EXPERIMENTAL INVESTIGATION ON FREE-CONVECTION INSIDE A TENT ENVELOPE OF TEXTILE FABRIC

Laminar free convection in an envelope enclosure of textile fabric is studied. The geometrical dimensions simulate those of small-capacity m embraned-fabric buildings, in particular those of square-type tents. T he convective heat transfer coefficients from a woven fabric (0.5 mm s trand diameter, 10 X 10 strands/cm2 and 1 mm thick) roof and a similar metallic smooth surface were measured. The relation between Nusselt a nd Rayleigh numbers for 10(5) less-than-or-equal-to Ra less-than-or-eq ual-to 10(8) were developed for both surfaces at isoflux conditions. T he present results showed that the heat transfer coefficient from the fabric surface of a tilted roof was two to three times higher than tha t for a similar smooth surface. Data was also obtained for the same te nt but with two openings at the top and bottom (area ratio 1:4) to all ow for ventilation air to pass through the tented cavity. For this rat io no significant effect upon the heat transfer coefficient from the r oof was recorded.