Eddy Convection in Cold and Heated Supersonic Jets

Shea, Sean; Lowe, K. Todd; Ng, Wing F.

doi:10.2514/6.2017-4044

Cited by 6 publications

(4 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In contrast to the near-nozzle region, the radial profiles at D eqA = 7, downstream of axial stations with a mean potential core region, indicate that the local convection velocity is measurably greater than the local mean velocity. These results are consistent with those reported by Ecker et al (2015) and Shea et al (2017). Bridges and Wernet (2017) analyzed convection velocities measured with time-resolved PIV and considered results from the literature for near-field hydrodynamic pressure convection velocity to interpret the findings.…”

Section: Axisymmetric Nozzle Configurationsupporting

confidence: 89%

Synthesis of convection velocity and turbulence measurements in three-stream jets

Stuber

Lowe

2019

Exp Fluids

Self Cite

View full text Add to dashboard Cite

Key flow regions linked to jet noise sources are investigated through comparison of convection velocity and turbulence measurements in high speed threestream nozzles. A time-resolved Doppler global velocimetry (DGV) instrument was applied in the Nozzle Acoustic Test Rig (NATR) at NASAs Aero-Acoustic Propulsion Lab to measure 250 kHz repetition laser scattering signals arising from seeding particles at 32 points in high speed flow. Particle image velocimetry (PIV) measurements previously reported by NASA provided mean velocity and turbulence intensity. Results for convection velocity of the particle concentration field were obtained from the DGV data for three-stream nozzle configurations using a cross-correlation approach. The three-stream cases included an axisymmetric and an asymmetric, offset nozzle configuration. For the axisymmetric case, areas of high convection velocity and turbulence intensity were found to occur 4 to 6 area-equivalent nozzle diameters downstream from the nozzle exit. Comparison of convection velocity between the axisymmetric and offset cases show this same region as having the greatest reduction in convection velocity due to the offset, up to 20% reduction for the offset case compared to the axisymmetric case. These findings suggest this region along the centerline near the end of the potential core is an important area for noise generation with jets and contributes to the noise reductions seen from three-stream offset nozzles.

show abstract

Section: Axisymmetric Nozzle Configurationsupporting

confidence: 89%

Synthesis of convection velocity and turbulence measurements in three-stream jets

Stuber

Lowe

2019

Exp Fluids

Self Cite

View full text Add to dashboard Cite

show abstract

“…The Harper-Bourne 11,12 and NASA experiments 2,8,9 have both found similar generic behavior as Tanna 1 and Tanna et al 14 measurements quantify the reduction in core length with an appropriate reduction in turbulence convection velocity (see Bridges & Wernet 2 also), which might indicate the weakness of the sound source in heated supersonic flows. Although the Ma and T R of these studies are somewhat beyond our concerns (involving supersonic source convection effects), Liu et al ( 17 , p.6) indicate that sound radiated by Mach waves is expected to enter at high frequencies at these speeds, hence the Shea/Stuber results 15,16 will be qualitatively applicable to the mild supersonic conditions under our consideration in which sound amplification due to turbulence/mean flow interaction (i.e. jet quietening effects) remain a low frequency phenomenon.…”

Section: Introductionmentioning

confidence: 74%

“…To set about showing that anyG 4 terms on the left hand side of the equation that governs ν(y 1 ,U) vanish depending on the choice of c 2 = f (U), we first integrate (13) by parts to re-write its right hand side in terms ofν(y 1 ,U) and insert the result, (12) & (15) into the i = 1 component of (7a). The latter can then be written in the following form…”

Section: Including Non-parallel Flow Effects At Lowest Order Formentioning

confidence: 99%

See 1 more Smart Citation

Effect of non-parallel mean flow on the acoustic spectrum of heated supersonic jets: Explanation of “jet quietening”

2019

View full text Add to dashboard Cite

Noise measurements of heated axisymmetric jets at fixed supersonic acoustic Mach number indicate that the acoustic spectrum reduces when the temperature ratio increases. The 'spectral quietening' effect has been observed both experimentally and computationally using Large Eddy Simulations (LES). It was explained by Afsar et al. (M. Z. Afsar and M. E. Goldstein & A. M. Fagan AIAAJ., Vol. 49, p. 2522, 2011) through the cancellation introduced by enthalpy flux/momentum flux coupling term using the generalized acoustic analogy formulation. But the parallel flow assumption is known to give inaccurate predictions at high jet speeds. In this paper we therefore extend the non-parallel flow asymptotic theory of Goldstein et al.

show abstract

Large-Eddy Simulations Analysis of Supersonic Heated Jets with Fluid Injection for Noise Reduction

2019

View full text Add to dashboard Cite

Eddy Convection in Cold and Heated Supersonic Jets

Cited by 6 publications

References 8 publications

Synthesis of convection velocity and turbulence measurements in three-stream jets

Synthesis of convection velocity and turbulence measurements in three-stream jets

Effect of non-parallel mean flow on the acoustic spectrum of heated supersonic jets: Explanation of “jet quietening”

Large-Eddy Simulations Analysis of Supersonic Heated Jets with Fluid Injection for Noise Reduction

Contact Info

Product

Resources

About