Achievements in the numerical modeling of fan noise radiation from aero-engines

Casalino, Damiano; Genito, Mariano

doi:10.1016/j.ast.2007.10.005

Cited by 16 publications

(7 citation statements)

References 28 publications

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“…The MIC has been widely accepted and used in a large number of numerical and analytical works. 52,53,54,55,56,33,57,34 In the last years some problems arose, in particular with time-domain numerical solvers using the MIC, that evidenced how, in the presence of impedance, not only the numerical solution diverges due to a numerical instability, but also the boundary condition itself is ill-posed and intrinsically unstable. 58,59,60,61 These results, however, seem to be in contrast with the experiments, since evidence of this instability has been reported only rarely.…”

Section: Historical Notementioning

confidence: 99%

Towards Lattice-Boltzmann Prediction of Turbofan Engine Noise

Casalino¹,

Ribeiro²,

Fares³

et al. 2014

20th AIAA/CEAS Aeroacoustics Conference

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The goal of the present paper is to report verification and validation studies carried out by Exa Corporation in the framework of turbofan engine noise prediction through the hybrid Lattice-Boltzmann/Ffowcs-Williams & Hawkings approach (LB)-(FW-H). The underlying noise generation and propagation mechanisms related to the jet flow field and the fan are addressed separately by considering a series of elementary numerical experiments. As far as fan and jet noise generation is concerned, validation studies are performed by comparing the LB solutions with literature experimental data, whereas, for the fan noise transmission through and radiation from the engine intake and bypass ducts, LB solutions are compared with finite element solutions of convected wave equations. In particular, for the fan noise propagation, specific verification analyses are carried out by considering tonal spinning duct modes in the presence of a liner, which is modelled as an equivalent acoustic porous medium. Finally, a capability overview is presented for a comprehensive turbofan engine noise prediction, by performing LB simulation for a generic but realistic turbofan engine

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Section: Historical Notementioning

confidence: 99%

Towards Lattice-Boltzmann Prediction of Turbofan Engine Noise

Casalino¹,

Ribeiro²,

Fares³

et al. 2014

20th AIAA/CEAS Aeroacoustics Conference

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“…Based on these steady solutions, the acoustic analogy theories and semi-empirical formulas are used to calculate the noise source. The Lilley equation (Equation ( 13)) is one of the broadband noise source models, which is applicable to the jet mixing noise [33,34]. The source terms in the equation are grouped according to whether they include the mean velocity gradients.…”

Section: Steady-state Processmentioning

confidence: 99%

Numerical Study on Flow and Noise Characteristics of High-Temperature and High-Pressure Steam Ejector

et al. 2023

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Based on the shear stress transfer (SST) k-ω model, Ffowcs-Williams and Hawkings (FW–H) equation, and Lilley sound source equation, the flow and sound field of high-temperature and high-pressure steam ejectors are simulated. The entrainment performance, near-field sound source, and far-field noise of the steam ejector are discussed. The influences of working parameters including the primary steam pressure, the secondary steam pressure, and the back pressure are analyzed. The results show that under the design conditions, the steam ejector has two shock waves and three sound source regions. A shear layer at the boundary of the first shock wave generates the Sound source-I, and the flow separation at the boundary of the second shock wave causes the Sound source-III. The Sound source-II is located near the mixing chamber wall and the sound pressure levels around the ejector depend on the distances from the Sound source-II. In terms of the entrainment performance, with the increasing primary pressure or the decreasing secondary pressure, as the driving pressure difference of the secondary steam decreases, so does the entrainment ratio. As the back pressure increases, the entrainment ratio firstly remains constant, and then rapidly decreases when the back pressure exceeds the critical value at pb = 5.5 MPa. In terms of the noise characteristics, the sound pressure level and the intensity of the second shock wave have a positive correlation. When the primary or secondary pressure increases, the sound pressure level increases. Moreover, with the increasing back pressure, the sound pressure level firstly decreases, reaches the minimum of 98.2 dB at the critical back pressure, and then slowly increases.

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“…9,10 The PML can also be used to generate a sound field entering the computational domain. 11,12 This so-called 'active' PML is used to define the source of sound radiating from the engine, typically from the fan. These sources are generally described in terms of acoustic duct modes.…”

Section: Sound Propagation Modelmentioning

confidence: 99%

Adaptive, High-Order Finite-Element Method for Convected Acoustics

et al. 2018

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An improved finite element method for predicting sound propagation in non-uniform flows is proposed. Sound waves are described by the linearised potential theory solved in the frequency domain. Solutions are calculated using the p-FEM method with highorder, hierarchic shape functions which results in a drastic improvement in computational efficiency. The memory and time requirements for solving large-scale problems are significantly reduced compared to standard finite element methods. An additional feature presented in this paper is an adaptive scheme to select the optimal interpolation order in each element so as to achieve a prescribed accuracy. This greatly simplifies the preparation of the numerical model. When performing a series of calculations at different frequencies there is no need to adjust the mesh to maintain a sufficient resolution. Instead the adaptive p-FEM method adjusts the interpolation order automatically to ensure an accurate solution is obtained. The performance of the method is demonstrated for three-dimensional test cases for noise radiation from a turbofan intake. Guidelines for preparing models using this adaptive, high-order approach are also discussed.

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Achievements in the numerical modeling of fan noise radiation from aero-engines

Cited by 16 publications

References 28 publications

Towards Lattice-Boltzmann Prediction of Turbofan Engine Noise

Towards Lattice-Boltzmann Prediction of Turbofan Engine Noise

Numerical Study on Flow and Noise Characteristics of High-Temperature and High-Pressure Steam Ejector

Adaptive, High-Order Finite-Element Method for Convected Acoustics

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