January 1, 2016
The radiative heat transfer inside a low-density carbon fiber insulator is analyzed using a three- dimensional direct simulation model. A robust procedure is presented for the numerical calculation of the geometric configuration factor to compute the radiative energy exchange processes among the small discretized surface areas of the fibrous material. The methodology is applied to a polygonal mesh of a fibrous insulator obtained from three-dimensional microscale imaging of the real material. The anisotro- pic values of the radiative conductivity are calculated for that geometry. The results yield both directional and thermal dependence of the radiative conductivity. The combined value of radiative and solid conduc- tivity are compared to experimental data available in the literature, and show excellent agreement.
Nouri, N., Panerai, F., Tagavi, K. A., Mansour, N. N., and Martin, A., “Evaluation of the anisotropic radiative conductivity of a low-density carbon fiber material from realistic microscale imaging,” Interna- tional Journal of Heat and Mass Transfer, Vol. 95, 2016, pp. 535–539.
DOI:10.1016/j.ijheatmasstransfer.2015.12.004
September 25, 2015
New paper about carbon oxidation in the journal "Carbon":
Oxidation is one of the main decomposition mechanisms of fibrous carbon/phenolic ablators employed in thermal protection systems for planetary entry capsules. The oxidation process is driven by two competing mechanisms: diffusion of reactants within the porous medium, and reaction rates at the surface of the fibers. These mechanisms are characterized by the Thiele number. Given that the Thiele number varies during an atmospheric entry, we aim to understand the effects of the diffusion/reaction processes on the decomposition of a porous carbon material in various regimes. We use a particle method for simulations of the oxidation process at microscale. The movement of oxygen reactants is simulated using a Brownian motion technique, and heterogeneous first-order reactions at the surface are modeled with a sticking probability law. To enable simulations of the fiber decomposition on actual materials, we use digitized computational grids obtained using X-ray micro-tomographic imaging. We present results for the oxidation of the substrate of the material used on the Mars Science Laboratory capsule that landed the Curiosity rover. We find that the depth of the reaction zone for this material is critically dependent on the Thiele number.
Ferguson, J. C., Panerai, F., Bailey, S. C. C., Lachaud, J. R., Martin, A., and Mansour, N. N., “Modeling the oxidation of low-density carbon fiber material based on micro-tomography,” Carbon, Vol. 96, January 2016, pp. 57–65.
DOI: 10.1016/j.carbon.2015.08.113
May 2, 2015
New paper just published in the AIAA Journal of Thermophysics and Heat Transfer!
[1] Davuluri, R. S. C., Zhang, H., and Martin, A., “Numerical study of spallation phenomenon in an arc-jet environment,” Journal of Thermophysics and Heat Transfer, vol. 29, no. 3, 2015.
doi:10.2514/1.T4586.
April 19, 2015
[1] Martin, A. and Boyd, I. D., “Modeling of heat transfer attenuation by ablative gases during the Stardust re-entry,” Journal of Thermophysics and Heat Transfer, Vol. 29, No. 3, July 2015.
DOI: 10.2514/1.T4202
[2] Weng, H. and Martin, A., “Numerical Investigation of Thermal Response Using Orthotropic Charring Ablative Material,” Journal of Thermophysics and Heat Transfer, Vol. 29, No. 3, July 2015.
DOI: 10.2514/1.T4576
February 11, 2015
Dr. Francesco Panerai, Research Associate in the research group, is being interview for the IXV re-entry demonstrator:
http://uknow.uky.edu/content/uk-postdoctoral-scholar-contributes-europes-experimental-spaceplane
January 12, 2015
Two new papers are available. The first from the AIAA SciTech2015 conference:
Weng, H. and Martin, A., “Numerical Investigation of Geometric Effects of Stardust Return Capsule Heat Shield,” 53rd AIAA Aerospace Sciences Meeting, AIAA Paper 2015-0211, Kissimmee, FL, January 5-9 2015.
DOI: 10.2514/6.2015-0211
The second from the Journal of Thermophysics and Heat Transfer:
Martin, A., Boyd, I. D., Cozmuta, I., and Wright, M. J., “Kinetic rates for gas phase chemistry of phenolic based carbon ablator decomposition in atmospheric air,” Journal of Thermophysics and Heat Transfer, 2015.
DOI: 10.2514/1.T4184
January 9, 2015
A new paper by Nima Nouri and Alexandre Martin has been published in the International Journal of Heat and Mass Transfer:
http://www.sciencedirect.com/science/article/pii/S0017931014011491
December 5, 2014
Congratulation to Justin Cooper who just won the 1st place in the 2014 Oswald Research and Creativity Competition, Physical & Engineering Sciences category for his paper titled: Flux Matching scheme for the Computation of Accurate Boundary Conditions on a Moving Mesh !!!
