Journal ArticleDOI
Noise radiation from the side edges of flaps
TLDR
In this article, a model based on a physical picture of boundary layer vorticity being swept around the edge by spanwise flow on the flap was developed and solved and the resulting noise radiation calculated.Abstract:
The recently observed phenomenon of high noise radiation from the side edges of flaps in flow is investigated by way of a simple two-dimensional model problem. The model is based upon a physical picture of boundary layer vorticity being swept around the edge by spanwise flow on the flap. The model problem is developed and solved and the resulting noise radiation calculated. Further, a mathematical condition for the vortex to be captured by the potential flow and swept around the edge is derived. The results show that the sound generation depends strongly upon the strength of the vorticity and distance from the edge and that it can be more intense than the more common trailing edge noise source in agreement with the experimental observations.read more
Citations
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Journal ArticleDOI
Aircraft noise reduction technologies: A bibliographic review
TL;DR: In this article, a bibliographical review of the main technologies employed for the mitigation of aircraft noise is presented, according to a component-based approach, analytical and semi-empirical models of the aeroacoustic mechanisms involved in the noise generation from airframe and engine components are presented as a key element of the noise reduction technology.
Journal ArticleDOI
Aircraft noise prediction
TL;DR: It is contended that the field of aircraft noise prediction has not yet reached a sufficient level of maturity, in particular, some parametric effects cannot be investigated, issues of accuracy are not currently addressed, and validation standards are still lacking.
Journal ArticleDOI
Noise Characteristics of Aircraft High Lift Systems
Y. P. Guo,M. C. Joshi +1 more
TL;DR: In this paper, the characteristics of far-field noise from aircraft high lift systems are discussed using both free microphone data and measurements from a phased microphone array, which reveal the dependence of the acoustic radiation on flow Mach numbers, effects of flap and/or slat deployment, and farfield directivity.
Journal ArticleDOI
Component-based empirical model for high-lift system noise prediction
TL;DR: In this paper, an empirical model for predicting noise from high lift systems, derived from a large database of airframe noise tests, involving various airplane models at various operating conditions, is presented.
Journal ArticleDOI
Formation of a Trailing Vortex
TL;DR: In this paper, the authors investigated the incompressible flowfield in the vicinity of a l ift ing rectangular finite wing to ascertain the nature and detailed characteristics of the formation of a trailing vortex.
References
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Journal ArticleDOI
Aerodynamic sound generation by turbulent flow in the vicinity of a scattering half plane
J. E. Ffowcs Williams,L. H. Hall +1 more
TL;DR: In this paper, the presence of the edge of a half plane in a turbulent fluid results in a large increase in the noise generated by that fluid at low Mach numbers, and the farfield sound has the same features as would be predicted by geometrical acoustics.
Journal ArticleDOI
Contributions to the theory of aerodynamic sound, with application to excess jet noise and the theory of the flute
TL;DR: In this article, a reformulation of the Lighthill (1952) theory of aerodynamic sound is described, and the form of the acoustic propagation operator is established for a non-uniform mean flow in the absence of vortical or entropy gradient source terms.
Journal ArticleDOI
A review of the theory of trailing edge noise
TL;DR: In this article, three different approaches to the subject are identified, consisting of theories based on Lighthill's acoustic analogy, the solution of special, linearized hydroacoustic problems, and ad hoc aerodynamic source models.
Journal ArticleDOI
An inviscid model of two-dimensional vortex shedding
TL;DR: In this article, an inviscid model of vortex shedding behind a square-based section is developed using a discrete-vortex approximation for the free shear layers, which is computed from the velocities of the discrete vortices, and in turn derived through a Schwartz-Christoffel transformation of the section.
Related Papers (5)
Reynolds-averaged Navier-Stokes computations of a flap-side-edge flowfield
Aerodynamic sound generation by turbulent flow in the vicinity of a scattering half plane
J. E. Ffowcs Williams,L. H. Hall +1 more