIFiRE-1 Flare]

65.065.0

2211

68

~

tanh1,

~01.1

,75.0max,25.1min

Sd

CCb

LIM

b

Modified SA Model with

Turbulence Flux Limiter

Matching specific

experimental

measurements requires

empirical “fix” to current

turbulence models.

Measurements on Full-Scale HIFiRE-1 at Mach 7.2 Duplicated Flight Conditions

6

Flare Heating Prediction with Wilcox Modified Reynolds Stress Limiter, CLIM=0.90

Adjusting stress limiter coefficient on SST model provides good qualitative

agreement with separation length and distributions in separated regions

Turbulent Shock Wave/Boundary Layer Interaction: Wedge-Induced Separation

Run M Re/ft T, K Wedge

angle

12 8 40E6 70 27°

16 8 40E6 70 30°

19 8 40E6 70 33°

24 8 40E6 70 36°

54 11 10E6 60 36°

DPLR with flux limiter (CLIM=0.90) significantly overpredicts length of separated region

and peak heating in reattachment region

Turbulent Shock Wave/Boundary Layer Interaction: Shock-Induced Separation

Run M Re/ft T, K SG angle

49 11 10E6 60 20°

DPLR with flux limiter (CLIM=0.90) significantly overpredicts length of separated region but is in

good agreement with heat transfer downstream of the attachment

AFOSR 7° Cone M=10 Flight Enthalpy Measurements

- Cone half angle: 7°

- Angle of attack: 0°

Run Mach

U

(m/s)

(kg/m3)

T

(K)

Nose

radius

(mm)

19 10 2845 .012 205 2.5

20 10 2850 .012 205 Sharp

8-ft, 7° cone installed in LENS I facility

Run 20

Large Double Cone and Hollow Cylinder/Flare Models Employed in Experimental Studies to Produce Measurements for “Blind” Validation Test Cases

Flight Matching and Cold Flow Freestream Conditions Employed in SWTBLI Studies on Large Cone Flare Configuration

Details of Cases Submitted

• Received detailed submissions from groups at NASA Langley

Research Center, NASA Ames Research Center, University of

Minnesota, and Texas A&M University, also plot solutions from

CUBRC

• All submission work was performed with researchers code of

choice, and all submissions at a minimum included a case

performed with the SST turbulence model, primary comparison

• Some submissions also provided with other models, will compare

• Comparisons will be presented in interaction region pressure,

interaction region heat flux, and forebody heat transfer

Interaction

Region Forebody

Heat

Transfer

Cone/Flare Mach 5 Cold Flow, ReL 120x106 – Run 26

• Mach 5, Cold Flow Case, Highest Reynolds

Number

• All submissions over predict the separated

region, evident in pressure plot

• Peak pressure and heat transfer magnitudes

predicted well and downstream pressure levels

compare well

• Predicted peak location is downstream of

experimental peak, in line with larger predicted

separation length

• No fully laminar data for this case to compare

Cone/Flare Mach 5 Flight Velocity Flow, ReL 35x106 – Run 28

• Mach 5, Flight Velocity Case

• All SST submissions over predict the separated region,

evident in pressure plot, S-A model achieves correct

separation length

• Peak pressure magnitudes predicted well and

downstream pressure levels compare well

• Predicted peak location is downstream of experimental

peak, in line with larger predicted separation length

• SST model submissions over predict peak heat flux, S-A

model predicts downstream heat flux, under predicts the

peak heat flux

• Laminar heat flux data well predicted, similar variation in

turbulent hear flux as previous case

Cone/Flare Mach 6 Cold Flow, ReL 45x106– Run 33

• Mach 6, Cold Flow Case


evident in pressure plot, S-A model achieves closer

separation length

• Peak pressure magnitudes predicted well, some over

prediction, downstream pressure levels compare well




model predicts downstream heat flux, under predicts the

peak heat flux

• Laminar heat flux data well predicted, tighter closer

prediction of turbulent hear flux



• Experimental data shows no or incipient separation (see

Schlieren frame)

•All SST submissions over predict the separated region,

evident in pressure plot, S-A model predicts attached flow

• Downstream pressure levels compare well

• Predicted peak heat flux location is downstream of

experimental peak, in line with larger predicted separation

length


model under predicts downstream heat flux

• Laminar heat flux data well predicted, forebody turbulent

flux well predicted, one case higher



• Experimental data shows no likely incipient separation

(see Schlieren frame)





experimental peak, larger predicted separation length

• SST model submissions over predict peak heat flux

lesser extent than Mach 6, S-A model under predicts

downstream heat flux


flux well predicted, one case lower

Cone/Flare Mach 8 Cold Flow, ReL 34x106

– Run 37

• Mach 8, Cold Flow Case


evident in pressure plot, S-A model achieves slightly

under predicted separation length

• Peak pressure magnitudes predicted well, some over

prediction, downstream pressure levels compare well



• SST model submissions over predict peak heat flux,

close downstream, S-A model under predicts flare heat

flux

• Laminar heat flux data well predicted, tighter close

prediction of forebody turbulent hear flux

Cone/Flare Mach 8 Flight Velocity Flow, ReL 11x106– Run 41


• Experimental data shows no to incipient separation (see

Schlieren frame)





