Fluid Flow and Heat Transfer Characteristics for a Corrugated Duct

点击翻译按钮获取中文摘要

Measurements for the pressure drop and the flow visualization were done for low Reynolds number fluid flow in corrugated ducts with sharp edge corners. The Reynolds number of the fluid flow ranges from 40 to 2000. The pearl graze was used for the flow visualization as a tracer. The critical Reynolds numbers and correlations for the friction factor and the Reynolds number for the fluid flow in the ducts were obtained from these results. These results were presented at the 26th Heat Transfer Symposium in Japan. The experiments were done for two ducts with the corrugation angle of 30 and 45 degrees. The total numbers of corrugation cycle were 19.5 and 25.5 for 30 and 45 degree ducts, respectively. The elevation of the corrugation is 10 mm for both ducts. The channel height of the ducts were 5, 10 and 15 mm. The following results were obtained: (1) The critical Reynolds numbers range from 100 to 210 and 60 to 220 for the ducts of 30 and 45 degree corrugation angles, respectively. (2) The friction factor for low Reynolds number fluid flow coincides with the value which is obtained by numerical computation with the assumption of laminar flow.The experiments for the mass transfer were done for low Reynolds number fluid flow. The Reynolds number ranges from 200 to 550. The naphthalene sublimation technique was used for measurement of the mass transfer coefficient. The corrugation angle is 30 degree, the length of one cycle is 20 mm, and the channel height of the duct is 10 mm. The total number of corrugation cycle is 13.5. the width of the duct is 110 nm. As the consequence, the aspect ratio of the cross section of the duct is 11. The following results were obtained: (1) The mean mass transfer coefficient in the periodically fully developed region coincides with the value which is obtained by the numerical computation with the assumption of laminar flow. (2) The effect of the turbulence of the low Reynolds number fluid flow to heat transfer is relatively small.