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1、RADIATIVEVIEWFACTORSViewfactordefinition2Viewfactoralgebra2Withspheres3Patchtoasphere3Frontal3Level3Tilted3Disctofrontalsphere3Cylindertolargesphere4Cylindertoitshemisphericalclosingcap4Spheretosphere5Smalltoverylarge5Equalspheres5Concentricspheres5Hemispheres6Withcylinders6Cylindertolargesphere6Cyl
2、indertoitshemisphericalclosingcap6Concentricvery-longcylinders6Concentricvery-longcylindertohemi-cylinder7Wiretoparallelcylinder,infiniteextent7Parallelvery-longexternalcylinders7Basetofinitecylinder7Equalfiniteconcentriccylinders8Withplatesanddiscs8Parallelconfigurations8Equalsquareplates8Unequalco
3、axialsquareplates9Boxinsideconcentricbox9Equalrectangularplates10Equaldiscs10Unequaldiscs11Striptostrip11Patchtoinfiniteplate11Patchtodisc11Perpendicularconfigurations12Squareplatetorectangularplate12Rectangularplatetoequalrectangularplate12Rectangularplatetounequalrectangularplate12Striptostrip13Ti
4、ltedconfigurations13Equaladjacentstrips13Triangularprism13References13VIEWFACTORDEFINITIONTheviewfactorF12isthefractionofenergyexitinganisothermal,opaque,anddiffusesurface1(byemissionorreflection),thatdirectlyimpingesonsurface2(andisabsorbedorreflected).Someviewfactorshavingananalyticalexpressionare
5、compiledbelow.Viewfactorsonlydependongeometry,andcanbecomputedfromthegeneralexpressionbelow.Considertwoinfinitesimalsurfacepatches,dA1anddA2(Fig.1),inarbitrarypositionandorientation,definedbytheirseparationdistancer12,andtheirrespectivetiltingrelativetothelineofcentres,b1andb2,with0£b1£p/2and0£b2£p/
6、2(i.e.seeingeachother).TheradiationpowerinterceptedbysurfacedA2comingdirectlyfromadiffusesurfacedA1istheproductofitsradianceL1=M1/p,timesitsperpendicularareadA1^,timesthesolidanglesubtendedbydA2,dW12;i.e.d2F12=L1dA1^dW12=L1(dA1cos(b1))dA2cos(b2)/r122.Thence:Fig.1.Geometryforview-factordefinition.Whe
7、nfinitesurfacesareinvolved,computingviewfactorsisjustaproblemofmathematicalintegration(notatrivialone,exceptinsimplecases).Recallthattheemittingsurface(exiting,ingeneral)mustbeisothermal,opaque,andLam