Simulation Of Supersonic Jet Noise With The Adaptation Of Overflow Cfd Code And Kirchhoff Surface Integral
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Simulation Of Supersonic Jet Noise With The Adaptation Of Overflow Cfd Code And Kirchhoff Surface Integral
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Author : National Aeronautics and Space Administration (NASA)
language : en
Publisher: Createspace Independent Publishing Platform
Release Date : 2018-06-19
Simulation Of Supersonic Jet Noise With The Adaptation Of Overflow Cfd Code And Kirchhoff Surface Integral written by National Aeronautics and Space Administration (NASA) and has been published by Createspace Independent Publishing Platform this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-06-19 with categories.
An acoustic prediction capability for supersonic axisymmetric jets was developed on the basis of OVERFLOW Navier-Stokes CFD (Computational Fluid Dynamics) code of NASA Langley Research Center. Reynolds-averaged turbulent stresses in the flow field are modeled with the aid of Spalart-Allmaras one-equation turbulence model. Appropriate acoustic and outflow boundary conditions were implemented to compute time-dependent acoustic pressure in the nonlinear source-field. Based on the specification of acoustic pressure, its temporal and normal derivatives on the Kirchhoff surface, the near-field and the far-field sound pressure levels are computed via Kirchhoff surface integral, with the Kirchhoff surface chosen to enclose the nonlinear sound source region described by the CFD code. The methods are validated by a comparison of the predictions of sound pressure levels with the available data for an axisymmetric turbulent supersonic (Mach 2) perfectly expanded jet. Kandula, Max and Caimi, Raoul and Steinrock, T. (Technical Monitor) Kennedy Space Center NASA/TM-2001-210263, NAS 1.15:210263
Simulation Of Supersonic Jet Noise With The Adaptation Of Overflow Cfd Code And Kirchhoff Surface Integral
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Author :
language : en
Publisher:
Release Date : 2001
Simulation Of Supersonic Jet Noise With The Adaptation Of Overflow Cfd Code And Kirchhoff Surface Integral written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with categories.
Simulation Of Supersonic Jet Noise With The Adaptation Of Overflow Cfd Code And Kirchhoff Surface Integral Nasa
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Author :
language : en
Publisher:
Release Date : 1998
Simulation Of Supersonic Jet Noise With The Adaptation Of Overflow Cfd Code And Kirchhoff Surface Integral Nasa written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1998 with categories.
Simulation Of Supersonic Jet Noise With The Adaptation Of Overflow Cfd Code And Kirchhoff Surface Integral
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Author : Max Kandula
language : en
Publisher:
Release Date : 2001
Simulation Of Supersonic Jet Noise With The Adaptation Of Overflow Cfd Code And Kirchhoff Surface Integral written by Max Kandula and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with categories.
Simulation Of Supersonic Jet Noise With The Adaptation Of Overflow Cfd Code And Kirchhoff Surface Integral Nasa Tm 2001 210263 Dec 6
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Author :
language : en
Publisher:
Release Date : 2002
Simulation Of Supersonic Jet Noise With The Adaptation Of Overflow Cfd Code And Kirchhoff Surface Integral Nasa Tm 2001 210263 Dec 6 written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with categories.
Monthly Catalog Of United States Government Publications
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Author :
language : en
Publisher:
Release Date : 2003
Monthly Catalog Of United States Government Publications written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with Government publications categories.
Identification Of Near Sound Field Boundary And Far Field Noise Predictions
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Author : Kyong Sang Lee
language : en
Publisher:
Release Date : 2007
Identification Of Near Sound Field Boundary And Far Field Noise Predictions written by Kyong Sang Lee and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.
The Generation And Radiation Of Supersonic Jet Noise Append 2 Shock Associated Noise Data
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Author :
language : en
Publisher:
Release Date : 1972
The Generation And Radiation Of Supersonic Jet Noise Append 2 Shock Associated Noise Data written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1972 with Jet planes categories.
Simulation Of Supersonic Jet Noise Reduction Using Fluid Inserts For Low Bypass Ratio Turbofans
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Author : Chitrarth Prasad
language : en
Publisher:
Release Date : 2019
Simulation Of Supersonic Jet Noise Reduction Using Fluid Inserts For Low Bypass Ratio Turbofans written by Chitrarth Prasad and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.
