Pot Apc Zuk Wright

8/12/2019 Pot Apc Zuk Wright

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National Aeronautics and Space Administration

www.nasa.gov

SLD Simulation Capabilities with LEWICE

Mark PotapczukWilliam Wright

CFD Methods for SLD Simulation WorkshopScottsdale, AZ October 19-20, 2006


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Outline

SLD Requirements

SLD Icing Physics

SLD Modeling in LEWICE Reproducing SLD Cloud Conditions in the IRT

Numerical Simulation of Ice Shapes from a Bimodal LargeDroplet Icing Cloud


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SLD Requirements


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SLD Requirements

BACKGROUND

Requirements (or metrics) need to be defined to provide a "target" forSLD simulation in quantified terms Essential features or characteristics that need to be simulated How accurately characteristics need to be simulated

These requirements will be developed by means of sensitivity studies,either experimental or computational

Requirements take into account recommendations from the IPHWG onAppendix X

OBJECTIVES

Identify the metrics that have to be met to assure adequate simulation ofthe SLD environment from an engineering perspective

Provide assessment of how accurately these elements must besimulated


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SLD Requirements

APPROACH

Conduct sensitivity tests in SLD conditions to estimate threshold whereLWC, drop size, temperature errors have noticeable effect on thegenerated ice shape Attempt to develop / identify methodology to link aero effects to ice feature

changes

Conduct SLD Instrumentation Workshop to identify what current state-of-the-art is for water content and drop size instrumentation Estimates of measurement error

Operational issues affecting accuracy Identify research investments to mitigate measurement issues

Get feedback from user community on SLD requirements at SLD ToolsWorkshop Incorporate feedback into development of draft requirements document

Develop draft requirements document which includes parameters to besimulated, and required accuracies Consolidate results from tests & workshops


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OBJECTIVE - Determine the variation in icing cloud parameters necessary toproduce a measurable change in resulting ice accumulation

APPROACH Identify nominal SLD icing conditions (freezing fractions of 0.3 and 0.7) Determine the variant conditions (i.e. the amount of variation from the nominal

LWC, MVD, temperature) Measure and compare ice shape parameters for nominal and variant conditions

Geometric parameters Ice mass

STATUS 3 sensitivity tests completed Results reported in AIAA-2005-0073, AIAA-2006-0469 Methodology to define accuracy still under development (attempting to couple

MVD, LWC changes to ice shape to aero effects)

SLD Sensitivity Studies

InduceKnownSpray

Variations

Quantify Ice ShapeFeature Changes

Horn angleHorn Thickness

Characterize AeroEffect of Ice Feature

Changes

AssessSignificance

Of Aero ChangesBy ComparingTo knowledge

Base

Horn angleHorn Thickness


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Contour plot method used in 2004 /2005 sensitivity tests has potential tocharacterize the effect of smallchanges in LWC, MVD on ice shape Provide link between changes in spray

cloud and ice shape changes

Preliminary estimate of minimalchange LWC, MVD to produce changein ice shape

2006 test entry to confirmmethodology


Ttot =7.9 F, T s = -1.6

F, 0=0.75, V=200 knots,AOA=2.5deg, 15 min spray

Contour Plot Showing Effect Of Change in MVD & LWC OnUpper Horn Thickness


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Follow-on aero testing

performed at UIUC

Contour plot method used in2004 / 2005 sensitivity testshas potential to characterizethe effect of small changes inLWC, MVD on aerodynamiceffects Provide link between

changes in spray cloud, iceshape changes, and aeroeffects

Preliminary estimate ofminimal change LWC, MVD

to produce change inaerodynamic characteristics Results are not yet published


Contour Plot Showing Effect Of Change inMVD & LWC On Cl max

LWC

M V D

0.5 0.6 0.7 0.8 0.9 1 1.120

25

30

35

40

Clmax0.80.780.760.740.720.70.680.660.640.620.6

0.580.56


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SLD Icing Physics


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SLD Icing Physics

Background

Identify the physical processes of ice accretion that areimpacted by the presence of super-cooled large droplets.Quantify the important physical characteristics of the identifiedprocesses. Develop a database of information for developmentof models to be used in simulation software.

