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Wednesday, November 25, 2020 | History

3 edition of Enhanced mixing of a rectangular supersonic jet by natural and induced screech found in the catalog.

Enhanced mixing of a rectangular supersonic jet by natural and induced screech

Enhanced mixing of a rectangular supersonic jet by natural and induced screech

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  • 16 Currently reading

Published by National Aeronautics and Space Administration, National Technical Information Service, distributor in [Washington, DC], [Springfield, Va .
Written in English

    Subjects:
  • Supersonic planes.

  • Edition Notes

    StatementEdward J. Rice and Ganesh Raman.
    SeriesNASA technical memorandum -- 106245., NASA technical memorandum -- 106245.
    ContributionsRaman, Ganesh., United States. National Aeronautics and Space Administration.
    The Physical Object
    FormatMicroform
    Pagination1 v.
    ID Numbers
    Open LibraryOL14701896M

    The maximum and minimum core length reductions caused by the rectangular tabs along the minor axis were 39%, at NPR 6 and 20%, at NPRs 5 and 8. Shadowgraphs of the jet show that the waves in the core were rendered weak by both rectangular and triangular tabs when placed along the minor axis.   The impact of a flat surface installed parallel to a supersonic rectangular jet of AR = 2 on the far field noise is studied. Far-field cold jet results at design, over-expanded and under-expanded conditions are compared between the free-field jet, the nozzle with the surface matching with the exit lip (h = 0De), and the surface at different stand-off positions away from the jet axis, h = 1, 2. Strykowski, PJ, Alvl, F & Krothapalli, A , Role of velocity ratio on supersonic jet mixing. in TT Huang, J Turner, M Kawahashi & MV Otugen (eds), High Speed Jet Flows. vol. , ASME, pp. , Proceedings of the ASME/JSME Fluids Engineering and Laser Anemometry Conference and Exhibition, Hilton Head, SC, USA, 8/13/


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Enhanced mixing of a rectangular supersonic jet by natural and induced screech Download PDF EPUB FB2

Location, an increase in screech level and jet mixing over that of the unbaffled natural jet were observed similar to the observation of Glass'. It appears that the initial mixing of this rectangular underexpanded supersonic jet is completely dominated by the screech feedback process which provides a high level of excitation back at the nozzle lip.

A screech level variation of over 30 decibels was achieved and the mixing was completely determined by the level of screech attained at the nozzle lip. The second form of self-excitation used the induced screech caused by obstacles or paddles located in the shear layers on either long side of the rectangular jet.

Enhanced mixing of multiple supersonic rectangular jets by synchronized screech. Instability modes excited by natural screech tones in a supersonic rectangular jets.

Ganesh Raman and Advances in understanding supersonic jet screech. Ganesh Raman. to reduce the internal mixing noise. Mixing enhancement of the supersonic jet flow from a converging-diverging rectangular nozzle operated at design pressure was obtained using paddles to induce screech and cause jet flapping.

Seiner and Krejsa I have discussed the status of supersonic jet noise reduction relative to the supersonic Size: KB. A screech level variation of over 30 decibels was achieved and the mixing was completely determined by the level of screech attained at the nozzle lip.

The second form of self-excitation used the induced screech caused by obstacles or paddles located in the shear layers on either long side of the rectangular : Edward J. Rice and Ganesh Raman.

A unique set of data is presented on the effect of synchronized screech on the mixing of a linear array of underexpanded jets. Two other cases are provided for comparison. One case is the multijet array with suppressed screech and the other case is a single equivalent rectangular jet with screech.

Rice EJ, Raman G () Enhanced mixing of a rectangular supersonic jet by natural and induced screech. AIAA shear flow conference, Orlando, United States, 6–9 July Samimy M, Kim JH, Clancy P, Martens S () Passive control of supersonic rectangular jets.

A review of jet mixing enhancement for aircraft propulsion applications Show all authors. K Knowles 1. K Knowles T. D., Cain, A. B., Chenault, C. Numerical simulation of enhanced mixing in jet plumes using pulsed blowing Raman, G., Rice, E.

Instability modes excited by natural screech tones in a supersonic rectangular jet. Phys. mixing performance than the rectangular jets in the subsonic and supersonic flow. n 1, k 2, on 3 conducted the experimental study of supersonic mixer nozzles in a co-flowing stream in the United Technologies Research Centre open jet acoustic wind tunnel.

