Abstract
Many techniques have been developed in order to obtain spectral density function from randomly sampled data, such as the computation of a slotted autocovariance function. Nevertheless, one may be interested in obtaining more information from laser Doppler signals than a spectral content, using more or less complex computations that can be easily conducted with an evenly sampled signal. That is the reason why reconstructing an evenly sampled signal from the original LDV data is of interest. The ability of a wavelet-based technique to reconstruct the signal with respect to statistical properties of the original one is explored, and spectral content of the reconstructed signal is given and compared with estimated spectral density function obtained through classical slotting technique. Furthermore, LDV signals taken from a screeching jet are reconstructed in order to perform spectral and bispectral analysis, showing the ability of the technique in recovering accurate information’s with only few LDV samples.
Similar content being viewed by others
Abbreviations
- i :
-
Denotes the ith signal sample
- j :
-
Denotes the jth resolution level of the analyzing wavelet, or the jth signal sample
- k :
-
Corresponds to the kth translated version of the analyzing wavelet, or slot k in slotting technique
- ψ(t):
-
Analyzing wavelet
- ψ jk (t):
-
Discretized mother wavelet
- a :
-
Scale
- \(\tilde{u}(a,t)\) :
-
Continuous wavelet coefficient
- \(\Updelta \tilde{u}_{jk}\) :
-
Increment of wavelet coefficient
- e :
-
Error of reconstruction
- u(t):
-
Original velocity signal
- \(\hat{u}(t)\) :
-
Reconstructed velocity signal
- S(f):
-
Spectral density function at frequency f
- b 2(f 1, f 2):
-
Bicoherence function
- \(\hat{R}(k \Updelta \tau)\) :
-
Slotted autocovariance function
- G uu (f):
-
Spectral density function
- \(\dot{N}\) :
-
Mean data rate of LDV signal
- N s :
-
Number of LDV samples available
- N min :
-
Minimum available LDV samples needed on a given support time to calculate a wavelet coefficient
- τ = βa :
-
Time support on which N min original samples must exist \(\beta \in [0;1]\)
- M :
-
Samples number of the evenly sampled grid
- M j :
-
Number of translated wavelet coefficient to be computed at scale j
- J :
-
Maximum number of resolution level to be computed
- f e :
-
Sampling frequency
- f s :
-
Screeching frequency
- \(\Updelta t\) :
-
Time interval between successive samples
References
Adrian R, Yao C (1987) Power spectra of fluid velocities measured by laser doppler velocimetry. Exp Fluids 5:17–28
Buchhave P, George WK Jr, Lurnley JL (1979) The measrument of turbulence with laser doppler anemometer. Annu Rev Fluid Mech 11:443–503
Collis WB, White PR, Hammond JK (1998) High order spectra: the bispectrum and trispectrum. Mech Syst Signal Process 12:375–394
Debauchies I (1990) Ten lectures on wavelets. SIAM
Farge M (1992) Wavelet transforms and their applications to turbulence. Annu Rev Fluid Mech 24:395–457
Ford C, Etter D (1998) Wavelet basis reconstruction of non uniformly sampled data. Bull AMS 79:61–78
Gaster M, Roberts J (1977) Spectral analysis of randomly sampled records by direct transform. Proc R Soc Lond 354:27–58
Jaunet V (2010) Etude d’un jet rectangulaire supersonique à nombre de mach 1.45 vectorise par actionneur fluidique. PhD thesis, University of Poitiers, FRANCE
Jaunet V, Aymer D, Collin E, Bonnet JP, Lebedv A, Fourment C (2010) 3d effects in a supersonic rectangular jet vectored by flow separation control, a numerical and experimental study. AIAA paper 2010–4976
Kaleva O, Ihalaien H, Saarenrinne P (2000) Wavelet based method for the estimation of the power spectrum from irregularly sampled data. In: Proceedings of the 10th International Symposium on Applications of Laser Techniques to Fluid Mechanics. Lisbon, Portugal, July 10–13
Mayo WT (1974) A discussion of limitations and extensions of power spectrum estimation with burst counter ldv systems. In: Proceedings of Second International Workshop on Laser Velocimetry, pp 90–1024
Nita LC (2000) Analyse spectrale de signaux aleatoires a temps continus echantillonnes non uniformement. PhD thesis, University of Paris Sud, France
Nobach H (2002) Local estimation for the slotted correlation function of randomly sampled lda data. Exp Fluids 32:337–345
Nobach H, Muller E, Tropea C (1994) Refined reconstruction techniques for lda data analysis. In: Proceedings 7th International Symposiym Applications Laser Technol, vol 36.2. Fluid Mech., Lisbon
Nobach HE, Tropea C (1998) Efficient estimation of power spectral density for laser doppler velocimetry data. Exp in Fluids 24:499–509
Raman G (1999) Supersonic jet screech: half-century from powell to the present. J Sound Vib 225:543–571
Rioul O, Duhamel P (1992) Fast algorithms for discrete and continuous wavelet transforms. Tran Inf Theory 38(N2):569–586
Torrence C, Compo G (1998) A practical guide to wavelet analysis. Bull AMS 79:61–78
Tummers MJ, Passchier MD (1996) Spectral estimation using a variable window and the slotting technique with local normalisation. Meas Sci Technol 7:1541–1546
Tummers MJ, Passchier MD (2001) Spectral analysis of biased lda data. Meas Sci Technol 12:1641–1650
van Maanen HRE, Nobach H, Benedict LH (1999) Improved estimator for the slotted autocorrelation function of randomly sampled lda data set. Meas Sci Technol 10:L4–L7
Walker H, Thomas F (1997) Experiments characterizing nonlinear shear layer dynamics in a supersonic rectangular jet undergoing screech. Phys Fluids 9:2562–2579
Acknowledgments
The authors wish to thank the Region Poitou-Charentes, the CNRS and the DGA-Spae for supporting part of this study.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Jaunet, V., Collin, E. & Bonnet, JP. Wavelet series method for reconstruction and spectral estimation of laser Doppler velocimetry data. Exp Fluids 52, 225–233 (2012). https://doi.org/10.1007/s00348-011-1222-z
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00348-011-1222-z