The Experts below are selected from a list of 246 Experts worldwide ranked by ideXlab platform
Lisong Zhang - One of the best experts on this subject based on the ideXlab platform.
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measurement and theoretical prediction on the surface emittance of carbonized layer of silica phenolic Ablative Material
International Journal of Heat and Mass Transfer, 2018Co-Authors: Hong Ye, Lisong ZhangAbstract:Abstract As a typical fiber reinforced resin-based Ablative Material, silica/phenolic composite has important applications in the thermal protection of high-speed aircrafts. At high temperature, it can form a carbonized layer, whose surface emittance is directly related to its capacity of radiative heat dissipation. In this work, carbonization experiments of the silica/phenolic composite and pure phenolic resin were designed to obtain their corresponding carbonized samples. The spectral emittances in the wavelength range from 2.5 to 25 μm of the carbonized samples were measured by a Fourier transform infrared spectroscopy with a blackbody furnace and a sample heater at temperatures from 200 to 500 °C. The results showed that the spectral emittance of the carbonized Ablative Material is close to that of the carbonized phenolic resin. The spectral emittances of the two carbonized samples increase with temperature and almost do not change with wavelength, indicating that the carbonized samples have the nature of a grey body. A prediction model of the total emittance was constructed based on the grey body assumption and a geometric model extracted from structure characterization of the carbonized Ablative Material. The predicted total emittances and those obtained from the integration of the measured spectral results are all higher than 0.8, and the deviations are below 10%. Theoretical predictions of the model show that the total emittance of the carbonized Ablative Material increases with the increasing porosity ( ϕ ) and total emittance ( e s ) of the fiber bundle covered with carbonized phenolic resin. Both the experimental and theoretical results reveal that the high total emittance of the carbonized silica/phenolic Ablative Material can be mainly attributed to the high emittance of the carbonized phenolic resin.
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Measurement and theoretical prediction on the surface emittance of carbonized layer of silica/phenolic Ablative Material
International Journal of Heat and Mass Transfer, 2018Co-Authors: Hong Ye, Lisong ZhangAbstract:Abstract As a typical fiber reinforced resin-based Ablative Material, silica/phenolic composite has important applications in the thermal protection of high-speed aircrafts. At high temperature, it can form a carbonized layer, whose surface emittance is directly related to its capacity of radiative heat dissipation. In this work, carbonization experiments of the silica/phenolic composite and pure phenolic resin were designed to obtain their corresponding carbonized samples. The spectral emittances in the wavelength range from 2.5 to 25 μm of the carbonized samples were measured by a Fourier transform infrared spectroscopy with a blackbody furnace and a sample heater at temperatures from 200 to 500 °C. The results showed that the spectral emittance of the carbonized Ablative Material is close to that of the carbonized phenolic resin. The spectral emittances of the two carbonized samples increase with temperature and almost do not change with wavelength, indicating that the carbonized samples have the nature of a grey body. A prediction model of the total emittance was constructed based on the grey body assumption and a geometric model extracted from structure characterization of the carbonized Ablative Material. The predicted total emittances and those obtained from the integration of the measured spectral results are all higher than 0.8, and the deviations are below 10%. Theoretical predictions of the model show that the total emittance of the carbonized Ablative Material increases with the increasing porosity ( ϕ ) and total emittance ( e s ) of the fiber bundle covered with carbonized phenolic resin. Both the experimental and theoretical results reveal that the high total emittance of the carbonized silica/phenolic Ablative Material can be mainly attributed to the high emittance of the carbonized phenolic resin.
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investigation on the effective thermal conductivity of carbonized high silica phenolic Ablative Material
International Journal of Heat and Mass Transfer, 2017Co-Authors: Yexin Xu, Hong Ye, Lisong ZhangAbstract:Abstract As a phenolic resin-based Ablative Material, high silica/phenolic composite is widely used in aerospace field. However, the effective thermal conductivity of carbonized Ablative Material formed during ablation process is rarely reported. In this work, carbonized sample of the high silica/phenolic Ablative Material was obtained by a carbonization process, and its effective thermal conductivity was measured from 100 to 970 °C. In addition, an analysis model of the effective thermal conductivity of the carbonized ablator consisting of fiber yarns and carbonized phenolic was established based on the result of structure analysis. The measured value of the effective thermal conductivity of the carbonized phenolic was used to inverse the transverse effective thermal conductivity of the fiber yarns. When the inversed values were adopted in different empirical models, it was found that the Clayton model is suitable for predicting the effective thermal conductivity of the carbonized high silica/phenolic.
