Acoustic energy in non-uniform flows

Morfey, C. L.

doi:10.1016/0022-460x(71)90381-6

Cited by 270 publications

(94 citation statements)

References 1 publication

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“…The termination plane is assumed to be non-reflecting, and this is forced by requiring that reflected modal amplitudes vanish. Acoustic power is computed at the source plane and termination plane based on acoustic potential modal amplitudes by using the definition of Morfey 13 , valid in the case of irrotational acoustic perturbations on irrotational mean flow. In addition, acoustic power is computed at any specified axial location using the Morfey definition, but by post-processing the acoustic potential.…”

Section: A Fem Model For Duct Propagationmentioning

confidence: 99%

Cut-on Cut-off Transition in Flow Ducts: Comparing Multiple-scales and Finite-element Solutions

Ovenden

Eversman

Rienstra³

2004

10th AIAA/CEAS Aeroacoustics Conference

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Section: A Fem Model For Duct Propagationmentioning

confidence: 99%

Cut-on Cut-off Transition in Flow Ducts: Comparing Multiple-scales and Finite-element Solutions

Ovenden

Eversman

Rienstra³

2004

10th AIAA/CEAS Aeroacoustics Conference

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“…(7), (28), (32) and taking the limit u 2 -0 while the product u 2ŝ remains finite [11], one obtains the following expression for the entropy produced by the flame at x ¼ x f :…”

Section: Methods I : Truncated Analytical Thermoacoustic Model At M A0mentioning

confidence: 99%

Accounting for convective effects in zero-Mach-number thermoacoustic models

Motheau

Selle

Nicoud

2014

Journal of Sound and Vibration

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a b s t r a c tThis paper presents a methodology to account for some mean-flow effects on thermoacoustic instabilities when using the zero-Mach-number assumption. It is shown that when a computational domain is represented under the M¼ 0 assumption, a nonzero-Machnumber element can simply be taken into account by imposing a proper acoustic impedance at the boundaries so as to mimic the mean flow effects in the outer, not computed flow domain. A model that accounts for the coupling between acoustic and entropy waves is presented. It relies on a "delayed entropy coupled boundary condition" (DECBC) for the Helmholtz equation satisfied by the acoustic pressure. The model proves able to capture low-frequency entropic modes even without mean-flow terms in the fluctuating-pressure equation.

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“…This is also the case here: Firstly, |f | 2 + |g| 2 is equal to the density of acoustic energy [32]. Secondly, as the Riemann invariants f and g propagate along the duct, summing over the coefficients (f h,0 , ..., g c,C+Q ) of the state vector (i.e.…”

Section: Non-normal Effectsmentioning

confidence: 97%

A Discrete-Time, State-Space Approach for the Investigation of Non-Normal Effects in Thermoacoustic Systems

Mangesius

Polifke

2011

International Journal of Spray and Combustion Dynamics

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A low-order, state-space modeling approach for thermoacoustic systems has been developed, which is based on present and past values of nodal characteristic wave amplitudes. The method allows to simulate the time evolution of the system state, but also the efficient computation of the (pseudo-)spectrum of the evolution operator. It is demonstrated by comparison with a frequencydomain "network model" that eigenmodes and asymptotic linear stability are predicted correctly. The influence of various model parameters (downstream reflection coefficient, temperature ratio across the heat source, magnitude and spread of heat source time delays) on transient growth of perturbation energy is explored. The discussion in the present paper is limited to simple test cases, but the approach can be generalized to systems with non-trivial topology.

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Acoustic energy in non-uniform flows

Cited by 270 publications

References 1 publication

Cut-on Cut-off Transition in Flow Ducts: Comparing Multiple-scales and Finite-element Solutions

Cut-on Cut-off Transition in Flow Ducts: Comparing Multiple-scales and Finite-element Solutions

Accounting for convective effects in zero-Mach-number thermoacoustic models

A Discrete-Time, State-Space Approach for the Investigation of Non-Normal Effects in Thermoacoustic Systems

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