Analytical and numerical study of the Entropy Wave Generator experiment on indirect combustion noise

Compact and non-compact analytical solutions of the subsonic operating point of the entropy wave generator experiment are compared with detailed numerical results obtained by large Eddy simulations. Two energy deposition methods are presented to account for the experimental ignition sequence and geometry: a single-block deposition as previously used and a delayed deposition that reproduces the experimental protocle closely. The unknown inlet acoustic reflection coefficient is assumed to be fully reflective to be more physically consistent with the actual experimental setup. The time delay between the activation of the heating modules must be considered to retrieve the temperature signal measured at the vibrometer and pressure signals at the microphones. Moreover, pressure signals extracted from the large Eddy simulations in the outlet duct using the delayed ignition model clearly reproduce the experimental signals better than the analytical models. An additional simulation with actual temperature fluctuations directly injected at the inlet of the computational domain clearly shows that the pressure fluctuations produced by the acceleration of the hot slug yields indirect noise almost entirely. Finally, the entropy spot is shown to be distorted when convecting through the turbulent flow in the entropy wave generator nozzle. Its amplitude decreases and its shape is dispersed, but hardly any dissipation occurs. The distortion appears to be negligible through the nozzle and become important only when convected over a long distance in the downstream duct. As the dominant frequencies of the entropy wave generator entropy forcing are very low, the effects of dispersion by the mean flow are however weak.

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A Study of Noise Generation by Turbulent Flow Instabilities in a Gas Turbine Model Combustor

Volume 2: Turbo Expo 2005 ◽

10.1115/gt2005-69029 ◽

2005 ◽

Cited By ~ 4

Author(s):

Clemens Olbricht ◽

Felix Flemming ◽

Amsini Sadiki ◽

Johannes Janicka ◽

Friedrich Bake ◽

...

Keyword(s):

Turbulent Flow ◽

Gas Turbine ◽

Swirling Flow ◽

Numerical Study ◽

Combustion Noise ◽

Flow Instabilities ◽

Noise Sources ◽

Eddy Simulation ◽

Exit Nozzle ◽

Model Gas Turbine Combustor

Due to successful noise reduction strategies concerning fan- and jet-noise in gas turbine configurations, the relevance of combustion noise is increasing. In order to distinguish between turbulent noise and combustion noise a model gas turbine combustor consisting of a swirl burner and an exit nozzle of Laval-shape is investigated. Because of the instationary character of the flow this configuration is analysed by means of Large Eddy Simulation (LES). Numerical results are first validated by comparison with experimental data. Then a numerical study of noise generated by turbulent flow instabilities is carried out. Providing an extensive temporal and spatial analysis of the isothermal flow length- and timescales as well as vorticitiy are investigated with regard to the formation of rotating flow-instabilities in the recirculating swirling flow. Subsequently a link to the acoustic perturbation equations (APE) is provided, from which the Lamb vector represents the essential noise sources. Therfore noise sources are identified and evaluated by means of LES based on the Lamb vector consideration. It results that the noise sources increase with an increasing swirl number.

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New wave generation

Journal of Fluid Mechanics ◽

10.1017/s0022112010002454 ◽

2010 ◽

Vol 657 ◽

pp. 308-334 ◽

Cited By ~ 44

Author(s):

MATTHIEU J. MERCIER ◽

DENIS MARTINAND ◽

MANIKANDAN MATHUR ◽

LOUIS GOSTIAUX ◽

THOMAS PEACOCK ◽

...

Keyword(s):

Wave Field ◽

Internal Waves ◽

Fourier Transforms ◽

Numerical Study ◽

Plane Waves ◽

Finite Depth ◽

Full Potential ◽

The Novel ◽

Wave Generator ◽

Generator Design

We present the results of a combined experimental and numerical study of the generation of internal waves using the novel internal wave generator design of Gostiaux et al. (Exp. Fluids, vol. 42, 2007, pp. 123–130). This mechanism, which involves a tunable source composed of oscillating plates, has so far been used for a few fundamental studies of internal waves, but its full potential is yet to be realized. Our study reveals that this approach is capable of producing a wide variety of two-dimensional wave fields, including plane waves, wave beams and discrete vertical modes in finite-depth stratifications. The effects of discretization by a finite number of plates, forcing amplitude and angle of propagation are investigated, and it is found that the method is remarkably efficient at generating a complete wave field despite forcing only one velocity component in a controllable manner. We furthermore find that the nature of the radiated wave field is well predicted using Fourier transforms of the spatial structure of the wave generator.

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Analytical and Numerical Study of Combustion Noise Through a Subsonic Nozzle

AIAA Journal ◽

10.2514/1.j051528 ◽

2013 ◽

Vol 51 (1) ◽

pp. 42-52 ◽

Cited By ~ 44

Author(s):

Ignacio Durán ◽

Stéphane Moreau ◽

Thierry Poinsot

Keyword(s):

Numerical Study ◽

Combustion Noise ◽

Subsonic Nozzle

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Experimental and Numerical Investigation of Direct and Indirect Combustion Noise Contributions in a Lean Premixed Laboratory Swirled Combustor

Volume 4B: Combustion, Fuels and Emissions ◽

10.1115/gt2016-57848 ◽

2016 ◽

Cited By ~ 4

Author(s):

Nancy Kings ◽

Wenjie Tao ◽

Philippe Scouflaire ◽

Franck Richecoeur ◽

Sébastien Ducruix

Keyword(s):

Numerical Study ◽

Combustion Noise ◽

Noise Generation ◽

Noise Emission ◽

Emission Data ◽

Spectral Content ◽

The Core ◽

Operation Conditions ◽

Aero Engines ◽

Generation Mechanisms

Combustors are contributing to the core noise emission of aero-engines in terms of direct and indirect combustion noise. The first is caused by the unsteady heat release rate, the second by the acceleration of inflow inhomogeneities, such as entropy fluctuations, at the combustor outlet or in the turbine. This work aims to investigate combustion noise generation mechanisms of a choked laboratory scale combustor by a combined experimental and numerical study. Therefore, the temperature fluctuations at the combustor outlet were determined experimentally as well as numerically and cross-checked together with pressure and OH* emission data in the frequency domain. A similar spectral content was found. Furthermore, the acoustic and entropy fluctuations at the combustion chamber outlet were evaluated for different operation conditions to estimate the direct and indirect combustion noise contributions of a laboratory combustor.

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