L_ NASA Technical Memorandum 106827 AIAA-95--0540 // Methods for Scaling Icing Test Conditions David N. Anderson Lewis Research Center Cleveland, Ohio N95-19284 (NASA-TM-106827) METHOOS FOR SCALING ICING TEST CONOITIGNS (NASA. Lewis Research Center) 11 p Unclas G3/03 0035008 Prepared for the 33rd Aerospace Sciences Meeting and Exhibit sponsored by the American Institute of Aeronautics and Astronautics Reno, Nevada, January 9-12, 1995 National Aeronautics and SpaceAdministration Methods for Scaling Icing Test Conditions DavidN. Anderson NASA Lewis ResearchCenter Cleveland, OH _$tokes Droplet rangeifStokes law appliestodrag,m Abstract "9 Latontheatoffrcezing, cal/gm a, Latentheatofvaporization, cal/gm Thisrelxalpresentstheresultsoftests atNASA Lewis toevaluate # Viscositgym,/cms several methods to establish mitable alternativetest conditions P Densityd,yne/cm3 whenthetestfacilitylimitsthe modelsize oroperatingconditions. Icingfree,rain l" Thefrst method was proposed by OlsnL It canbeappliedwhen full-sizemod_ mutested andallthe desiredtestoonditionsexcept Subscripts: liquid-wat_ omtent caabe obtainedinthe fatty. Theothertwo Air a methodsdiseugsedare: amodific,ationoftbeFrenchscaling law i Ice and the AEDC scaling method. Icing tests were made with R Reference size and conditions cylinders at both reference and scaled conditions representing aurf Surface mixed andglaze ice intheNASA Lewis IcingResearchTunnel. S Scale size and conditions Reference and scale ice shapes were compared toevaluate each tot total method. TheOlsen methodwas tested with liquid-water content Water W raying from 1.3to .8g/m3. Over thisrange,ice shapes produced usingtheOls_ mc_od were _ Tbemodified French and AEDC methods produced scaled ice shapes which approximated Introduction thereferencsehapeswhen modelsizewas reducedtohalfthe referencseizefortheglaze-icceasestested. In wind tunnel testing the researcher is oPamfacedwith facility limitationswhich laucmt testingatdesired oonditions. In addition, the test article must normally be reduced in size relative to the Nomenclature device of interest. Therefore reliable techniques are needed to permit the sealing of test oonditio_s in such a way that an A¢ Accumulation parameter,dimensionless experimental ice shape adequately naxtsents that which would b Relative heat factor,dimensionless aeerete on the reference (full-size) hardware at the required ¢ Characteristic model length, em ainpeed and cloudconditions Inm _ort_ _d the_ Specific heat, c,al/gmK of the NASA Lewis Icing Research Tunnel 0RT), studies have Convective filmheat-transfer coefficient, been carried out for several years to evaluate various scaling ¢ cal/see m2K methods, ReferenceIshowedthat anumber ofpublished scaling k Thermalconductivity, cal/see mK lawsaleqmU_ scaleforrimeicebutnotformixed or glaze. Rime K Langmui_sInertia Parameter, dimensionless ice results from immediate freezing of water that impacts the ModifiedInertia Parameter, dimensiodess model;therefore,hmt-nmsfer emsidmaions are not important and LWC Liquid-water oontent,ghn3 only the droplettrajectory and wateraccumulationneedtobe n Freezing fraction,dimensionless matched beCween reference and scale eonditioas to produce Nu NusseRnumber,dimensionless properly scaled ice shapes. For mixed and glaze ice, however, P Ambient staticpressure,nt/m2 heat-transfer atthe leading edge must be includedinthe scaling Ra Gas constant for air, 287.0 ntm/kgK analysis. Thepooragreement ofthe ice-shapes for reference and Pw Vaporpressure ofwater,nt/m2 scaleconditions reported inreference 1wasattributed inpartto Re Reynoldsnumberbasedonmodelsized,imensionless problemswith the heattransfeanralysis. Re8 Reynolds number basedondropletdiameter, dimensionless This report