Analysis of Burning Candle - COMSOL · 2011. 3. 8. · Analysis of Burning Candle COMSOL Conference...
Transcript of Analysis of Burning Candle - COMSOL · 2011. 3. 8. · Analysis of Burning Candle COMSOL Conference...
![Page 1: Analysis of Burning Candle - COMSOL · 2011. 3. 8. · Analysis of Burning Candle COMSOL Conference October 7-9, 2010 . 1 . Presented at the COMSOL Conference 2010 Boston. Candle](https://reader035.fdocuments.us/reader035/viewer/2022062417/6147d44aa830d0442101b09d/html5/thumbnails/1.jpg)
Analysis of Burning Candle
COMSOL Conference
October 7-9, 2010
1
COMSOL Conference 2010 Boston Presented at the
![Page 2: Analysis of Burning Candle - COMSOL · 2011. 3. 8. · Analysis of Burning Candle COMSOL Conference October 7-9, 2010 . 1 . Presented at the COMSOL Conference 2010 Boston. Candle](https://reader035.fdocuments.us/reader035/viewer/2022062417/6147d44aa830d0442101b09d/html5/thumbnails/2.jpg)
Candle Multiphysics
• Heat
– Conduction
– Radiation
– Convection
• Fluid flow
• Phase change
• Combustion
2
![Page 3: Analysis of Burning Candle - COMSOL · 2011. 3. 8. · Analysis of Burning Candle COMSOL Conference October 7-9, 2010 . 1 . Presented at the COMSOL Conference 2010 Boston. Candle](https://reader035.fdocuments.us/reader035/viewer/2022062417/6147d44aa830d0442101b09d/html5/thumbnails/3.jpg)
Simplifying assumptions
• Heat of combustion approximated by a simple heat source
• Stationary analysis
• Symmetric boundary conditions
3
![Page 4: Analysis of Burning Candle - COMSOL · 2011. 3. 8. · Analysis of Burning Candle COMSOL Conference October 7-9, 2010 . 1 . Presented at the COMSOL Conference 2010 Boston. Candle](https://reader035.fdocuments.us/reader035/viewer/2022062417/6147d44aa830d0442101b09d/html5/thumbnails/4.jpg)
Model set up
• Air flow is described by conservation of mass, momentum, and energy
• Artificial diffusion added in plume
4
0 u
gIuuuuu
3
2Tp
upcQTk
![Page 5: Analysis of Burning Candle - COMSOL · 2011. 3. 8. · Analysis of Burning Candle COMSOL Conference October 7-9, 2010 . 1 . Presented at the COMSOL Conference 2010 Boston. Candle](https://reader035.fdocuments.us/reader035/viewer/2022062417/6147d44aa830d0442101b09d/html5/thumbnails/5.jpg)
Model set up
• Conduction in the solid domains:
• Anisotropic thermal conductivity
• Convective term added in fluid domains
5
QTk
![Page 6: Analysis of Burning Candle - COMSOL · 2011. 3. 8. · Analysis of Burning Candle COMSOL Conference October 7-9, 2010 . 1 . Presented at the COMSOL Conference 2010 Boston. Candle](https://reader035.fdocuments.us/reader035/viewer/2022062417/6147d44aa830d0442101b09d/html5/thumbnails/6.jpg)
Model set up
• Surface heat flux due to radiation
• Mutual irradiation (Gm) is a function of the radiosity
• Flame surface radiation is non-locally coupled to the radiating gas volume
6
44 TTFGq ambambmr
441 TTFGJ ambambm
![Page 7: Analysis of Burning Candle - COMSOL · 2011. 3. 8. · Analysis of Burning Candle COMSOL Conference October 7-9, 2010 . 1 . Presented at the COMSOL Conference 2010 Boston. Candle](https://reader035.fdocuments.us/reader035/viewer/2022062417/6147d44aa830d0442101b09d/html5/thumbnails/7.jpg)
Model set up
• Surface radiosity is a function of the average value of T4 in the radiating gas volume
• Heat flux qr is set to zero at the boundary
• Source term is included in the flame region to account for cooling due to radiation
7
V
ATQ
4
