Signal Analysis and Characterization of Natural Circulation Two-Phase Flows in the Time, Amplitude and Frequency Domains

Natural circulation is an important passive feature incorporated in the heat transport systems of the Advanced Heavy Water Reactor, currently being designed and developed at the Bhabha Atomic Research Centre. The natural circulation systems generally have low driving heads and experience two phase, oscillatory and reversing flows. One of the main features of multiphase flows is the existence of characteristic dynamic structures called flow pattern or regime according to which the different phases can flow. The development of flow pattern characterization and diagnostic methods is of crucial importance for an efficient engineering of such phenomena. The natural circulation phenomena at different operating regimes are being studied extensively in various experimental facilities and this paper highlights the dynamic signal analysis performed on one such facility where the phenomena in 1" sized parallel channels are investigated.