A fractal reconstruction method for LDV spectral analysis

• Published in: Experiments in fluids Vol. 13; no. 2-3; pp. 91 - 97
• Main Authors: CHAO, Y. C, LEU, J. H
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01-06-1992; Berlin
• Subjects: Exact sciences and technology; Fluid dynamics; Fundamental areas of phenomenology (including applications); Instrumentation for fluid dynamics; Physics; Interpolation; Turbulent flow; Fractal dimension; Doppler laser anemometer; Signal reconstruction; Experimental study; Shear layer; Spectral analysis
• ISSN: 0723-4864; 1432-1114
• DOI: 10.1007/BF00218154

An unequally spaced fractal interpolation method is developed to reconstruct the low data rate laser Doppler velocimetry (LDV) signal for better spectral results. The reconstructed result not only augments the data points to improve the statistics but also retains the turbulent fractal dimension of the flow. In other words, the interpolated data are flow turbulence-correlated data which are physically reasonable. This method is demonstrated on the LDV spectral measurements in the shear layer of a jet flow and the results are compared against the hot-wire spectral data. When the data rate of the LDV signal is low, the fractal interpolation method can suitably restore the major spectral peaks while the conventional sample-and-hold fails. Effects of the data rate, data record length, sampling rate and the fractal dimension on the accuracy of the spectral reconstruction are also discussed. (Author)