消防服用织物热防护性能数值模拟

Numerical simulation on thermal protection performance of textile used for fire fighting suit

消防服用织物在纯火焰对流热作用下与纯辐射热作用下的传热机制有一定区别,表现在服装与热源之间换热边界条件上。建立纯火焰对流作用下消防服传热模型,分析火焰与服装织物外层之间的换热边界条件,运用实验法确定火焰换热系数经验式,研究衣下微气层传导对流传热特征。火焰传热系数由辐射换热系数和对流换热系数组成;火焰热流密度为84kW/m2时,衣下微小空气层厚度不超过9mm时其热传递以传导换热为主,空气层越厚导热系数越小;空气层厚度大于9mm时其热传递以对流换热为主,空气层越厚传热系数越大。

There is difference between the heat transfer mechanism of textile used for fire fighting suit under pure flame convective heat or pure radiant heat.The key of heat transfer mechanism is boundary condition of heat transfer between suit and heat origin.The boundary condition of heat transfer between flame and textile of suit was analyzed by establishing the heat transfer model of fire fighting suit under pure flame convection.The empirical formula was determined by experiment and the characteristics of convective heat transfer of little air layer under the suit was researched.The flame heat transfer coefficient was composed by radiation heat transfer coefficient and convective heat transfer coefficient.As the flame heat flux is 84 kW/m2,the heat transfer is dominated by conduction heat transfer for the case that the thickness of small air layer under clothing is not more than 9 mm.The thick the air layer is,the smaller the thermal conductivity is.Convective heat transfer is the main heat transfer mechanism under the same condition for the case that the thickness of small air layer is greater than 9 mm.The thicker the air layer is,the greater the thermal conductivity is.