Flow induced vibrations in cylindrical bundles

Flow induced vibrations are an important solid-fluid interaction taking place in structures where elastically suspended objects are subjects to the fluid flow. Heat exchangers are only one of many applications where flow induced vibrations play an important role in determining the lifespan of the design. The phenomena itself is hard to predict. The one dimensional approach, seems to be inappropriate for some of the problems encountered. It is adequate for the problem for which it was designed, i.e. for a vibrating cylinder in the field of rigid cylinders. As long as the cylinders don't experience flow conditions leading to fluidelastic instabilities, the model predictions are quite accurate. These problems can be partially resolved through the use of analysis into normal modes. The assembly we will be concerned with in this work is a row consisting of a finite number of cylinders pulsating in the flow. The flow-cylinder configuration is the first step in the process of calculating the vibrational characteristics for array of cylinders in fluid flow. what are the properties that determine the fate of the assembly vibrations? The important parameters are the streaming Reynolds number, the Reynolds number of the incoming flow, the wavenumber and frequency of the oscillations generated by oscillating cylinders and the amplitude of the oscillations. In this paper, the authors' task will be to determine what combination of the above mentioned parameters will lead to instability and how they are related to one another. In other words, the authors are going to carry out a normal modes analysis and extend it with parametric analysis