An experimental study of tone excited heated jets

Lepicovsky, J.; Ahuja, K. K.; Salikuddin, M.

doi:10.2514/6.1984-2341

Cited by 8 publications

(11 citation statements)

References 7 publications

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“…The studies in W.C. Hill et al [13,14], J. Lepicovsky et al [15], and J. Lepicovsky [16] illustrate the difficulties of conducting small-scale laboratory studies which can claim to be truly representative of full-scale aero-propulsion conditions. W.C. Hill et al [13,14] thoroughly investigated nozzle exit boundary layer conditions on round jet development, although only for incompressible flow.…”

Section: Introductionmentioning

confidence: 99%

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

2018

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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.

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Section: Introductionmentioning

confidence: 99%

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

2018

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“…This is the common feature (and disadvantage) of this method of frequency response investigation based on constant input power--cf. e.g., [27]. In contrary, the other method lies in keeping SPL constant by means of input power variation--see, e.g., [22].…”

Section: Resultsmentioning

confidence: 99%

Annular impinging jet with recirculation zone expanded by acoustic excitation

Trávníček

Tesař

2004

International Journal of Heat and Mass Transfer

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Flow visualization and mass transfer (naphthalene sublimation) experiments were performed on acoustically excited annular air jet with diameter ratio D i /D o =0.95. Two different regimes of the time-mean flow field were found, differing in the size of the central recirculation zone, with either the single stagnation point or the stagnation circle. The switching between the two regimes is accomplished by acoustic excitation, under identical geometry conditions. An effective stabilization of the large recirculation zone, as well as remarkable augmentation of average heat/mass transfer by 23%, have been achieved at the excitation Strouhal number Sh=0.94.

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“…Lepicovsky, Ahuja, and Salikuddin studied toneexcited heated jets and concluded that the jet sensitivity to excitation is a strong function of jet velocity (ref. 19). In general, the researchers found that the addition of heat decreased the excitation level required for a low Mach number jet (M = 0.3) to respond while increasing the excitation level needed for a higher Mach number jet to respond (M = 0.8).…”

Section: Basic Principles Of Jet Excitationmentioning

confidence: 94%

“…However, they found no significant change in preferred excitation Stouhal number (ref. 19 The effect of initial turbulence intensity on jet response to excitation has also been investigated. Raman, Zaman and Rice performed a series of experiments in 1989 where the initial turbulence was varied from 0.15 to 5 percent using screens and boundary layer trips placed inside the jet (ref.…”

Section: Basic Principles Of Jet Excitationmentioning

confidence: 99%

Acoustics of excited jets—a historical perspective

Brown

2005

The Journal of the Acoustical Society of America

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The idea that a jet may be excited by an external forcing is not new. The first demonstration of a jet responding to external pressure waves occurred in the late 1800s. It was not, however, until the 1950s, with the advent of commercial jet aircraft, that interest in the subject greatly increased. Researchers first used excited jets to study the structure of the jet and attempt to determine the nature of the noise sources. The jet actuators of the time limited the range (size and Mach number) of jets could be excited. As the actuators improved, more realistic jets could be studied. This has led to a better understanding of how jet excitation may be used not only as a research tool, but also as a method to reduce jet noise.

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An experimental study of tone excited heated jets

Cited by 8 publications

References 7 publications

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

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

Annular impinging jet with recirculation zone expanded by acoustic excitation

Acoustics of excited jets—a historical perspective

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