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Wednesday, July 15, 2020 | History

3 edition of Mixing enhancement by tabs in round supersonic jets found in the catalog.

Mixing enhancement by tabs in round supersonic jets

Mixing enhancement by tabs in round supersonic jets

  • 328 Want to read
  • 6 Currently reading

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

    Subjects:
  • Shear layers.,
  • Mixing layers (Fluids),
  • Computational fluid dynamics.,
  • Navier-Stokes equation.,
  • Mass flow.,
  • Supersonic jet flow.,
  • Vorticity.

  • Edition Notes

    StatementJohn M. Seiner, C.E. Grosch.
    Series[NASA contractor report] -- NASA/CR 207690., NASA contractor report -- NASA CR-207690.
    ContributionsGrosch, C. E., United States. National Aeronautics and Space Administration.
    The Physical Object
    FormatMicroform
    Pagination1 v.
    ID Numbers
    Open LibraryOL15547829M

    Experimental observations show that the presence of small tabs on the edge of a hot, compressible jet exiting into a slower moving, colder ambient flow can increase the rate of spreading of the jet. Calculations were carried out using the time dependent, three dimensional, compressible Navier-Stokes equations in order to study the effect of the tabs on the flow.   Among the controlled jets, the semicircular corrugated tab is found to be the best mixing promoter at NPRs 6 and 7, for the Mach 2 jet. However at NPRs 4, 5 and 8, the mixing promoting performance of uncorrugated tabs is the best; as high as 91% reduction in jet core length is achieved with semicircular corrugations.

    Mixing characteristics of a Mach 2 jet controlled by shifted tabs have been studied at different levels of expansion at the nozzle exit. Two identical rectangular flat tabs of aspect ratios (length. AbstractControl of Mach elliptic jet with ventilated triangular tabs is studied experimentally, in the presence of different levels of pressure gradient at the nozzle exit. Three different sets of ventilated tabs with circular, triangular and trapezoidal ventilations were studied. Two tabs were placed, at the ends of major and minor axes, at the exit of the elliptic nozzle of aspect ratio.

    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. Ahuja, K. K., Manes, J., Massey, K. C. Control of jet mixing and supersonic jet noise by resonance effects in wake shedding from parallel plates. 1st Joint CEAS/AIAA Aeroacoustics Conference, Munich, Germany, 12–15 June , paper no. CEAS/AIAA– Google Scholar.


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Mixing enhancement by tabs in round supersonic jets Download PDF EPUB FB2

This paper discusses results of an experimental study on jet-mixing enhancement of heated and unheataed, subsonic and underexpanded supersonic model jets by mechanical protuberances (tabs.

Get this from a library. Mixing enhancement by tabs in round supersonic jets. [John M Seiner; C E Grosch; United States. National Aeronautics and Space Administration.]. experiments on subsonic and supersonic jets to assess influence of compressibility, (2) parametric study on tab geometry to optimize effect for given flow blockage (this effort led to 'delta-tab'), (3) quantify mixing enhancement in the jet, (4) analyze mechanisms of streamwise vorticity generation.

Prior publications on the investigation: 1. Get this from a library. Supersonic jet mixing enhancement by 'delta-tabs'. [K B M Q Zaman; M F Reeder; M Samimy; United States.

National Aeronautics and Space Administration.]. The mixing promoting capability of right-angle triangular tab with sharp and truncated vertex has been investigated by placing two identical tabs at the extremities of an exit diameter of a Mach 2 axi-symmetric nozzle.

The mixing promoting efficiency of these tabs have been quantified in the presence of adverse and almost zero pressure by: 2.

The mixing promoting capability of right-angled triangular tab with sharp and truncated vertex has been investigated by placing two identical tabs at the exit of a Mach 2 axi-symmetric nozzle. The mixing promoting efficiency of these tabs have been quantified in the presence of adverse and marginally favourable pressure gradients at the nozzle by: 2.

Mixing enhancement of two gaseous streams at high Mach numbers plays an important role in the design of supersonic ejectors and supersonic combustors. In order to obtain mixing enhancements in supersonic jets, many nozzles with exotic shapes have been developed [1].

primary jet is firstly operated at subsonic regime. The jet’s mixing enhancement effect caused by the air tab can achieve the best when the injection velocity is set at.

