Acoustic Resonance in Heat Exchanger Tube Bundles—Part I: Physical Nature of the Phenomenon

Abstract

The intense acoustic resonance resulting from gas flow across a bank of heat exchanger tubes in a duct has been investigated experimentally and theoretically. At low gas velocities, the acoustic tone emanating from tube bundles increases in proportion to the flow velocity. When the frequency approaches a bound acoustic transverse mode of the tube bundle, intense sound can result. Sound levels as high as 173 db were measured within the bundle. During resonance, the sound correlates vortex shedding from the tubes and the pressure drop increases in some bundles.

An in-Depth Study of Vortex Shedding, Acoustic Resonance and Turbulent Forces in Normal Triangle Tube Arrays

“…These results and others in the literature [e.g., Blevins & Bressler (1987a)] suggest that the higher component excites the lower modes only weakly, if at all. At high Reynolds numbers, the low component f T becomes the only relevant excitation anyway.…”

“…In fact, the first-mode component disappears altogether (see Figure 6(b)) and the SPL displays the characteristics of a forced response excited by the periodic source whose frequency ( f T ) changes linearly with the flow velocity. This contradicts the classical acoustic resonance behaviour in staggered arrays as reported in the literature Blevins & Bressler 1987a, 1987b. Secondly, the corresponding frequency distribution in Figure 6(a) indicates that a lock-in phenomenon does not exist in this case.…”

Effect of Arrangement of Tube Banks on Acoustic Resonance

“…It is considered that it is difficult to generate the acoustic resonance of low order mode for small tube pitch ratio. This is the similar tendencies with the charts of Blevins & Bressler [13,14]. On the other hand, the acoustic damping ratio of L/D = 1.44 for staggered arrangement agreed well with that of the in-line arrangement of L/D = 1.44.…”

“…Chen [6], Fitz-hugh [9] and Rae & Wharmby [10] have proposed Strouhal number charts for tube banks to estimate the vortex shedding frequency of a heat exchanger at the design stage. And Blevins & Bressler [13,14] have shown that the acoustic resonance of first transverse mode do not occur in the tube banks for small tube pitch ratio. However, the effect of arrangement in the tube banks on acoustic resonance was not clear in detail.…”

On the Generation Mechanism of High Level Sound Generated in a Boiler and Heat Exchanger

“…However, Weaver [5] and Funakawa [6] showed that the periodic vortex shedding exists even in the case of a closely aggregated bank by the flow visualization. Blevins [7] presented that the cause of high level sound was acoustic resonance because the vortex shedding frequency proportional to the flow velocity was seen at non-resonance, but at resonance the frequency became the acoustic frequency of the duct by a lock-in phenomenon. However, in actuality, this is thought of to be a self-sustained tone because high level sound is kept constant by increasing the flow velocity.…”