1. RADIATION AND COMBUSTION PHENOMENA
PROF. SEUNG WOOK BAEK
DEPARTMENT OF AEROSPACE ENGINEERING, KAIST, IN KOREA
ROOM: Building N7-2 #3304
TELEPHONE : 3714
Cellphone : 010 –
TA : Jonghan Won
ROOM: Building N7-2 # 3315
TELEPHONE : 3754
Cellphone :

2. RADIATIVE HEAT TRANSFER
GAS RADIATION
EXAMPLE
THIS PROBLEM HAS SOME OF THE FEATURES OF A FLAME IN A PREMIXED COMBUSTABLE GAS STREAM. ew
PROPULSION AND COMBUSTION LABORATORY
RADIATIVE HEAT TRANSFER

3. RADIATIVE HEAT TRANSFER
GAS RADIATION
FOR THIN GAS
LINEARIZE
PROPULSION AND COMBUSTION LABORATORY
RADIATIVE HEAT TRANSFER

4. RADIATIVE HEAT TRANSFER
GAS RADIATION
INTRODUCE
INTRODUCE
PROPULSION AND COMBUSTION LABORATORY
RADIATIVE HEAT TRANSFER

5. RADIATIVE HEAT TRANSFER
GAS RADIATION
FOR , SHOULD APPROACH RATHER THAN ! WHAT IS WRONG?
PROPULSION AND COMBUSTION LABORATORY
RADIATIVE HEAT TRANSFER

6. RADIATIVE HEAT TRANSFER
GAS RADIATION
EXAMPLE
RADIATION AFFECTED STEADY BUOYANCY DRIVEN FLOW IN A VERTICAL SLOT
BASIC ASSUMPTION
INCOMPRESSIBLE FLOW EXCEPT FOR BUOYANCY (BOUSSINESQ APPROXIMATION: FOR VERY SMALL DENSITY CHANGE)
PROPULSION AND COMBUSTION LABORATORY
RADIATIVE HEAT TRANSFER

7. RADIATIVE HEAT TRANSFER
GAS RADIATION
MASS (PARALLEL FLOW IN x)
X- MOMENTUM
IF THE TEMPERATURE WERE TO APPROACH A UNIFORM VALUE, SAY , THEN CONVECTION WOULD STOP.
PROPULSION AND COMBUSTION LABORATORY
RADIATIVE HEAT TRANSFER

8. RADIATIVE HEAT TRANSFER
GAS RADIATION
IS THE HYDROSTATIC PRESSURE CORRESPONDING TO DENSITY AND TEMPERATURE
ENERGY (THERMAL)
MOTION HAS NO EFFECT ON TEMPERATURE DISTRIBUTION ! (SOLVED BEFORE)
FOR BUOYANCY
DRIVEN FLOW, THEN
LET
PROPULSION AND COMBUSTION LABORATORY
RADIATIVE HEAT TRANSFER

9. RADIATIVE HEAT TRANSFER
GAS RADIATION
FOR COMBINED (FORCED BUOYANCY DRIVEN) FLOWS, THE PRESSURE TERM BECOMES APPRECIABLE.
CONSTITUTION
MOTION IS GOVERNED BY
FOR MOST OF NATURAL CONVECTION PROBLEM, THE DENSITY VARIATION IS MAINLY CAUSED BY THE THERAMAL EXPANSION OF THE FLUID.
PROPULSION AND COMBUSTION LABORATORY
RADIATIVE HEAT TRANSFER

10. RADIATIVE HEAT TRANSFER
GAS RADIATION
INTRODUCE
, COEFFICIENT OF THERMAL EXPANSION
THEN
AND
FROM THE PREVIOUS RESULTS ON
LINEARIZED THIN GAS BETWEEN TWO PLATES
PROPULSION AND COMBUSTION LABORATORY
RADIATIVE HEAT TRANSFER

11. RADIATIVE HEAT TRANSFER
SLIDE 22 IN FILE 7
GAS RADIATION
REARRANGE
PROPULSION AND COMBUSTION LABORATORY
RADIATIVE HEAT TRANSFER

12. RADIATIVE HEAT TRANSFER
GAS RADIATION
INTEGRATE TWICE
PROPULSION AND COMBUSTION LABORATORY
RADIATIVE HEAT TRANSFER

13. RADIATIVE HEAT TRANSFER
GAS RADIATION
BC’S
FROM
FROM
WITH
PROPULSION AND COMBUSTION LABORATORY
RADIATIVE HEAT TRANSFER

14. RADIATIVE HEAT TRANSFER
GAS RADIATION OR
IN TERMS OF OR
PROPULSION AND COMBUSTION LABORATORY
RADIATIVE HEAT TRANSFER

15. RADIATIVE HEAT TRANSFER
GAS RADIATION
FINALLY, THE CONDITION OF NO NET FLOW,
GIVES THE TEMPERATURE WHICH IS THE BASE FOR BUOYANCY.
PROPULSION AND COMBUSTION LABORATORY
RADIATIVE HEAT TRANSFER

16. RADIATIVE HEAT TRANSFER
GAS RADIATION
WHICH GIVES
WHAT HAPPENS AS OR ?
HW#5 [REF.1] P.734 #14-1, 14-4
PROPULSION AND COMBUSTION LABORATORY
RADIATIVE HEAT TRANSFER

17. HW#5 [REF.1] P.734 #14-1, 14-4
14-1. A slab of non-scattering solid material has a gray absorption coefficient of and
refractive index It is 2 cm thick and has an approximately linear temperature distri-
bution within it as established by thermal conduction. What is the emitted intensity normal
to the slab? What average slab temperature would give the same emitted normal intensity?
14-4. A non-scattering stagnant gray medium with absorption coefficient is contained
between black parallel plates 10 cm apart as shown (assume constant density and ).
Plot the temperature distribution T(z) (neglect thermal conduction). What is the net energy
flux being transferred by radiation from the lower to the upper plate? If the plates are gray
with ε1 = 0.8 and ε2 = 0.4, what is the energy flux being transferred?
< 14-1 >
< 14-4 >