الفهرس 
Introduction
Summery and ConclusionsOnly 14 pages are availabe for public view
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Abstract
Heat transfer characteristics of pulsating turbulent air pipe flow under different conditions of Reynolds number and pulsation frequency are numerically and experimentally investigated. This situation finds applications in modern power generation facilities and several industrial processes. The outer surface of the pipe was subjected to a uniform heat flux. The pulsating mechanism was installed downstream of the pipe. The flow and heat transfer characteristics are predicted numerically using the computational fluid dynamics (CFD) Fluent code. The two equations of turbulence model (k-) are employed in this investigation. The numerical results showed a little reduction in the mean time-averaged Nusselt number with respect to that of the steady flow. However, in the fully developed established region, the local Nusselt number either increases or decreases over the steady flow-values depending on pulsating frequency. These noticed deviations are rather small in magnitude for the selected frequency range. The experiments were performed over a range of Reynolds number of 10850 to 37100 and a range of pulsation frequency of 6.7 to 68 Hz. The results showed that Nusselt number is strongly affected by both pulsation frequency and Reynolds number. Its local value either increases or decreases over the steady flow value. The variation is more pronounced in the entrance region than that in the downstream fully developed region. It is observed also that the relative mean Nusselt number either increases or decreases, depending on the frequency range. Although the deviations are small, it seems to be obvious at higher values of Reynolds number. The obtained heat transfer results are classified according to turbulent bursting model and looked to be qualitatively consistent with previous investigations. The characteristics of heat transfer are qualitatively consistent with the available present experimental and numerical predictions.