presents the results of tests of three methods not Sc Schmidt number, dimensionless discussed in reference 1. The first is the Olsen method2,a t Ambient static temperature,oC mod_cafionoftbeoRen.usedrule, LWCxfune=constant Inthe T Ambient static temperature,K Olsen method, in addition to keeping the water catch constant V Airspced, m/s between scale and reference situations, the scale and reference freezifnrgactioanrsealsomatched.Thesecondisamodification #0 Collection efficiency atleadingedge, dimensionless of the French scaling method presented by Charpinand Fasso 3. d_ Droplet medianvolume diameter, mm CharpinandFasso'osriginaalnalysiinscludedaconvective heat- ¢ Droplet-energy transfer term inenergy equation,K transfercoefficientapplicable toturbulent flow (Nu., Re'S). Itwas 0 Air-energytransfer terminenergy equation, K speculated in reference 1 that sealed ice shapes might match 2 Dropletrange,m referencsehapesbettefrfalaminar-flow form(Nu_,Re"s)ofthe convective heat=transfercoefficient were used. Thismodification selected,andwhenturn,elconditionshadstabilized, the waterspray was made to the Frenoh method as it was tested in thisstudy. was initiated. Thespray-barconditions typicallystabilized aft=" Fimlly,theAEDC _ was tested;ithadnotbeenincludedin about 1 minute. When the spray-bar air and water pressures the studyofreference 1. Thismethcxi,likethe French,matches reachedsteadyvalues, theshield shown infigure 2 wasraisedto droplet l_jectodes, _¢umuhtion parmnet_ and several of the expose the cylinder, midthe spray6mer was started. Whea the termsintheheatbalancebetween scale and reference situaticms. ixesml_d sprayperiodwas completed, the spraywas shutoffmd Theheatbalance analysis incorporatesalaminm'-flowformofthe the tunnel broughttoidleto permit personnel enlzyinto thetest convective film zoetticieat section. Theice shapewas then_ themodel wasaleaned and the procedure repeatedforthenextsprayconditio_z. Tests were conducted withcylinders ofdifferentdiametersinthe Lewis Icing Research Tunnel (IRT). Several sets of reference The ice shape was recorded manuallyfor ew.h test. A heal_ conditions were firstchosen alongwitha scale size and airspeed. aluminumblock with a semicircular cut-out of the appropriate FortheOlsenmethod,thescale size andairspeedwerematched to dimmtcrwasusedtomeJtasliceintotheice normaltothecylinder theirrespective reference values. Theothertwomethodspermit a_isatthetest-sec6on centerline. A cardboardtmnplate,alsowith themodel size tobescaled, andtestairspeeds were chosentobe asemicircularcut-outtomatchthe cylinder dimneter,was placed thesameorless thantheref=ence. Eachmethod beingevaluated intlmresultingg_pintheice,mdthe ice shapewas Wacedontothe was used to detennine the remaining scaled conditions which csrdbo_d template. TheU_-_g was laterdigidzed forcomput_ oonesgxaxkdwith eachsetc£refe_mce condition& Tests wee run storagoeftheinform_c_ withbothreferencemd scale oonditionsforeacJatestcase,and the ice shapes were reccaded andcompared. Reference conditions includedcylinder diametersof 15.6 and 5.1cm(6 and 2 in),total _ding Methoch Tested _of -7.8to-2.1°C (18 to28°F), airspeeds of76to 94 m/s (170 to210 mph),median volume dropletdiameters of28to Three scaling methodswere tested: amethod devised byOlsen2 30tan,liquid-watercontents of.6 to 1.3 g/m3, andspraytimes of forconecting forLWC changes, amodifiedversion oftheFrench 7.8to19.1 rain To testthe Olsen method,LWC wasvariedfrom scaling law described in refe_nce 3, and the AEDC scaling .8to 1.3 g/m3. Scaled tests ofthe mcxlifiedFrench and AEDC _pro_h 4. Each ofthese methods willbedescribed here. methods were made with 2.5-cm-diameter cylinders and with scaled airspeedsof61 to94 m/s. Inthe following discussion the