-20

-10

0

10

20

30

40

0 50 100 150 200 250

MVD ( m )

%

m

n = 0.3 n = 0.6 n = 0.9


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Approach

Investigate icing physics processes that arecharacteristic of SLD

Develop a thorough understanding of SLD icing physics

Provide data that will be useful in identifying necessarychanges to icing facilities or to measurement equipment

Provide data that will be useful in development of SLDmodels to be used in ice accretion codes

SLD Icing Physics


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Location Wichita State UniversityPrincipal Investigator Jason Tan & Michael Papadakis

Objective Identify droplet dynamic issues relevant to SLD icing

Droplet deformation & breakup prior to impact Droplet splash/deposition/bounce

Near-wall effects Supercooling large droplets LWC measurement of large MVD spray cloud

Status AIAA papers: 2003-0391 & 0392, 2004-0410, 2006-463

WSU Droplet Break-up Analysis


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Status Test completed July-August 2004

Results analyzed: AIAA 2005-0077, 2006-0466

Cranfield Droplet Splashing Research

Location - Cranfield UniversityPrincipal Investigators - David Hammond,

NASA, WSUObjective Characterize large droplet impact / splash

Quantify the incoming/splashed drop size, velocity,and angle

Measure the mass resulting from the splash process

Approach Use a low turbulence vertical tunnel to

accelerate droplets of known size toward atarget plate having a controlled water film

Quantify drop size, velocity, angle of impactsplash with high speed imaging methods

Correlate droplet impact/splash parameters

with mass splashed from target plate waterfilm


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Location Glenn Icing Research TunnelPrincipal Investigator Mark PotapczukObjective Determine whether large droplet

encounters result in mass loss

Ice Mass Measurements on Airfoils

SLD Mass Loss Experiment

-2

-1

-1

0

1

1

2

-2 -2 -1 -1 0 1 1 2 2

X (in)

Y ( i n

)

Clean airfoil20 microns40 microns70 microns100 microns

120 microns175 microns

Directly measure the mass of ice deposited on a well-definedtarget geometry under Appendix C and SLD conditions Method 1: maintain K 0, A c , and velocity over range of drop sizes Method2: maintain A c , , and freezing fraction over range of

model sizes and drop diameters

Determine ice shapes with LEWICE assuming no splashing Compare ice shape tracings to LEWICE results and compare

measured and calculated ice mass values AIAA paper 2003-0387


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Location NASA Glenn Icing Research TunnelPrincipal Investigator Michael PapadakisObjective Measure collection efficiency in SLD

SLD impingement on an MS-317airfoil (LEWICE vs. experiment )

SLD impingement on a NACA 65 2415airfoil (LEWICE vs. experiment)

Clean Geometry SLD Study


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Location NASA Glenn Icing Research Tunnel (US)Principal Investigator Michael Papadakis

ObjectiveMeasure collection efficiency in airfoils with existing iceshapes

Approach

Use existing blotter strip method for collection efficiencymeasurement on ice shape models

Status: Tests completed

FAA contractor report completed Dec. 2005

SLD Ice Shape Study


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WSU/NASA DrIFT ExperimentLocation Droplet Imaging Flow Tunnel (DrIFT)

Principal InvestigatorsMichael Papadakis, Jason Tan, Dean Miller

ObjectiveInvestigate imaging methods to studydroplet dynamics

Approach WSU re-design/fabricated tunnel inlet to facilitate droplet

dynamics experiments

Mono-dispersed droplet stream (44, 70,107, 160, 350 m)aimed at test articles Iced and un-iced NACA-0012 airfoil Multi-element airfoil

NASA high speed imaging techniques used to study dropletsplash and breakup

Phantom camera with optical backlighting Gated intensified camera with laser sheet

Status Testing conducted in July and Sept 2005 Qualitative imagery of droplet impact and breakup

obtained Data currently being analyzed


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SLD Modeling in LEWICE


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Background

Develop an interim model for SLD ice growth that can beadded to LEWICE. Develop a framework for introduction ofupdated SLD icing physics into models as they becomeavailable.