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Investigation on the effective thermal conductivity of carbonized high silica/phenolic Ablative Material
International Journal of Heat and Mass Transfer, 2017Co-Authors: Yexin Xu, Hong Ye, Lisong ZhangAbstract:Abstract As a phenolic resin-based Ablative Material, high silica/phenolic composite is widely used in aerospace field. However, the effective thermal conductivity of carbonized Ablative Material formed during ablation process is rarely reported. In this work, carbonized sample of the high silica/phenolic Ablative Material was obtained by a carbonization process, and its effective thermal conductivity was measured from 100 to 970 °C. In addition, an analysis model of the effective thermal conductivity of the carbonized ablator consisting of fiber yarns and carbonized phenolic was established based on the result of structure analysis. The measured value of the effective thermal conductivity of the carbonized phenolic was used to inverse the transverse effective thermal conductivity of the fiber yarns. When the inversed values were adopted in different empirical models, it was found that the Clayton model is suitable for predicting the effective thermal conductivity of the carbonized high silica/phenolic.
Hong Ye - One of the best experts on this subject based on the ideXlab platform.
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measurement and theoretical prediction on the surface emittance of carbonized layer of silica phenolic Ablative Material
International Journal of Heat and Mass Transfer, 2018Co-Authors: Hong Ye, Lisong ZhangAbstract:Abstract As a typical fiber reinforced resin-based Ablative Material, silica/phenolic composite has important applications in the thermal protection of high-speed aircrafts. At high temperature, it can form a carbonized layer, whose surface emittance is directly related to its capacity of radiative heat dissipation. In this work, carbonization experiments of the silica/phenolic composite and pure phenolic resin were designed to obtain their corresponding carbonized samples. The spectral emittances in the wavelength range from 2.5 to 25 μm of the carbonized samples were measured by a Fourier transform infrared spectroscopy with a blackbody furnace and a sample heater at temperatures from 200 to 500 °C. The results showed that the spectral emittance of the carbonized Ablative Material is close to that of the carbonized phenolic resin. The spectral emittances of the two carbonized samples increase with temperature and almost do not change with wavelength, indicating that the carbonized samples have the nature of a grey body. A prediction model of the total emittance was constructed based on the grey body assumption and a geometric model extracted from structure characterization of the carbonized Ablative Material. The predicted total emittances and those obtained from the integration of the measured spectral results are all higher than 0.8, and the deviations are below 10%. Theoretical predictions of the model show that the total emittance of the carbonized Ablative Material increases with the increasing porosity ( ϕ ) and total emittance ( e s ) of the fiber bundle covered with carbonized phenolic resin. Both the experimental and theoretical results reveal that the high total emittance of the carbonized silica/phenolic Ablative Material can be mainly attributed to the high emittance of the carbonized phenolic resin.
