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Tuesday, July 28, 2020 | History

1 edition of Combustion noise prediction, entropy/vorticity effects found in the catalog.

Combustion noise prediction, entropy/vorticity effects

Combustion noise prediction, entropy/vorticity effects

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Published by The Service, National Technical Information Service [distributor in Washington, D.C, Springfield, Va .
Written in English

    Subjects:
  • Aircraft gas-turbines -- Noise.,
  • Aerodynamic noise.

  • Edition Notes

    StatementWarren C. Strahle ... [et al.] ; prepared for U.S. Department of Transportation, Federal Aviation Administration, Systems Research & Development Service.
    ContributionsStrahle, Warren C., United States. Federal Aviation Administration. Systems Research and Development Service., Georgia Institute of Technology. School of Aerospace Engineering.
    The Physical Object
    Paginationxi, 141 p. :
    Number of Pages141
    ID Numbers
    Open LibraryOL15253659M

      , “ The Fast Random Particle Method for Combustion Noise Prediction,” 20th AIAA/CEAS Aeroacoustics Conference, June Google Scholar [17] Mühlbauer B., Ewert R., Kornow O. and Noll B., “ Evaluation of the RPM Approach for the Simulation of Broadband Combustion Noise,” AIAA Journal, Vol. 48, No. 7, July , pp. – Recent improvements in combustion noise investigation: from combustion chamber to nozzle flow. Aerospace Lab. Journal. T. Livebardon, S. Moreau, L. Gicquel, T. Poinsot, E. Bouty. Combining LES of combustion chamber and an actuator disk theory to predict combustion noise in a helicopter engine. Comb. Flame , , ~poinsot.

      fluctuating flow quantities (pressure, vorticity and entropy) exiting a combustion chamber and the interaction of these quantities with the turbine. • Core noise simulation methods (high and low fidelity) need further development, refinement and validation. State of the Artyscom/wp-content/uploads/sites/20/   (13,1) – 1st BPF Shear layers AIAA Exhaust noise prediction of realistic 3D lined turbofans submitted to Flow Vorticity inhomogeneities Indirect Noise caused by acceleration of entropy and vorticity fluctuations Direct Combustion Noise  › 百度文库 › 互联网.

    entropy wave attenuation, which improved the combustion noise prediction at turbine exit [6]. In an attempt to predict the combustion noise at turbine exit of the Rolls-Royce ANTLE aero-engine, the level of combustion noise has been over-predicted by almost two order of magnitude [6]. Mahmoudi et al. [6]   A. Combustion Noise from Heterogeneous Propellant 13 B. Cross-flow Effects on Combustion Noise 30 C. Temperature Fluctuations 41 IV. Order of Magnitude Calculations 61 A. Turbulcnce Noise 63 B. Combustion Noise 69 C. Entropy Noise 72 V. Motor Prediction 73 VI. Conclusions 83 Appendix - General Theory 85 References ii


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Combustion noise prediction, entropy/vorticity effects Download PDF EPUB FB2

An experimental and theoretical Combustion noise prediction was conducted to see if entropy noise and vorticity-nozzle interaction noise, as well as direct combustion noise, could be isolated in gas turbine combustor tests.

Moreover, a unified correlation, with a rational theoretical basis, was developed for direct noise from combustor rig tests. It was found that: (1) vorticity noise was at least as large as Get this from a library.

Combustion noise prediction, entropy/vorticity effects. [Warren C Strahle; United States. Federal Aviation Administration. Systems Research and Development Service.; Georgia Institute of Technology. School of Aerospace Engineering.;] COMBUSTION NOISE PREDICTION: ENTROPY/VORTICITY EFFECTS. An experimental and theoretical program was conducted to see if entropy noise and vorticity-nozzle interaction noise, as well as direct combustion noise, could be isolated in gas turbine combustor tests.

Moreover, a unified correlation, with a rational theoretical basis, was developed for ?id= Vorticity as well as entropy fluctuations, originating from the highly turbulent combustion zone, are convected with the flow and produce noise during their acceleration in the outlet nozzle of   The indirect combustion noise, identified by the early works of Marble and Candel and Morfey in the seventies, is an additional noise generated when a fluid with a non-uniform entropy or vorticity distribution is accelerated, as it is when convected through the choked nozzle located at the outlet of the combustion chamber in a gas turbine.

Note that the term “indirect combustion noise” refers to the noise generated by the acceleration of both entropy and vorticity waves. 9 The acceleration of vorticity waves also generates sound, which may be relevant for azimuthal modes. 10 In combusting flows, the former is likely to be more significant for two reasons: first, unsteady combustion generates large temperature fluctuations   Since flight effects reduce jet noise more than combustor entropy, and vorticity fluctuations.

