报告内容：关于池火燃烧和辐射特性的专题报告（第二部分）
报 告 人：John de Ris博士（中科院外国专家特聘研究员）
报告时间：12月20日下午3:00
报告地点：火灾实验室多媒体会议室
参加人员：欢迎感兴趣的师生参加！

报告摘要：
The talk presents a model for the radiant fraction, incompleteness of combustion, and

effective radiation temperature with its associated absorption coefficientfor buoyant

turbulent diffusion flames characteristic of fires.Effects of heat loss (gain) to  nearby

surfaces are included.
The combustion of the turbulent diffusion flamesis driven by the local Rayleigh

instability of the flamelets. It results inthe: (1) volumetric heat release rate,

(2) radiant fraction, and

(3) incompleteness of combustion all being constants independent of the fire size.
Radiation comes primarily from luminous soot. The radiative heat loss from

 flamelets causes their local extinction with release of soot. Radiative

extinctionoccurs in both buoyant turbulent diffusion flamesas well as

laminar “candle” flames at their smoke point.It results in a close correspondence

between turbulent and laminar flames for their soot formation rates and dependence

on dependence on the flame adiabatic stoichiometric temperature.

The correspondence produces a simple empirical relationship between the

incompleteness of combustion of turbulent flames to the fuel’s laminar-flame

smoke point flame-height.
The effective flame radiation temperature riseabove ambient is estimated to

be 75% of the effective convective temperature rise. Conservation of energy

then provides a simple expression relating the radiant fraction, convective fraction

and incompleteness of combustion.The expression produces a simple correlation

of over 300 measurements for the radiant fraction from burning hydrocarbon

gases (CH4, C2H6, C3H8, C2H4, C3H6 and C4H8) in terms of their enthalpy

available for radiation and theiroxidant to fuel stoichiometric mass ratio.
Fuels appear to divide into two classes: moderately sooty and extremely sooty flames.

Each has its own relationship between radiant fractions and incompleteness of

combustion.
In summary, the model provides the radiant fraction, incompleteness of combustion,

effective flame radiation temperature and absorption coefficient in terms

of tabulated fuel properties.