A Simplified Method for Determining Acoustic and Tube Eigenfrequencies in Heat Exchangers

A method of computation of eigenfrequencies of large tube arrays is presented, which is based on homogenization techniques. It is supposed that the fluid is compressible, at rest and contained in a cavity; the bundle geometry is assumed to be repetitive; an equivalent sound velocity through the tubes can then be calculated, and the fluid-structure interaction is taken into account. A new eigenvalue problem is so obtained, defined over a simpler domain, i.e., the region occupied by both fluid and tubes; it is then easy to solve it for computing the eigenfrequencies of the coupled system. Numerical and experimental results are presented and some details of the experimental apparatus are given.