Prediction of the Efficiency of Acoustic Damping Cavities

Searby, Geoffrey; Nicole, Aurélie; Habiballah, Mohammed; Laroche, Emmanuel

doi:10.2514/1.32325

Cited by 43 publications

(34 citation statements)

References 9 publications

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“…From numerically obtained acoustic velocity ¦elds of eigenmodes and analytical solutions for the dissipation in oscillating shear layers, they determined the damping of the eigenmodes. A comparison of the hybrid approach with analytical solutions available for simple geometries and with results from computational §uid dynamics (CFD) calculations for more complex con¦gurations has resulted in a good agreement between the methods [5].…”

Section: Evaluation Of Dampingmentioning

confidence: 95%

“…Searby et al [5,8] recently have proposed a hybrid approach to determine the acoustic damping due to viscous and thermal dissipation. From numerically obtained acoustic velocity ¦elds of eigenmodes and analytical solutions for the dissipation in oscillating shear layers, they determined the damping of the eigenmodes.…”

Section: Evaluation Of Dampingmentioning

confidence: 99%

“…With increasing absorber length, the resonance frequencies of the coupled system are decreasing and the symmetry of the modes in the combustion chamber may exhibit signi¦cant changes. Furthermore, it has been shown experimentally [4] as well as numerically [4,5] that maximum damping of a quarter-wave absorber mounted to a combustor is not obtained at an absorber length L A determined by Eq. (2) but at larger lengths.…”

Section: Introductionmentioning

confidence: 99%

“…The modal analysis is done based on a 3D model in order to allow a quantitative comparison with a reference experiment. Searby et al have published a method to derive quantitative values for the damping rate from the acoustic velocity ¦elds of eigenmodes [5]. This method is used in this work to determine the damping behavior of the absorber rings and the predictions are compared with experimental data.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

On the acoustics of rocket combustors equipped with quarter wave absorbers

Oschwald¹,

Marpert²

2011

Progress in Propulsion Physics

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The acoustic resonance spectrum and the dissipation of speci¦c modes in combustors equipped with absorbers have been investigated experimentally and numerically. It is found that the application of absorber rings to a combustor changes its resonance behavior signi¦cantly. Based on the acoustic ¦elds obtained by three-dimensional (3D) modal analysis, the damping behavior for modes is predicted and compared to measurements. There is a good agreement between prediction and experimental data with respect to the general trend of the dependence of damping on the absorber length. However, the experimentally determined dissipation rates are signi¦cantly larger than the predicted values.

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Section: Evaluation Of Dampingmentioning

confidence: 95%

Section: Evaluation Of Dampingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

On the acoustics of rocket combustors equipped with quarter wave absorbers

Oschwald¹,

Marpert²

2011

Progress in Propulsion Physics

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“…This is the interesting frequency bandwidth for the thrust chamber considered. Beyond this limit, internal absorber e¨ects from linear viscous and thermal wall resistances [4] increasingly dominate, since they are proportional to the square root of frequency, making deviations between model and experiment greater:…”

Section: Absorber Parametersmentioning

confidence: 99%

High-frequency instabilities in rocket thrust chambers: an engineering approach

Fassl¹

2011

Progress in Propulsion Physics

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The prediction and prevention of high-frequency (HF) instabilities in rocket engines remain challenging tasks not only for science to understand the ruling processes and to measure, simulate, and model them, but also for industry to ¦nd pragmatic ways of combining existing knowledge and experimental experience from laboratory or industrial full-scale tests and applying them systematically already at the early stages of rocket engine development programs. The French German REST program constitutes a scienti¦c platform aiming at combining both scienti¦c investigation and industrial viewpoint. The concept of Astrium£s stability analysis tool STABAN was elaborated in REST and systematically developed and adjusted. It constitutes an engineering approach in the frequency domain enabling quick applicability to any engine hardware. At future REST phases, the main focus will be to validate STABAN against scienti¦c and industrial test data and to classify thrust chambers into instability risk families. NOMENCLATURE

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Control of Acoustically Coupled Combustion Instabilities

Ducruix

Schuller

Durox

et al. 2010

Handbook of Combustion

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This chapter reviews control methods for combustion instability. It specifically considers the rather general situation where instabilities are coupled by acoustic modes. The chapter begins with fundamental acoustic principles for reactive flows, leading to the acoustic energy balance equation. This equation is used to describe the three main control strategies that can be envisaged for combustion instabilities: (i) passive control methods (PCM); (ii) flame dynamic control methods (FDCM); (iii) active control methods (ACM). These schemes are considered successively. The survey begins with passive control methods (PCM) in which the dissipation of acoustic energy is augmented by ad hoc systems (acoustic liners, Helmholtz resonators, quarter wave cavities, and various other devices), which enhance absorption of acoustic energy. It is shown that such devices can be effectively used to modify the impedance of a boundary and that this can change the resonance properties of the combustor. Control of injection and flame dynamics is then envisaged. For this second group of methods (FDCM) it is shown that the flame geometry has a profound effect on the combustion response to incoming perturbations. The modification of the flow and flame configurations can thus be used to control the system response. It is then indicated that the dynamics of the injection system can be designed to decouple the system from the manifold feeding reactants into the combustor. Recent work indicates that the flame dynamics can be modified so that the combustion region becomes less susceptible to perturbations impinging on the flame. Finally, active control methods (ACM) are considered, and their application to combustion instability reduction is described. Implementation in the form of a closed loop control aims at modifying the feedback mechanism to hinder the resonant coupling between unsteady combustion dynamics and system acoustics. ACMs have been developed using various strategies, ranging from the control of injection parameters (fuel flow, air flow, secondary jets, etc.) to the active modulation of acoustic boundary conditions up‐ and downstream of the combustion chamber. Under application of the active control system, instabilities can be totally suppressed and the instability‐related flame extinctions are eliminated.

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Prediction of the Efficiency of Acoustic Damping Cavities

Cited by 43 publications

References 9 publications

On the acoustics of rocket combustors equipped with quarter wave absorbers

On the acoustics of rocket combustors equipped with quarter wave absorbers

High-frequency instabilities in rocket thrust chambers: an engineering approach

Control of Acoustically Coupled Combustion Instabilities

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