Heat Transfer on Cylinder Covered with Close-fitting Fabrics : Part II. Heat Transfer on the Stagnation Point

The objective of investigation is to get a clear idea of the nature of wind penetration effects in clothing. The preceding study of wind penetration through fabric is extended, in this paper, to determine the heat transfer of fabric system. With the aid of heat transfer equation of porous media, the thermal insulation value of fabric layer can be described as a function of such arguments as α*, some pertinent properties of fabric and wind velocity, where α* is the characteristic number of contact layer referring to the manner of contact between fabric and cylinder. Quantitative agreement' between the theory and experimental data is considerably good. Then it is seen that the dynamic pressure of wind sets up penetration, and thereby augments heat transfer process. The insulation value decreases with an increasing wind velocity and the behaviour of the decreasing depends largely on α*. Therefore α* is an essential factor for assessing the value of a sample fabric in wind.