Effect of initial conditions on a circular jet

Antonia, R. A.; Zhao, Quanbin

doi:10.1007/s003480100289

Cited by 73 publications

(32 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We refer to these cases as 'medium' forcing amplitude and focus on two aspects: (i) differences between low and medium forcing amplitude; (ii) the range of parameters for which the bifurcation phenomenon occurs. The excitation amplitude 0.05 U j is comparable to a turbulence intensity often occurring in jet flows studies, both in experimental and numerical works [39][40][41][42][43].…”

Section: Medium Amplitude Forcingmentioning

confidence: 61%

Parametric Analysis of Excited Round Jets - Numerical Study

Tyliszczak

Geurts

2014

Flow Turbulence Combust

View full text Add to dashboard Cite

A computational analysis of excited round jets is presented with emphasis on jet bifurcation phenomenon due to superposition of axial and flapping forcing terms. Various excitation parameters are examined including the amplitudes of the forcing, their frequencies and phase shift. It is shown that alteration of these parameters significantly influences the spatial jet evolution. This dependence may be used to control the jet behaviour in a wide range of qualitatively different flow structures, starting from a modification of the spreading rate of a single connected jet, through large scale deformation of an asymmetric jet, onto jet bifurcation leading to a doubly and even triply split time-averaged jet, displaying different strengths and locations of the branches. We establish that: (i) jet splitting is possible only when the amplitudes of the forcing terms are comparable to or larger than the level of natural turbulence; (ii) the angle between the developing jet branches can be directly controlled by the frequency of the axial forcing and the phase shift between axial and flapping forcing. An optimum forcing frequency is determined, leading to the largest spreading rate.

show abstract

Section: Medium Amplitude Forcingmentioning

confidence: 61%

Parametric Analysis of Excited Round Jets - Numerical Study

Tyliszczak

Geurts

2014

Flow Turbulence Combust

View full text Add to dashboard Cite

show abstract

“…They explained that a secondary peak heat transfer occurs because of intermittent motions which entrain ambient fluid and break up the thermal boundary layer on the wall. Antonia & Zhao (2001) examined two circular jets-a pipe jet with a fully developed turbulent flow profile and a contraction jet with a laminar top-hat velocity profile at the nozzle exit-and discussed the similarities and differences between the two. Quinn (2006) demonstrated the effects of nozzle configurations on the mixing characteristics from the mean velocity and pressure distributions of an orifice plate and contoured nozzle jets.…”

Section: Introductionmentioning

confidence: 99%

Heat Transfer Enhancement of Impinging Jet by Notched – Orifice Nozzle

Shakouchi¹,

Kito²

2012

An Overview of Heat Transfer Phenomena

View full text Add to dashboard Cite

“…Two further nozzles were manufactured and included a short parallel extension at nozzle exit (different lengths for each nozzle size −34.1 mm in LU48P and 31.8 mm in LU60P, see Figure 2c,d). Nozzles with internal parallel wall exits have been observed to remove the vena contracta effect (R.A. Antonia and Q. Zhao [24]); this also allowed examination of the consequences of allowing the boundary layer to recover from the influence of the high favourable pressure gradient in the convergent section. Tests were performed at jet Reynolds numbers representative of engineering applications (Re J > 10 6 ), with the nozzle operated at NPRs from 1.3 to 2.4, i.e., from low subsonic to supersonic (underexpanded) Mach numbers.…”

Section: Test Nozzle Geometriesmentioning

confidence: 99%

Influence of Nozzle Exit Conditions on the Near-Field Development of High Subsonic and Underexpanded Axisymmetric Jets

2018

View full text Add to dashboard Cite

Detailed knowledge of jet plume development in the near-field (the first 10-15 nozzle exit diameters for a round jet) is important in aero-engine propulsion system design, e.g., for jet noise and plume infrared (IR) signature assessment. Nozzle exit Mach numbers are often high subsonic but improperly expanded (e.g., shock-containing) plumes also occur; high Reynolds numbers (O (10 6 )) are typical. The near-field is obviously influenced by nozzle exit conditions (velocity/turbulence profiles) so knowledge of exit boundary layer characteristics is desirable. Therefore, an experimental study was carried out to provide detailed data on nozzle inlet and exit conditions and near-field development for convergent round nozzles operated at Nozzle Pressure Ratios (NPRs) corresponding to high subsonic and supersonic (underexpanded) jet plumes. Both pneumatic probe and Laser Doppler Anemometry (LDA) measurements were made. The data revealed that internal nozzle acceleration led to a dramatic reduction in wall boundary layer thickness and a more laminar-like profile shape. The addition of a parallel wall extension to the end of the nozzle allowed the boundary layer to return to a turbulent state, increasing its thickness, and removing vena contracta effects. Differences in nozzle exit boundary layers exerted a noticeable influence but only in the first few diameters of plume development. The addition of the exit extension removed the vena contracta effects of the convergence only design. At underexpanded NPRs, this change to nozzle geometry modified the shock cell pattern and shortened the potential core length of the jet.

show abstract

Effect of initial conditions on a circular jet

Cited by 73 publications

References 0 publications

Parametric Analysis of Excited Round Jets - Numerical Study

Parametric Analysis of Excited Round Jets - Numerical Study

Heat Transfer Enhancement of Impinging Jet by Notched – Orifice Nozzle

Influence of Nozzle Exit Conditions on the Near-Field Development of High Subsonic and Underexpanded Axisymmetric Jets

Contact Info

Product

Resources

About