TRANSIENT CONVECTIVE HEAT-TRANSFER IN A HELICAL COILED TUBE WITH PULSATILE FULLY-DEVELOPED TURBULENT-FLOW

Experiments were conducted to investigate the effects of pulsation upo n transient heat transfer characteristics for fully-developed turbulen t flow in a uniformly heated helical coiled tube. The non-uniform feat her of local heat transfer with steady flow was also examined. The sec ondary flow mechanism and the effect of interaction between the flow o scillation and secondary flow were analyzed on the basis of the experi mental data. Some new phenomena were observed and explained. A series of correlations were proposed for the average and local heat transfer coefficients both under steady and oscillatory flow conditions. The re sults showed that there were considerable variations in local and peri pherally time-average Nusselt numbers for pulsating flow in a wide ran ge of parameters. (C) 1998 Elsevier Science Ltd. All rights reserved.