termreference is app_ed to the conditions andice shape to be simulated while the simulation (sometimes with reduced size and sometimes with al_ed test Deacription of Experiment conditions) is termed aca/e.Thesubscript R will be used for referenceconditions and model size,while the subscriptSwillbe NASA Lewis Icing Research Tunnel. The _ts were usedtoindicatescale conditions and size. performed h the NASA Lewis Icing Research Tunnels 0RT) showninfigure l. TheIRThas atest section widthof 2.74m(9 OlsenMethod The approach suggested by Olsen2 was a fl) and a height of 1.83 m (6 ft.) Itis capable of operation at modific_ion ofthefamiliarrule, test-sectvi_ooncitieuspto 160m/s(350mph.).A rcfi'igm-afion systempermitasccuratceontroolfthetest-secttieonnSg_..m__ t.wc::Lwc R_ (D from -40 to5°C (-40 to40°F .) Awater-spray system° with8 spraybarsprovides theabilitytocontroltest-section liquid-water ooatentfrom .2 to3 g/m3 anddropletmedian volume diameters from 15to40 tim. Equatioo (l) followsfrommatchingthescale and refermce accumulationparameters,where theaccumulatiopanrameteris Two sets of spray nozzles, known as the rood-1 andstandard nozzles, are used in the IRT to provide different ranges of LWC Vx liquid-watercontentanddroplet size6. Ac= (2) cPl Scaling Test Hardware. Ice accretion was measured on hollow circularalumimancylindem Eachcylinderwas mouatedvea_ically in the center of the test section. Cylinders with 15.2-, 5.1- and Equation (1) is valid o_y if the scale model size matches the 2.5-cm(6-, 2-and 1-ia)diano.ers wereuse& Figure2 showshow reference size and ffnone ofthe testconditions, exceptthe scale the test cylinders were mounted in the IRT test sectiez. A LWC, differs from the refereace value. Thus, the equations retractable shield protected the testcylinder fi'omice duringthe applicable tothe use ofLWC xtime =constantare: waterspraybm'start-uptran_ Fisure 2 showstiffsshieldintho cs = cR (3) reCactedposition; phantom linesindicateitslocation when lowered toprotect thecylinder from theinitial st_'ay. Test_. Tests were pea'formedby first establishing the tunneal/_peedand_. Waterspray conditions werethen Theconvectivheeat-transcfoeerfficifeonrttheleadinegdgeofan 8s = '_R (4) airfooirlcylindewrhichOlsenusedinequatio(n9)is hc = 1.05 .s (12) v,= rR (5) ¢ r.wcs= [_ _wr ] (6) The_ _, fl@ine_s ._o_(9) canbef°undfrom.the methodofIAmgmuirendBlodgettwhichfollows. Langmuir and Blodgetgtaveforcylinders: LN_ R 1.4(£ 0 - .125)-u LIeU s Po= (13) 1 + 1.4(Ko -.125)')4 ts = ,_ (8) wliereK0was_ as x0 = _----_--_"- .m) + .m (14) Equafims O)-(8)oonstitme tbeLWCxtime =constantlaw. With theexceptioonfequatio(n8), theyarealsothebasisof theOlscn scalingmeeo_ However, equation (8) overly simplities theheat In equation (14), MAstot_ is Langmuir and Blodgett's range balance atthe leading edge ofthe model. Itisonlyvalidforrime _, definedmtbera6o ofthe actualrangeof adroplet acted conditionswhe_ heat transferdoes notaffectthe ice shape, or for upon by the dragof the airflow divided by the range ff thedrag situations inwhich thereislittledifferencebetween thescale and were determined by Stokes law. Thisparameterisafunctionof referenceLWC. Formixed-orglaze-iceconditions with significant Rea Itwm tabulatedbyLangmuir and Blodgett; f_ thisstudythe d_J_tcmx_sbetweenscale andre_erenceLWC,referonoe 1showed fotlowing fittotheir tabulationwas used: thatthisscalinlgawdoesnotaecm'aterleyproductehehornangle becauseoftheeffecotftheliquid-watceorntenotntheleading- ;tsar, edgeheatbalance. (15") ffz0 - .132m(_) + .oo44m5(_6)2 ToaocountfortheLWC effects,theOlsen analysis requiresthatthe scaleandreferencefieezing fzaction be equal. Messinger vdefined I-.o762).