Near-field structure of underexpanded elliptic jets
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Quantitative measurements of velocity for a low aspect ratio underexpanded elliptical jet are presented. Four jets at nozzle pressure ratios NPR = [2.2, 2.6, 3.4, 4.2] are studied for a smoothly contoured elliptical nozzle with an aspect ratio a/b = 2. High-resolution planar particle image velocimetry is used to extract information about the velocity fields and turbulent statistics. All four jets display the expected axis switching phenomenon, with the axis switching gaining strength with increasing pressure ratio. Evidence of regular reflection is seen for jets at pressure ratios of 2.6 and above. Measurements of fluctuating velocity indicate an oscillatory flapping mode in the minor axis plane for all but the highest pressure ratio. At the highest pressure ratio of NPR = 4.2, there is evidence of a cut-and-connect vortex bifurcation previously only observed for jets with higher aspect ratio.
The authors gratefully acknowledge the support given to the project by the Australian Research Council.
- Courant R, Friedrichs K (1956) Supersonic flow and shock waves. Wiley, Hoboken, NJGoogle Scholar
- Mitchell D (2013) Aeroacoustic feedback loops in underexpanded supersonic jet flows, PhD thesis. Monash University, MelbourneGoogle Scholar
- Mitchell D, Honnery D, Soria J (2012) The visualization of the acoustic feedback loop in impinging underexpanded supersonic jet flows using ultra-high frame rate schlieren. J Vis TBAGoogle Scholar
- Soria J (2006) Turbulence and coherent structures in fluids, plasmas and nonlinear media, world scientific, chap particle image velocimetry—application to turbulence studies, pp 319–330Google Scholar
- Verma S, Rathakrishnan E (2001) Effect of mach number on the acoustic field of a 2:1 elliptic-slot jet. Aeronaut J 105:9–16Google Scholar
- Yoon J, Lee S (2003) Investigation of the near-field structure of an elliptic jet using stereoscopic particle image velocimetry. Flow Meas Instrum 14:2034–2046Google Scholar