experimental peak, larger predicted separation length


model under predicts flare heat flux


flux well predicted, one case lower

Comparison of Code, Grid Resolution, and Turbulence Model

• Peter Gnoffo submitted several variations on code, grid, and

model

• Mach 5, Cold Flow, Highest Reynolds Number, No Observed Fully

Laminar Flow on Cone

• LAURA solution with S-A model achieves closest match to

separated region length, FUN3D with K-Omega largest over

prediction

• Downstream pressures well predicted, FUN3D with K-Omega as

well if plot carried out further, peak pressure magnitude well

predicted, peak predicted downstream

• SST model achieves proper heat flux peak magnitude, S-A cases

under predict peak, K-Omega under predicts flare heat flux

Large Hollow Cylinder Flare Test Cases for Flight Matching and Cold Flow Freestream Conditions

Hollow Cylinder/Flare Mach 5 Flight Velocity Flow, ReL 32x106– Run 17

• Mach 5, Flight Velocity, Low Reynolds Number

• All submissions over predict the separated region,

evident in pressure plot

• Peak pressure under predicted, peak heat flux

over predicted with exception of S-A, downstream

pressure levels compare well, NASA and CUBRC

DPLR solutions agree well



separation length

• Fully laminar data agrees well, variation on

turbulent heat flux


• Mach 5, Flight Velocity, High Reynolds Number



• Peak pressure under predicted, peak heat flux

over predicted with exception of S-A, downstream





separation length


turbulent heat flux


• Mach 6, Flight Velocity, Low Reynolds Number



• Peak pressure predicted well, peak heat flux over

predicted with exception of S-A, downstream





separation length


turbulent heat flux, mostly over predicted


• Mach 6, Flight Velocity, High Reynolds Number


evident in pressure plot, all very similar


predicted (No S-A), downstream pressure levels

compare well



separation length


turbulent heat flux, mostly over predicted

Hollow Cylinder/Flare Mach 7 Flight Velocity Flow, ReL 17x106 – Run 18

• Mach 7, Flight Velocity


evident in pressure plot, all very similar


predicted with the exception of S-A, downstream

pressure levels compare well

• Predicted peak location looks to be better

predicted in this case


turbulent forebody heat flux, range of agreement

Hollow Cylinder/Flare Mach 8 Flight Velocity Flow, ReL 11x106 – Run 21

• Mach 8, Flight Velocity




predicted, with the exception of S-A which under

predicts peak but gets downstream heat flux,

downstream pressure levels compare well



separation length


turbulent heat flux, one case under predicts

Summary of Results

Summary:

• Dataset of turbulent shock interaction results now available for comparison to

research and design tools and associated turbulence models

• All submissions presented here compare well with upstream and downstream

pressure, and with available laminar heat flux upstream of transition, nice check

on provided freestream conditions, prediction of attached laminar flow solved

at this point

• Forebody turbulent heat flux prediction varied case to case, some predicted

well

• Most submissions employing SST model over predicted interaction region

length, S-A model closer to correct length when separated, predicted attached

flow

• Most submissions (SST) show over prediction of heat flux downstream of

interaction, higher Mach number cone flare cases exception, S-A tends to

under predict peak heat flux downstream of interaction

Questions for Discussion

• We observe better prediction of forebody heat-flux in these cases

than was shown in earlier cases (HIFiRE-1 and Mach 10 Enthalpy

Cone), how much does this influence interaction region agreement?

• Observe, particularly in hollow cylinder flare case, that specifying

transition location does not change result, how does transition

location influence comparison?

• Cone Flare comparisons show variation in interaction length between

submissions, Hollow Cylinder flare shows little to no variation in

length, Mach 8 case shows the most, should DPLR solutions match?

• Thoughts on S-A producing better agreement of separation length and

under prediction of heat flux on flare

• Hot wall experiment

• Near wall fluctuation measurements with Focused Laser Differential

Interferometry (FLDI)

• Data release time frame and process

Next Steps

• Data Release:

• Data will be transmitted to presenters within the next two weeks

• Will include specified freestream conditions, model geometries, surface

pressure and heat flux, standard deviation values for mean interval, and

uncertainty information

• Other individuals and groups may also obtain the results by contacting Mike

Holden and Tim Wadhams at CUBRC, will be emailed as requests come in

• Data considered to be Distribution A, Public Release

• Currently planning a second round of work and presentations at

a future AIAA session, will inform the original set of invitees, any

others let us know

• Further Experiments

• Wall temperature variation to explore Tw/To ratio independent of enthalpy

• Near wall turbulence fluctuation measurements, considering techniques,

currently pursuing Focused Differential Laser Interferometry (FLDI) [small

measurement region] and in stream stagnation temperature fluctuation

comparisons of experimental and computational results from

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