Spatial Spectra of Jet Turbulence Measured by Particle Image Velocimetry

The unique capabilities of particle image velocimetry (PIV) have been utilized together with two-point similarity theory to measure spatial spectra in a ‘homogenized’ fully-developed turbulence jet at relatively high Reynolds number (20,000). The theory developed by Ewing et al. [1] was found to be in excellent agreement with the data, and in fact key to the present application. Despite relatively poor spatial resolution of the scales of motion (up to 15 times the Kolmogorov microscale) and limited dynamic range due to progressive jet velocity decay, it was possible to produce highly accurate spectra over three decades. Key factors for these results are a very large ensemble of statistically independent realizations (N = 10,841) and a very large, composite eld of view (20 relevant integral length scales) which limited the effect of windowing on the spectra.