Investigation of Aircraft Heaters XXXIV-Experimental Determination of Thermal And Hydrodynamical Behavior of Air Flowing Between a Flat and a Wave- Shaped Plate.

摘要

An experimental investigation has been performed on the thermal and hydrodynamical behavior of air flowing along a passage of which one side was flat (and steam-heated) and the other side was wave-shaped (and unheated). Two series of tests were conducted: One series in which the wave-shaped plate and the steam-heated plate were placed in exact opposition (thermal boundary layer at leading edge of flat plate and flow over wave plate beginning at same point) and the other series in which the leading edge of the wave plate was placed 9 inches upstream of the leading edge of the heated plate, thereby promoting turbulence upstream of the beginning of the thermal boundary layer. In the first series of tests, two wave plates of different amplitude and wavelength were used. A range of air weight rates and spacings between the heated plate and the wave plate was investigated. An analysis of the heat-transfer and pressure-drop data reveals that the turbulence produced by air flowing over wavy surfaces approxi- mately doubles the heat-transfer rate for narrow duct widths. Of course, at large duct widths the effect is negligible. The pressure drop was greatly increased over that for a straight duct. The pressure drop was increased to at least 4 times for large duct widths and to at least 10 times for small duct widths.