![Page 8: Analysis of Burning Candle - COMSOL · 2011. 3. 8. · Analysis of Burning Candle COMSOL Conference October 7-9, 2010 . 1 . Presented at the COMSOL Conference 2010 Boston. Candle](https://reader035.fdocuments.us/reader035/viewer/2022062417/6147d44aa830d0442101b09d/html5/thumbnails/8.jpg)
Model validation
• Temperature as function of position along wax surface
• Temperature as a function of candle height
• Location of interface between solid and liquid
8
![Page 9: Analysis of Burning Candle - COMSOL · 2011. 3. 8. · Analysis of Burning Candle COMSOL Conference October 7-9, 2010 . 1 . Presented at the COMSOL Conference 2010 Boston. Candle](https://reader035.fdocuments.us/reader035/viewer/2022062417/6147d44aa830d0442101b09d/html5/thumbnails/9.jpg)
Validation
Measured (C) FEA (C) Full Candle 40 46 Half Candle 44 49
Average temperature of glass along top outer edge
S-L interface: 54 C Line: Measured Area: Predicted
Full Candle
40
45
50
55
60
65
70
75
80
85
90
0 5 10 15 20 25 30 35 40 45 50
Distance from Center (mm)
Tem
pera
ture
(deg
C)
FEAMeasured
1mm below surface Radial through wick
9
![Page 10: Analysis of Burning Candle - COMSOL · 2011. 3. 8. · Analysis of Burning Candle COMSOL Conference October 7-9, 2010 . 1 . Presented at the COMSOL Conference 2010 Boston. Candle](https://reader035.fdocuments.us/reader035/viewer/2022062417/6147d44aa830d0442101b09d/html5/thumbnails/10.jpg)
Full candle
¼ “ candle
½ Full candle
Results: Temperature @ Wax surface
10
![Page 11: Analysis of Burning Candle - COMSOL · 2011. 3. 8. · Analysis of Burning Candle COMSOL Conference October 7-9, 2010 . 1 . Presented at the COMSOL Conference 2010 Boston. Candle](https://reader035.fdocuments.us/reader035/viewer/2022062417/6147d44aa830d0442101b09d/html5/thumbnails/11.jpg)
1mm below surface
5mm above surface
10mm above surface
Surface
Results: Temperature
10mm above surface
11
![Page 12: Analysis of Burning Candle - COMSOL · 2011. 3. 8. · Analysis of Burning Candle COMSOL Conference October 7-9, 2010 . 1 . Presented at the COMSOL Conference 2010 Boston. Candle](https://reader035.fdocuments.us/reader035/viewer/2022062417/6147d44aa830d0442101b09d/html5/thumbnails/12.jpg)
Results: Wick location
Surface Temperature along Radial Line through Wick - Full Candle
50
70
90
110
130
150
170
190
210
230
250
270
0 5 10 15 20 25 30 35 40 45 50
Distance from Center (mm)
Tem
pera
ture
on
Surfa
ce (d
egC
) Baseline0.125" Toward Center0.125" Toward Edge
Temperature 1 mm Down along Radial Line through Wick - Full Candle
50
55
60
65
70
75
80
85
90
0 5 10 15 20 25 30 35 40 45 50
Distance from Center (mm)
Tem
pera
ture
on
Surfa
ce (d
egC
) Baseline0.125" Toward Center0.125" Toward Edge
12
![Page 13: Analysis of Burning Candle - COMSOL · 2011. 3. 8. · Analysis of Burning Candle COMSOL Conference October 7-9, 2010 . 1 . Presented at the COMSOL Conference 2010 Boston. Candle](https://reader035.fdocuments.us/reader035/viewer/2022062417/6147d44aa830d0442101b09d/html5/thumbnails/13.jpg)
Results: Flow
½ Full candle Full candle ¼ “ candle
13
![Page 14: Analysis of Burning Candle - COMSOL · 2011. 3. 8. · Analysis of Burning Candle COMSOL Conference October 7-9, 2010 . 1 . Presented at the COMSOL Conference 2010 Boston. Candle](https://reader035.fdocuments.us/reader035/viewer/2022062417/6147d44aa830d0442101b09d/html5/thumbnails/14.jpg)
Summary
• Analysis incorporating – Conduction
– Convection
– Radiation
– Phase change
• Validated model
• Effects of candle location/height
– Temperature distribution
– Flow
14