Only a fraction of the general, the semi-empirical methods for turbofan core/combustion-noise prediction in use today have their roots in developments that mainly took place during the s.

These early advances in core/combustion-noise   Journal of Sound and Vibration () 66(4), JET ENGINE COMBUSTION NOISE: PRESSURE, ENTROPY AND VORTICITY PERTURBATIONS PRODUCED BY UNSTEADY COMBUSTION OR HEAT ADDITION N. CUMPSTY Department of Engineering, University of Cambridge, Cambridge CB3 OEL, England (Received 6 Novemberand in revised fm 23 February ) By idealizing combustion   increased the relative importance of combustion noise.

Two main mechanisms of combustion-noise generation have been identified: direct combustion noise, generated by acoustic waves propagating to the outlet, and indirect combustion noise, caused by the acceleration of entropy waves (or hot spots) and vorticity waves through turbine   This paper reviews both direct and indirect combustion noise.

For convenience, they will simply be referred to as combustion noise and entropy noise. Combustion noise has been studied for well over half a century.

However, because of the large number of parameters involved and the complexities inherent in the combustion processes, a widely accepted theory has yet to be :// A hybrid methodology combining a detailed Large Eddy Simulation of a combustion chamber sector, an analytical propagation model of the extracted acoustic and entropy waves at the combustor exit through the turbine stages, and a far-field acoustic propagation through a variable exhaust temperature field was shown to predict far-field combustion noise from helicopter and aircraft propulsion The generation of indirect combustion noise by compositional inhomogeneities is examined theoretically.

For this, the compact-nozzle theory of Marble & Candel (J. Sound Vib., vol. 55 (2),pp. –) is extended to a multi-component gas mixture, and the chemical potential function is introduced as an additional acoustic source ://   Effects of shear layer growth on the indirect noise in compound nozzles.

Numerical Prediction of Far-Field Combustion Noise from Aeronautical Engines. 19 February | Acoustics, Vol. 1, No. 1 Entropy and Vorticity Waves in an Annular Model Combustor and Nozzle for the Prediction of the Ratio Between Indirect and Direct Combustion :// The results are used to assess the combustion-noise prediction capability of the Aircraft Noise Prediction Program (ANOPP) and an improvement to the combustion-noise module GECOR is :// /_Combustion_noise_modeling_and_prediction.

Transfer Functions of Acoustic, Entropy and Vorticity Waves in an Annular Model Combustor and Nozzle for the Prediction of the Ratio Between Indirect and Direct Combustion Noise AIAA Paper No. /Prediction-of-Combustion-Noise-in-a-Model. The results are used to assess the combustion-noise prediction capability of the Aircraft Noise Prediction Program (ANOPP) and an improvement to the combustion-noise module GECOR is ://   Indirect combustion noise (entropy noise) Entropy noise is one (of two) components of combustion noise Unsteady combustion generates: • Acoustic waves which propagate within the combustor.

• Entropy waves (hot/cold spots) which are “swept” downstream, advecting with the flow. In a non-accelerating flow they are “silent”. The two well-known mechanisms for indirect combustion noise and instability consist of entropy perturbations and vorticity accelerated through the nozzle [15–19].

From a thermoacoustic point of view, the acoustics generated at the nozzle and traveling back to the combustion chamber can become the key feedback mechanism for a very low /Effects-of-Nozzle-Helmholtz-Number-on-Indirect. by the flame propagate to the outlet, and indirect combustion noise (or entropy noise), in which entropy waves generate noise as they are accelerated with the mean flow through the turbine :// The present work studies the effect of entropy dispersion on the level of combustion noise at the turbine outlet of the Rolls-Royce ANTLE aero-engine.

A new model for the decay of entropy waves, based on modelling dispersion effects, is developed and utilised in a low-order network model of the combustor (i.e. LOTAN code that solves the.

Compact and non-compact analytical solutions of the subsonic operating point of the entropy wave generator experiment are compared with detailed The linearised Euler equations are solved using the Magnus expansion to obtain the reflection and transmission coefficients of the annular nozzle for acoustic, entropy and vorticity perturbations.

Predictions which account for flow physics, such as a non-zero mean flow angle and the generation of vorticity noise, are obtained for the first ://The present work studies the effect of entropy dispersion on the level of combustion noise at the turbine outlet of the RollsRoyce ANTLE aero-engine.

The main objective in this work is to assess the effect of entropy dispersion on the level of combustion noise generated in a realistic combustor and turbine of the Rolls-Royce ANTLE ://