(Rse)+.019ms(_6)_+.00orsm3(_ 63) thefi-eezingfraction as thatfraction of water which freezes inthe m'eaofimpact. From theMessinger energyequation, thefreezing fzacticoannbeexpresseads K inequatio(n14) istheinertiaparameter *÷ 0 o) n = LWC _--13° pwb2V K= (IO 18p,,c where _representsthe transfer ofdropleetnergytothesurface, When nsisequatewdithr_thefollowinegxpressiornesultfsorthe V2 scale temperature: ¢ = tt- * - _ (10) 2%.. ..{.. ,) (1"/) 0represents thetransfer ofenergyfrom the airtothe surface: ts = tR+ V_'_.w LWC$ LWCR V2 Pw.mf-Pw 0 =t_/- t -•_ +.693 gmK A, (11) 2_, joule p Equation (I7)mustbesolvediteratively fortempentu_since0s isitselafRmctionoftemperatur(eseeequatio(nII)).Equations In equation (11), ris the recovery factor, taken as .875 in this (3) - (7) and(17) make upthe Olsen method. Although itisless study,and_ factor.693gm K/jouleisthe ratioofthe evaporative convenient thanthe LWC x time =constant method, the greater totheconvective heat transfer coefficient rigor oftheanalysis shouldprovideimproved rcpreduction ofice 3 shapewshen LISZTisvaried. h, ,,,k__R.le .s (23) ModifiedFrenchScalingMethod The original Frenckscaling law waspublished byCharpin andFasso3. Thismethod canbe applied to_tmicm forwhichtbestole size dces notnecessmly match the reference.Inaddition,aconvenient scaleairspeed maybe chosen For the modifiedFrenchmethod, hcis takenfrom equation (12) a_rdin$ totheuq_es ofthetestfadlity, itncednotequal the imtead ofequation (23). Whenequation (12) issobstituted into refttem=airspeed. Thislawwastestedinrefereme I whemit was equation (22) andthe scale and refeaence relative heat factors notedthattheform ofthe omvectivc heat transferocmflicientused equated, thescale liquid-water ¢ontent canbe founck in the Charpin andFasso analysis was appropriate to turbulent tiow. The iceshapesfi-omtests scaledusing the Fremh method in tbeIRTdid not always match the reference shapes in thatstudy, (24) endtbeform ofthedisorepan_ suggested thatbetter resultsmight be addevod ff a laminar-flow film coefficient were used in the analysi_ With this modification to the French method, the following equations can be used to determine scaling test conditions: This equation is the only one that differs from the equatiom published in Charpin andFasso3 descn'bingthe odgiual French method. cs = [ut_ted by,re. ] (m) Once the LWCs is known, the sc4de enommter time can be determined from equation (2): vs = [_,.c_.d byte'] (19) cs v_ LWC_ _s = _x (25) c++Vs LWCs The_ml¢ _ffaticpressure canbefoundfromthetotal presmre for the test facility: Finally, the scale statictemperatureisfound bysetting thescale mdrdetmce freezingftmf,m (.ceequation(9)) intheMes._ger energy equation equal. The equation thatresults is3 Ps =Pm 1 2R,Ts} (20) t.--t++_ i ";"_ It canbe shown (see, for example, Ruff4)thatwhen the droplet t_ ,re,f,.,,.+) equation of motion for the scale and reference situatiom are equated, the scale droplet size canbe found fromthe following 1+b(ps PR} (]+_)S+_=%2K approximateexpression: Thevaporpressmes, Pw_ andPw_ arethose oxtesponding with (21) the temperaturests andt_e Thus, equation (26) must be solved iteratively forthe scale temtxratme, t_, Thevaporpressures for thisstudyweretakenfrom reference 10. Althoughequatio(n26)isidentictaolthatintheodginalFrench The relative heatfactor was defmodbyTribus9as analysist,hestatic _ it giv_ for the Frenchand tmxlifiFerdenchmethodswillnotbethesamebecausetberdative heat factorfound frmn equation (22) will differ for the two LWC V_Oep,w analyses, h practice,thedifferemein tempemurmis smaU, b = (22) h, however, and themain distinction between thescale resultsfi'om the two methods willbe the valueofthe liquid-water omtent. TheFra_ method_mtes bswithbR.midthe scalemidreference AEDC TheAEDC scaling malysis4is similartothatof Charpin atle,_ _ po,,_e _o matched.