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radiative properties of alumina/aluminum particles and influence on radiative heat transfer in solid rocket motor

Chinese Journal of Aeronautics 2022年第2期35卷 98-116页

作者： Xuefan HAO Hu ZHANG Xiao HOU Guihua TANG State Key Laboratory for Strength and Vibration of Mechanical Structures Xi’an Jiaotong UniversityXi’an 710049China Shaanxi Key Laboratory of Environment and Control for Flight Vehicle Xi'an Jiaotong UniversityXi’an 710049China College of Astronautics Northwestern Polytechnical UniversityXi’an 710072China Key Laboratory of Thermo-Fluid Science and Engineering Ministry of EducationXi’an Jiaotong UniversityXi’an 710049China

The thermal radiation of micron-sized condensed phase particles plays a dominant role during the heat transfer process in aluminized Solid Rocket Motors(SRMs).Open research mainly focuses on the radiative properties of alumina particles while the study considering the presence of aluminum is *** addition,the thermal radiation inside the SRM with consideration of the participating particles is seldom *** this work,the multiscale method of predicting the thermal environment inside SRMs is established from the particle radiation at microscale to the twophase flow and heat transfer at *** effective gray radiative properties of individual particles(alumina,aluminum,and hybrid alumina/aluminum)and particles cloud are investigated with the Mie theory and approximate *** a numerical method for predicting the thermal environment inside SRMs with considering particle radiation is established and applied in a subscale *** convective and radiative heat flux distributions along inner wall of motor are obtained,and it is found that the heat transfer in the combustion chamber is dominated by thermal radiation and the radiative heat flux is essentially a constant of 5.6–6.8 MW/m^(2).The convective heat transfer plays a dominant role in the nozzle and the heat flux reaches the maximum value of 11.2 MW/m^(2) near the *** the combustion efficiency of aluminum drops,the radiative heat flux remains unchanged in most regions and increases slightly along the diverging section wall of the nozzle.

关键词： Alumina Aluminum Condensed phase particle radiative heat transfer radiative properties Solid rocket motor

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Effects of microlens array orientation errors on plenoptic imaging of flame radiative properties and uncertainty analysis

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Science China(Technological Sciences) 2021年第10期64卷 2119-2141页

作者： LI SuNing YUAN Yuan TAN HePing School of Energy Science and Engineering Harbin Institute of TechnologyHarbin 150001China

Plenoptic imaging(PI)systems can flexibly record both spatial and angular information on flame radiation,enabling volumetric reconstruction of complex *** accuracy and efficiency of the reconstruction are significantly affected by the orientation parameters of the microlens array(MLA)in the *** investigate the influence of potential parameter errors on flame light fields,we establish a typical orientation error model and employ ray-splitting-based Monte Carlo method to simulate the entire and sectioned PI for the three-dimensional flame under four error conditions,in which different radiative properties of flame(extinction coefficient,scattering albedo,and scattering phase function)are *** the proposed uncertainty evaluation scheme,the flame image characteristics,intensity,structure deviations,and their local distribution for four error types are *** results show that the extinction coefficient and the MLA error type determine the flame PI uncertainty features,while the scattering properties only change the deviation *** major impact of the extinction coefficient on the transfer and accumulation of uncertainty in flame-sectioned PI is also revealed.

关键词： radiative transfer plenoptic imaging radiative properties uncertainty quantification parameter errors flame reconstruction

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Thermal radiative properties of Xonotlite Insulation Material

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Journal of Thermal Science 2005年第3期14卷 281-283,253页

作者： Xinxin ZHANG Gaosheng WEI Fan YU Department of Thermal Engineering University of Science ＆ Technology Beijing Beijing 100083 China

This paper presents experimental results of thermal radiative properties of xonotlite-type calcium silicate insulation material. Transmittance spectra were first taken using Fourier transform infrared spectrometer （FTIR） for the samples with p = 234 kg/m^3. Specific extinction coefficient spectra were then obtained by applying Beer＇s law. Finally, by using the diffusion approximation, the specific Rossland mean extinction coefficients and radiative thermal conductivities were obtained for various temperatures. The results show that the specific spectral extinction coefficient of xonotlite is larger than 7 m^2/kg in the whole measured spectra, and diffusion approximation equation is a reasonable description of radiative heat transfer in xonotlite insulation material. The specific Rossland mean extinction coefficient of xonotlite has a maximum value at 400 K and the radiative thermal conductivity is almost proportional to the cube of temperature.

