2 edition of Investigation of the Near Noise Fields of A Choked Axisymmetric Air Jet. found in the catalog.
Investigation of the Near Noise Fields of A Choked Axisymmetric Air Jet.
National Research Council of Canada. National Aeronautical Establishment. Structures and Materials Section.
|Series||Canada Nrc Aeronautical Report lr -- 506, Publication (National Research Council Canada) -- 10352|
|Contributions||Westley, R., Woolley, J.H.|
conditions that screech is the dominant noise source mechanism. Narrowband spectra are given for a single near field microphone located in the nozzle exit plane as well as fluctuating pressure measurements acquired on the nozzle exit. These measurements may prove useful in understanding the initial acoustic jet excitation due to the screech mechanism. A new model of the axisymmetric body referred to in earlier studies as the “Iowa Body” was constructed with the tail truncated at a diameter of cm to accommodate a swirling jet of diameter D= cm issuing from the base, as shown in Figure jet diameter is smaller than the diameter, D p = cm, of the propeller used by Hyun and Patel ().
The results show that: The head and tail of car are the main aerodynamic noise source radiation areas, and most of the dipole source’s SPL value is more than 70dB; the variation in car speed greatly impacts on the directivity of aerodynamic noise field near the car’s tail surface (θ=°~°). About the Book: Jet Aeroacoustics is a growing area, a function of the significant near-field and far-field jet noise axisymmetric jet Lawrence S. Ukeiley and Michael K. Ponton Effect of nozzle internal contour on jet aeroacoustics K. Viswanathan and L. T. Clark Acoustic and mean flow measurements of high-speed, helium-air mixture jets.
A review of jet mixing enhancement for aircraft propulsion applications. A review of jet mixing enhancement for aircraft propulsion applications Show all authors. K Knowles 1. M., Zaman, K. B.M.Q., Reeder, M. F. Effect of tabs on the flow and noise field of an axisymmetric jet. FOREWORD This manual is intended to give an overview of the role of control valves in the behaviour of a process control loop. This overview consists the information on ﬂuid.
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An experimental investigation was completed of the near sound field of a choked axisymmetric air jet of in diameter. The results include surveys of tbe sound pres sure levels in the area surrounding the jet and the identification of various screech by: , “ An Investigation of the Near Noise Fields of a Choked Axisymmetric Jet,” AFOSR-UTIAS Symposium on Aerodynamic Noise, University of Toronto Press,pp.
– Google Scholar  Westley R. and Woolley J. H., “ The Near Field Sound Pressures of a Choked Jet when Oscillating in the Spinning Mode,” AIAA PaperCited by: An Investigation of the Near Noise Fields of a Choked Axisymmetric Air Jet, Proceedings of AFOSR-UTIAS Symposium on Aerodynamic Noise, University of Toronto Press, Toronto, ON.
Westley and J. Woolley, “An investigation of the near noise fields of a choked axisymmetric air jet,” National Research Council of Canada, National Aeronautical Establishment, Aeronautical Report No.
LR, June Cited by: It is found that although the instantaneous flow fields accompanying the flapping and helical jet screech tones are not axisymmetric yet, the long time average mean flow field is still almost axisymmetric.
This is because of the slow rotation of the flapping plane around the jet by: A noise generation mechanism for a nearly ideally expanded supersonic jet is proposed. It is suggested that the dominant part of the noise of a supersonic jet is generated at two rather localized regions of the jet.
These regions are located at distances quite far downstream of the nozzle exit. Large-scale instabilities of the jet flow are believed to be responsible for transferring the kinetic energy of the jet into noise radiation.
On the noise emanating from a two-dimensional jet above critical pressure. WESTLEY and J. WOOLLEY NRC/NAE Report CR An investigation of the near noise fields of a choked axisymmetric air jet. WESTLEY and J. WOOLLEY AGARD Conf.
Proc. 42, Paper The near field sound pressures of a choked jet during a. “The near-field sound pressures of a choked jet when operating in the spinning mode,” AIAA 2nd AeroAcoustics Conference, AIAA Paper Google Scholar; Westley, R., and Woolley, J.
H.(). “ Sound pressures of a choked jet oscillating in the spinning mode,” AIAA Aeroacoustics Specialists Conf., 2nd, Prog. Astronaut. Reynolds number. Also, the jet characteristics are dependent on such factors as the shape of the nozzle from which the jet exits, the region or environment into which the jet enters, the initial velocity profile of the jet at the nozzle exit, the orientation of the jet with respect to the gravity vector, and even the external shape of the nozzle.
An investigation of the noise generation mechanism of turbulent structures in a subsonic air jet has been done theoretically as well as experimentally. Based on the results obtained, it is proposed that the rate of change of velocities of the jet structures plays an important role in the generation of sound in an air jet.
This chapter provides an overview of the present understanding of jet noise from both an experimental and analytical viewpoint. First, a general review of experimental observations is provided. Only single axisymmetric jets are considered. Then a historical review of theoretical contributions to jet noise understanding and prediction is provided.
The flow field inside an atmospheric induction burner was found to be well described by a confined impinging axisymmetric jet, either turbulent or laminar, depending on the flow rate injected. Westley and J. Woolley, An investigation of the near noise fields of a choked axisymmetric jet, AFOSR-UTIAS Symposium on Aerodynamic Noise (University of Toronto Press, ), pp.
– Google Scholar; R. ambient are expected to be above the critical ratio (~ for hydrogen), exit flows choke and an underexpanded jet with complex near-field shock structure forms. A Mach disk serves as the boundary between the supersonic and subsonic jet portions, and can be several factors larger than the original release diameter.
The third technique pulses air tangential into the shear layer at a frequency coinciding with the preferred modes of the jet (St~, f~2kHz).\ud Near and far-field acoustic measurements were made in anechoic chamber with an array of 10 free-field microphones.
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WESTLEY, J. WOOLLEY,National Research Council of Canada, National Aeronautical Establishment, Aeronautical Report LR, June, An investigation of the near noise fields of a choked axisymmetric air jet. This paper deals with an experimental investigation on the suppression of high-speed jet noise using air/water microjet injection at the nozzle exit.
The far-field acoustic measurements from a high temperature M j = and M j = axisymmetric jet issuing from a converging nozzle show the suppression of screech tones, Mach wave radiation. Abstract. The noise of supersonic jets issued from choked or convergent-divergent nozzles is a subject of considerable current interest.
When these jets are operated at off-design pressure ratios, measured noise spectra invariably show that they are made up of discrete and broadband components.
“ An Investigation of the Turbulent Integral Length Scales in an Underexpanded Axisymmetric Jet,” Australian Conference on Laser Diagnostics in Fluid Mechanics and Combustion (Damon Honnery and Daniel Edgington-Mitchell 09 December to 11 December ), Monash University Publ., Clayton, VC, Australia,pp.
7. Suppress jet noise, radar reflection, and infrared radiation (IR) if desired. 8. Two-dimensional and axisymmetric nozzles, thrust vector control if desired. 9. Do all of the above with minimal cost, weight, and boat tail drag while meeting life and reliability goals.
Introduction to. Aircraft Noise traces the origins of this problem to the introduction of the jet engine into the airline fleet in the late s and describes the legal restrictions now placed on the industry.
It explains the derivation of the special noise units and assessment scales now used around the world; noise exposure modeling and forecasting; the major sources of aircraft noise and their control; and.The story of BA flight and the words every passenger dreads 'Ladies and gentlemen, this is your captain speaking.
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