Supersonic Jet Noise Reductions Predicted With Increased Jet Spreading Rate
DOWNLOAD
Download Supersonic Jet Noise Reductions Predicted With Increased Jet Spreading Rate PDF/ePub or read online books in Mobi eBooks. Click Download or Read Online button to get Supersonic Jet Noise Reductions Predicted With Increased Jet Spreading Rate book now. This website allows unlimited access to, at the time of writing, more than 1.5 million titles, including hundreds of thousands of titles in various foreign languages. If the content not found or just blank you must refresh this page
Supersonic Jet Noise Reductions Predicted With Increased Jet Spreading Rate
DOWNLOAD
Author :
language : en
Publisher:
Release Date : 1995
Supersonic Jet Noise Reductions Predicted With Increased Jet Spreading Rate written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with categories.
The Generation And Radiation Of Supersonic Jet Noise Future Studies For Definition Of Supersonic Jet Noise Generation And Reduction Mechanisms
DOWNLOAD
Author :
language : en
Publisher:
Release Date : 1972
The Generation And Radiation Of Supersonic Jet Noise Future Studies For Definition Of Supersonic Jet Noise Generation And Reduction Mechanisms 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.
Simulations Of The Flow Generated By Fluidic Inserts For Supersonic Jet Noise Reduction Based On Steady Rans Simulations
DOWNLOAD
Author : Matthew Kapusta
language : en
Publisher:
Release Date : 2015
Simulations Of The Flow Generated By Fluidic Inserts For Supersonic Jet Noise Reduction Based On Steady Rans Simulations written by Matthew Kapusta and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
The investigation of military jet noise prediction and reduction is an ongoing activity. Supersonic military jets radiate higher noise levels than commercial aircraft and are not subject to noise requirements. The noise generating mechanisms for high-speed jets are not entirely understood, making it difficult to set strict noise standards similar to those imposed for commercial aircraft. However, many noise reduction techniques have been applied to attempt to alleviate environmental and health concerns. Little success has been achieved to date for noise reduction of exhaust jets on supersonic tactical aircraft.A newly developed method involves a system that generates fluidic inserts in a supersonic nozzle flow to produce noise reduction. Numerical simulations have been performed for a military-style basline nozzle and with the noise reduction method of fluidic inserts used at a design Mach number of 1.65 and at various off design conditions. The purpose of the current numerical study is to provide insight for the flow field generated by the fluidic inserts used to reduce supersonic jet noise. The supersonic jet simulations are based on the use of high fidelity meshes combined with advanced CFD technology. Steady Reynolds-averaged Navier-Stokes (RANS) simulations are used to predict the flow field. Noise measurements have been performed experimentally and the results from the numerical simulations provide a correlation between aerodynamic properties and the corresponding noise reduction. The complex nozzle geometry is modeled using both an unstructured mesh and a multiblock structured mesh. The grids are generated by ANSYS ICEM and Gridgen respectively. The numerical simulations are performed using ANSYS CFX and Wind-US. The simulations with Wind-US use the Spalart-Allmaras turbulence model, while the simulations with ANSYS CFX use the Menter SST turbulence model. The results from the two flow solvers are compared and provide good agreement. The objective is to simulate a military-style nozzle, which resembles engines of the GE F404 family, with fluidic inserts. The purpose of the fluidic inserts is to alter the flow field similar to that of a hard wall corrugation in order to reduce components of noise radiation. The addition of the fluidic inserts increases the complexity of the flow field for the supersonic jet. The numerical simulations performed help to better distinguish the effects on the flow field due to the fluidic inserts. Preliminary work has been performed on a simpler geometry to provide further insight to the effect of the fluidic inserts on the supersonic jet flow field. These simulations are performed by fluid injection into a supersonic freestream over a flat plate. All numerical simulations used a freestream Mach number of 1.5. The numerical simulations used a wide range of pressure ratios for injecting the fluid into the supersonic freestream. By changing the pressure ratio of the fluid injection, the deflection of the freestream flow was better understood. Simulations on a full three dimensional nozzle with fluidic inserts were performed with conditions based on the preliminary studies. Parameters such as total pressure and total temperature provide a representation of the fluidic insert shape. Other integrated flow properties at the nozzle exit such as streamwise vorticity and pressure differential were used to correlate with the noise reduction seen in the experiments.
Supersonic Coaxial Jet Noise Predictions
DOWNLOAD
Author : Milo D. Dahl
language : en
Publisher:
Release Date : 1995
Supersonic Coaxial Jet Noise Predictions written by Milo D. Dahl and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with categories.
The Generation And Radiation Of Supersonic Jet Noise Append 2 Shock Associated Noise Data
DOWNLOAD
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.
Scientific And Technical Aerospace Reports
DOWNLOAD
Author :
language : en
Publisher:
Release Date : 1995
Scientific And Technical Aerospace Reports written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with Aeronautics categories.
Simulation Of Supersonic Jet Noise Reduction Using Fluid Inserts For Low Bypass Ratio Turbofans
DOWNLOAD
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.
High Speed Jet Flows
DOWNLOAD
Author :
language : en
Publisher:
Release Date : 1995
High Speed Jet Flows written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with categories.
Monthly Catalogue United States Public Documents
DOWNLOAD
Author :
language : en
Publisher:
Release Date : 1995-11
Monthly Catalogue United States Public Documents written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995-11 with Government publications categories.
Monthly Catalog Of United States Government Publications
DOWNLOAD
Author :
language : en
Publisher:
Release Date : 1995
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 1995 with Government publications categories.