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Approach

Utilize the data from the SLD Icing Physics studies todevelop mathematical models that can be used incomputational tools such as LEWICE

Incorporate the models into the code and compare outputto SLD ice shape database

Document changes to LEWICE as models are developed



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Develop Droplet Breakup Model

Status Model has been incorporated into LEWICE 3.2.2 Thorough testing of model has been completed Upgrades to model can be included as more break-up testing

and modeling is conducted DVD of experimental ice shape and prediction comparison

available AIAA-2004-0412 ,AIAA-2005-1243 , AIAA-2006-0464

Location Glenn Research Center Principal Investigator William Wright

Objective Allow SLD droplet break-up to influence

ice shape developmentApproach Incorporate droplet dynamics model

into LEWICE and investigate influenceon ice shape development


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Develop Droplet Splashing Model

Status Model has been incorporated into LEWICE 3.0 Thorough testing of model has been completed

Upgrades to model can be included as more splashing testingand modeling is conducted DVD of experimental ice shape and prediction comparison

available AIAA-2004-0412, AIAA-2005-1243, AIAA-2006-0464

Location: Glenn Research Center Principal Investigator: William Wright

Objective Allow SLD droplet splashing to

influence ice shape developmentApproach Incorporate droplet splashing model

into LEWICE and investigate influenceon ice shape development


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Compare LEWICE Model to Mass Loss Data

Status Some initial comparisons have been conducted Mass agreement improved with droplet splashing

model added

Location Glenn Research Center

Principal Investigator William Wright,Mark Potapczuk

SLD Mass Loss Experiment

-2

-1

-1

0

1

1

2

-2 -2 -1 -1 0 1 1 2 2

X (in)

Y ( i n

)

Clean airfoil20 microns40 microns70 microns

100 microns120 microns175 micronsObjective

Identify strengths and weaknessesof SLD model

Approach Run LEWICE for conditions used indevelopment of SLD ice shapedatabase and compare ice shapes


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Droplet Trajectory and Impact

All physical effects modeled Turbulence

Saffman lift Bassett force (buoyancy) Gravity Drop deformation

Drop breakup Drop splashing Splashed drop trajectory

Impingement limit search for collection efficiency


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Drop Breakup Model

Drop breaks completely if We a > 13 Conservative assumption (drops take 2-3 cm to break

completely) Secondary drop size determined by empirical

relationship No experimental data available for validation

d s

d o= 6.2 w

a

14

Re d 1

2


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Splashing Model Requirements

Fraction of impinging mass ejected Size, velocity, angle of ejected drops

Tracking/re-impinging of ejected drops


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Current Model

Track one splashed drop for each incoming drop Use MVD of splashed distribution

Add splashed mass if drop re-impinges Drop-drop and drop-film interactions assumed part of

correlation

Asymptotic effects imposed when extrapolating


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Empirical Splashing Model (Part 1)

d sd o

= 8.72 e0.0281 K

V x,sV x,o

=1.075 0.0025 o

V y,s

V y,o= 0.3 0.002 o

( ) ( )

( )200*0092.0

1sin17.0

= n L

K

o

s

em

m


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Empirical Splashing Model (Part 2)

25.1

25.1Re*

==

w

nw

w

w d V d

OhK

Splash Threshold:

( )

200

sin

125.0

25.1

859.0

>

= LWC

K K l Ln


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Validation Data (Impingement)

NASA/WSU Impingement Database 19 geometries (7 ice shape geometries)

10 different MVDs (11 m - 236 m) 0 AOA 8 32 - 57 chord 175 mph (152 kts)


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LEWICE Impingement Runs

All conditions were computed with 4 options: Potential flow, no splashing (PF-NS) Potential Flow, splashing (PF-S) Navir-Stokes, no splashing (NS-NS) Navir-Stokes, splashing (NS-S)

All cases use 27-bin drop size

Grids for Navir-Stokes generated with ICEG2D option Grid refinement performed on high AOA cases only

WIND 5.0 used as Navir-Stokes solver Spalart-Allmaras turbulence model used 27 solutions needed for impingement cases


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Impingement Parameters Compared

Maximum Beta Results also compared to scaling method

Total Water Catch

Upper and Lower Impingement Limits Measured from leading edge as a percent chord

Upper and Lower Location where = 0.1 Occasionally used for sizing de-icing equipment

dsW V LWC m = ***&


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GLC305 AOA=6, MVD=92

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

-0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1

s/c

C o

l l e c t

i o n

E f f i c i e n c y LEWICE SLD

ExperimentLEWICE 2.0

Typical Splashing Results

Maximum Beta

LowerImpingement Limit

Upper Impingement Limit10% Limits

N i l A i d S Ad i i i


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Validation Data (Ice Shapes)

3017 IRT Ice Shapes 3049 LEWICE Runs

944 Appendix C conditions

682 SLD conditions ran with three options Monodisperse MVD 27 bin distribution (no splash) 27 bin distribution (with splash)