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Measurement and theoretical prediction on the surface emittance of carbonized layer of silica/phenolic Ablative Material
International Journal of Heat and Mass Transfer, 2018Co-Authors: Hong Ye, Lisong ZhangAbstract:Abstract As a typical fiber reinforced resin-based Ablative Material, silica/phenolic composite has important applications in the thermal protection of high-speed aircrafts. At high temperature, it can form a carbonized layer, whose surface emittance is directly related to its capacity of radiative heat dissipation. In this work, carbonization experiments of the silica/phenolic composite and pure phenolic resin were designed to obtain their corresponding carbonized samples. The spectral emittances in the wavelength range from 2.5 to 25 μm of the carbonized samples were measured by a Fourier transform infrared spectroscopy with a blackbody furnace and a sample heater at temperatures from 200 to 500 °C. The results showed that the spectral emittance of the carbonized Ablative Material is close to that of the carbonized phenolic resin. The spectral emittances of the two carbonized samples increase with temperature and almost do not change with wavelength, indicating that the carbonized samples have the nature of a grey body. A prediction model of the total emittance was constructed based on the grey body assumption and a geometric model extracted from structure characterization of the carbonized Ablative Material. The predicted total emittances and those obtained from the integration of the measured spectral results are all higher than 0.8, and the deviations are below 10%. Theoretical predictions of the model show that the total emittance of the carbonized Ablative Material increases with the increasing porosity ( ϕ ) and total emittance ( e s ) of the fiber bundle covered with carbonized phenolic resin. Both the experimental and theoretical results reveal that the high total emittance of the carbonized silica/phenolic Ablative Material can be mainly attributed to the high emittance of the carbonized phenolic resin.
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investigation on the effective thermal conductivity of carbonized high silica phenolic Ablative Material
International Journal of Heat and Mass Transfer, 2017Co-Authors: Yexin Xu, Hong Ye, Lisong ZhangAbstract:Abstract As a phenolic resin-based Ablative Material, high silica/phenolic composite is widely used in aerospace field. However, the effective thermal conductivity of carbonized Ablative Material formed during ablation process is rarely reported. In this work, carbonized sample of the high silica/phenolic Ablative Material was obtained by a carbonization process, and its effective thermal conductivity was measured from 100 to 970 °C. In addition, an analysis model of the effective thermal conductivity of the carbonized ablator consisting of fiber yarns and carbonized phenolic was established based on the result of structure analysis. The measured value of the effective thermal conductivity of the carbonized phenolic was used to inverse the transverse effective thermal conductivity of the fiber yarns. When the inversed values were adopted in different empirical models, it was found that the Clayton model is suitable for predicting the effective thermal conductivity of the carbonized high silica/phenolic.
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Investigation on the effective thermal conductivity of carbonized high silica/phenolic Ablative Material
International Journal of Heat and Mass Transfer, 2017Co-Authors: Yexin Xu, Hong Ye, Lisong ZhangAbstract:Abstract As a phenolic resin-based Ablative Material, high silica/phenolic composite is widely used in aerospace field. However, the effective thermal conductivity of carbonized Ablative Material formed during ablation process is rarely reported. In this work, carbonized sample of the high silica/phenolic Ablative Material was obtained by a carbonization process, and its effective thermal conductivity was measured from 100 to 970 °C. In addition, an analysis model of the effective thermal conductivity of the carbonized ablator consisting of fiber yarns and carbonized phenolic was established based on the result of structure analysis. The measured value of the effective thermal conductivity of the carbonized phenolic was used to inverse the transverse effective thermal conductivity of the fiber yarns. When the inversed values were adopted in different empirical models, it was found that the Clayton model is suitable for predicting the effective thermal conductivity of the carbonized high silica/phenolic.
Nagi N Mansour - One of the best experts on this subject based on the ideXlab platform.
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multidimensional Material response simulations of a full scale tiled Ablative heatshield
Aerospace Science and Technology, 2018Co-Authors: Jeremie B E Meurisse, Jean Lachaud, Francesco Panerai, Chun Tang, Nagi N MansourAbstract:Abstract The Mars Science Laboratory (MSL) was protected during Mars atmospheric entry by a 4.5 meter diameter heatshield, which was constructed by assembling 113 thermal tiles made of NASA's flagship porous Ablative Material, Phenolic Impregnated Carbon Ablator (PICA). Analysis and certification of the tiles thickness were based on a one-dimensional model of the PICA response to the entry aerothermal environment. This work provides a detailed three-dimensional heat and mass transfer analysis of the full-scale MSL tiled heatshield. One-dimensional and three-dimensional Material response models are compared at different locations of the heatshield. The three-dimensional analysis is made possible by the use of the Porous Material Analysis Toolbox based on OpenFOAM (PATO) to simulate the Material response. PATO solves the conservation equations of solid mass, gas mass, gas momentum and total energy, using a volume-averaged formulation that includes production of gases from the decomposition of polymeric matrix. Boundary conditions at the heatshield forebody surface were interpolated in time and space from the aerothermal environment computed with the Data Parallel Line Relaxation (DPLR) code at discrete points of the MSL trajectory. A mesh consisting of two million cells was created in Pointwise, and the Material response was performed using 840 processors on NASA's Pleiades supercomputer. The present work constitutes the first demonstration of a three-dimensional Material response simulation of a full-scale Ablative heatshield with tiled interfaces. It is found that three-dimensional effects are pronounced at the heatshield outer flank, where maximum heating and heat loads occur for laminar flows.
