The Design, Fabrication, and Commissioning of a High-Speed Aeroacoustic Wind Tunnel for Studies of Surface Pressure Fluctuations Beneath Turbulent Boundary Layers

Giardino, Frank

doi:10.22215/etd/2018-12858

Cited by 2 publications

(5 citation statements)

References 52 publications

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“…The outlet of the ejector is placed in front of this collector. See Giardino 32 for full chamber details. Figure 7 is a modified version of Figure 4, showing the placement of microphones within the scale model.…”

Section: Acoustic Data Measurement and Processing Proceduresmentioning

confidence: 99%

An experimental investigation of the use of an outlet silencer to quiet ejectors

Desmarais

Rocha

2020

International Journal of Aeroacoustics

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Ejectors are simple fluid movers and mixers used in a range of industries; however, the attractiveness of their simplicity can be offset by high levels of noise generation. This work experimentally investigates the use of a silencer affixed to the outlet of a subsonic air–air ejector as a means of quieting the ejector. An emphasis is placed on finding a silencer design which has a minimal impact on the mass flow rate exhausting from the ejector (pumping performance). This paper discusses the results of 10 different silencer designs, tested in an attempt to further understand noise generation mechanisms and to find a practical method to reduce the noise of ejectors. It is found that the placement of a perforated cone at the mid-length of the silencer is the only solution tested which provides a significant acoustic advantage with only a small drop in pumping performance. Other solutions tested provide either no acoustic advantage or have too great of a reduction in pumping performance. It is found that the size and shape of the ejector can be designed in such a way to reduce the overlap of natural modes and thus the overall noise levels of the ejector caused by high levels of resonance. The use of acoustic foam to dampen acoustic natural modes proves that the natural modes of the ejector are a significant contributor to the overall noise levels.

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Section: Acoustic Data Measurement and Processing Proceduresmentioning

confidence: 99%

An experimental investigation of the use of an outlet silencer to quiet ejectors

Desmarais

Rocha

2020

International Journal of Aeroacoustics

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“…The anechoic chamber used in this work was designed and commissioned by Giardino [82] in 2018. An overview is presented here, however, for full details see the work of Giardino.…”

Section: Anechoic Chambermentioning

confidence: 99%

“…Front (top left) rear (top right) and partial cutaway (bottom) view of the acoustic chamber as used in its nominal configuration, adapted from[82] …”

mentioning

confidence: 99%

“…The predicted transmission loss for the anechoic chamber silencers, adapted from[82] section. The roof of the chamber contains two roughly 6 inch (152 mm) diameter holes which are capped with silencers to allow the chamber pressure to equalize with the outside atmosphere while preventing noise contamination inside the chamber.…”

mentioning

confidence: 99%

“…The differential pressure transducer calibration results The atmospheric pressure transducer calibration results, data from Giardino[82] Acoustic signature of the "valve noise" for all Mach numbers…”

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confidence: 99%

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A Theoretical and Experimental Investigation on Ejector Acoustics and Ejector Silencer Design

Desmarais¹

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Ejectors are common devices used across many industries, however, they are often plagued by the presence of low frequency pressure pulsations causing both broadband and tonal noise. This thesis presents a theoretical and experimental investigation into the acoustics of an ejector-silencer combination with the emphasis placed on silencer design. More specifically, the noise generated by the jet, the diffuser and natural modes is explained and estimated. The noise generation mechanisms of impingement tones and edgetones are presented but accurate predictions are found to be hard to make. An outline of the experimental facility is followed by the mechanical, acoustical and aerodynamic design details of the approximately 70:1 ejector scale model. A detailed analysis on the primary nozzle control and calibration is presented before beginning an aerodynamic and acoustic characterization of both the ejector and the wind tunnel facility. From experimentation, it is found that the placement of a perforated cone in front of the solid cone is beneficial in reducing the noise generated without overly affecting the entrainment ratio. Other configurations tested tend not to be as acoustically effective or to decrease the entrainment ratio below an acceptable level. Experiments prove that the low frequency noise generated by the ejector is mainly caused by natural mode excitation.iv

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The Design, Fabrication, and Commissioning of a High-Speed Aeroacoustic Wind Tunnel for Studies of Surface Pressure Fluctuations Beneath Turbulent Boundary Layers

Cited by 2 publications

References 52 publications

An experimental investigation of the use of an outlet silencer to quiet ejectors

An experimental investigation of the use of an outlet silencer to quiet ejectors

A Theoretical and Experimental Investigation on Ejector Acoustics and Ejector Silencer Design

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