Share

Numerical Simulation of Acoustic Propagation in a Turbulent Channel Flow with an Acoustic Liner

2018
Download Numerical Simulation of Acoustic Propagation in a Turbulent Channel Flow with an Acoustic Liner PDF Online Free

Author :
Release : 2018
Genre :
Kind : eBook
Book Rating : /5 ( reviews)

GET EBOOK


Book Synopsis Numerical Simulation of Acoustic Propagation in a Turbulent Channel Flow with an Acoustic Liner by : Robin Sebastian

Download or read book Numerical Simulation of Acoustic Propagation in a Turbulent Channel Flow with an Acoustic Liner written by Robin Sebastian. This book was released on 2018. Available in PDF, EPUB and Kindle. Book excerpt: Acoustic liners are a key technology in aeronautics for the passive reduction of the noise generated by aircraft engines. They are employed in a complex flow scenario in which the acoustic waves, the turbulent flow, and the acoustic liner are interacting.During this thesis, in a context of high performance computing, a compressible Navier-Stokes solver has been developed to perform implicit large eddy simulations of a model problem of this interaction: a turbulent plane channel flow with one wall modeled as an impedance condition.As a preliminary step the wall-turbulence in rigid channel flows and associated large-scale motions are investigated. A straightforward algorithm to detect these flow features is developed and the effect of compressibility on the flow structures and their contribution to the drag are studied. Then, the interaction between the acoustic liner and turbulent flow is investigated assuming periodicity in the streamwise direction. It is shown that low resistance and low resonance frequency tend to trigger flow instability, which modifies the conventional wall-turbulence and also results in drag increase.Finally, the simulation of a spatial channel flow was addressed. In this case no periodicity is assumed and an acoustic wave can be injected at the inlet of the domain. The effect of turbulence on sound attenuation is studied without liner, before a liner is introduced on a part of the channel bottom wall. In this more realistic case, it is confirmed that low resistance acoustic liners trigger an instability at the leading edge of the liner, resulting in drag increase and excess noise generation.

Numerical Simulation of Turbulent Flows and Noise Generation

2009-03-07 Technology & Engineering
Download Numerical Simulation of Turbulent Flows and Noise Generation PDF Online Free

Author :
Release : 2009-03-07
Genre : Technology & Engineering
Kind : eBook
Book Rating : 561/5 ( reviews)

GET EBOOK


Book Synopsis Numerical Simulation of Turbulent Flows and Noise Generation by : Christophe Brun

Download or read book Numerical Simulation of Turbulent Flows and Noise Generation written by Christophe Brun. This book was released on 2009-03-07. Available in PDF, EPUB and Kindle. Book excerpt: Large Eddy Simulation (LES) is a high-fidelity approach to the numerical simulation of turbulent flows. Recent developments have shown LES to be able to predict aerodynamic noise generation and propagation as well as the turbulent flow, by means of either a hybrid or a direct approach. This book is based on the results of two French/German research groups working on LES simulations in complex geometries and noise generation in turbulent flows. The results provide insights into modern prediction approaches for turbulent flows and noise generation mechanisms as well as their use for novel noise reduction concepts.

Large Eddy Simulation of Acoustic Propagation in Turbulent Flow Through Ducts and Mufflers

2012
Download Large Eddy Simulation of Acoustic Propagation in Turbulent Flow Through Ducts and Mufflers PDF Online Free

Author :
Release : 2012
Genre :
Kind : eBook
Book Rating : /5 ( reviews)

GET EBOOK


Book Synopsis Large Eddy Simulation of Acoustic Propagation in Turbulent Flow Through Ducts and Mufflers by : Nishant Kumar Singh

Download or read book Large Eddy Simulation of Acoustic Propagation in Turbulent Flow Through Ducts and Mufflers written by Nishant Kumar Singh. This book was released on 2012. Available in PDF, EPUB and Kindle. Book excerpt: This research involves study of acoustic propagation of pulse in a simple expansion muffler, which is very often used in HVAC or automotive exhausts. A hybrid pressure-based compressible solver is developed and validated for a low Mach number flow simulation of acoustic pulse. This new solver is developed using C++ based OpenFOAM toolkit and further tested for low Mach number flow test case. The analysis of simple expansion muffler for various structures, frequency ranges and numerical schemes is performed and results are summarized. RANS simulation of duct and muffler with mean flow is conducted and results are presented with inherent limitations associated with the method. Further, a mixed synthetic inflow boundary condition is also developed and validated for LES of channel flow. The mixed synthetic boundary is then used for LES of a simple expansion muffler to analyse the flow-acoustic and acoustic-pulse interactions inside the expansion muffler. The improvement in the prediction of tonal noise and vortex shedding inside the chamber is highlighted in comparison to the RANS method. Further, the effect of forced pulsation on flow-acoustic is observed in regard to the shift in Strouhal number inside the simple expansion muffler. Finally, a set of benchmark results for experimental analysis of the simple expansion muffler both, with and without flow is obtained to compare attenuation in forced pulsation for various mean-flow velocities. These experimental results are then used for validation of the proposed pressure-based compressible solver.

Numerical Simulation of Noise Propagation in Jet Engine Ducts

1973 Airplanes
Download Numerical Simulation of Noise Propagation in Jet Engine Ducts PDF Online Free

Author :
Release : 1973
Genre : Airplanes
Kind : eBook
Book Rating : /5 ( reviews)

GET EBOOK


Book Synopsis Numerical Simulation of Noise Propagation in Jet Engine Ducts by : Kenneth J. Baumeister

Download or read book Numerical Simulation of Noise Propagation in Jet Engine Ducts written by Kenneth J. Baumeister. This book was released on 1973. Available in PDF, EPUB and Kindle. Book excerpt: A finite difference formulation is presented which is useful in the study of acoustically treated inlet and exhaust ducts used in turbofan engines. The difference formulation can readily handle acoustic flow field complications, such as axial variations in wall impedance and cross-sectional area, that would occur in a sonic inlet. In formulating the difference solutions, the continuous acoustic field is lumped into a series of grid points spread uniformly throughout the field. At each point, the pressure is separated into its real and imaginary terms. Example solutions are presented for sound propagation in a one-dimensional straight hard-wall duct and in a two-dimensional straight soft-wall duct without steady flow.

Numerical Simulation of Two-dimensional Acoustic Liners with High Speed Grazing Flow

2009
Download Numerical Simulation of Two-dimensional Acoustic Liners with High Speed Grazing Flow PDF Online Free

Author :
Release : 2009
Genre :
Kind : eBook
Book Rating : /5 ( reviews)

GET EBOOK


Book Synopsis Numerical Simulation of Two-dimensional Acoustic Liners with High Speed Grazing Flow by : Qi Zhang

Download or read book Numerical Simulation of Two-dimensional Acoustic Liners with High Speed Grazing Flow written by Qi Zhang. This book was released on 2009. Available in PDF, EPUB and Kindle. Book excerpt:

You may also like...