关键词： xonotlite insulation radiative properties extinction coefficient

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Modeling infrared radiative properties of nanoscale metallic complex slit arrays

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Journal of Central South University 2014年第10期21卷 3927-3935页

作者：王爱华牛义红陈玉彬 School of Materials and Metallurgy Northeastern University Department of Mechanical Engineering National Cheng Kung University

The radiative properties(absorptance, reflectance, and transmittance) of deep slits with five nanoscale slit profile variations at the transverse magnetic wave incidence were numerically investigated by employing the finite difference time domain method. For slits with attached features, their radiative properties can be much different due to the modified cavity geometry and dangled structures, even at wavelengths between 3 and 15 μm. The shifts of cavity resonance excitation result in higher transmittance through narrower slits at specific wavelengths and resonance modes are confirmed with the electromagnetic fields. Opposite roles possibly played by features in increasing or decreasing absorptance are determined by the feature position and demonstrated by Poynting vectors. Correlations among all properties of a representative slit array and the slit density are also comprehensively studied. When multiple slit types coexist in an array(complex slits), a wide-band transmittance or absorptance enhancement is feasible by merging spectral peaks contributed from each type of slits distinctively. Discrepancy among infrared properties of four selected slit combinations is explained while effects of slit density are also discussed.

关键词： finite difference time domain method subwavelength structures radiative properties complex slit arrays cavity resonance

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Optical properties and Spectroscopic Parameters of Sm(DBM)_3 Doped Polymethyl Methacrylate

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Journal of Rare Earths 2004年第1期22卷 31-35页

作者：董宁陈彪尹民宁利新张其锦夏上达 Structure Research Laboratory Department of Polymer Science and Engineering

Optical absorption spectra of Sm(DBM) 3 doped PMMA (polymethyl methacrylate) in near infrared and visible region are presented. The energy levels were assigned and analyzed in terms of the free-ion Hamiltonian model. Energy levels and reduced matrix elements calculations were carried out using the complete 198 SLJ basis sets for the 4f5 configuration. Judd-Ofelt parameters were evaluated and used to predict the radiative properties of the sample. The theoretical and experimental values for radiative lifetimes and branching ratios were discussed.

关键词： optics radiative properties Judd-Ofelt theory PMMA rare earths

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Impact of solar reflectivity and infrared emissivity on the thermal performance of metal and concrete roofs in cloudy warmhumid climate

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Frontiers of Architectural Research 2024年第4期13卷 842-857页

作者： Jefferson Torres-Quezada Antonio Isalgué Helena Coch CONSISO Lab Universidad Católica de CuencaCuenca 010102Ecuador Architecture Energy and EnvironmentPolytechnic University of CataloniaBarcelona 08028Spain

Regions near latitude 0are characterized by warm-humid climate and also by high *** these regions,metal roofs has been the most widely used ***,in the last decades,the use of heavy concrete roofs has increased *** its material characteristics,this roof typology offers a higher thermal resistance and thermal mass than a metal *** strategies focus on the use of these characteristics,as well as the use of high reflectivity and ***,the impact of cloudiness on the effectiveness of these strategies has been little *** research focuses on the impact of reflectivity and emissivity change on the thermal performance of these two roofs in a cloudy warm-humid *** achieve this objective,simulations validated with measurements were *** results show that the efficiency of reflectivity and emissivity is lower in this region compared to other *** impact of these properties is further reduced with increasing thermal mass or decreasing thermal transmittance,so the effectiveness of reflectivity and emissivity is minimal on the concrete ***,this study supports that a metal roof with a reflectivity and emissivity above 0.70 can offer lower daily average temperatures than a concrete roof.

