Experimental Study on Acoustic Energy Absorbers to Suppress Acoustic Resonance in Tube Bundles of Boiler Plants

Abstract

The present paper deals with acoustic resonance in tube bundles which occurred in actual boiler plants. A practical method to suppress the resonant noise is proposed based on scale model tests. In those experiments, besides the transverse modes which are relatively well-known, longitudinal modes which are known to be difficult to suppress, were realized. The relation of both kinds of acoustic modes to vortex shedding frequency was clarified. In the following step, a design method of the acoustic energy absorbers is proposed based on the feedback system stability theory. According to this theory, acoustic energy absorbers were equipped in the duct of the test model, and remarkable increase of the critical flow velocity was confirmed for both types of resonant mode. Based on these results, this method was applied to the actual boiler plants and it was confirmed that the proposed method is the effective countermeasure for both types of acoustic resonant modes.

Flow induced acoustic resonance in in-line tube banks

“…The triangular structure under the test apparatus is the model of the recovery system of the combustion ash. The similarity of this device in detail was explained in the paper [14].…”

“…The acoustic resonance generated from this test model could be suppressed by setting the acoustic absorbers [14]. Acoustic absorbers were made of glass wool and they were covered by acrylic plates.…”

Vibration Induced by Cross-Flow

“…2.48 [166] suffered a resonance in the transverse and longitudinal modes. A scale model experiment discovered these modes.…”

“…They identified the resonant mode shapes and showed that the resonance frequencies of longitudinal modes are almost double those of transverse modes. On the other hand, Nishida et al [166] used plant boiler scale models. Their results on resonance phenomena are shown in Figs.…”

“…Using a test Experimental setup for stability evaluation by forced water-flow fluctuation [158]. Resonance occurrence in boiler scale model apparatus [166]. [168].…”