Measurements in the annular shear layer of high subsonic and under-expanded round jets

Tao, Feng; McGuirk, James J.

doi:10.1007/s00348-015-2090-8

Cited by 16 publications

(19 citation statements)

References 47 publications

(60 reference statements)

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“…13b. The PIV data also indicates that the weak shock oscillations persist past the end of the mean potential core, which has been reported in other supersonic jet flow studies (Wishart and Krothepalli 1994;Gross et al 2010;Feng and McGuirk 2016). At the end of the time-averaged potential core, the shear layers have merged and the high turbulence in this region should dominate the flow.…”

Section: Smc015 Set Point 1401 Piv and Raman Resultssupporting

confidence: 82%

Raman temperature and density measurements in supersonic jets

Wernet

Georgiadis

Locke³

2021

Exp Fluids

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Prediction of flow-field properties in supersonic jets using computational fluid dynamics (CFD) code predictions has become routine; however, obtaining accurate solutions becomes more challenging when there is a significant temperature difference between the jet core and the ambient air and/or compressibility effects are significant. Benchmark sets of flow field property data are required in order to assess current CFD capabilities and develop better modeling approaches for these turbulent flow fields where accurate calculation of temperatures and turbulent heat flux is important. Particle Image Velocimetry, spontaneous rotational Raman scattering spectroscopy, and Background-Oriented Schlieren (BOS) have been previously used to acquire measurements of the mean and root-mean-square (rms) velocities, the mean and rms gas temperatures, and density gradients in subsonic jet flows and film cooling flows. In this work, the ability to measure density is added to the list of measurands available using the acquired Raman spectra. The suite of measurement techniques are now applied to supersonic jet flows. The computation of the local gas pressure in the potential core of an over-expanded jet is demonstrated using the Raman measured gas temperature and density. Additionally, a unique density feature in temperature matched, perfectly expanded jet flow shear layers identified using BOS was verified using the Raman measurement technique. These non-intrusive flow measurements are compared against RANS predictions of the supersonic jet flow properties as a means of assessing their prediction accuracy. Graphic abstract

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Section: Smc015 Set Point 1401 Piv and Raman Resultssupporting

confidence: 82%

Raman temperature and density measurements in supersonic jets

Wernet

Georgiadis

Locke³

2021

Exp Fluids

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“…Experiments were carried out using the Loughborough University High Pressure Nozzle Test Facility; full details are given in T. Feng and J.J. McGuirk [12,23] and only a brief description is provided here. Continuous air mass flow up to 0.8 kg/s was available at a maximum gauge pressure of 13.8 Bar (1.38 × 10 6 Pascal), intercooled and dried to a dew point of −40 • C and stored in eight interlinked air receivers with a capacity of 110 m 3 .…”

Section: Experimental Facilitymentioning

confidence: 99%

“…Subsonic and perfectly expanded supersonic jets with nozzle exit Mach numbers from 0.3 to 1.7 were studied and the potential core length was shown to increase with M 2 J . Work on axisymmetric jets was recently extended by T. Feng and J.J. McGuirk [12] to consider moderately underexpanded NPRs. The annular shear layer data of J.C. Lau and T. Feng and J.J. McGuirk [10][11][12] were all in agreement, but did not collapse onto the best-fit curve of planar data provided in M.F.…”

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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“…While the first 2-3D axial distance of the shear layer bordering a round jet will behave like a planar flow, annular effects grow downstream. Feng & McGuirk (2016) conducted measurements to investigate this, indicating similar but stronger suppression of growth rate with M c was observed in annular shear layers, as also present in the data of Lau, Morris & Fisher (1979) when plotted in this format. Note, Barone et al (2006) also pointed out that, although compressibility effects in shear layers were well correlated by M C alone, this may not be universal, and the total temperature ratio may also be influential.…”

Section: Compressibility Effects In High-speed Shear Layersmentioning

confidence: 64%

“…In addition, both nozzle inlet and exit profiles were measured, to aid in validation of LES studies which simulate both internal nozzle as well as jet flow (Bres et al 2018;Wang & McGuirk 2020). The cold flow data of Feng & McGuirk (2016) for compressible annular shear layer development mentioned in § 2.2 were taken with this nozzle design, and it was adopted for the current measurement programme (more details are provided below).…”

Section: Nozzle Exit Profile Effectsmentioning

confidence: 99%