纺织学报 ›› 2020, Vol. 41 ›› Issue (01): 139-144.doi: 10.13475/j.fzxb.20181105406

• 服装工程 • 上一篇    下一篇

非稳态自然对流换热系数计算方法及其在防护服隔热预报中的运用

丁宁1, 林洁2()   

  1. 1.中国民航大学 航空工程学院, 天津 300300
    2.中国民航大学 中欧航空工程师学院, 天津 300300
  • 收稿日期:2018-11-20 修回日期:2019-09-25 出版日期:2020-01-15 发布日期:2020-01-14
  • 通讯作者: 林洁
  • 作者简介:丁宁(1982—),男,副教授,博士。主要从事机械及流体研究。
  • 基金资助:
    中国民航大学科研启动基金项目(2016QD07X)

Free convection calculation method for performance prediction of thermal protective clothing in an unsteady thermal state

DING Ning1, LIN Jie2()   

  1. 1. College of Aeronautical Engineering, Civil Aviation University of China, Tianjin 300300, China
    2. Sino-European Institute of Aviation Engineering, Civil Aviation University of China, Tianjin 300300, China
  • Received:2018-11-20 Revised:2019-09-25 Online:2020-01-15 Published:2020-01-14
  • Contact: LIN Jie

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摘要：

为得到相对精确的热防护服非稳态隔热性能预测数值,基于传热系统的非稳态传热模型,在防护服材料外表面分别为恒温边界条件和Howard模型对流边界条件下,利用有限差分法分别计算了2种边界条件下模拟皮肤处温度的时程曲线,所得结果均与实验测量值差别较大。在细致分析传热过程的基础上,综合运用傅里叶定律、牛顿冷却定律、以及Howard模型对流边界条件,在线化假设下提出了一种自然对流换热系数计算方法,代入非稳态模型后利用有限差分法进行了求解,随着时间步长的加密,计算结果迅速向实验测量值收敛,当时间步长为0.001 s时,计算结果与测量结果误差小于0.1 ℃。

关键词: 热防护服, 隔热性能, 热传递, 自然对流, 数值模拟

Abstract:

A method for the surface heat transfer coefficient calculation of free convection is proposed, which plays an important part in the numerical heat insulation prediction of thermal protective clothing under unsteady thermal state in high temperature environments, where heat transferred by free convection cannot be ignored or even is the main part. A typical heat transfer model was presented under an unsteady thermal state, using finite difference method. Two sets of numerical results were obtained under two boundary conditions at the outer surface of clothing, these conditions being constant temperature boundary condition and Howard model's free convection boundary condition. However, the comparison between experimental and the two numerical analysis results showed obvious differences. For improvement, a method using Fourier's law, Newton cooling law and free convection condition of Howard model was proposed under linear assumption to calculate free convection heat transfer coefficient. Improving the heat transfer model with this method, three sets of numerical results were obtained using finite difference method with different time steps, and the comparison between experimental and these three numerical results showed fast convergence to experimental results with time step getting smaller. The difference between the calculated and experimental results was less than 0.1 ℃ when time step was set to 0.001 s.

Key words: thermal protective clothing, thermal insulation, heat transfer, free convection, numerical simulation

中图分类号: 

  • O242.1

图1

传热系统组成"

表1

材料的物理属性"

材料
编号		 密度/
(kg·m-3)		 比热/
(J·(kg·℃)-1)		 热传导率/
(W·(m·℃)-1)		 厚度/
mm
材料1 300 1 377 0.082 0.6
材料2 862 2 100 0.370 6.0
材料3 74.2 1 726 0.045 3.6
材料4 1.18 1 005 0.028 5.0

图2

不同边界条件和本文方法的不同时间步长计算结果"

图3

Δt=0.001 s的计算误差"

图4

Δt=0.001 s时皮肤表面热流密度随时间的变化"

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