9 Different geometries Time: 0.5 to 69.7 min (scaled condition) Chord: 1.5 (cylinder) to 78 in Velocity : 65 to 323 kts (0.19*10 6 < Re < 14.6*10 6) LWC: 0.3 to 2.8 g/m 3

MVD: 12 to 305 m Temperature (total): -20 to 34 F

N ti l A ti d S Ad i i t ti


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Icing Parameters Compared

Icing Limit Upper & lower

Horn Height Upper & lower

Stagnation freezing fraction Leading edge minimum thickness

Horn Angle Upper & lower

Iced Area

Ice Weight (if measured)



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Overall Comparison

Parameter Averages

0

10

20

30

40

50

60

70

80

90

100

overall rime mixed glaze

% C h o r d

D i f f e r e n c e

f r o m

E x p .

LEWICEExperimentSLD LEWICEDistributionDistribution & Splash



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HF1012936

-5.0

-4.0

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

-4.0 -2.0 0.0 2.0 4.0 6.0 8.0 10.0

x, in.

y ,

i n

Lewice ice shape lewice limits icing limits

Typical Icing Results

Chord = 36 V = 175 kts AOA = 4 T o = 30.5F

LWC = 0.54 g/m3

MVD = 20 mTime = 22.5 min GLC305 Airfoil



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AE1168136

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

-1.5 -0.5 0.5 1.5 2.5 3.5

x, in.

y ,

i

Lewice ice shape lew upper horn lew lower horn

icing upper horn icing lower horn lewice limits icing limits

Typical SLD Results

Chord = 21 V = 100 kts AOA = 0 T o = 4.2 F

LWC = 1 g/m 3 MVD = 120 mTime = 9.4 min NACA0012 Airfoil



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AE1193336

-2.5-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

-1.5 -0.5 0.5 1.5 2.5 3.5 4.5 5.5

x, in.

y

, i

Lewice ice shape lew upper horn lew lower horn

icing upper horn icing lower horn lewice limits icing limits

Need Feather Model?

Chord = 21 V = 200 kts AOA = 0 T o = 20 FLWC = 0.5 g/m3 MVD = 160 mTime = 16.9 min NACA0012 Airfoil



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Reproducing SLD

Conditions in the IRT



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Reproducing SLD Conditions in the IRT

Background

Determine the characteristics of SLD icing conditions that must

be reproduced in a ground based icing facility. Identify the range of SLD conditions that can be produced using

the current capabilities of the IRT.

Develop methods for reproducing characteristics of in-flightSLD icing conditions that cannot be simulated currently.

Document those characteristics that cannot be reproduced inthe facility in its current configuration.



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Reproducing SLD Conditions in the IRT

Approach

Assess current capability to produce SLDWhat set or range of icing conditions can be produced in an icing tunnelwith current spray system technology

Investigate and document constant or time varying icingconditions in natural SLD encounters

Examine the data from SLD in-fl ight encounters and characterize the cloudand flight condi tions for an SLD ice shape

Develop SLD cloud simulation methodCreate operating conditions in the IRT that produce a cloud similar to thatfound in natural SLD encounters by altering spray times and conditions

Document Range of LWC and MVD vs. Appendix X Document drop size distribution vs. Appendix X


l l d l h d


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Location Glenn Research Center

Principal Investigators Dean Miller, Mark Potapczuk, RobertIde, & John Oldenburg

Objective

Attempt to generate a Bi-Modal SLD spray cloud in an icingtunnel

Approach

Sequentially spray a small drop (20 m MVD) condition,then a large drop (130 m MVD) condition

Maintain freezing fraction for both conditions Vary order / time of spray conditions Generate a sequenced ice shape Document ice shape with ice tracings and photographs

Develop SLD Cloud Simulation Method

Compare sequenced SLD ice shape to ice shape generated from non-sequenced 20 m MVD or 130 m MVD icing spray

Status

2 tests completed, reported in AIAA-2005-0076, AIAA-2006-0462

Currently investigating another alternate technique



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Alternate method underdevelopment Sequencing not required

Utilizes existing IRTnozzles Adds hydraulic (water

only) nozzle Preliminary results

suggest can match bi-modal cases with flatarea in cumulative LWCcurve

Prototype nozzles underevaluation Engineering issues to be

resolved

Develop SLD Cloud Simulation Method

Target SLD Spectra

00.10.20.30.40.50.6

0.70.80.9

1

1 10 100 1000Drop Diameter, (um)

C u m

M a s s F r a c t

i o n

16.4 20a10dp SUM MSC2 Boeing1

Cumulative LWC From SimultaneousSpray (Mod-1 & Hydraulic Nozzle)



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SLD Cloud Uniformity in the NASA IRT

Principal Investigators - JackOldenburg and Mark PotapczukObjectives Icing Research Tunnel (IRT)

enhancements to improve SLDuniformity allowing a broader range

of icing test possibilities under SLDconditions.

