A REVIEW OF THEORETICAL-MODELS FOR FLUIDELASTIC INSTABILITY OF CYLINDER ARRAYS IN CROSS-FLOW

A review of all known theoretical models of fluidelastic instability f or cylinder arrays subject to fluid cross-flow is presented. Particula r emphasis is given to the physics of the different instability mechan isms, and the assumptions made are analysed and discussed. Comparisons are made between the models, and with available experimental data; th ese comparisons are in terms of the critical how velocity for instabil ity to occur and of the subcritical response of cylinders in the array . Despite the considerable differences in the theoretical models, ther e is some agreement in the general conclusions obtained. In particular , it is shown that the most important parameter for predicting fluidel astic instability is the unsteady nature of the interstitial flow in t he array; specifically, the phase-lag between cylinder motion and flui d forces generated thereby. Methods appropriate for using the analyses , which are predominantly. two-dimensional in nature, to predict the s tability of three-dimensional heat exchanger spans subject to nonunifo rm flow are also evaluated. Finally, the effect of nonlinearities, bot h structural and fluid, on the post-instability behaviour is reviewed. For loosely supported tubes with impacting occurring at the loose sup ports, the possibility of chaotic motion, with a consequent increase i n wear rate, is predicted. (C) 1995 Academic Press Limited