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Shock Structure And Noise Of Supersonic Jets In Simulated Flight To Mach 04
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Book Synopsis Shock Structure and Noise of Supersonic Jets in Simulated Flight to Mach 0.4 by : Thomas D. Norum
Download or read book Shock Structure and Noise of Supersonic Jets in Simulated Flight to Mach 0.4 written by Thomas D. Norum and published by . This book was released on 1988 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Shock Structure and Noise of Supersonic Jets in Simulated Flight to Mach 0.4 by : Thomas D. Norum
Download or read book Shock Structure and Noise of Supersonic Jets in Simulated Flight to Mach 0.4 written by Thomas D. Norum and published by . This book was released on 1988 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Simulation of Supersonic Jet Noise Reduction Using Fluid Inserts for Low Bypass Ratio Turbofans by : Chitrarth Prasad
Download or read book Simulation of Supersonic Jet Noise Reduction Using Fluid Inserts for Low Bypass Ratio Turbofans written by Chitrarth Prasad and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis The Generation and Radiation of Supersonic Jet Noise by : Lockheed-Georgia Company
Download or read book The Generation and Radiation of Supersonic Jet Noise written by Lockheed-Georgia Company and published by . This book was released on 1972 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis NASA Scientific and Technical Publications by :
Download or read book NASA Scientific and Technical Publications written by and published by . This book was released on 1991 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NASA Technical Paper written by and published by . This book was released on 1988 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Noise Sources in Turbulent Shear Flows: Fundamentals and Applications by : Roberto Camussi
Download or read book Noise Sources in Turbulent Shear Flows: Fundamentals and Applications written by Roberto Camussi and published by Springer Science & Business Media. This book was released on 2013-02-11 with total page 453 pages. Available in PDF, EPUB and Kindle. Book excerpt: The articles in this volume present the state-of-the-art in noise prediction, modeling and measurement. The articles are partially based on class notes provided during the course `Noise sources in turbulent shear flows', given at CISM on April 2011. The first part contains general concepts of aero acoustics, including vortex sound theory and acoustic analogies, in the second part particular emphasis is put into arguments of interest for engineers and relevant for aircraft design: jet noise, airfoil broadband noise, boundary layer noise (including interior noise and its control) and the concept of noise sources, their theoretical modeling and identification in turbulent lows. All these arguments are treated extensively with the inclusion of many practical examples and references to engineering applications.
Book Synopsis Simulated High Speed Flight Effects on Supersonic Jet Noise by : Thomas D. Norum
Download or read book Simulated High Speed Flight Effects on Supersonic Jet Noise written by Thomas D. Norum and published by . This book was released on 1993 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Experimental Investigation of the Noise Reduction of Supersonic Exhaust Jets with Fluidic Inserts by : Russell Powers
Download or read book Experimental Investigation of the Noise Reduction of Supersonic Exhaust Jets with Fluidic Inserts written by Russell Powers and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The noise produced by the supersonic, high temperature jets that exhaust from military aircraft is becoming a hazard to naval personnel and a disturbance to communities near military bases. Methods to reduce the noise produced from these jets in a practical full-scale environment are difficult. The development and analysis of distributed nozzle blowing for the reduction of radiated noise from supersonic jets is described. Model scale experiments of jets that simulate the exhaust jets from typical low-bypass ratio military jet aircraft engines during takeoff are performed. Fluidic inserts are created that use distributed blowing in the divergent section of the nozzle to simulate mechanical, hardwall corrugations, while having the advantage of being an active control method. This research focuses on model scale experiments to better understand the fluidic insert noise reduction method. Distributed blowing within the divergent section of the military-style convergent divergent nozzle alters the shock structure of the jet in addition to creating streamwise vorticity for the reduction of mixing noise. Enhancements to the fluidic insert design have been performed along with experiments over a large number of injection parameters and core jet conditions. Primarily military-style round nozzles have been used, with preliminary measurements of hardwall corrugations and fluidic inserts in rectangular nozzle geometries also performed. It has been shown that the noise reduction of the fluidic inserts is most heavily dependent upon the momentum flux ratio between the injector and core jet. Maximum reductions of approximately 5.5 dB OASPL have been observed with practical mass flow rates and injection pressures. The first measurements with fluidic inserts in the presence of a forward flight stream have been performed. Optimal noise reduction occurs at similar injector parameters in the presence of forward flight. Fluidic inserts in the presence of a forward flight stream were observed to reduce the peak mixing noise below the already reduced levels by nearly 4 dB OASPL and the broadband shock-associated noise by nearly 3 dB OASPL. Unsteady velocity measurements are used to