Jet Noise Measurements: Past and Present

Harper-Bourne, Marcus

doi:10.1260/1475-472x.9.4-5.559

Cited by 32 publications

(19 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1). In conclusion, the scaling estimates (4) and (5) are considered useful to compare our simulation results in a reasonable manner with reference data at different (nozzle-exit) flow conditions, resulting in good overall agreement.…”

Section: E Scaling Of Spl With Turbulence Level and Reynolds Numbermentioning

confidence: 61%

“…This is important as different flow states are considered a main reason for discrepancies in acoustic measurements among jet-flow experiments in the literature. 5,6 The general effects related to a specific nozzle-exit turbulence level on jet-flow development and noise have already been widely addressed in the literature. It is well-known that for low turbulence levels at the nozzle exit, the jet shear-layer development is governed by the laminar-turbulent transition process associated with classical Kelvin-Helmholtz (KH)-type instabilities.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Laminar and turbulent nozzle-jet flows and their acoustic near-field

2014

View full text Add to dashboard Cite

A new, fully localised, energy growth optimal is found over large times and in long pipe domains at a given mass flow rate. This optimal emerges at a threshold disturbance energy below which a nonlinear version of the known (streamwise-independent) linear optimal [P. J. Schmid and D. S. Henningson, "Optimal energy density growth in Hagen-Poiseuille flow," J. Fluid Mech. 277, 192-225 (1994)] is selected and appears to remain the optimal up until the critical energy at which transition is triggered. The form of this optimal is similar to that found in short pipes [Pringle et al., "Mini-mal seeds for shear flow turbulence: Using nonlinear transient growth to touch the edge of chaos," J. Fluid Mech. 702, 415-443 (2012)], but now with full localisation in the streamwise direction. This fully localised optimal perturbation represents the best approximation yet of the minimal seed (the smallest perturbation which is arbitrarily close to states capable of triggering a turbulent episode) for "real" (laboratory) pipe flows. Dependence of the optimal with respect to several parameters has been computed and establishes that the structure is robust. C 2015 AIP Publishing LLC.

show abstract

Section: E Scaling Of Spl With Turbulence Level and Reynolds Numbermentioning

confidence: 61%

Section: Introductionmentioning

confidence: 99%

Laminar and turbulent nozzle-jet flows and their acoustic near-field

2014

View full text Add to dashboard Cite

show abstract

“…Compressed air passed through a 30 inch diameter plenum chamber and exhausted through the nozzle into the ambient of the test chamber. With the large contraction ratio and flow conditioning units within the plenum, this facility falls into the category of "University type" in the terminology of [2]. (However, the facility type is immaterial since the noise and flow differences are studied in the same facility and are obviously tied to differences in the nozzles themselves).…”

Section: Experimental Facility and Proceduresmentioning

confidence: 99%

“…Substantial differences in subsonic jet noise databases have been reported in [1,2]. It was noted that data taken in cleaner "University-type" facilities [3][4][5][6] were actually noisier relative to data taken in "Industrialtype" facilities [1,7,8].…”

Section: Introductionmentioning

confidence: 99%

Effect of Initial Condition on Subsonic Jet Noise from Two Rectangular Nozzles

Zaman

2012

18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference)

View full text Add to dashboard Cite

Differences in jet noise data from two small 8:1 aspect ratio nozzles are investigated experimentally. The interiors of the two nozzles are identical but one has a thin-lip at the exit while the has a perpendicular face at the exit (thick-lip). It is found that the thin-lip nozzle is substantially noisier throughout the subsonic Mach number range. As much as 5dB difference in OASPL is noticed around M j =0.96. Hotwire measurements are carried out for the characteristics of the exit boundary layer and, overall, the noise difference can be ascribed to differences in the boundary layer state. The boundary layer of the quieter (thick-lip) nozzle goes through transition around M j =0.25 and at higher M j it remains "nominally turbulent". In comparison, the boundary layer of the thin-lip nozzle is found to remain "nominally laminar" at high subsonic conditions. The nominally laminar state involves significantly larger turbulence intensities commensurate with the higher radiated noise.

show abstract

“…The database was already used in previous jet-noise studies. 25,26,27,28 It will be shown that wave refraction is the dominant cause for the Helmholtz number scaling in the rear arc. The development of a prediction model based on these findings is discussed in section VI.…”

Section: Introductionmentioning

confidence: 99%