- document
-
Avallone, F. (author), Ragni, D. (author)Noise reduction is one of the major challenges to the societal acceptance of wind turbines. Aerodynamic noise sources are the dominant ones, assuming that mechanical noise can be reduced by correct insulation and periodic maintenance of the gearbox and drive train and by adding insulating material in the wind-turbine nacelle. The dominant...book chapter 2023
- document
-
Utzmann, J. (author), Munz, C.D. (author)This paper advances the idea of a heterogeneous domain decomposition for Computational Aeroacoustics (CAA). Direct simulations of aeroacoustic problems are accelerated by sub-dividing the computational domain into smaller domains. In each of these sub-domains the equations, the discretization, the mesh and the time step may be different and are...conference paper 2006
- document
-
Sandberg, R.D. (author), Sandham, N.D. (author)This paper presents two-dimensional direct numerical simulations (DNS) of noise generated at trailing edges (TE) with zero thickness. The simulations are conducted specifying either no-slip or slip walls in order to investigate viscous effects. In both cases, small amplitude disturbances are introduced close to the inflow boundary that serve as...conference paper 2006
- document
-
Sandberg, R.D. (author), Jones, L.E. (author), Sandham, N.D. (author)This paper presents a non-reflecting boundary condition that significantly reduces the spurious pressure oscillations that are produced when vortical structures in a compressible flow cross the computational farfield boundaries. The method is based on commonly used characteristic boundary conditions. Here, incoming characteristics are ramped to...conference paper 2006
- document
-
Lörcher, F. (author), Gassner, G. (author), Munz, C.D. (author)Numerical schemes for wave propagation over long distances need good wave propagation properties with low dispersion and low dissipation errors. Suitable numerical methods are methods with high order of accuracy in space and time. For space discretization on structured grids, high order finite difference schemes are efficient, and, if a...conference paper 2006
- document
-
Huang, X. (author), Ma, Z. (author), Zhang, X. (author)This paper outlines the method of a block-structured adaptive mesh refinement (AMR) and its application to the computation of noise radiation from a realistic engine exhaust geometry with flow. The computational model described allows acoustic waves, propagating inside the bypass duct of a generic aircraft engine, to be admitted into a...conference paper 2006
- document
-
Gröschel, E. (author), Schröder, W. (author), Meinke, M. (author)The acoustic simulations of a cold single stream jet at Mach number 0.9 and Reynolds number 3,600 and two heated coaxial jets at Mach number 0.9 and Reynolds numbers 3,600 and 400,000 are performed. The computation of the acoustic field is performed by a two-step approach using a large-eddy simulation (LES) for the flow field and approximate...conference paper 2006
- document
-
Chiba, K. (author), Imamura, T. (author), Amemiya, K. (author), Jeong, S. (author), Yamamoto, K. (author)The multi-objective design exploration of the two-dimensional shielding effect for engine noise using V-tale wing has been performed. Two objective functions are considered as the minimization of the sound pressure level at the side and bottom locations relative to the fuselage, which values are evaluated by using the linearized Euler equation....conference paper 2006
- document
-
Kok, J.C. (author)A new high-order, finite-volume scheme is presented that preserves the symmetry property and the dispersion relation of the convective operator. The scheme is applied to large-eddy simulation of compressible, turbulent flow and to the solution of the linearized Euler equations for aeroacoustic applications. For large-eddy simulation, the...conference paper 2006
- document
-
Bailly, C. (author), Bogey, C. (author)This paper presents a short overview of recent developments of low-dispersive and low-dissipation finite-difference schemes as an alternative to more classical methods of applied mathematics. Needs of accurate and efficient numerical solvers in computational aeroacoustics have motivated these developements over the last two decades. Properties...conference paper 2006
- document
-
Taghaddosi, F. (author), Habashi, W.G. (author)A three-dimensional computational aeroacoustics code has been developed for the simulation of tone noise generated by turbofan engine inlets. The code is based on the linearized Euler equations, rewritten in terms of acoustic potential and solved in the frequency domain. Spatial discretization is performed using a spectral element method....conference paper 2006
- document
-
Bernacki, M. (author), Piperno, S. (author)We present in this paper a time-domain Discontinuous Galerkin dissipation-free method for the transient solution of the three-dimensional linearized Euler equations around a steady-state solution. In the general context of a non-uniform supporting flow, we prove, using the well-known symmetrization of Euler equations, that some aeroacoustic...conference paper 2006
- document
-
Arina, R. (author), Ceresola, N. (author)A numerical simulation of the turbulent flow field of a transonic cavity and its associated far-field sound radiation, are presented. The test case is based on the experimental case M219 of QinetiQ. Two different turbulent simulations are performed, the first one is a URANS simulation with a k-w-EARSM turbulence model. while a DES turbulence...conference paper 2006
- document
-
Ragni, D. (author), Avallone, F. (author), van der Velden, W.C.P. (author)The far-field noise and flow field of a novel curved trailing-edge serration (i.e. iron-shaped) are investigated. Spectra of the far-field broadband noise, directivity plots and the flow-field over the iron-shaped serration are obtained from numerical computations performed using a compressible Lattice-Boltzmann solver. The new design is...conference paper 2017
- document
-
Zhang, Xueqing (author), Sciacchitano, A. (author), Pröbsting, S. (author)The present study investigates the feasibility of high-lift devices noise prediction based on measurements of time-resolved particle image velocimetry (TR-PIV). The model under investigation is a NACA 0015 airfoil with Gurney flap with height of 6% chord length. The velocity fields around and downstream the Gurney flap are measured by PIV and...conference paper 2016
- document
-
Moore, P.D. (author)Jet noise is an extensively studied phenomenon since the deployment of the first civil jet aircraft more than 50 years ago. Jet noise makes up a considerable portion of the total noise of jet aircraft, and the expansion of the numbers of airplanes and airports has only been possible by keeping the noise of airplanes under control. However, while...doctoral thesis 2009
- document
-
Pröbsting, S. (author)Noise generated aerodynamically by the airflow over a lifting surface is often of concern for applications as diverse as air and ground transportation, heating, ventilation, air-conditioning systems, and wind turbines. The thesis describes the application of advanced optical flow measurements techniques for the visualization and description of...doctoral thesis 2015
- document
- De Jong, A.T. (author) doctoral thesis 2012
- document
-
Violato, D.V. (author)To meet the increasingly stringent noise regulation, aircraft manufacturers are searching for solutions to jet noise. This, which constitutes a significant amount of the total noise emitted by civil aircrafts, is generated by the mixing processes between the exhaust flow leaving the engine and the atmosphere. A detailed understanding of such...doctoral thesis 2013
- document
-
Koschatzky, V. (author)This thesis deals with the problem of noise. Sound is a constant presence in our lives. Most of the times it is something wanted and it serves a purpose, such as communication through speech or entertainment by listening to music. On the other hand, quite often sound is an annoying and unwanted by-product of some other activity necessary to us....doctoral thesis 2011