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Influence of the Acoustic liner in Large Eddy Simulation of Longitudinal Thermoacoustic Instability in a Model Annular Combustor

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Journal of Thermal Science 2024年第2期33卷 710-724页

作者： MENG Sheng ZHANG Man GAO Yi AECC Commercial Aircraft Engine Co. Ltd.Shanghai200241China School of Aeronautics and Astronautics Shanghai Jiao Tong UniversityShanghai200240China

Although extensive efforts have been made to dampen the thermoacoustic instability,successfully controlling the pressure oscillations in modern gas turbines or aeroengines remains challenging.The influence of the Acoustic liner on the longitudinal thermoacoustic mode in a model annular combustor is investigated by Large Eddy Simulation(LES) in this work.The result of the self-excited longitudinal thermoacoustic instability without the liner agrees well with the frequency and acoustic analysis of the pressure mode based on experimental data.Three different bias flow velocities of the liner located downstream of the combustor are then simulated.The results reveal that the existence of the liner influences not only the acoustic field but also the flow field.When the bias velocity is large,it leads to intense turbulence-induced fluctuations,and the pressure oscillation is modulated intermittently.It shows that the weak coupling between flow and pressure oscillations plays a significant role in the onset of the intermittency of a thermoacoustic system.Based on the dynamic analysis of the thermoacoustic system with the Acoustic liner,this intermittency is caused by the influence of the flow field on the flame-acoustic coupling.Finally,a low-order modeling method based on Van der Pol(VdP) oscillator with additive stochastic forcing is conducted to reproduce the evolving dynamics of the thermoacoustic system.Although the numerical cases demonstrated in this work are relatively simpler than those in a practical combustion system,the results are helpful for us to understand the effect of the Acoustic liner and show the attractive potential to apply this device to suppress thermoacoustic instability.

关键词： thermoacoustic instability Acoustic liner Large Eddy Simulation low-order modeling

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Development of Acoustic liner in aero engine: A review

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Science China(Technological Sciences) 2020年第12期63卷 2491-2504页

作者： MA XuQiang SU ZhengTao Aviation Key Laboratory of Science and Technology on Materials and Application Research for Vibration and Noise Reduction AECC Beijing Institute of Aeronautical MaterialsBeijing 100095China

Noise reduction for aircraft engine has attracted great concern due to the strict noise control regulation nowadays. Conventional perforated sheet-over-honeycomb Acoustic liners have been widely used to attenuate turbofan engine noise. To dampen the broadband noise and resist the harsh service conditions with high temperature and pressure in modern turbofan engine,new Acoustic liner concepts are proposed and evaluated in the latest decade. In this review,available studies regarding the recent development of liners are gathered. The paper starts with the introduction of acoustic absorption mechanism of local-reacting and extended-reacting liners. The progress of novel passive liners(e.g.,mesh-cap liner,variable-depth liner,metal foam liner,hybrid liner,etc.) is summarized. Furthermore,adaptive liners with tunable geometry dimension or bias flow are illustrated in details.Metamaterial is also mentioned as a hot candidate in the next generation of Acoustic liners. Finally,this review identifies benefits and some technical challenges with the goal of unveiling the potential of novel Acoustic liner technologies in aero engine.

关键词： aero engine noise Acoustic liner Helmholtz resonators composites

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Investigation of straightforward impedance eduction method on single-degree-of-freedom Acoustic liners

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Chinese Journal of Aeronautics 2018年第12期31卷 2221-2233页

作者： Xianghai QIU Bo XIN Long WU Yang MENG Xiaodong JING Fluid and acoustic Engineering Laboratory School of Energy and Power Engineering Beihang University

In order to address the current aircraft noise problem, the knowledge of impedance of Acoustic liners subjected to high-intensity sound and grazing flow is of crucial importance to the design of high-efficiency acoustic nacelles. To this end, the present study is twofold. Firstly, the StraightForward impedance eduction Method(SFM) is evaluated by the strategy that the impedance of a liner specimen is firstly experimentally educed on a flow duct using the SFM, and then its accuracy is checked by comparing the numerical prediction with the measured wall sound pressure of the flow duct. Secondly, the effects of grazing flow and high-intensity sound on the impedance behavior of two single-layer liners are investigated based on comparisons between educed impedance and predictions by three impedance models. The performance of the SFM is validated by showing that the educed impedance leads to excellent agreement between the simulation and the measured wall sound pressure for different grazing flow Mach numbers and Sound Pressure Levels(SPLs) and over a frequency range from 3000 Hz down to 500 Hz. The grazing flow effect generally has the tendency that the acoustic resistance exhibits a slight decrease before it increases linearly with an increase in Mach,predicted successfully by the sound-vortex interaction theoretical model and the Kooi semi-empirical impedance model. However, the Goodrich semi-empirical impedance model gives only a simple linear relation of acoustic resistance starting from Mach zero. Additionally, when the SPL increases from 110 to 140 d B in the present investigation, the acoustic resistance exhibits a significant increase at all frequencies in the absence of flow; however, the resistance decreases slightly under a grazing flow of Mach 0.117. It indicates that the SPL effect can be greatly inhibited when flow is present,and the grazing flow effect can be reduced partly as well at a relatively high SPL.

关键词： Acoustic liner Experimental validation Grazing flow effect High sound intensity effect Impedance eduction Numerical evaluation Straightforward impedance eduction method

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Transfer element method with application to acoustic design of aeroengine nacelle

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Chinese Journal of Aeronautics 2015年第2期28卷 327-345页

作者： Wang Xiaoyu Sun Xiaofeng School of Energy and Power Engineering Beihang University Collaborative Innovation Center for Advanced Aero-Engine

In the present survey, various methods for the acoustic design of aeroengine nacelle are first briefly introduced along with the comments on their advantages and disadvantages for practi- cal application, and then detailed analysis and discussion focus on a kind of new method which is called ＂transfer element method＂（TEM） with emphasis on its application in the following three problems： turbomachinery noise generations, sound transmission in ducts and radiation from the inlet and outlet of ducts, as well as the interaction between them. In the theoretical frame of the TEM, the solution of acoustic field in an infinite duct with stator sound source or liner is extended to that in a finite domain with all knows and unknowns on the interface plane, and the relevant acoustic field is solved by setting up matching equation. In addition, based on combining the TEM with the boundary element method （BEM） by establishing the pressure and its derivative con- tinuum conditions on the inlet and outlet surface, the sound radiation from the inlet and outlet of ducts can also be investigated. Finally, the effects of various interactions between the sound source and acoustic treatment have been discussed in this survey. The numerical examples indicate that it is quite important to consider the effect of such interactions on sound attenuation during the acoustic design of aeroengine nacelle.

关键词： Duct acoustics Equivalent surface sourcemethod Interaction of sound sourceand acoustic treatment Acoustic liner Three-dimensional liftingsurface theory Transfer element method Aeroengine noise

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