The design constraints on jet engines for high performance supersonic military aircraft require lower bypass ratios and supersonic exhaust velocities, which result in very high noise levels. This is a great concern to the US Navy as the noise generated from the jet exhaust of high performance supersonic military aircraft can affect the hearing and performance of personnel working in close proximity of the aircraft. There have been reports about the US Department of Veteran Affairs spending over hundreds of millions of dollars in disability payments for hearing loss compensation to former Navy personnel. In addition to this, jet noise is also a source of annoyance in communities in the vicinity of airbases and military training routes.Over the years, several noise reduction methods have been proposed with varying levels of success. The most effective noise reduction strategies include the installation of chevrons, and the use of corrugated seals, among many others. One primary disadvantage of these technologies is that they are passive technologies and cannot be switched off or modified after take-off and hence may reduce overall aircraft performance. An active, though steady, noise reduction technology is the use of fluid inserts in the divergent section of a converging-diverging nozzle. The fluid inserts consist of rows of injectors that inject a small amount of bypass air into the diverging section of the nozzle. It has been shown that by altering the configuration and operating conditions of the fluid inserts, noise reduction for both mixing and shock noise can be achieved. Since this blowing can be controlled, the fluid inserts can be switched off or modified after take-off to minimize any performance penalty to the aircraft.Although considerable experimental research has been performed to explore the effects of fluid inserts on the jet exhaust, the available data have been found to be insufficient to correlate the noise reduction with changes in the flow-field due to the noise reduction device. The present study is an extension to the previousresearch on fluid inserts that uses Large Eddy Simulation (LES) with the Ffowcs Williams-Hawkings (FWH) analogy for farfield noise prediction. The simulations are carried out using a commercially available CFD package, STAR-CCM+. The project aims to simulate and analyze the unsteady flow changes associated withthe noise reduction device to help understand the detailed mechanisms for the observed noise reductions.Different fluid insert configurations are used to analyze the effect of individual injector placement in a fluid insert on noise generation. It is observed that the changes in upstream noise correlate extremely well with the shock structure of the fluid insert jets downstream of the nozzle exit. Further insight into the noisereduction patterns is obtained by using two-point space time correlations and the use of the modal techniques such as Proper Orthogonal Decomposition on the near-field data on the FWH surface, which show that fluid inserts reduce the amplitude of the noise radiating coherent structures. Using Doaks Momentum Potential Theory, it is observed that the changes associated with fluid insertson the hydrodynamic and acoustic modes correlate well with the far-field noise reduction.
Numerical Simulations Of Sound Generation From Jet Flows Through Orifices And Lobed Mixers
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Author : Kaveh Habibi
language : en
Publisher:
Release Date : 2019
Numerical Simulations Of Sound Generation From Jet Flows Through Orifices And Lobed Mixers written by Kaveh Habibi and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.
"The design of modern aircraft turbofan engines with low noise emissions requires a thorough understanding of noise generation and absorption phenomena in turbulent mixing jets as well as passive noise reduction devices, e.g. lobed mixers or acoustic liners. At the design stage, such understanding should be provided by reliable and accurate prediction tools to avoid prohibitively expensive experiments. Common acoustic prediction tools are either based on semi-empirical models limited to specific applications, or high-order computational fluid dynamics (CFD) codes, involving prohibitive costs for complex problems. The present study investigates the application and validation of a relatively novel approach in Computational Aeroacoustics (CAA) in which the unsteady near-field flow that contains important noise sources is simulated using a three-dimensional Lattice Boltzmann Method (LBM). The far-field sound pressure is predicted using the Ffwocs Williams-Hawkings (FW-H) surface integral method. The effects of turbulence modelling, Reynolds number, Mach number and non-isothermal boundary conditions were tested for canonical jet noise problems. A commercial code, PowerFLOW, based on the Lattice Boltzmann kernel was utilized for the simulations. In the first part of this study, turbulent jet simulations were performed for various configurations including a circular pipe, the SMC000 single-stream nozzle, and internal mixing nozzles with various types of forced mixers. Mean flow and turbulence statistics were obtained as well as sound pressure levels in the far-field. Predictions were compared with experimental data at similar operating conditions for verification. In most cases in which direct comparison were made with experimental data, 1/3 octave band spectral levels were found in good agreement with measured values up to Strouhal number (St) of ~3.0-4.0, also the overall sound pressure levels from simulation were mostly within ~1.0 dB range of measured sound levels. In all case studies, the actual nozzle including various mixer configurations was included in the computational domain in order to achieve realistic flow conditions. In some cases, inflow conditions needed to be imposed using forcing functions in order to mimic experimental conditions and induce enough perturbation for jet transition to turbulence. Both regular and high-order D3Q19 LBM schemes were tested in this study. The former method was restricted to a relatively low Mach numbers up to 0.5, where the latter can technically simulate the flow-field within the higher subsonic range through high-order terms in the discretized momentum equations. In another parallel study, the problem of sound absorption by turbulent jets was studied using a similar Lattice Boltzmann technique. The sound and turbulent flow inside a standing wave tube terminated by a circular orifice in presence of a mean flow was simulated. The computational domain comprised a standard virtual impedance tube apparatus in which sound waves were produced by periodic pressure imposed at one end. A turbulent jet was formed at the discharge of a circular orifice plate by the steady flow inside the tube. The acoustic impedance and sound absorption coefficient of the orifice plate were calculated from a wave decomposition of the sound field upstream of the orifice. Simulations were carried out for different excitation frequencies, amplitudes and orifice Mach numbers. Results and trends were in quantitative agreement with available analytical solution and experimental data. Altogether, the work documented here supports the accuracy and validity of the LBM for detailed flow simulations of complex turbulent jets. This method offers some advantages over Navier-Stokes based simulations for internal and external flows"--
