Passive alternation and control of convective transport phenomena utilizing an alternate attached-detached rib-array
Passive alteration of heat transfer augmentation along a thermal boundary layer using alternately emplaced attached and detached ribs is examined experimentally. The detached ribs are lifted from the wall with clearance-to-rib height ratio from c/h = 0 to 1.2. The Reynolds number based on channel hydraulic diameter varies from Re = 8,000 to 50,000. The rib pitch-to-height ratio and rib-to-channel height ratio are fixed at Pi/h = 5.0 and h/2B = 0.26, respectively. Laser holographic interferometry associated with the thermocouple is used to determine the local heat transfer on the floor of the composite ribbed wall. To understand the mechanisms of heat transfer enhancement by altering the rib clearance, smoke injection flow visualization is conducted in the composite ribbed duct flows. Results show that increasing the rib clearance from c/h = 0 to 0.2 decreases the heat transfer of the composite ribbed wall due to the reduction in fin effect. Owing to an alternation of turbulent transportation, an abrupt jump in the average heat transfer coefficient is observed for increasing the rib clearance ratio from 0.2 to 0.4. Consequently, there exists a critical rib clearance ratio between c/h = 0.2 and 0.4 for the transition of turbulent transportation from the cavity flow to the separated-reattached flow in the composite ribbed channel.
- Research Organization:
- Chung-Hua Univ., Hsinchu (TW)
- OSTI ID:
- 20002433
- Report Number(s):
- CONF-990805--
- Country of Publication:
- United States
- Language:
- English
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