考虑气体扩散渗透的隔热材料瞬态隔热性能数值模拟  

Numerical Simulation on Transient Insulating Properties of Thermal Insulation Materials With Gas Permeation

作　　者：周优均 李东辉[1] 夏新林[1] 

机构地区：[1]哈尔滨工业大学能源科学与工程学院,哈尔滨150001

出　　处：《宇航材料工艺》2014年第1期29-32,共4页Aerospace Materials & Technology

基　　金：国家自然科学基金(51176038);高等学校博士学科点专项科技基金(20112302110017)

摘　　要：高超声速飞行器机动飞行时环境压力变化导致隔热材料沿厚度方向存在压力梯度,进而引起隔热材料内气体的扩散渗透,影响隔热材料隔热性能。为研究气体扩散渗透对隔热材料隔热性能的影响,建立了隔热材料内气体扩散渗透模型,采用罗斯兰德近似、有限体积法建立了隔热材料内扩散渗透及辐射导热传热计算模型,对气体扩散渗透条件下的瞬态隔热性能进行了数值模拟。算例模拟结果表明:对2 cm厚纳米隔热材料,在外界气压为0.1 MPa,绝热面为真空的状况下,当渗透率大于10-14m2时,气体扩散渗透开始影响隔热材料内传热,导致隔热性能降低,气体黏性系数对气体扩散渗透有显著影响,随着黏性系数降低,气体扩散渗流现象显著;衰减系数对绝热面温度响应有显著影响,随着衰减系数增大,绝热面温度响应显著降低。Pressure gradient in the insulation materials along the thickness direction, which results from the chan- ges in pressure around the maneuvering hypersonic vehicles, will lead to gas diffusion and permeation in thermal insula- tion materials and affect the insulating property. In order to study the influences of gas diffusion and permeation on ma- terials insulating properties, a heat transfer model combined conduction radiation with gas diffusion and permeation was established under Rosseland approximation for radiation heat transfer. The established control equations were solved by finite volume method and the transient insulting properties under the condition of gas diffusion and permeation were nu- merically studied. Results show that gas permeation begins to influence the heat transfer process and worsen transient in- sulating property for a 2 cm nanometer insulation material when its permeability is greater than 10-14 ㎡ under the condi- tion where the heated surface is at environment pressure of 0.1 MPa and the unheated surface is in vacuum. Gas viscos- ity has a significant influence on gas diffusion and permeation process and the diffusion process enhances with the de- crease in viscosity. Extinction coefficient has more significant influence on the thermal response at the insulated surface than gas diffusion parameters and the temperature response decreases with the increase of extinction coefficient.

关 键 词：隔热材料 传热 辐射 扩散渗透 

分 类 号：TK124[动力工程及工程热物理—工程热物理]