Radiofrequency plasma stabilization of a low-Reynolds-number channel flow
2014; Cambridge University Press; Volume: 748; Linguagem: Inglês
10.1017/jfm.2014.189
ISSN1469-7645
AutoresTimothy Jesse Fuller, Andrea Hsu, Rodrigo Sánchez-González, Jacob C. Dean, Simon W. North, Rodney Bowersox,
Tópico(s)Combustion and flame dynamics
ResumoAbstract The effects of plasma heating and thermal non-equilibrium on the statistical properties of a low-Reynolds-number ( $Re_{\tau } = 49$ ) turbulent channel flow were experimentally quantified using particle image velocimetry, two-line planar laser-induced fluorescence, coherent anti-Stokes Raman spectroscopy and emission spectroscopy. Tests were conducted at two radiofrequency plasma settings. The nitrogen, in air, was vibrationally excited to $T_{vib} \sim 1240\ \mathrm{K}$ and 1550 K for 150 W and 300 W plasma settings, respectively, while the vibrational temperature of the oxygen and the rotational/translational temperatures of all species remained near room temperature. The peak axial turbulence intensities in the shear layers were reduced by 15 and 30 % in moving across the plasma for the 150 and 300 W cases, respectively. The plasma did not alter the transverse intensities. The Reynolds shear stresses were reduced by 30 and 50 % for the 150 and 300 W cases. The corresponding Reynolds shear stress correlation coefficient was also reduced, which indicates that the large-scale structures were diminished. Finally, the plasma enhanced the turbulence decay in the zero-shear regions, where the power law decay $t^{-1/n}$ exponential factor $n$ decreased from 1.0 to 0.8.
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