Enhancement of supersonic jet mixing plays a vital role in. The total noise spectrum from an incorrectly expanded jet flow contains discrete components (or screech) in addition to the basic turbulent mixing noise and the broadband shock-associated noise.

In order to study the trends and dependencies of the broadband component accurately, it is vital to keep the contamination by screech to a minimum in. The primary focus of this research project is on a particularly complex aeroacoustic process called “jet screech”.

Screech is a closed-loop feedback process that operates as follows: A sound wave reaches the nozzle lip. Its arrival perturbs the edge of the jet, creating an instability in the jet shear layer. Rice EJ, Raman G () The role of natural and induced screech in the enhanced mixing of a rectangular supersonic jet.

45th Annual Meeting of the Division of Fluid Dynamics, APS, Tallahassee, Florida Google Scholar. RICE, G. RAMAN,American Institute of Aeronautics and Astronautics PaperEnhanced mixing of a rectangular supersonic jet by natural and induced screech. Abstract. Outline of presentation are: (1) Review of experimental apparatus.

(2) Effect of natural screech of jet mixing; converging nozzle, underexpanded jet and converging-diverging nozzle, design pressure.(3) Effect of induced screech on jet mixing: produced by paddles in shear layers, similar to edge tones, and converging-diverging nozzle, design pressure.

Screech is a component of supersonic jet noise that is connected to the presence of a train of shock cells within the jet column.

For a turbulent jet, the unsteady shear layers interact with the shocks to create sound. While this process is generally broadbanded, screech is a special case of shock-noise that arises from the creation of a. Raman, G.

& Taghavi, R. Resonant interaction of a linear array of supersonic rectangular jets: an experimental study. AIAA Paper (also NASA CR.

Rice, E. & Raman, G. Enhanced mixing of a rectangular supersonic jet by natural and induced screech. The evolution of hydrodynamic instability modes self‐excited by harmonically related natural screech tones was experimentally investigated.

A convergent rectangular nozzle with an aspect ratio of was used to produce a supersonic shock‐containing jet. Measurements in the flow field were made using standard hot‐film probes positioned only in the subsonic (outer) portions of the flow.

E.J. Rice, G. Raman Enhanced mixing of a rectangular supersonic jet by natural and induced screech AIAA Shear Flow Conference, Orlando, Florida (). Two methods of excitation were used to control the jet mixing.

The first used the natural screech of an underexpanded supersonic jet from a converging nozzle. The supersonic jet flow from a rectangular single expansion ramp nozzle, operating at an overexpanded condition, has been analysed using large eddy simulation. The screech mode was extracted using.

ESTS lobed nozzle is found to be efficient in supersonic jet mixing applications. In this study, the influence of a number of lobes on the aspects of mixing is probed using the 2D-PIV measurements. Self-sustained oscillations of a planar under-expanded supersonic jets are visualized by means of shadowgraph.

By interrupting the feedback loop by means of. Get this from a library. Enhanced mixing of a rectangular supersonic jet by natural and induced screech. [Edward J Rice; Ganesh Raman; United States. A highly underexpanded jet with a nozzle pressure ratio of is excited by a vortex excitation.

Modulations on flow characteristics by the vortex excitation are revealed by comparing the excited. The deformation of the periodic spanwise structures results in the formation of strong streamwise vortices that appear to govern the mixing of the jet. It is shown that the presence of coherent vorticity of significant strength, in addition to the shock cell strength, is largely responsible for determining the screech intensity.

The noise generated by shock-containing supersonic jets can be divided into three dominant components: screech, broadband shock-associated noise, and turbulent mixing noise. The turbulent mixing noise is not unique to supersonic jets and has been dealt with extensively in the literature of subsonic jets classically2–5 and more recently in.

Large Eddy Simulation of a Stable Supersonic Jet Impinging on a Flat Plate A. Dauptain1, B. Cuenot2, and L.Y.M. Gicquel3 Cerfacs, 42 ave. Coriolis Toulouse - France This paper describes a numerical study based on Large Eddy Simulation (LES) of the flow induced by a supersonic jet impinging on a flat plate in a stable regime.

This. Supersonic Square Jet Mixing in Presence of It is well established that supersonic jet core is a highly corners might be a primary cause for the greatly enhanced mixing experienced by a square jet compared to a circular jet under identical conditions.

