1、.I,1(I#NATIONALADVISORYCOMMITTEEFOR AERONAUTICS-.PERFORATEDTECHNICAL NOTE 3669SHEETS AS A POROUS MATERIAL FORDISTRIBUTEDSUCTION AND INJECTIONBy Robert E. Dannenberg, Bruno J. Gambucci,and James A. WeibergAmes Aeronautical LaboratoryMoffett Field, Ca.lif.WashingtonApril 1956.,. . . . . . . . . . . .
2、. . ._-. . . . -,-_Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TECH LIBRARY KAFB, NMQ IllullllllfllllllnlnuTOYKIONALADVISORY COMMITTEEFOR AERONAUTICS 00LL1487TECHNICAL NOTE 3669PERFORATED SHEETS AS A POROUS MATERIALSUCTION AND INJECTIONBy Robert
3、E. Dsmnenberg, Bruno J.and James A. WeibergFOR DISTRIBUTEDGambucci,Measurements were made ofperforated metal sheets havingthe resistance to air flow of a series ofopen areas ranging from less than1 percent up to 41 percent. The results showd that the permeabili ofa perforated sheet is governed princ
4、ipally by its open-area ratio. Thenumber of holes per squsre inch, the sheet thiclmess, and the shape ofthe individualholes had little or no effect on permeabty.As a porous material for boundary-layer-controlapplicatims by meansof distributed suction or injection,punch-perforated sheets can be madet
5、o any desired permeability. For these applicatims it is usually neces-sary to have different permeability at different locations. To achievea graent permeabity the size and/or spactig of the holes h succes-sive rows can be varied commensuratelywith the prescribed variation inpermeability. Gradient p
6、ermeability also can be-achieved th uniformlyperforated sheets combined with some form of resistance backing to fur-nish the gradient effect.INTRODUCTION.,h wind-tunnel and flight applications of various aerodynamicsystems using distributed suction or injection, two types of materialarrangementshave
7、 been used in the porous region. b one type, a singlematerial.(e.g., sintered metals) provides both the outer surface and thecontrol of porous-flow resistivity. The other type is a composite orsandwich arrangement of two or more clifferent materials which, in combti- ,tion, have properties not posse
8、ssed by a single material.The physical propties of the material used in the porous regionfor any aerodynamic type of system involving either pvz. The miulmum permeabilityshown in the figure (correspondingto that of a sheet with l/4-percentopenarea) is representative of a nonaerodynamic application o
9、f an extremelydense material for filtration use. This limit may be considered as aboutthe minimum value of permeability required in any typq of porous material.The minhum permeability required for aercxiynamicapplication,particu-larly for boisry-layer control,would be expected to correspond to about
10、the permeability of a l-percent open area perforat whereasfor perforated sheets the flow velocity increased approximately as thesquare root of the pressure difference. This dissimilarity h flow char-acteristics of porous regions having labyrinth type of passageways andthose having straight-throughho
11、les could have an brportant effect on theperformance of suction or injection systems at off-design conditions. Asillustrated in figure 13, for two systems having the identical designconditions, a change h the pressure across the porous surface wouldproduce a seater chsnge in the flow quantity for th
12、e surface withlabyrinth-likepassageways than for that with straight-throughholes.Since the basic requirement of suction and injection systems generally isto maintain a specifiedflow quautity, a system using a pforated sheetmaterial in the porous region would have the advantage of betig less sensi-ti
13、ve to pressure changes than one using granular or fibrous materials.CONCLUDING REMARKS .Measurements were made of the air-flow resistance characteristicsofperforated metal.sheetswith straight-throughholes. The primary factor .affecting the flow resistance of a perforated sheet was fetid to be theope
14、n-arearatio. The number of holes per sgyare inch, the sheet thick-ness and the shape of the individualholes had little or no effect on thepermeability in the range of variables tested.As a porous material, punch-perforated sheets can be made to anydesired permeability. For gxadient permeability, the
15、 punched sheets canbe used either (1) alone, with a nonuniform perforation pattern toprovide the gradient variation or (2)with a uniform perforation pattern,to provide the outer surface of a composite or sandwich ty-peof assemblyin which a second underlying porous material (e.g.,fibrous-glasscompact
16、s) furnishes the adient variation.Ames Aeronautical LaboratoryNational Advisory Committee for AeronauticsMoffett Field, Calif., 1955.Dannenberg, Robert E., Weiberg, Janes A., and Gambucci, Bruno J.:The Resistance to Air Flow of Porous Materials Suitable forBoundary-Iay-Control Applications Using tie