complement acoustic results of jets with fluidic inserts. Measured axial turbulence intensities and mean axial velocity are examined to illuminate the differences in the flow field from jets with fluidic inserts. Comparisons of laser Doppler measurements with RANS CFD simulations are shown with good agreement. Analysis of the effect of spatial turbulence on the measured quantities is performed. Experimental model scale measurements of jets with and without fluidic inserts over a simulated carrier deck are presented. The model carrier environment consists of a ground plane of adjustable distance below the jet, and a simulated jet blast deflector similar to those found in practice. Measurements are performed with far-field microphones, near-field microphones, and unsteady pressure sensors. The constructive and destructive interference that results from the interaction of the direct and reflected sound waves is observed and compared with results from free jets. The noise reduction of fluidic inserts in a realistic carrier deck environment with steering of the ``quiet planes'' is examined. The overall sound pressure level in heat-simulated jets is reduced by 3-5 dB depending on the specific angle and ground plane height. Jets impinging upon a modeled jet blast deflector are tested in addition to jets solely in the presence of the carrier deck. Observed modifications to the acoustic field from the presence of the jet blast deflector include downstream acoustic shielding and low frequency augmentation. The region of maximum noise radiation for heat-simulated jets from nozzles with fluidic inserts impinging on the jet blast deflector is reduced in overall sound pressure level by 4-7 dB. This region includes areas where aircraft carrier personnel are located.
Book Synopsis NASA Scientific and Technical Publications by :
Download or read book NASA Scientific and Technical Publications written by and published by . This book was released on 1987 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Supersonic Jet Shock Noise Reduction by :
Download or read book Supersonic Jet Shock Noise Reduction written by and published by . This book was released on 1984 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Vital Role of Shock-Cell and Mach Disk in Noise Production of Jet Engines by : Gibin Raju
Download or read book Vital Role of Shock-Cell and Mach Disk in Noise Production of Jet Engines written by Gibin Raju and published by . This book was released on 2018-07-17 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: Master's Thesis from the year 2018 in the subject Engineering - Aerospace Technology, grade: 3.64, University of Cincinnati, language: English, abstract: The aim of this thesis is to discuss the vital role of shock-cell and Mach disk in noise production of jet engines. This study focuses on calculation of shock-cell spacing and Mach disk from various configuration of C-D Nozzles using Shadowgraph technique and detailing on how it varies with the test conditions. In the past three decades, the air traffic has nearly increased by about 40% and have always called for alternative propulsion techniques to replace or support the current traditional propulsion methodology in order to travel longer distances in shorter frame of time. In the light of current demand, the thesis draws motivation from increase in noise levels due to technological advancements of meeting higher specific thrust thus, achieving higher efficiency. The thesis emphasizes on the study of shock-cell noise by developing a complete view of the shock-cell structure and associated parameters with an imperfectly expanded supersonic jet on CD Nozzles over range of under-expanded, design and over-expanded operating conditions. In the entire thesis study, the heated jets from the different C-D Nozzle are analyzed for proper visualization for the shock-cell structure. Shadowgraph is used in current study as it offers very high flexibility and acts as an excellent technique for visualizing the shock diamond exhaust structure and turbulent eddies. A systematic analysis has been performed to quantify the shadowgraph data through semantic video analysis and measured the shock-cell spacing over different temperature ratios (TR) and nozzle pressure ratios (NPR). Circular, rectangular and method of characteristics (MOC) convergent-divergent nozzles of 1.5 design Mach number with and without plates were tested to interpret the results. The data recorded during the experiment was processed to obtain an averaged image.
Book Synopsis Research and Technology Program Digest Flash Index by :
Download or read book Research and Technology Program Digest Flash Index written by and published by . This book was released on 1967 with total page 794 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Ground Measurements of the Shock-wave Noise from Airplanes in Level Flight at Mach Numbers to 1.4 and at Altitudes to 45,000 Feet by : Domenic J. Maglieri
Download or read book Ground Measurements of the Shock-wave Noise from Airplanes in Level Flight at Mach Numbers to 1.4 and at Altitudes to 45,000 Feet written by Domenic J. Maglieri and published by . This book was released on 1959 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Government Reports Annual Index by :
Download or read book Government Reports Annual Index written by and published by . This book was released on 1988 with total page 1068 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Research and Technology Program Digest by : United States. National Aeronautics and Space Administration
Download or read book Research and Technology Program Digest written by United States. National Aeronautics and Space Administration and published by . This book was released on with total page 792 pages. Available in PDF, EPUB and Kindle. Book excerpt: