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

Ullrich, Wolfram C.; Sattelmayer, Thomas

doi:10.2514/6.2015-2972

Cited by 6 publications

(5 citation statements)

References 31 publications

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“…Their work included the direct and indirect sources of combustion noise. Ullrich and Sattelmayer [24] examined the basic effects of direct and indirect combustion noise generation numerically. They evaluated the coupling behavior between acoustic, entropy and vorticity waves and the fluctuating heat release in terms of frequencydependent transfer functions.…”

Section: -Introductionmentioning

confidence: 99%

A comprehensive investigation of acoustic power level in a moderate or intense low oxygen dilution in a jet-in-hot-coflow under various working conditions

Mousavi

Kamali

Sotoudeh

et al. 2019

Aerospace Science and Technology

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Section: -Introductionmentioning

confidence: 99%

A comprehensive investigation of acoustic power level in a moderate or intense low oxygen dilution in a jet-in-hot-coflow under various working conditions

Mousavi

Kamali

Sotoudeh

et al. 2019

Aerospace Science and Technology

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“…They further showed that the resonances (caused by multiple reflections of waves between the choked nozzle and the heat release zone) that occur in the combustor can have significant effect particularly on the magnitude of the indirect entropy noise [1]. Ullrich & Sattelmayer [35] studied an annular model combustor using hybrid CFD/CAA approach and reproduced the results obtained analytically by Dowling & Mahmoudi [1]. For low frequencies they found very good agreement with the analytical solution of Dowling & Mahmoudi [1], while for high frequencies due to insufficient grid resolution the agreement with the analytical solution was not so good.…”

Section: Introductionmentioning

confidence: 99%

Acoustic and Entropy Waves in Nozzles in Combustion Noise Framework

2017

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A low-order model is presented to study the propagation and interaction of acoustic and entropic perturbations through a convergent-divergent nozzle. The calculations deal with choked, unchoked, as well as compact and non-compact nozzles. In the choked case, a normal shock exists in the divergent section of the nozzle. To validate the models developed, cylindrical configurations corresponding to Entropy-WaveGenerator (EWG) and Hot-Acoustic-Testrig (HAT) of DLR are studied. For the EWG, an entropy wave is generated upstream of a nozzle by an electrical heating device, and for the HAT a speaker is used to generate pressure waves. In these two configurations and for the choked case, the supersonic region between the nozzle throat and the normal shock is assumed to be acoustically compact. The results of the low-order model are found to give excellent agreement with the experimental results of the EWG and HAT rigs. To give insight into the physics, the model is used to undertake a parametric study for a range of nozzle lengths and shock strengths. The low order model is finally used to calculate the direct to indirect (entropy and vorticity) combustion noise ratio for an idealised thin-annular combustor. For this model combustor the direct acoustic noise is found to dominate within the combustor while, the entropy indirect noise is found to be the main source of noise downstream of the choked nozzle. The indirect vorticity noise has a negligible contribution.

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“…Chen 28,29 used the time-domain CFD method to study the effect of structural parameters and vortex velocity in the hole on the acoustic impedance, calculated the contribution of the perforated plate to the acoustic impedance of the bias-flow and grazing flow conditions, and fitted an exact expression for the perforated acoustic impedance, and the calculated muffler transmission loss agreed well with the experimental value in most cases, but because of the limitation of the extraction method, it is not suitable for the case above 0.2 Mach number. Therefore, this paper will use the L-NS equation to solve the perforation acoustic impedance in the frequency domain, Chu 30 and Ullrich 31 proved that the L-NS equation can characterise the linear propagation process of acoustic wave, vortex wave and entropy wave, and the interaction between the three acoustic modes and the mean flow. Xin 32 found that turbulent viscosity is an important effect on the coupling of flow and acoustics when solving the L-NS equation in the frequency domain.…”

Section: Introductionmentioning

confidence: 99%

Acoustic impedance extraction method and acoustic characteristics analysis of perforated plates under grazing flow

Wen,

Wu,

et al. 2023

Journal of Low Frequency Noise, Vibration and Active Control

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As an important component of inlet and exhaust mufflers, the acoustic characteristics of perforated components are inevitably affected by the flow of air. Therefore, obtaining the acoustic impedance of the perforated element under airflow conditions is a prerequisite for accurate calculation of the muffler’s muffling performance. In this work, the frequency domain linear Navier–Stokes (L-NS) method is used to extract the acoustic impedance of perforated plates under grazing flow. The predicted perforated acoustic impedance is consistent with the calculation results of published acoustic impedance expression, and the impedance boundary condition is defined to calculate the transmission loss (TL) of the perforated muffler, which agrees well with the experimental results and verifies the accuracy of the method. The effect of perforation angles on the transmission loss of mufflers in different Mach numbers ( Ma) and aperture plate thickness ratio ( dh/ tp) is analyzed by the frequency domain L-NS method. The results show that when 1≤ dh/ tp<2 and Ma≤2, the effect of perforation angles on the muffler performance is obvious, and the angle tilted upstream shifts the resonant frequency to a lower frequency while its corresponding peak value is also increased. As an engineering application, it has certain significance for the prediction of muffler muffling performance and the regulation of the muffling frequency band.

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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

Cited by 6 publications

References 31 publications

A comprehensive investigation of acoustic power level in a moderate or intense low oxygen dilution in a jet-in-hot-coflow under various working conditions

A comprehensive investigation of acoustic power level in a moderate or intense low oxygen dilution in a jet-in-hot-coflow under various working conditions

Acoustic and Entropy Waves in Nozzles in Combustion Noise Framework

Acoustic impedance extraction method and acoustic characteristics analysis of perforated plates under grazing flow

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