Heat transfer characteristics of oscillating turbulent air flow in a circular pipe heated at uniform heat flux were experimentally examined. The experiments were performed over range of Reynolds number 10 × 103 to 5 × 104 and oscillating frequencies from 5 to 100 Hz. Thermocouple, the temperature control system and the other measurement systems were installed on the oscillating section. For both steady and oscillating flows, the bulk and wall temperature, pressure drop and frequency were measured. Installing oscillating downstream of tested tube exit, result showed that Nu is strongly affected by the oscillating frequency and Reynolds number. The variation is more pronounced in the entrance region than in the downstream fully developed region. In oscillatory flow, a heat transfer enhancement of up to 28% at constant pumping power was achieved.
Key words: Heat transfer, oscillating flow, mixing.
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