On the elimination of aerodynamic noise in a staggered tube bank

Acoustic resonance in a staggered tube bank was investigated. The regular flow pattern between the tubes was disturbed by the omission of some tubes in the bank and by displacing the rows in either the transverse or the longitudinal direction. It was found that the acoustic resonance can be eliminated by unequal longitudinal pitches in two successive rows. The most effective row for the removal of tubes to eliminate acoustic resonance was the first row while the third (and last) row removals were totally ineffective.