Experimental Study Of Jet Exhaust Simulation Parameters
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Experimental Study Of Jet Exhaust Simulation Parameters
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Author : William Bernard Compton
language : en
Publisher:
Release Date : 1973
Experimental Study Of Jet Exhaust Simulation Parameters written by William Bernard Compton and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1973 with categories.
An Experimental Study Of Jet Exhaust Simulation
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Author :
language : en
Publisher:
Release Date : 1974
An Experimental Study Of Jet Exhaust Simulation written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1974 with categories.
Experimental Investigation Of The Noise Reduction Of Supersonic Exhaust Jets With Fluidic Inserts
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Author : Russell Powers
language : en
Publisher:
Release Date : 2015
Experimental Investigation Of The Noise Reduction Of Supersonic Exhaust Jets With Fluidic Inserts written by Russell Powers 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 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.
An Analytical And Experimental Analysis Of Factors Affecting Exhaust System Performance In Sea Level Static Jet Engine Test Facilities
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Author : David Laurence Bailey
language : en
Publisher:
Release Date : 1972
An Analytical And Experimental Analysis Of Factors Affecting Exhaust System Performance In Sea Level Static Jet Engine Test Facilities written by David Laurence Bailey and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1972 with categories.
The study was motivated by a request from the Naval Air Rework Facility, NAS North Island, that work be conducted to obtain information on parameters affecting exhaust system performance in sea level static jet engine test facilities. The cost of pollution abatement devices makes it mandatory that accurate knowledge of flow parameters be developed. The study investigated by theory and experiment certain parameters of test cell design. A computer program based on the one-dimensional mass, momentum and energy conservation equations was developed. Components were designed to test on a scale of 24:1 the effects of varying exhaust system configurations. Theoretical results were found to be in good agreement with experimental data, indicating that the program may be used to analyze full scale systems. Recommendations for future development in the analysis and experimental program were made. (Author).
Scientific And Technical Aerospace Reports
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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.
Experimental Method For Correcting Nozzle Afterbody Drag For The Effects Of Jet Temperature
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Author : W. L. Peters
language : en
Publisher:
Release Date : 1981
Experimental Method For Correcting Nozzle Afterbody Drag For The Effects Of Jet Temperature written by W. L. Peters and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1981 with Airplanes categories.
The objective of this investigation was to isolate those parameters defined as jet mixing effects on afterbody drag in an effort to develop a method of correcting or simulating the effects of jet temperature in wind tunnel experiments. Data used in the investigation were obtained from experiments conducted in the AEDC Aerodynamic Wind Tunnel (1T) with a strut-mounted model at free-stream Mach numbers from 0.6 to 1.2. Integrated afterbody pressure drag coefficient data were acquired for three nozzle area ratios (1.0, 1.24, and 2.96) using various unheated jet exhaust gas compositions that allowed a variation in gas constant from 55 to 767 ft/lbf/lbm-deg R. Jet mixing effects on afterbody drag coefficient produced by varying jet gas constant and nozzle area ratio at nozzle design pressure ratio, and the drag effects resulting from variations in nozzle pressure ratio at certain overexpanded jet conditions were observed to be similar functions of mass flux ratio. A simple experimental method has been proposed to allow corrections of afterbody drag coefficient data obtained in the wind tunnel (using an ambient temperature air jet) for the effects of jet gas constant. By inference, a similar drag correction can be obtained for the combined effect of gas constant and temperature, assuming their product defines the effects on drag produced by variations in either property. (Author).
An Evaluation Of Jet Simulation Parameters For Nozzle Afterbody Testing At Transonic Mach Numbers
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Author : William Lee Peters
language : en
Publisher:
Release Date : 1976
An Evaluation Of Jet Simulation Parameters For Nozzle Afterbody Testing At Transonic Mach Numbers written by William Lee Peters and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1976 with Airplanes categories.