#oc_ befoundfrom and Fasso in that both matchscale end rcfaence droplet equation (13). For the convective film c_eflicienL the original trajeztories,accumulationparameters and heatbal_ analyses. Frenchmethod used I-Iowcv_,time_mmsiom usedtoevaluate smm of tbe_ are differ_t, diff_mt tram in the heat-balance analysis are matched andsolution techniques are not always the same. Thus, the resulting scale test conditions for the two methods vary 1.14Rz "s/b""4k., somewhat The full set of equations used to determine scale h,, = 03) conditionsfrom givenreference conditions isgiven here. As withthe Frenchand modified Fresh methods, theuser ofthe AEDC method canchcose scale size andairspeed: The 9s in equation (32) arethe scale andreference air energy transferterms,where Owas given byRuff as cs = [u_-_ uyw_l (27) e=t,_- t- --+ 04) (2s) 2_,,, When scale and reference droplet energy transfer terms (see Pw,surfis thevaporpressure atthe surfacetemperaturte_f, t_f equation(I0))intheMessinge7requationarematched,the static =O°Cwasusedinthisstudy. Thevaporpresmres were takenfrom scale temperature canbefound: reference 10. To insure that the total amount of ice acereted for the scale situation matches the reference accretion, the accumulation is= t_÷ (29) 2cp,w 2 cp.w parameter,A_, (equation (2)) mustmatch. Thus, the scale icing _ time is csLWC R V_ 'ts= _ (363 AswiththeFrenchmethod, the scale static pressure isfound from ce Lwc s vs thetotal_ forthe testf_lity: The complete set of scale condition_ can thus be found from equations (27) - (32) and(35), and this constitutes the AEDC (3o) methodtestedhere. P8 =Ptot,s 1 2R'Ts) Results Thedroplestizeisfoundbymatchintghepartic_laejectorieRsu.ff didthibsymatchingthemodifiedinertpiaarameterK,o: Theevaluationofscalingmethods willbebased onhowwell scale ice shapes match therefevmce shape_ The qualityof agreement '_o.s= x;_ (3D between ice shapes isasubjective judgcm_L In this study, the followingatmbutmwereconsi_ inevaluating howwell scaled ice shapes matched the reference shapes: therelative qumtity of Where Kowas defined by equation (14) in thediscussion of the ice accreted, the generalshape of ice, the thickness ofice at the Olsen method. The scale drop size, 6s, is found by solving leading edge and (if applicable) the size and angle of horns. equation (31),using equations (14) - (16), iteratively. Differences inthese characteristics between scaled andreference shapes are only sgnificant when they exceed the run-to-run The freezing fraction, n,was defined byequation (9). Thescale variationsobserved whentestconditions arerepeated. liq_d.water oont_ LWC_ cannowbe detemfi_ byequating ns withne. Since the droplet energy terms are matched in Ruffs Figure 3 shows results of repeatability tests for some of the method(_ =_ was the basis of equation (29)) andthe collection conditions used inthisstudy. Figure3(a) represents ahornglaze efficien,c8yo,,mustalsomatch, ice for which repeatability was excellent Repeatability of ice shapes intheIRTisgenerallyvery good12,butcannotalways be es h_s v_ expected to be as good as that show_ Figure 3Co)presents Lwc s -- 02) = LWCROah_e Vs repeatability test results at a temperatme higher than that of figure 3(a). At thisoondition, the ice shape and quantitywere sensitive tosmall changesintemperature,andthe irregular shape Here Ruff used the convective heat transfer coefificient from was hardertorepeatthan the shape offigure 3(a). Kreithn Olsen Method. The Olsen method corrects forthe effectofLWC suitable. on heat balance by substitutingequation (17) for equation (g) to adjust the static temperature. To illusUate the ice-shape ARD..Q.._t_b_ The same refez_nce conditioas and size ratios _ thiscorrection provides, some resultsfor thesimple weretestedwiththeAI/DCmethod asfortheFrench and ngxiified ruleLWCxtime=oonstantbased onequatiom (3) through(8) will Frenchmethod shown above. Theresultsaregiven infigure 7. be shown fast Ice shapes from refereace (1) at liquid-water contents of 1 and .8 8/m3 are compared in figure 4 with the Tberefe:mce iceshapefromthetest resultsoffigure 6(a) has beea reference shapeat 1.3g/m3. Theice isglaze for allliquid-water usedasthe_ fortheAEE_ mett_ in7(a). Again, thesize contents. Figure 4(a) gives ice shapes on a 5.I-era-diameter wasscaledfi'om 5.1 to2.5om andthe airapced from76 to61m/s cylinder and40)) ona 15.4-¢m-diameter. Thetotalaccumulation foreme tests. Thescale iceshape isgivenbythe dottedline. The appearedto remainapproximately constantas LWC was varied; scale test results matched the reference shape approximately however,because adecreaseinLWC_ the release oflatent althoughtherelativqeuantitoyfice accreted appeared to be heatattheleading-edgiem,pingingwaterfrozefastefrorlow mmewhatlesfsorthesoaletdestthanfortberderence.Inviewof liqeid-watceorntenttshanforhigh.Thiseffecotanbeseeninthe theexpectedvanabilitiynshapeshownbyfigure3(b)atthese decreafmg hornangles ineach figure as theLWCwas decreas_ conditions the AEDC method provided a reasonable guide to soalh Figure 5 shows the ice shapes which resulted from applying the Olsen method using tbe same testconditions asthose infigure 4. Figure7Co)presents the same refermce ease asfigure 6(b). The Figure 5(a) givesresultsoftests withthe 5.I-era-diameter oylinder resulting ice shape matched the reference shape aswell as that and 5@) with the 15.4-cm-diameter. Notethata temperature fromusingthemodifiedFrenchmethod. TheAEDC andmodified increase of 2.8°C was requiredto mmpensate forthe change in Fremhmeex_ appear tohaveprovided approximatelyequivalent LWC fi'om 1.3to .8 ghn3. Theice shapes showed littlevariation scaling guidanceforthe conditions ofthese tests. over thisLWC rangewhen the Olsen method was applied. Modified French Method. Figure 6 compares results using the Concluding Remarks modified French scaling method with those from the original Thisstm'yhas imp tM of,x re anabzin8 French method. Reference tests used a5.l-cm-diameter cylinder tbeteadm-ed ineaablish meax The and scale tests were with a2.5-cm-diameter cylinder. Thesolid line represents the reference ice shape ineach case. Thedashed Olsen method inU'oduced a heat-balance analysis to correct lineshows tbe iceshape obtained whe--scale testconditions were temperature when the only scale test parameterwhich oan_be established using the original French method of Charpin and matchedtothe rofereo_eisLWC. Theice shapes which resulted Fasso3aad thedottedline,the ice shape using the modifiedFrench whea theOlsen method was appliedmaintainedboth the quantity methodasdisoassedabove. Thecooctinates ofthe iceshapes have of ice andthe shapewhen the liquid-water content was reduced been adjusted to present them at a common scale forease of from 1.3 to .8 g/m3. It was shown to give a significant compariso_ inscalediceshapes over the often-applied ruleLWC x time=constantwith ts=t_ Figure 6(a) gives the results for a relatively warm glaze ice condition. In addition to scaling the size by a factor of 2, the A modification ofthe French methodin whicha convective film airspeed was scaled from 76 m/s to 61 m/s. In view of the coeflScie_suitableforlaminarflow was substitutedforthe original di_iculty in repeating this ice shape (see figure 3('o)), boththe turbulent-flowooeff_ent improved the ability of scaled iceshapes French and the modified French method appeared to provide a tore_odace rderem¢ shapesfortheconditions tested. Finally,_e AEDC method was tested. It also used a laminar-flow film