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Civil-Comp Proceedings
ISSN 1759-3433
CCP: 86
Edited by: B.H.V. Topping
Paper 80

Inverse Analysis for Radiating Components in a Free Turbulent Steam Jet

I. Jancskar and A. Ivanyi

Department of Information Technology, University of Pécs, Hungary

Full Bibliographic Reference for this paper
I. Jancskar, A. Ivanyi, "Inverse Analysis for Radiating Components in a Free Turbulent Steam Jet", in B.H.V. Topping, (Editor), "Proceedings of the Eleventh International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 80, 2007. doi:10.4203/ccp.86.80
Keywords: inverse radiation problem, absorption coefficient profile, axisymmetric free jet, infrared image processing.

Human activity and many industrial processes release considerable amount of energy into the atmosphere. Thermal sensing is of prime importance to detect, identify and analyze the effects of these processes. In this paper an inverse radiation problem is presented for simultaneous estimation of the absorption coefficient and the temperature distribution profiles from the infrared radiation intensity measurement of axisymmetric free steam jet in the range of optically thin limit. The hot steam jet can be detected if it contains condensed water droplets, because the gaseous form is transparent in the wave-band of the detector. The summation of the time-series instantaneous images results the Reynolds-averaged flow pattern. The detector waveband has been taken into account and band-averaged intensities and Planck-averaged coefficients have been applied in the calculations. By exploiting the axisymmetric round jet assumption, the absorption coefficient distribution in the jet cross-section is approximated by an analytical function. The inverse radiation problem is solved by iterative minimization of the performance function applying the conjugate gradient method. The proposed iterative minimization procedure utilizes the strong correlation between the temperature and the absorption coefficient fields. The inverse method has been validated by the results of a finite element simulation. The steam jet and necessary boundary conditions were chosen in a simplified form. Test results confirm that the functional approximation of the temperature and the absorption coefficient distributions is acceptable. The quantitative analysis, in the presented examples determining the liquid water content, requires additional information over the effective droplet radius. This parameter is needed for the calculations and cannot be derived from the detected infrared images. The presented method could be helpful in predicting the environmental load caused by steam jets released into the atmosphere.

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