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AEROACOUSTIC RESPONSE OF ISOLATED STRAIGHT FIN CYLINDERS WITH DIFFERENT FIN HEIGHT IN CROSS FLOW
Md Rashidul Islam, Atef Mohany

Last modified: 2018-05-04

Abstract


The Finned tube bundles in heat exchangers are susceptible to flow-excited acoustic resonance phenomena. During acoustic resonance, the flow field couples with the acoustic field generating very high-intensity noise. Characterizing the sound intensity and its underlying mechanism is critical to the design of heat exchangers. However, this characterization presents a challenging problem, as it is influenced by various fin parameters and its arrangement around the bare tube. For straight finned cylinders, several studies investigated the effect of the fin thickness, fin pitch as well as fin spacing on the flow-acoustic resonance phenomena whereas the effect of fin height is not studied. Thus, in this work, the effect of fin height is investigated experimentally. Finned cylinders with same fin thickness t = 1.5 mm, equispaced fins of pitch p =3 mm and three different diameter ratio Df/Dr =1.5, 2, 2.5 were experimentally studied. In general, acoustic pressure from the finned cylinders was found higher and the onset of resonance was earlier compared to the equivalent diameter bare cylinders having same frontal area flow blockage. It is observed that increasing the Df/Dr i.e. the fin height results in the increase in acoustic pressure substantially. Moreover, increasing the height shifted the onset of acoustic resonance slightly earlier.

 


Keywords


Flow sound interaction; Vortex-shedding; Aeroacoustics; Flow-acoustic resonance

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