The objective of this investigation was to evaluate various jet simulation parameters in an attempt to establish a method of matching hot jet interference with cold jet flows. Successful parameters were determined based on their ability to correlate integrated afterbody pressure drag, a measurement of aerodynamic interference, for jet flows of varying total temperature. Data used in this investigation were obtained from experiments conducted in the AEDC Propulsion Wind Tunnel (16T) with three different isolated nozzle/afterbody configurations at free-stream Mach numbers from 0.6 to 1.5. Gas temperature effects on pressure drag were acquired with a convergent nozzle utilizing an air/ethylene burner to produce gas temperatures from 540 to 3,300 R. In addition, the jet effects of varying internal nozzle geometry, specifically nozzle divergence half-angle and nozzle exit-to-throat area ratio, were investigated utilizing high-pressure air as the nozzle exhaust gas. Jet simulation parameters were evaluated for jet flows where nozzle exit-to-throat area ratio was varied from 1.0 to approximately 1.5 and where divergence half-angle was varied from 0 to 10 deg.
Numerical And Experimental Studies On Combustion Engines And Vehicles
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Author : Paweł Woś
language : en
Publisher: BoD – Books on Demand
Release Date : 2020-11-26
Numerical And Experimental Studies On Combustion Engines And Vehicles written by Paweł Woś and has been published by BoD – Books on Demand this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-11-26 with Technology & Engineering categories.
The matters discussed and presented in the chapters of this book cover a wide spectrum of topics and research methods commonly used in the field of engine combustion technology and vehicle functional systems. This book contains the results of both computational analyses and experimental studies on jet and reciprocating combustion engines as well heavy-duty onroad vehicles. Special attention is devoted to research and measures toward preventing the emission of harmful exhaust components, reducing fuel consumption or using unconventional methods of engine fueling or using renewable and alternative fuels in different applications. Some technical improvements in design and control of vehicle systems are also presented.
Nasa Technical Memorandum
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Author :
language : en
Publisher:
Release Date : 1989
Nasa Technical Memorandum written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1989 with Aeronautics categories.
Optimization And Modeling Of Noise Reduction For Turbulent Jets With Induced Asymmetry
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Author : Sara Rostamimonjezi
language : en
Publisher:
Release Date : 2013
Optimization And Modeling Of Noise Reduction For Turbulent Jets With Induced Asymmetry written by Sara Rostamimonjezi and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
This project relates to the development of next-generation high-speed aircraft that are efficient and environmentally compliant. The emphasis of the research is on reducing noise from high-performance engines that will power these aircraft. A strong component of engine noise is jet mixing noise that comes from the turbulent mixing process between the high-speed exhaust flow of the engine and the atmosphere. The fan flow deflection method (FFD) suppresses jet noise by deflecting the fan stream downward, by a few degrees, with respect to the core stream. This reduces the convective Mach number of the primary shear layer and turbulent kinetic energy in the downward direction and therefore reduces the noise emitted towards the ground. The redistribution of the fan stream is achieved with inserting airfoil-shaped vanes inside the fan duct. Aerodynamic optimization of FFD has been done by Dr. Juntao Xiong using a computational fluid dynamics code to maximize reduction of noise perceived by the community while minimizing aerodynamic losses. The optimal vane airfoils are used in a parametric experimental study of 50 4-vane deflector configurations. The vane chord length, angle of attack, and azimuthal location are the parameters studied in acoustic optimization. The best vane configuration yields a reduction in cumulative (downward + sideline) effective perceived noise level (EPNL) of 5.3 dB. The optimization study underscores the sensitivity of FFD to deflector parameters and the need for careful design in the practical implementation of this noise reduction approach. An analytical model based on Reynolds Averaged Navier Stokes (RANS) and acoustic analogy is developed to predict the spectral changes from a known baseline in the direction of peak emission. A generalized form for space-time correlation is introduced that allows shapes beyond the traditional exponential forms. Azimuthal directivity based on the wavepacket model of jet noise is integrated with the acoustic analogy model. A physics-based definition of convective Mach number is proposed. The predicted noise reduction is in reasonable agreement with the experiments. The study underscores the importance of a proper definition of convective Mach number when modeling noise in the direction of peak emission.