Future SLD experiments willproduce more reliable and robustdata than has been previouslyavailable.

Description Six columns of vertical airfoil shaped struts were added to the IRT spray bars Improved LWC uniformity. Increased the performance capabilities of the tunnel Increased the confidence level of the cloud operational characteristics Enhancements to SLD uniformity will allow a broader range of icing test possibilities

Status All work for the experiment is done and has been satisfactory evaluated- March

2006



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Numerical Simulation of IceShapes from a Bimodal

Large Droplet Icing Cloud


l b f h


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Target SLD Spectra

0

0.2

0.4

0.6

0.8

1

1 10 100 1000

Drop Diameter, ( m)

C u m

M a s s

F r a c t

i o n

MVD50 22 171.5 SUM

Droplet Distribution for ZLE with MVD > 50 m


LEWICE droplet distribution for MVD > 50 m


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12.5 30.5 61.75 135 225 315 405 567 850.50.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

f r a c

t i o n a

l L W C

LEWICE droplet distribution for MVD > 50 m

Droplet Diameter, ( m)

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

1 10 100 1000

Drop Diam. ( m)

C u m .

% L

W C


Component Spr s of Bi mod l Seq encing


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-5

0

5

10

-5 0 5 10 15X, in

Y , i

n

Airfoil171.5 microns22 microns

171.5 micron MVD:

LWC = 0.878 g/m 3

22 micron MVD:

LWC = 1.3 g/m 3

Common conditions:V = 150 knots

Ts = 17 F

Time = 20 min.

Component Sprays of Bi-modal Sequencing


Component Sprays of Bi modal Sequencing


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171.5 micron MVD

LWC = 0.878 g/m 3

22 micron MVD

LWC = 1.3 g/m 3

Common conditions: V = 150 knots, Ts = 17 F, Time = 20 min.

Component Sprays of Bi-modal Sequencing


Ice Shapes Produced by Sequencing


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-5

0

5

10

-5 0 5 10 15X, in

Y , i

n

Airfoil171.5, 22 microns22, 171.5 microns

171.5 micron MVD:

LWC = 0.878 g/m 3

t = 4 min.22 micron MVD:

LWC = 1.3 g/m 3

t = 1 min.Common conditions:

V = 150 knots

Ts = 17 FTtotal = 20 min.





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171.5 - 22 micron 22 171.5 micron

Common conditions: V = 150 knots, Ts = 17 F, Time = 20 min.



LEWICE Results for Large-Small Sequence


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171.5 micron MVD:

LWC = 0.878 g/m 3


LWC = 1.3 g/m 3


V = 150 knots

Ts = 17F

Ttotal = 20 min.

LEWICE Results for Large Small Sequence

-5

0

5

10

-5 0 5 10 15X, in

Y , i

n

Airfoil171.5, 22 micronsLEWICE dist.LEWICE seq.


LEWICE Results for Small-Large Sequence


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171.5 micron MVD:

LWC = 0.878 g/m 3


LWC = 1.3 g/m 3


V = 150 knots

Ts = 17F

Ttotal = 20 min.-5

0

5

10

-5 0 5 10 15X, in

Y , i

n

Airfoil22, 171.5 micronsLEWICE dist.LEWICE seq.

LEWICE Results for Small Large Sequence


Conclusions (1)


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Conclusions (1)

Icing physics studies conducted on large dropletbreak-up, splashing, and re-impingement

Mass loss experiments performed suggesting effect

of splashing at all drop sizes Quantitative analysis shows that LEWICE

impingement results with splashing are comparableto experimental accuracy Average difference less than 30% for all parameters

Splashing model improves impingement limit but notnecessarily icing limit results in SLD regime

Splashing model more likely to under predict results Effects much less pronounced in 3.2


Conclusions (2)


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Conclusions (2)

Experimental methods under development toreproduce bi-modal droplet distributions

LEWICE reproduces bi-modal ice shapes very well

LEWICE results show little difference betweensequenced spray and actual bi-modal ice shape

Pot Apc Zuk Wright

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