Burning characteristics of candle flames in sub-atmospheric pressures: An experimental study and scaling analysis
KAUST DepartmentClean Combustion Research Center
Combustion and Laser Diagnostics Laboratory
Mechanical Engineering Program
Physical Science and Engineering (PSE) Division
Online Publication Date2018-07-08
Print Publication Date2019
Permanent link to this recordhttp://hdl.handle.net/10754/628241
MetadataShow full item record
AbstractBurning characteristics (mass burning rate, natural convection boundary layer thickness, flame height and dark zone height) of laminar diffusion flames produced by a candle at sub-atmospheric pressures in the range of P = 50-100 kPa were experimentally studied in a reduced-pressure chamber; such data are not reported to date. Scaling analysis was performed to interpret the pressure dependence. The new experimental findings for candle flames in the sub-atmospheric pressures were well interpreted by the proposed scaling laws: (1) the mass burning rate was higher for a candle with larger wick length, and it increased with increasing ambient pressure, a stagnant layer B-number model based on natural convection boundary (flame boundary layer thickness) was developed to scale the mass burning rate of candle flames at various pressures; (2) the flame boundary layer thickness was wider in lower pressure and can be well represented by a natural convection boundary layer solution; (3) flame height was higher for a candle with larger wick length, meanwhile the ratio of flame height to burning rate was independent of pressure; (4) the flame dark zone height representing a soot formation length scale changes little with pressure, meanwhile its ratio to the total flame height is scaled with pressure by P∞-1/2/Lw,e3/4 (L is effective wick length inside flame). This work provided new experimental data and scaling laws of candle flame behaviors in sub-atmospheric pressures, which provided information for future characterization and soot modeling for diffusion flames associated with melting and evaporation processes of solid fuels.
CitationWang Q, Hu L, Palacios A, Chung SH (2018) Burning characteristics of candle flames in sub-atmospheric pressures: An experimental study and scaling analysis. Proceedings of the Combustion Institute. Available: http://dx.doi.org/10.1016/j.proci.2018.06.113.
SponsorsThis work was supported jointly by National Natural Science Foundation of China (51606057), Newton Advanced Fellowship of Royal Society, UK (NA140102), Fundamental Research Funds for the Central Universities (JZ2018HGTB0256; WK2320000035; WK2320000038), NSFC-STINT joint project (51811530015), Key Research Program of Frontier Sciences of Chinese Academy of Science (CAS) (QYZDB-SSW-JSC029) and China Postdoctoral Science Foundation funded project (2018T110625; 2016M590580). SHC was supported by KAUST.