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谈和平, L.H. Liu*, H.P. Tan, B.X. Li
Journal of Quantitative Spectroscopy & Radiative Transfer 73(2002)641-648,-0001,():
-1年11月30日
An iteration method is extended to analyze the influences of the turbulent fluctuation on the reconstruction of Reynolds time-averaged temperature in turbulent axisymmetric free flames when the temperature profiles are retrieved by the low time-resolution data of outgoing emission and transmission radiation intensities. A simplified probability density function is used to simulate the turbulent fluctuation of temperature and absorption coefficient. The effects of turbulent fluctuating intensities on the estimation of the Reynolds time-averaged temperature and absorption coefficient are examined. The results show that the effects of turbulent fluctuation on the reconstruction of time-averaged absorption coefficient are not significant. In the case of weak turbulent fluctuation, the influences of turbulent fluctuation on the estimation of time-averaged temperature profiles are small. But in the case of strong turbulent fluctuation, the influences of turbulent fluctuation on the estimation of time-averaged temperature profiles are significant.
Inverse radiation problem, Temperature profile, Turbulent flow, Axisymmetric free flame
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【期刊论文】Ray tracing method for transient coupled heat transfer in an anisotropic scattering layer
谈和平, He-Ping Tana, *, Hong-Liang Yia, Ping-Yang Wangb, Li-Ming Ruana, Timothy W. Tongc
International Journal of Heat and Mass Transfer 47(2004)4045-4059,-0001,():
-1年11月30日
A radiative transfer model for a linearly or nonlinearly anisotropic scattering medium is developed by the ray tracing method. Under specular reflection, the radiative transfer coefficients of absorbing and anisotropic scattering layer with opaque boundaries are deduced. Coupled radiative and conductive heat transfer is solved. The advantage of the method is that it only needs to disperse spatial position, but not solid angle. A comparison of the present results with the previous results shows that the radiative transfer coefficients of an anisotropic scattering slab are correct. The influence of optical thickness, surface emissivity, spectrum characteristics, albedo, and boundary conditions on the transient temperature and the heat flux distribution are analyzed. According to analyzed results of linear scattering and nonlinear scattering, it is found that the ratio of two-dimensionless heat fluxes with two different scattering phase functions is a monotone function of optical thickness. It can be used as a benchmark to verify the results.
Coupled radiative and conductive heat transfer, Opaque boundaries, Radiative transfer coefficients, Anisotropic scattering, Scattering phase functions
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【期刊论文】Internal distribution of radiation absorption in a semitransparent spherical particle
谈和平, L.H. Liua, *, H.P. Tana, T.W. Tongb
Journal of Quantitative Spectroscopy & Radiative Transfer 72(2002)747-756,-0001,():
-1年11月30日
The internal distribution of spectral radiation absorption in a semitransparent spherical particle irradiated uniformly and isotropically is determined by the ray tracing method, and the detailed computation formulae for the internal spectral radiation absorption are deduced. The computed results show that the peak of internal volumetric spectral radiation absorption may locate at the interior shell of the particle. The dimensionless volumetric spectral radiation absorption is higher near the center for weakly absorbing or small spheres, but the dimensionless volumetric spectral radiation absorption is higher near the surface for strongly absorbing or large spheres. The corresponding physical interpretations of the internal spectral absorption distribution are given.
Semitransparent medium, Spherical particle, Internal radiation absorption, Ray tracing method
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谈和平, L.H. Liua, *, H.P. Tana, T.W. Tongb
International Journal of Heat and Mass Transfer 44(2001)3335-3344,-0001,():
-1年11月30日
The non-Fourier effects on transient temperature response in semitransparent medium with black boundary surfaces caused by laser pulse are studied. The processes of the coupled conduction and radiation heat transfer in a one-dimensional semitransparent slab with black boundaries are analyzed numerically. The hyperbolic heat conduction equation is solved by the flux-splitting method, and the radiative transfer equation is solved by the discrete ordinate method. The transient temperature response obtained from hyperbolic heat conduction equation is compared with those obtained from the classical parabolic heat conduction equation. The results show that the non-Fourier effect can be important when the conduction-to-radiation parameter and the thermal relaxation time of heat conduction are larger. Under this condition, for the laser-flash measurement of the thermal diffusivity in semitransparent materials, omitting the non-Fourier effect can result in significant errors.
Non-Fourier effect, Radiation-conduction coupled teat transfer,, Transient heat transfer, Semitransparent medium
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谈和平, L.H. Liu*, H.P. Tan
Journal of Quantitative Spectroscopy & Radiative Transfer 74(2002)115-123,-0001,():
-1年11月30日
The internal distribution of radiative absorption in one-dimensional semitransparent slab exposed to collimated irradiation is determined by the ray tracing method, and the detailed computation formulae for the distribution of radiative absorption are deduced. It is found that the ray will be polarized by specular reflection of slab boundaries even if the collimated irradiation is unpolarized, and the extent of polarization increases with the internal reflection times. The effects of polarization on the radiative absorption are analyzed and the radiative absorption distributions are compared with those obtained from the case in which the effects of polarization are omitted. The results show that the large differences between re6ectances of perpendicular and parallel polarized components are the main causes resulting in errors of radiative absorption distribution. The polarization of incident beam has significant influences on the radiative absorption. Even for an unpolarized beam irradiated near Brewster's angle, omitting the effects of polarization will result in large errors, and the errors increase with the refractive index.
Semitransparent medium, Collimated irradiation, Radiative heating, Polarization effect, Ray tracing method
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