One of the primary differences among various test methods used to evaluate fabrics for thermal protective clothing is the presence or absence of a horizontal air gap between the fabric to be tested and the test sensor. Numerical modeling and flow visualization experiments were used to study the effect of the size of this air space on bench-top test results. The relative magnitudes of conduction, convection and radiation heat transfer in the air gap are shown, and photographs of the flow patterns in these enclosures are included. Applications of this work to other areas of fire protection engineering are dis cussed.
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