关键词： Concrete roof Metal roof radiative properties Simulations Measurements

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Optical properties of Nd^3＋ in Nd（DBM）3Phen-doped Poly（methyl methacrylate）

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Chinese Journal of Chemical Physics 2006年第3期19卷 273-276页

作者： Zhi-qiang Zheng Hao Liang Hai Ming Qi-jin Zhang Jian-ping Xie Department of Physics Fujian Normal University Fuzhou 350007 China Department of Physics University of Science and Technology of China Hefei 230025 China Department of Polymer Science and Engineering University of Science and Technology of China Hefei 230025 China

Nd（DBM）3Phen-doped （DBM is dibenzoylmethane and Phen is phenanthroline） polymethyl methacrylate （PMMA） is prepared. Optical absorption, excitation and emission spectra were analyzed for Nd^3＋ in Nd（DBM）3Phen-doped PMMA. Using the Judd-Ofelt theory, the absorption spectrum was analyzed. The Judd-Ofelt（J-O） intensity parameters of Nd（DBM）3Phen-doped polymethyl methacrylate were calculated to be Ω2 = 20.97 × 10^-20 cm^2, Ω4= 3.42 × 10^-20 cm^2, Ω6 = 2.90 × 10^-20 cm^2. The radiative lifetime （631 μs） of the excited 4F3/2 level is given. The stimulated emission cross-sections and the fluorescence branch ratios for the ^4F3/2 →^4Ij′ transitions are also evaluated. Analysis reveals that Nd（DBM）3Phen-doped PMMA is promising for application in polymer optical fibers and planar waveguides.

关键词： radiative properties Judd-Ofelt analysis Nd(DBM)3Phen Polymer

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Effects of Contact Resistance on Heat Transfer Behaviors of Fibrous Insulation

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Chinese Journal of Aeronautics 2009年第5期22卷 569-574页

作者： Zhao Shuyuan Zhang Boming Du Shanyi Center for Composite Materials and Structure Harbin Institute of Technology Harbin 150080 China

In this article, a numerical model combining conduction and radiation is developed based on two flux approximation to predict the heat transfer behavior of fibrous insulation used in thermal protection systems. Monte Carlo method is utilized to determine the modified radiative properties with experimentally measured transient external temperature as high as 1 000 K. It is found that the estimated radiative properties become time-independent after about t = 3 000 s. By comparing the predicted to the measured results in transient state, the contact resistance exerts significant influences upon the temperature distribution in the specimen. Results show that the averaged absolute deviation is 3.25% when contact resistance is neglected in heat transfer model, while 1.82% with no contact resistance.

关键词： heat transfer Monte Carlo methods radiative properties effective thermal conductivity contact resistance

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Effect of Cloud Water Content on the Atmospheric Extinction

Effect of Cloud Water Content on the Atmospheric Extinction

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2011 2nd International Conference on Challenges in Environmental Science and Computer Engineering(CESCE 2011)

作者： Xiying Wang Chenji Niu Hong Qi Liming Ruan School of Energy Science and Engineering Harbin Institute of Technology Postdoctoral Research Center of Instruments Science and Technology Harbin Institute of Technology

The aerosol particles play an important role in the research of atmospheric radiation and climate *** the process of calculating the radiative properties of aerosol particles,the complex refractive index is an important ***,it can not be measured *** the atmospheric aerosol is a particle system composed of various components in a wide range of sizes,the‘Continental type’of aerosol particles have been chosen in this paper,and the equivalent complex refractive indices of particles are calculated with Bruggeman mixing *** radiative properties of aerosol particles under different water contents are determined with Mie theory at the wavelength of 0.55μ*** results show that the extinction coefficients and albedo increase with the increase in water *** the water content in cloud is greater than 60%,the humidity becomes a dominant *** scattering of particles will increase as a result of the humidification in the atmosphere.

关键词： Aerosol particles radiative properties effective medium theory water content complex refractive index

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