The primary jet is subsequently changed to be at supersonic regime, but the injection velocity for the air tab is maintained at. Four tabs enhance molecular mixing more than two tabs do, although two tabs cause the velocity profile to decay faster than four tabs do.

The product formation rate is nearly constant with respect to streamwise distance, for turbulent jets with zero, two, and four tabs. Mixing enhancement is % in ESTS nozzle, chevron (%) and beveled (%).

Streamwise vorticity production is widespread in ESTS lobed nozzle. Mechanism of vorticity production in ESTS nozzle is explained for the first time. Primary tabs are highly effective in reducing the supersonic core length of the coaxial jet than secondary tabs, and hence, the jet mixing increases.

Two different flow categories of the manipulated jet have been identified. Research in supersonic jet mixing enhancement has seen a revival with the increased awareness of environmental impacts aircrafts have as well as with the advent of the scramjet. Passive and active means or mixing enhancement haven been researched into, and while delta/solid tabs have proved to be the best in terms of entrainment, air tabs have.

The primary jet is firstly operated at subsonic regime (Me=). The jet’s mixing enhancement effect caused by the air tab can achieve the best when the injection velocity is set at M= The primary jet is subsequently changed to be at supersonic regime (Me=), but the injection velocity for the air tab is maintained at M= Mixing Enhancement by Tabs in Round Supersonic Jets.

By John M. Seiner and C. Grosch. Abstract. The objective of this study was to analyze jet plume mass flow entrainment rates associated with the introduction of counter-rotating streamwise vorticity by prism shaped devices (tabs) located at the lip of the nozzle.

We have examined the. The mixing promotion caused by two identical triangular tabs, with sharp and truncated vertices, offering a geometrical blockage of % each, placed at the exit of a Mach 2 circular nozzle, was studied in the presence of adverse and marginally favorable pressure gradients.

The pressure decay along the jet centerline and the pressure profiles along and normal to the tabs were measured. Triangular tabs for supersonic jet mixing enhancement 27 January | The Aeronautical Journal, Vol. No. A LES Study on Passive Mixing in Supersonic Shear Layer Flows Considering Effects of Baffle Configuration.

mechanical tabs placed at the lip of a round nozzle with cold or heated flow enhanced the jet mixing considerably. The jet flow velocity is reduced significantly, and for heated jets, the temperature of required to understand the effects of tab length and width on jet mixing enhancement.

The difference in the area enclosed by pitot pressure curves of uncontrolled and controlled jets is larger for the corrugated tabs, indicating the mixing caused by corrugated tabs is much larger than the plain tabs.

For this case, the jets with tabs show their individual identity up to about 18D. texts All Books All Texts latest This Just In Smithsonian Libraries FEDLINK (US) Genealogy Lincoln Collection. The results of a three year study on vortex enhancement of supersonic mixing are discussed.

Recent interests in compressible mixing has spurred research in the field of high speed shear layers. It was established that shear layer. The distortion of a jet by tabs - Volume 70 Issue 4 - L.

Bradbury, A. Khadem. DOI: /sx Corpus ID: Momentum Diffusion Near Jet Exit in a Round Jet Controlled by Half Delta-Wing Tabs @article{ItoMomentumDN, title={Momentum Diffusion Near Jet Exit in a Round Jet Controlled by Half Delta-Wing Tabs}, author={Yasumasa Ito and Kosuke Naganawa and Yasuhiko Sakai and Koji Iwano}, journal={Flow Turbulence and Combustion}.

1. Introduction. Sufficient mixing between the supersonic crossflow and the fuel is very important for the supersonic combustion process in the scramjet engine, and it attracts an increasing attention novel mixing enhancement devices have been proposed by the researchers, and they were summarized in detail by Seiner et al.

The transverse injection strategy has been .Abstract. The efficacy of introducing mixing promoting small-scale vortices by two rectangular tabs, of aspect ratioandplaced at diametrically opposite locations at the exit of a Mach convergent–divergent circular nozzle has been experimentally investigated, for NPRs from 4 to 8, covering overexpanded, correctly expanded and underexpanded states of the jet.