In the present study, the optical method using liquid crystal thermography is empoloyed to measure temperature and heat transfer distributions between adjacent including ribs in a rectangular duct. The duct aspect ratio is 1/8, and the parallel ribs were arranged staggered on the two wide walls. The rib height-to-hydraulic diameter ratio is 0.06, with an attack angle of 60 deg . The ptich-to-highet ratio equals 10. The Reynolds number range is from 1000 to 6000. A steady state method is used to obtain the local heat transfer coefficients. The secondary flows caused by including ribs create a significant spanwise variation in heat transfer coefficient on the rib roughened wall with high heat transfer coefficient at one end of the rib and low levels at the other end. In the streamwise distributioin beteen two consecutive ribs, the temperature distribution shows a sawtooth fashion. Based on the local Nusselt Numbers, the average Nussel numbers are evaluated to investigate the augmentation of heat transfer by the presence of angled ribs.
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