It is well known that gas heat exchangers are prone to aeroacoustic instabilities, which often lead to severe noise levels, structural vibrations and fatigue. These are unacceptable, as they threaten the component integrity and expose the plant workers to excessive noise levels. Such phenomenon is due to a cooperative interplay between the Karman vortices generated by the cross-flow and the heat exchanger acoustical modes (mainly those transverse to the tube banks). Energy exchanges are then such that, for certain operating velocities, self-excitation of one or more acoustical modes arises. Actually, this problem is solved by placing rigid baffles inside the container, which modify the acoustic modal fields and eventually inhibit the instability. However, an effective location of such baffles is more or less difficult depending on the system complexity and on the range of flow velocities of interest. For realistic industrial components - using a restricted number of acoustical baffles - their optimal location is a challenging problem, as trial and error experimentation is often a costly and frustrating procedure. In this paper we improve a recently proposed strategy for the optimal location of a given number of baffles, in order to inhibit instability of the acoustical modes in a given frequency range. Our approach is based on a stochastic global optimization technique. Some preliminary experiments are also performed and compared with the simulation results.
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