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Tomographic Reconstruction of Probability Density Functions in Turbulent Flames.


pdf icon Tomographic Reconstruction of Probability Density Functions in Turbulent Flames. (373 K)
Vallikul, P.; Goulard, R.; Mavriplis, C.; Nyden, M. R.

Interscience Communications Ltd.; National Institute of Standards and Technology; Building Research Establishment; and Society of Fire Protection Engineers; Swedish National Testing and Research Institute. Interflam '96. International Interflam Conference, 7th Proceedings. March 26-28, 1996, Cambridge, England, Interscience Communications Ltd., London, England, Franks, C. A.; Grayson, S., Editor(s)(s), 235-243 pp, 1996.

Keywords:

fire safety; smoke measurement; turbulent flames; density effects; algorithms

Abstract:

Local probability density functions (PDF) of absorption coefficients within turbulent flames have been retrieved from their multi-angular absorption data of path-integrated probability density functions via a series of numerical techniques. First the Filter Back-Projection (FBP) technique has been used to reconstruct local moments within the flame then the moments are transformed to the local PDFs by using the singular value decomposition (SVD) technique. The FBP technique transforms the absorption data into the frequency domain where noisy components can be truncated while turbulent components are still preserved in the form of reconstructed moments. The reconstruction algorithm is tested by using both synthetic and experimental absorption data. Reconstruction from synthetic data allows the reconstruction algorithm to be evaluated independently of path measurement noise. On the other hand, reconstruction from experimental data demonstrates the capability of determining the local PDF analytically within the turbulent flame. Good reconstruction results are obtained from both cases and the reconstruction algorithm is justified.