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toward Ablative Material response coupling in dplr
11th AIAA ASME Joint Thermophysics and Heat Transfer Conference, 2014Co-Authors: Suman Muppidi, Michael Barnhardt, Nagi N MansourAbstract:The present paper describes preliminary development of an in-depth Material response model within NASA’s DPLR software. A complete description of the formulation of a fluid-coupled, Ablative Material response model is provided. The model accounts for finiterate chemistry and convection of pyrolysis gases through a porous medium. The Material response equations are implemented in DPLR to produce a structured solver, which is implemented on a parallel computing platform. An independent coupling interface allows the new DPLR-ARM code to communicate boundary data with DPLR, enabling coupled simulations of fluid and Material response. A preliminary demonstration of the feasibility of this approach is presented by analysis of two conduction-only problems: a titanium ballistic range projectile, and a carbon ablator subject to low heat flux in an arc jet. Results of the simulations show that proper characterization of Material properties, such as surface emissivity, and the non-isotropy and temperature dependence of thermal conductivity, have a strong influence on the predicted temperature field. Additionally, it is found that the solution is sensitive to frequency of data exchange in the coupling procedure.
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Porous-Material Analysis Toolbox Based on OpenFOAM and Applications
Journal of Thermophysics and Heat Transfer, 2014Co-Authors: Jean Lachaud, Nagi N MansourAbstract:The Porous-Material Analysis Toolbox based on OpenFOAM is a fully portable OpenFOAM library. It is implemented to test innovative multiscale physics-based models for reacting porous Materials that undergo recession. Current developments are focused on Ablative Materials. The Ablative Material response module implemented in the Porous-Material Analysis Toolbox relies on an original high-fidelity ablation model. The governing equations are volume-averaged forms of the conservation equations for gas mass, gas species, solid mass, gas momentum, and total energy. It may also simply be used as a state-of-the-art ablation model when the right model options are chosen. As applications, three physical analyses are presented: 1) volume-averaged study of the oxidation of a carbon-fiber preform under dry air, 2) three-dimensional analysis of the pyrolysis gas flow in a porous Ablative Material sample facing an arcjet, and 3) comparison of a state-of-the-art and a high-fidelity model for the thermal and chemical respo...
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A Short Review of Ablative-Material Response Models and Simulation Tools
2011Co-Authors: Jean Lachaud, Thierry Magin, Ioana Cozmuta, Nagi N MansourAbstract:NASA Ames Research Center, 94035 Moffett Field, CA, USAABSTRACTA review of the governing equations and boundary con-ditions used to model the response of Ablative materi-als submitted to a high-enthalpy flow is proposed. Theheritage of model-development efforts undertaken in the1960s is extremely clear: the bases of the models used inthe community are mathematically equivalent. Most ofthe Material-response codes implement a single model inwhich the equation parameters may be modified to modeldifferent Materials or conditions. The level of fidelityof the models implemented in design tools only slightlyvaries. Research and development codes are generallymore advanced but often not as robust. The capabilitiesof each of these codes are summarized in a color-codedtable along with research and development efforts cur-rently in progress.Key words: Ablative Material; modeling; design tool.NOMENCLATURELatinF
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a short review of Ablative Material response models and simulation tools
2011Co-Authors: Jean Lachaud, Thierry Magin, Ioana Cozmuta, Nagi N MansourAbstract:A review of the governing equations and boundary conditions used to model the response of Ablative Materials submitted to a high-enthalpy flow is proposed. The heritage of model-development efforts undertaken in the 1960s is extremely clear: the bases of the models used in the community are mathematically equivalent. Most of the Material-response codes implement a single model in which the equation parameters may be modified to model different Materials or conditions. The level of fidelity of the models implemented in design tools only slightly varies. Research and development codes are generally more advanced but often not as robust. The capabilities of each of these codes are summarized in a color-coded table along with research and development efforts currently in progress.