Pressure Profiles. Annual Review of Fluid Mechanics Mixing Enhancement in Supersonic Free Shear Flows E J Gutmark, K C Schadow, and, and K H Yu Annual Review of Fluid Mechanics Wave Packets and Turbulent Jet Noise Peter Jordan and Tim Colonius Annual Review of Fluid Mechanics.

Drops as small mixing chambers with the rate of mixing enhanced by motion in a. The paper conducted a series of experimental study on V-shaped grooves influence of supersonic free jet through rectangular nozzles, such as two different screech modes, changing rules of sound pressure level of the screech mode, 3D-dynamic spectrum of sound pressure and schlieren photographs of the flow field.

mixing flow. Because of the highly compressible state of the supersonic flow, the mixing efficiency of the two supersonic flows is not high, which directly affects the combustion efficiency and the propulsion system performance.

Adding a transverse jet to the supersonic flow, the secondary eject method, is a potential method of controlling flow. low aft wall angle rectangular cavity. It is already known that the mixing can be enhanced by active and passive mixing techniques.

In active mixing method, turbulence, shock ———————————————— * Assistant Professor, Department of Mechanical Engineering, College of Engineering, Attingal, Kerala.

Keywords:— Numerical simulation, supersonic jet, perfect gas, Navier-Stokes equations, mixing enhancement, forced jet, spectral initial conditions. 1 Introduction. The study of the mixing properties of jets has an important role in many industrial applications such as: turbulent mixing of the jet.

[7] studied supersonic jet-plate flows from a supersonic rectangular nozzle, and they showed that the gap distance between the nozzle exit and plate surface was an important parameter with respect to the jet screech tone.

Research has also shown that jet noise characteristics are influenced by the flat plate (flap) length []. Corrugated Tabs for Supersonic Jet Control (Keynote Paper) Rathakrishnan E* ABSTRACT The efficiency of corrugated tabs in promoting the mixing of Mach axi-symmetric free jet has been investigated experimentally.

Two rectangular tabs of % blockage, with corrugations at the edges, located diametrically. Numerical Simulation of Supersonic Jet Flows and their Noise S.-C.

Lo⁄, G. Blaisdell y, and A. Lyrintzis z School of Aeronautics and Astronautics Purdue University West Lafayette, IN Large-eddy simulations (LES) of a circular supersonic fully expanded jet and an under-expanded jet.

A systematic study has been undertaken to quantify the effects of jet Mach number and nozzle size on the noise radiated by supersonic jets. All the tests were carried out at an experimental bench of the supersonic jet.

Results indicate that the field distribution of supersonic jet screech tones is characterized with very strong directivity. Supersonic Jet Noise Supersonic Jet Noise Tam, C K W Since the beginning of the Annual Review of Fluid Mechanics there have been three review articles (Ffowcs Williams; Goldstein ) written on the subject of jet noise.

However, all of these articles consider only subsonic jets. It turns out that the noise characteristics of supersonic jets are quite complex. Imperfectly expanded supersonic jets under strong screech could generate both fundamental screech tones and multiple tones at the harmonics of the fundamental frequency.

The paper compares the fundamental frequency of jets from both AR = 3 (Aspect Ratio) and AR = 4 rectangular nozzles, and conducts analysis of harmonics on Sound Pressure Level (SPL) spectrums of jet noise. A SYSTEMATIC STUDY OF SUPERSONIC JET NOISE The purpose of this work is to study the acoustic fields associated with two different nozzle configurations; a rectangular and a circular.

Both nozzles are designed with the same exit Mach number and have an identical momentum and energy flux. In order to investigate the characteristic of the supersonic jet screech tones, an experimental bench of the supersonic jet was designed and a free field noise signal acquisition system was established.

Effects of the nozzle size and jet Mach number on jet noise sound field distribution was analyzed, through the result comparison of supersonic jet noise experimental measurement.The rate at which a supersonic jet mixes with the surrounding ambient fluid is important for many aerospace applications, notably in jet air-craft and rocket propulsion.

For these applica-tions enhanced mixing is often highly desirable, for example to reduce jet noise, improve thrust augmentation or to improve combustion chamber design in.When a jet airplane is flying faster than Mach 1—beyond the speed of sound—the air entering the engines is moving supersonically as well.

But no turbojet engine compressor—the rotating disks and blades at the face of the engine that compress the air before it is mixed with fuel—is capable of handling supersonic air flow.