fairly good approximation. ¢oemdent andwas shown toprovide asimilarly-effective method Figure6(o) showstheresultsforscaling fromalower-temperature ofapproximating reference ice shapes. referencecasethanthatoffigure6(a). Mixed iceresulted fromthis test. Forthisexperiment, the scale airspeedwas the sameas the Althoughtberesultsweae_ a11ofthese scaling methods reference, 94 m/s. Distinctive hornswere formecL TheFrench need tobeevaluated under awide range of conditions and with gaveaniceshape(dashedlinew)hichreproducendeither differentgeometries tofullyconfirmtheir effectiveaem the horn size nor the ice thickness at the leading edge of the cylinder. The total quantity of soaledice appeared to match the rofcamceshape,howev_. Inc_elrast,the modified French method Referencu gave a shape (dottedline)which closely approximated the referenceicealthoughthere isasmalldifferenicnethehornangle. I. Andem_ David N.: "Rime-, Mixed- and Glaze-Ice Evaluations of Three Scaling Laws," AIAA 94-O718, January, Theseresultsprovideprdiminm7ocafirmationthat the substitution 1994. of a laminar-flow film coefficient for the originalturbulent-flow cce_cient intheFrenchanalysisprovidedimproved scaling forthe 2. Olsen, WilliamA.,unpublished notes. conditions considered. However, for tests with high Re it is possa_olethat the originalform ofthe Frenchmethodmaybemore 3. Char#n, Frmmis and Famo, Guy, "Icing Testing in the Lm-se Modane Wind Tmmel on Full Scale and Reduced Scale Models," L'Aermaufique et l'Asmmaufique, no 38, 1972. English translation published asNASA TM-75373. 4. Rnff, G.A., "Analysis md Vefitication of the Icing scalingEquati_" AEDC-TR-S5-30,VolI(Rev),March, 1986. 5. Soeder, Rmald I-Lend Andracchio, Charles, R., NASA "Lewis Icing Research Tunnel User Manual," NASA TM 102319, June, 1990. 6. Ide,Robert F., "Liquid Water Content end Droplet Size Calibration of the NASA Lewis Icing Rese.ar_ Tunnel," NASA TM 102447, Jimuary, !990. 7. Messinger,B I..",EquilibriuTmemlx:ratureofan UnheatedIcingStaqaoeasaFunotioaofAkslmed,"J._ Sci.20No. I,January,1953,pp29-42. Figare 2. Test Cylinder and Shield Mounted in IRT. 8. Langmuir, Irving and BlodgettK,atharineB.:"A MathematicalInvestigatioonfWaterIM_let Trajectcmes," Army Air Fcx_es Technical Report No. 5418, February, 1946. 9. Tribus, Myron; Young, G.B.W.; end Boelter, L.M-K.: "Analysis of Heat Transfer Over a Small Cylinder in Icing exactions on Monnt Washington," TransASME 70,pp 971-976, 1948. 10. Pruppach_, Hans R. and Klett, James D., Microphy_ica of Cloud8 and Precipitation, P,_del, Boston, 1980. 11. K_th, Frank, Principles of Heat Transfer, Inteznational, Sczantm, 1958. 12. Shin, Jaiwon and Bond, _H., "Results of an (a) c, 5.1 cm; V,94 m/s; tto¢,-7.8°C; 8, 30 tim;LWC, 1.3 g/m 3, Icing Test on aNACA 0012 in the NASA Lewis Icing Research t-,7.8 rain TunneL" NASA TM-105374, AIAA 92-0647, January, 1992. _ $8004twFm (b) c, 5.1 cm; V,61 m/s; t_t, -2.9°C; 8,20 _ LWC, 1.37 g/m3; r,6.6 rain. Fipre 1. NASA Lewis Icing Resear.,h Tunnel (IRT). Figare 3. _ of Ice Shapes for Repeated Tests. (a)CytindD_iam,5.1an(2in). tb)CytindDeiran_5,.l6,_n(6in). Figure 4. Results of Scaling With LWC x Time ffi_t. Airspeed,94m/s(210mph); TotalTemp, -7.8°C(18_r'3;DropletMedian Volume Dimmst_, 30 $tm_LWC xTime, 10.15 gmin/m3. .__ Lwc, 1.3g/mS;Time,7.Srain LWC, 1.0 ghn3; Time, 10.1 rain ............... LWC, .8 g/m3; Time, 12.7 rain ,._. .. X. k (a)CylinderDiam.,5.1ma (2in). (b)CylimlerDian_,l5.6an (6in). Figm_ 5. l_mlts foFOlsm Scalinglv_Imd. Airspeed, 94m/s (210 mph); Drop_Mediffia VolumeDiamct_, 30 _an; LWCx Time, 10.15 gmin/m 3. LWC, 1.3 8/m3; Time, 7.8 rain; Total Temp., -7.8°C LWC, 1.0 8/m3; Time, 10.1 min; Total Temp., -6.2°C ............... LWC, .8 g/m3; Time, 12.7 rain; Total Temp., -5.0°C 8