Yexin Xu - One of the best experts on this subject based on the ideXlab platform.
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investigation on the effective thermal conductivity of carbonized high silica phenolic Ablative Material
International Journal of Heat and Mass Transfer, 2017Co-Authors: Yexin Xu, Hong Ye, Lisong ZhangAbstract:Abstract As a phenolic resin-based Ablative Material, high silica/phenolic composite is widely used in aerospace field. However, the effective thermal conductivity of carbonized Ablative Material formed during ablation process is rarely reported. In this work, carbonized sample of the high silica/phenolic Ablative Material was obtained by a carbonization process, and its effective thermal conductivity was measured from 100 to 970 °C. In addition, an analysis model of the effective thermal conductivity of the carbonized ablator consisting of fiber yarns and carbonized phenolic was established based on the result of structure analysis. The measured value of the effective thermal conductivity of the carbonized phenolic was used to inverse the transverse effective thermal conductivity of the fiber yarns. When the inversed values were adopted in different empirical models, it was found that the Clayton model is suitable for predicting the effective thermal conductivity of the carbonized high silica/phenolic.
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Investigation on the effective thermal conductivity of carbonized high silica/phenolic Ablative Material
International Journal of Heat and Mass Transfer, 2017Co-Authors: Yexin Xu, Hong Ye, Lisong ZhangAbstract:Abstract As a phenolic resin-based Ablative Material, high silica/phenolic composite is widely used in aerospace field. However, the effective thermal conductivity of carbonized Ablative Material formed during ablation process is rarely reported. In this work, carbonized sample of the high silica/phenolic Ablative Material was obtained by a carbonization process, and its effective thermal conductivity was measured from 100 to 970 °C. In addition, an analysis model of the effective thermal conductivity of the carbonized ablator consisting of fiber yarns and carbonized phenolic was established based on the result of structure analysis. The measured value of the effective thermal conductivity of the carbonized phenolic was used to inverse the transverse effective thermal conductivity of the fiber yarns. When the inversed values were adopted in different empirical models, it was found that the Clayton model is suitable for predicting the effective thermal conductivity of the carbonized high silica/phenolic.
Thierry Magin - One of the best experts on this subject based on the ideXlab platform.
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Two-way coupled simulations of stagnation-point ablation with transient Material response
International Journal of Thermal Sciences, 2018Co-Authors: Pierre Schrooyen, Alessandro Turchi, Koen Hillewaert, Philippe Chatelain, Thierry MaginAbstract:Abstract Ablative Materials are extensively used in aerospace applications to protect the integrity of the spacecraft during atmospheric entry. Both thermal and mechanical stresses have to be withstood in the severe operating conditions typical of space missions. An accurate modeling of the phenomena taking place when these Materials are exposed to such a harsh environment is crucial to ensure the success of future, more demanding, missions. This study aims to couple two tools able to handle two different aspects of the Ablative Material modeling: a stagnation-line flow solver featuring an integrated Ablative boundary condition, and a Material response code. The coupling algorithm allows for time accurate solutions of the Ablative Material thermal response accounting for detailed surface chemistry, in-depth Material behavior, and surface recession. Two different coupling strategies have been implemented, based either on a direct or an iterative procedure. The developed tool is used to rebuild plasma wind tunnel experiments performed in the von Karman Institute Plasmatron facility. The outcomes of the two strategies are compared, showing a satisfactory agreement with the experimental data. Among the two analyzed coupling procedures, the direct coupling proved to be computationally less expensive, while conserving the same accuracy of the more complex iterative procedure for the analyzed cases. A sensitivity analysis is also conducted to understand the discrepancy with experimental data and show the effects of four uncertain Material parameters: thermal conductivity, density, emissivity, and catalytic efficiency.
