R ADIATION AND C OMBUSTION P HENOMENA P ROF. S EUNG W OOK B AEK D EPARTMENT OF A EROSPACE E NGINEERING, KAIST, IN KOREA R OOM : Building N7-2 #3304 T ELEPHONE : 3714 Cellphone: 010 – T A : Bonchan Gu R OOM : Building N7-2 # 3315 T ELEPHONE : 3754 Cellphone: 010 – P ROF. S EUNG W OOK B AEK D EPARTMENT OF A EROSPACE E NGINEERING, KAIST, IN KOREA R OOM : Building N7-2 #3304 T ELEPHONE : 3714 Cellphone: 010 – T A : Bonchan Gu R OOM : Building N7-2 # 3315 T ELEPHONE : 3754 Cellphone: 010 –

G RADING S YSTEM Homework (20%), 1 Final Exam (80%) T EXT : None R EFERENCES … 1.Siegel, R. and Howell, J.R., Thermal radiation heat transfer, 4 th, Taylor&Francis, Sparrow, E.M. and Cess, R.D., Radiation heat transfer, Brooks/Cole Publishing Company, Michael F. Modest, Radiative Heat transfer, 2 nd Academic Press, M. Quinn Brewster, Thermal Radiative Heat Transfer and Properties, Wiley-Interscience, 1992 R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY

O UTLINE… PART I. RADIATIVE EQUILIBRIUM PART II. RADIATIVE NON-EQUILIBRIUM 1.ENCLOSURE (SURFACE) RADIATION 2.GAS RADIATION PART III. RADIATIVE PROPERTIES PART IV. RADIATION AFFECTED TRANSPORT PHENOMENA R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY

T HERMAL R ADIATION A fundamental difference between conduction and radiation is in their distribution. R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY I NTRODUCTION ConductionRadiation Temporal Spatial Specular Distribution Geometry Quantum mechanics Optics Explicitly,

Its importance becomes intensified at high temperature levels: furnaces, combustion chamber, rocket nozzle, nuclear power plant, etc. No medium required With conduction and convection – nonlinear integro- differential equation : Difficult to solve!!! Radiative physical property depends on surface roughness, material, thickness of coating, temperature, angle, etc. R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY I NTRODUCTION

Classical electromagnetic wave theory T HEORY OF R ADIANT E NERGY P ROPAGATION E XCEPTIONS Spectral distribution of the energy emitted from a body and the radiative properties of gases - explained by only quantum mechanics [particle(photon) theory] R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY I NTRODUCTION

S PECTRUM OF E LECTROMAGNETIC R ADIATION R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY I NTRODUCTION

S PECTRUM OF E LECTROMAGNETIC R ADIATION NEAR V ISIBLE R AY R EGION R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY I NTRODUCTION Wavelength [ ㎛ ] Ultraviolet Red Infra-red Violet Thermal Visible

P ART I. R ADIATIVE E QUILIBRIUM A D IRECTIONAL V OLUME S OLID A NGLE R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY

T WO M ORE D EFINITIONS D IFFERENTIATE WITH R ESPECT TO F ROM THIS R ELATION R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE E QUILIBRIUM

F OR I SOTROPIC R ADIATION AT E QUILIBRIUM D IVIDE BY, D IFFERENTIATE WITH R ESPECT TO THERMALOPTICS emissive power unprojected area projected area R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE E QUILIBRIUM

F OR I SOTROPIC B LACKBODY R ADIATION AT E QUILIBRIUM R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE E QUILIBRIUM

T HEN, THERMALOPTICS Stefan-Boltzmann Law : Stefan-Boltzmann Constant R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE E QUILIBRIUM

D EFINITION … An ideal body that allows all the incident radiation to pass into it ( no reflected energy) and absorbs internally all the incident radiation ( no transmitted energy) ; perfect absorber of incident radiation. P ERFECT E MITTER IN E ACH D IRECTION AND AT E VERY W AVE L ENGTH In equilibrium condition, the blackbody must radiate exactly as much energy as it absorbs. The intensity of radiation from a blackbody is independent of the direction of emission. B LACKBODY R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE E QUILIBRIUM

S PECTRAL D ISTRIBUTION OF B LACKBODY E MISSIVE P OWER R ADIATIVE E QUILIBRIUM UNIFORM ISOTROPIC M ATTER R ADIATION FOR S PHERE R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE E QUILIBRIUM U SING S IMILARLY

: Wien’s (D ISPLACEMENT ) L AW R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE E QUILIBRIUM At a higher temperature, the peak intensity shifts to a shorter wavelength

F ROM Wien’s L AW M ONOCHROMATIC ( S PECTRAL ) B LACKBODY E MMISIVE P OWER AT E QUILIBRIUM WITH, R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE E QUILIBRIUM

H AS A M AXIMUM AT W AVELENGTH FOR A G IVEN T EMPERATURE R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE E QUILIBRIUM

H EMISPHERICAL S PECTRAL E MISSIVE P OWER OF B LACKBODY FOR S EVERAL D IFFERENT T EMPERATURES R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE E QUILIBRIUM

When radiation travels from one medium into another, the frequency remains constant while the wavelength changes because of the change in propagation velocity. Wave number : the number of waves per unit length. R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE E QUILIBRIUM

BLACKBODY EMISSION INTO VACUUM T HE Planck D ISTRIBUTION OF THE M ONOCHROMATIC E MISSIVE P OWER WHERE F ROM O RIGIN OF Q UANTUM M ECHANICS R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE E QUILIBRIUM Planck’s constant : Boltzmann’s constant :

T HE Rayleigh-Jeans D ISTRIBUTION F OR R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE E QUILIBRIUM

S PECTRAL D ISTRIBUTION OF B LACKBODY H EMISPHERICAL E MISSIVE P OWER R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE E QUILIBRIUM

1.Energy emitted at all wave lengths increases as the temperature increases. 2. Peak spectral emissive power shifts toward a smaller wavelength as the temperature is increased. 3.Red light becomes visible first as the temperature is raised – at sufficiently high temperature, the light emitted becomes white. C HARACTERISTICS… R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE E QUILIBRIUM

T EMPERATURE M EASUREMENT U SING 4 W AVELENGTH P YROMETER Planck’s D ISTRIBUTION L AW F OR N ON-BLACKBODIES, R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE E QUILIBRIUM

T HE I NTENSITY OF R ADIATION M EASURED BY A P HOTODIODE FOR GRAY BODIES a calibration factor including all radiation absorbed between the emission source and the photodiode (e.g. windows, optical elements, filter, etc.) R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE E QUILIBRIUM

F OR N ON- G RAY B ODY S HOULD D ETERMINEFOR C ALIBRATION U SING G RAPHS FOR R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE E QUILIBRIUM

E MISSIVITY OF T UNGSTEN R IBBON AS A F UNCTION OF T EMPERATURE FOR D IFFERENT W AVELENGTH R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE E QUILIBRIUM

R ELATIVE E MISSIVE P OWER AS A F UNCTION OF W AVELENGTH FOR D IFFERENT T EMPERATURES R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE E QUILIBRIUM

R ELATIVE V OLTAGE O UTPUTS U SING T UNGSTEN L AMP AS A FUNCTION OF T EMPERATURE D EPENDING ON D IFFERENT C HANNELS AND D IFFERENT S ETUPS R ADIATIVE H EAT T RANSFER P ROPULSION AND C OMBUSTION L ABORATORY R ADIATIVE E QUILIBRIUM