17、s Suction. NACATN 3094, 1954. -. -.- -. - _ - -Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-10 NACA TN 3669Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-I-1.50105I5 10 I D 5Suction air velocity,
18、v, fpsFigure 1.- Range of permeabity of interest for materiala used in theporous region of systems using area suction,for high lift or forstabilization of the laminar boundary layer.-. ._. - -.- - - -Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-“W
19、wim2 3 459Figure 2.- Detailsf low of various0.016 inch.6107 8Holediem., HelmNACA TN 3669,IIPercent12256789100.023.023.023.026.026.023.o.020.04507914.5 0.6024.1 1.047 2.057.6 3.073.7 3.9134 5.6U. slot 0.020 x 0.=5 140 30(a)Perforation description.of the perforation pattern and the resistance to airme
20、tsl sheets with die-punchedholes; thickness =Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA TN 3669 13Sheeto 1A 2a75 30 4v 5d 6h 7n 80 9a 10w II.Suction oir velocity, v, fps(b)Flow-resistance characteristics.Figure 2.- Concluded., .- .- -. - -
21、. . -. - . .-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-14 NACA TN 3669I 34 5 67 8Holedim., Holes PercentSheet in. per sq h. w=1 0.01352 .Oq3 .W4 . W375 .0076 .0135.196: .27717.564.9129.825;. 6139.8110.25.25.50.871.02.03.837.67(a)Perforation des
22、cription.Figure 3.- Details of the perforation patterns aud the resistance to airflow of various brass sheets with drilled holes; thictiess = 0.016 inch.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA TN 3669 15Sheeto IA 2a75 30 4v 5L1 6L 7“n 81
23、0Suction air velocity, v, fps(b) Flow-resistance characteristics.Figure 3.- Concluded.-. -. -. . - - - - z . . -.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-16B-.=._.=_.-.-Electrolyticallydepositednickel40countSquarehole: o.olkinchHOles/q in.: 1,
24、600Percentopen: 9.3TkkkneEw: o. tichElectrolicalJydepositednickel65.countS-e hole: O.Cthiclmess = 0.016 tich.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA TN 3669 19.55ISuction air velocity, v, fpsSheet(b)Flow-resistance characteristics.Figure
25、 .- Concluded.o IA 2a75 30 4v 5a 61 5Y” 10Pressure difference across sheetrequired to induce a euction airvelocity af 1 foot per second, inchesaf water.- . . .- .- _. .-. . - .-.- Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-20 NACA TN 3669Holedla
26、m.: 0.113inch Holedlam.: .0.0935InchHoles/sqb. : 1 Holes/sqIn.: 1.8Percentopen: 1.2-j Percentopen: u(a)Perforation description.(b)Flow-resistance characteristicsFure 6.- Effect of sheet thickness on the resistance to air flow ofvarious hilled brass sheets.Provided by IHSNot for ResaleNo reproduction
27、 or networking permitted without license from IHS-,-,-NACA TN 3669. SCIc5I.5I-.,.-,.,“. .- . . ?. w;,;,.”. Zij-E,:,/.,.,+,.-.:., :.4,:.”:2,:., .q;,.:.;,., .-7 ?/.,.Y.”,.-.,t. . .“”.:.,:., ., .,2 0 , . . ;-.,.;.;.,: “:.;.”;:”.-:.; ,-:;:,.“%.:;+.,.-.-.,.,:,-,.,.,:,:j:,.y.%.?.,“. - - .-,.- - - - - . .
28、. . .-. - - - - . - . - - - - . . . . - - -.- - -.- “- .- - .- - .“ - .“ -. .- -. .-/-. . -. - - - . . . . . . .- - - . . .- .- A- A- - - . . . . . . . . .- . . . . . - . . . . . - - - . . . . . -L .-.-.”- . -”- -. -A- - - - -.-.4K.-:- ”- ”-” ”2.”.-”.2. . -.-.*. . . . . . . “ -AL. - - “- “- - “-A. .
29、 - . . . .4-.-A-21090(a) Single sheet incorporating its om permeability. Open area ecjyals5.4 percent.A-208%8(b)High-strength assembly with sheets bonded to fibrous-glass compact.Compact provides for permeability. Open area of surface sheetequals 27 percent.Figure 11.- Illustrated forms of punch-per
30、forated sheets used as a poroussurface. Both installationshave eq and uniform permeability.- - - - -Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-26 NACA TN 3669-.:,:;:,:.:.,%:.l,.q,:.,:M:i:.!:;ii: Range of permeabtityfor:!,1. Perfacatalsheetsmdwov
31、anwireclothmaterialswith= op =ea of lessthanabout7 percent.2. Perforatedsheetandvovenwireclothrrat with OPI=- of aboutU. percmt or greaterandticamposfteaasdl.y vith a second, smredense,undcr-W mat- (ref.Xl).3. ter Wpers (ref.12).4. Feltcloths(ref.U).5. GramJar and sinteredmetals(ref.12).t = 70 F.Pro
32、vided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-I20100806040200/Straigo;et$rough-+=Design point(typical for lift- controlapplication)/4 6 8 10k Labyrinth-likepassageways3=27II2Flow quantity per unit area, cu ftisecisq ftFigure 13. - Variation of suction flow quantitywith pressure differenceacross a porous region with either straight-throughholes or labinth-like passageways.NACA - Langley Field, V&*Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
