Linear Acoustic Formulas for Calculation of Rotating Blade Noise

Farassat, F.

doi:10.2514/3.60051

Cited by 321 publications

(149 citation statements)

References 9 publications

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“…The penetrable integral solution of FW-H equation solved by Farassat et al [30][31][32][33][34][35] can be written in the form of…”

Section: Fw-h Acoustic Analogy Methodsmentioning

confidence: 99%

On aerodynamic noises radiated by the pantograph system of high-speed trains

Zhang

2013

Acta Mech Sin

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Pantograph system of high-speed trains become significant source of aerodynamic noise when travelling speed exceeds 300 km/h. In this paper, a hybrid method of non-linear acoustic solver (NLAS) and Ffowcs WilliamsHawkings (FW-H) acoustic analogy is used to predict the aerodynamic noise of pantograph system in this speed range. When the simulation method is validated by a benchmark problem of flows around a cylinder of finite span, we calculate the near flow field and far acoustic field surrounding the pantograph system. And then, the frequency spectra and acoustic attenuation with distance are analyzed, showing that the pantograph system noise is a typical broadband one with most acoustic power restricted in the medium-high frequency range from 200 Hz to 5 kHz. The aerodynamic noise of pantograph systems radiates outwards in the form of spherical waves in the far field. Analysis of the overall sound pressure level (OASPL) at different speeds exhibits that the acoustic power grows approximately as the 4th power of train speed. The comparison of noise reduction effects for four types of pantograph covers demonstrates that only case 1 can lessen the total noise by about 3 dB as baffles on both sides can shield sound wave in the spanwise direction. The covers produce additional aerodynamic noise themselves in the other three cases and lead to the rise of OASPLs.

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“…The penetrable integral solution of FW-H equation solved by Farassat et al [30][31][32][33][34][35] can be written in the form of…”

Section: Fw-h Acoustic Analogy Methodsmentioning

confidence: 99%

On aerodynamic noises radiated by the pantograph system of high-speed trains

Zhang

2013

Acta Mech Sin

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“…All of the linear propagation can be determined by the FW-H equation. For three-dimensional fl ows, the time-domain FW-H formulations developed by Farassat 11 are efficient and amenable to numerical computations. Some additional efficiency can be obtained by restricting the source to uniform, rectilinear motion.…”

Section: Acoustic Equationsmentioning

confidence: 99%

Aeroacoustic Analysis of a Simplified Landing Gear

Lockard

Khorrami

2003

9th AIAA/CEAS Aeroacoustics Conference and Exhibit

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A hybrid approach is used to investigate the noise generated by a simplified landing gear without small scale parts such as hydraulic lines and fasteners. The Ffowcs Williams and Hawkings equation is used to predict the noise at far-field observer locations from flow data provided by an unsteady computational fluid dynamics calculation. A simulation with 13 million grid points has been completed, and comparisons are made between calculations with different turbulence models. Results indicate that the turbulence model has a profound effect on the levels and character of the unsteadiness. Flow data on solid surfaces and a set of permeable surfaces surrounding the gear have been collected. Noise predictions using the porous surfaces appear to be contaminated by errors caused by large wake fluctuations passing through the surfaces. However, comparisons between predictions using the solid surfaces with the near-field CFD solution are in good agreement giving confidence in the far-field results.

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“…The solution using the collapsing sphere approach is singularity free and is given 3 American Institute of Aeronautics and Astronautics…”

Section: The Governing Equationsmentioning

confidence: 99%

A study of supersonic surface sources - The Ffowcs Williams-Hawkings equation and the Kirchhoff formula

Farassat

Kenneth

Dunn

1998

4th AIAA/CEAS Aeroacoustics Conference

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In this paper we address the mathematical problem of noise generation from high speed moving surfaces. The problem we are solving is the linear wave equation with sources on a moving surface. The Ffowcs Williams-Hawkings (FW-H) equation as well as the governing equation for deriving the Kirchhoff formula for moving surfaces are both this type of partial differential equation. We give a new exact solution of this problem here in closed form which is valid for subsonic and supersonic motion of the surface but it is particularly suitable for supersonically moving surfaces. This new solution is the simplest of all high speed formulations of Langley and is denoted formulation 4 following the tradition of numbering of our major results for the prediction of the noise of rotating blades. We show that for a smooth surface moving at supersonic speed, our solution has only removable singularities.Thus it can be used for numerical work.

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Linear Acoustic Formulas for Calculation of Rotating Blade Noise

Cited by 321 publications

References 9 publications

On aerodynamic noises radiated by the pantograph system of high-speed trains

On aerodynamic noises radiated by the pantograph system of high-speed trains

Aeroacoustic Analysis of a Simplified Landing Gear

A study of supersonic surface sources - The Ffowcs Williams-Hawkings equation and the Kirchhoff formula

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