Experimental study of heat transfer in pulsating turbulent flow in a pipe

Abstract

Heat transfer characteristics of pulsating turbulent air flow in a pipe heated at uniform heat flux were experimentally investigated. The experiments were performed over a range of 10 4 < Re < 4 × 10 4 and 6.6 ⩽ f ⩽ 68 Hz. This situation finds applications in modern power generation facilities and industrial processes. With installing the oscillator downstream of the tested tube exit, results showed that Nu 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 Nu 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.