Optimal and off-design operations of acoustic dampers using perforated plates backed by a cavity

Scarpato, Alessandro; Ducruix, Sébastien; Schuller, Thierry

doi:10.1016/j.jsv.2013.03.030

Cited by 29 publications

(9 citation statements)

References 35 publications

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“…Previous theoretical studies suggest that vortex shedding may be at the origin of ITA modes [3], while others mention a possible counter-reaction of the flame to its own production of acoustics [2]. This section shows that mode conversion [17,[37][38][39][40], i.e. the transformation of an acoustic wave into a convective wave is the mechanism that must be introduced into the analysis to understand the instability loop.…”

Section: Description Of Physical Phenomena Responsible For Ita Modesmentioning

confidence: 86%

DNS of Intrinsic ThermoAcoustic modes in laminar premixed flames

Courtine

Selle

Poinsot

2015

Combustion and Flame

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OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. , Emmert et al. 2015 suggest that thermoacoustic modes can appear in combustors with anechoic terminations, which have no acoustic eigenmodes. These modes, called here Intrinsic ThermoAcoustic (ITA), can be predicted with simple theoretical arguments, but have been ignored for a long time. They are reproduced in this paper using Direct Numerical Simulation (DNS) of a laminar premixed Bunsen type flame. DNS results and theory are compared showing very good agreement in terms of both frequency and mode structure. DNS confirms that the frequency of ITA modes does not depend on any acoustic characteristic of the burner. Based on a numerical evaluation of the Flame Transfer Function, stability limits of ITA modes predicted by theory are also recovered in the DNS with reasonable accuracy. Finally, DNS is used to analyze the mechanisms of ITA modes.

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Section: Description Of Physical Phenomena Responsible For Ita Modesmentioning

confidence: 86%

DNS of Intrinsic ThermoAcoustic modes in laminar premixed flames

Courtine

Selle

Poinsot

2015

Combustion and Flame

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“…Tonon, Moers & Hirschberg (2013) extensively investigated the inflow vena contracta, a parameter strongly related to the inflow discharge coefficient, and obtained a semi-empirical correction model for a two-dimensional wall perforation. Scarpato et al (2012) and Scarpato, Ducruix & Schuller (2013) performed extensive work on modelling the acoustic properties of perforate backed by a cavity with bias flow at low Strouhal number. Zhou & Bodén (2014) investigated the bias flow under medium and high-level acoustic excitation and found more complex acoustic properties compared with the no-bias flow case.…”

Section: Literature Reviewmentioning

confidence: 99%

Numerical investigation of a honeycomb liner grazed by laminar and turbulent boundary layers

Zhang

Bodony

2016

J. Fluid Mech.

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Direct numerical simulations are used to study the interaction of a cavity-backed circular orifice with grazing laminar and turbulent boundary layers and incident sound waves. The flow conditions and geometry are representative of single degree-of-freedom acoustic liners applied in the inlet and exhaust ducts of aircraft engines and are the same as those from experiments conducted at NASA Langley. The simulations identify the fluid mechanics of how the sound field and state of the grazing boundary layer impact the in-orifice flow and suggest a simple flow analogy that enables scaling estimates. From the scaling estimates the simulations are then used to develop reduced-order models for the in-orifice flow and a time-domain impedance model is constructed. The liner is found to increase drag at all conditions studied by an amount that increases with the incident sound pressure amplitude.

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“…These two problems are very different as illustrated in Fig. 19: Problem A consists in maximizing acoustic absorption per unit area, as was done in [18,66,67]. When identical dampers are distributed over a surface, the ideal purge mass flow per damper for best normal-incidence absorption depends on the number of dampers per unit area.…”

Section: Resultsmentioning

confidence: 99%

Stabilization of acoustic modes using Helmholtz and Quarter-Wave resonators tuned at exceptional points

Bourquard

Noiray

2019

Journal of Sound and Vibration

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Acoustic dampers are efficient and cost-effective means for suppressing thermoacoustic instabilities in combustion chambers. However, their design and the choice of their purging air mass flow is a challenging task, when one aims at ensuring thermoacoustic stability after their implementation. In the present experimental and theoretical study, Helmholtz (HH) and Quarter-Wave (QW) dampers are considered. A model for their acoustic impedance is derived and experimentally validated. In a second part, a thermoacoustic instability is mimicked by an electro-acoustic feedback loop in a rectangular cavity, to which the dampers are added. The length of the dampers can be adjusted, so that the system can be studied for tuned and detuned conditions. The stability of the coupled system is investigated experimentally and then analytically, which shows that for tuned dampers, the best stabilization is achieved at the exceptional point. The stabilization capabilities of HH and QW dampers are compared for given damper volume and purge mass flow.

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Optimal and off-design operations of acoustic dampers using perforated plates backed by a cavity

Cited by 29 publications

References 35 publications

DNS of Intrinsic ThermoAcoustic modes in laminar premixed flames

DNS of Intrinsic ThermoAcoustic modes in laminar premixed flames

Numerical investigation of a honeycomb liner grazed by laminar and turbulent boundary layers

Stabilization of acoustic modes using Helmholtz and Quarter-Wave resonators tuned at exceptional points

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