Flow noise from spoilers in ducts

Abstract

Measurements of flow noise produced by strip spoilers in the air duct of a ventilation system and radiated from an open exhaust termination unit into a reverberation chamber have been made. The results agree with the previous work of Nelson and Morfey ͓J. Sound Vib. 79, 263-289 ͑1981͔͒. Prediction of flow noise produced by multiple spoilers requires the values of the ratio of the mean drag forces that act on the spoilers, the phase relationship between the fluctuating drag forces that act on the spoilers, and the coherence function of the noise sources. The latter is empirically derived from the measured results, where the predicted results agree well with the experimental results within 3 dB at most frequencies except for very high frequencies.

Recent advances in building acoustics: An overview of prediction methods and their applications

“…Much theoretical and experimental work in the prediction of duct-borne sound has been conducted. For example, work on the development of a prediction method for flow noise from multiple in-duct spoilers M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 22 was conducted by Mak et al [127][128][129][130]. Based on the earlier work, Mak et al [131] recently used a large-eddy simulation turbulence model to further develop the method so that engineers can use it to predict the flow noise from in-duct spoilers using computational fluid dynamics.…”

Pressure Losses across Multiple Fittings in Ventilation Ducts

“…This experiment was a part of our previous test on flow noise caused by in-duct elements [24]. The experimental system is shown in Figure 1.…”

A four-part setting on examining the anxiety-provoking capacity of the sound of dental equipment

“…These concerns have led to a large number of studies examining noise and vibration problems both in the environment and in dentistry. [12][13][14] The effect of the sound of dental equipment on dental anxiety is of importance as it affects oral health, which in turn has an influence on general health. The specific problem that motivated this study is that few systematic investigations have examined the effect of the sound of dental equipment on dental anxiety.…”