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emission spectroscopic boundary layer investigation during Ablative Material testing in plasmatron
Journal of Visualized Experiments, 2016Co-Authors: Olivier Chazot, Bernd Helber, Annick Hubin, Thierry MaginAbstract:Ablative Thermal Protection Systems (TPS) allowed the first humans to safely return to Earth from the moon and are still considered as the only solution for future high-speed reentry missions. But despite the advancements made since Apollo, heat flux prediction remains an imperfect science and engineers resort to safety factors to determine the TPS thickness. This goes at the expense of embarked payload, hampering, for example, sample return missions. Ground testing in plasma wind-tunnels is currently the only affordable possibility for both Material qualification and validation of Material response codes. The subsonic 1.2MW Inductively Coupled Plasmatron facility at the von Karman Institute for Fluid Dynamics is able to reproduce a wide range of reentry environments. This protocol describes a procedure for the study of the gas/surface interaction on Ablative Materials in high enthalpy flows and presents sample results of a non-pyrolyzing, ablating carbon fiber precursor. With this publication, the authors envisage the definition of a standard procedure, facilitating comparison with other laboratories and contributing to ongoing efforts to improve heat shield reliability and reduce design uncertainties. The described core techniques are non-intrusive methods to track the Material recession with a high-speed camera along with the chemistry in the reactive boundary layer, probed by emission spectroscopy. Although optical emission spectroscopy is limited to line-of-sight measurements and is further constrained to electronically excited atoms and molecules, its simplicity and broad applicability still make it the technique of choice for analysis of the reactive boundary layer. Recession of the ablating sample further requires that the distance of the measurement location with respect to the surface is known at all times during the experiment. Calibration of the optical system of the applied three spectrometers allowed quantitative comparison. At the fiber scale, results from a post-test microscopy analysis are presented.
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discontinuous galerkin discretization for one dimensional in depth thermal response of Ablative Material
Gordon Research Conference Atmospheric reentry physics, 2013Co-Authors: Pierre Schrooyen, Thierry Magin, Koen Hillewaert, Philippe ChatelainAbstract:This poster shows the development of a one dimensional Material response code to a high enthalpy flux using a discontinuous Galerkin formulation. Results are compared with other state-of-the-art code.
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A Short Review of Ablative-Material Response Models and Simulation Tools
2011Co-Authors: Jean Lachaud, Thierry Magin, Ioana Cozmuta, Nagi N MansourAbstract:NASA Ames Research Center, 94035 Moffett Field, CA, USAABSTRACTA review of the governing equations and boundary con-ditions used to model the response of Ablative materi-als submitted to a high-enthalpy flow is proposed. Theheritage of model-development efforts undertaken in the1960s is extremely clear: the bases of the models used inthe community are mathematically equivalent. Most ofthe Material-response codes implement a single model inwhich the equation parameters may be modified to modeldifferent Materials or conditions. The level of fidelityof the models implemented in design tools only slightlyvaries. Research and development codes are generallymore advanced but often not as robust. The capabilitiesof each of these codes are summarized in a color-codedtable along with research and development efforts cur-rently in progress.Key words: Ablative Material; modeling; design tool.NOMENCLATURELatinF
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a short review of Ablative Material response models and simulation tools
2011Co-Authors: Jean Lachaud, Thierry Magin, Ioana Cozmuta, Nagi N MansourAbstract:A review of the governing equations and boundary conditions used to model the response of Ablative Materials submitted to a high-enthalpy flow is proposed. The heritage of model-development efforts undertaken in the 1960s is extremely clear: the bases of the models used in the community are mathematically equivalent. Most of the Material-response codes implement a single model in which the equation parameters may be modified to model different Materials or conditions. The level of fidelity of the models implemented in design tools only slightly varies. Research and development codes are generally more advanced but often not as robust. The capabilities of each of these codes are summarized in a color-coded table along with research and development efforts currently in progress.
