April 30, 2021
The work of Justin Cooper, a PhD student in GSIL, featured in NASA News:
https://www.nasa.gov/centers/armstrong/features/armstrong-assists-with-o...
November 9, 2018
July 17, 2018
[1] Sparks, J. D., Myers, G. I., Whitmer, E. C., Nichols, J. T., Dietz, C. J., Khouri, N., Smith, S. W., and Martin, A., “Overview of the second test-flight of the Kentucky Re-entry Universal Payload System (KRUPS),” 12th AIAA/ASME Joint Thermophysics and Heat Transfer Conference, AIAA Paper 2018- 3589, Atlanta, GA, June 2018.
DOI: 10.2514/6.2018- 3589
[2] Cooper, J. M., Schroeder, O. M., Weng, H., and Martin, A., “Implementation and Verification of a Surface Recession Module in a Finite Volume Ablation Solver,” 12th AIAA/ASME Joint Thermophysics and Heat Transfer Conference, AIAA Paper 2018-3272, Atlanta, GA, June 2018.
DOI: 10.2514/6.2018- 3272
February 8, 2018
A new journal article was recently published in the journal of Experiments Fluids:
Abstract
The near surface flow over a dimpled surface with flow injection through it was documented using time-resolved particle image velocimetry. The instantaneous flow structure, time-averaged statistics, and results from snapshot proper orthogonal decomposition were used to examine the coherent structures forming near the dimpled surface. In particular, the modifications made to the flow structures by the addition of flow injection through the surface were studied. It was observed that without flow injection, inclined flow structures with alternating vorticity from neighboring dimples are generated by the dimples and advect downstream. This behavior is coupled with fluid becoming entrained inside the dimples, recirculating and ejecting away from the surface. When flow injection was introduced through the surface, the flow structures became more disorganized, but some of the features of the semi-periodic structures observed without flow injection were preserved. The structures with flow injection appear in multiple wall-normal layers, formed from vortical structures shed from upstream dimples, with a corresponding increase in the size of the advecting structures. As a result of the more complex flow field observed with flow injection, there was an increase in turbulent kinetic energy and Reynolds shear stress, with the Reynolds shear stress representing an increase in vertical transport of momentum by sweeping and ejecting motions that were not present without flow injection.
Borchetta, C. G., Martin, A., and Bailey, S. C. C., “Examination of the effect of blowing on the near-surface flow structure over a dimpled surface,” Experiments in Fluids, vol. 59, no. 3, Article 36, 2017.
doi: 10.1007/s00348-018-2498-z.
January 26, 2018
A new journal article was recently published in the journal of Experimental Thermal and Fluid Science:
Abstract
Spallation is a phenomenon in which solid particles are ejected off the surface of an ablative material in a high-enthalpy, high-shear flow field. The main contributor to this phenomenon in carbon-based heat shields is the mechanical erosion of carbon fibers weakened by oxidation decomposition. The dynamics of this phenomenon, which are poorly characterized in the literature, strongly affect the ablation rate of the material. In state-of-the-art codes, ablation by spallation is modeled using a “failure” ablation rate that is empirically determined. The present study aims at understanding the rate of ablation of low-density carbon materials. Results from a test campaign at the NASA Langley Hypersonic Materials Environmental Test System (HYMETS) arc jet facility are used to examine spallation. High-speed multi-camera imagery at 44,000 fps is used to generate velocity vectors of spalled particles emitted from carbon-fiber samples exposed to an arc jet airflow. The imagery recorded approximately 4×106 unique particles, indicating that spallation is a potentially non-trivial process. The velocities of the particles ejected from the surface were found to be between 10 m/s and 20 m/s, accelerating to velocities as high as 250 m/s further away from the sample surface. Although the particle diameters were not directly observable, estimates suggest anywhere from 0.06% to 5.6% of the mass loss from the sample occurred due to spallation.
Bailey, S. C. C., Bauer, D., Panerai, F., Splinter, S. C., Danehy, P. M., Hardy, J. M., and Martin, A., “Experimental analysis of spallation particle trajectories in an arc-jet environment,” Experimental Thermal and Fluid Science, 2018.
doi: 10.1016/j.expthermflusci.2018.01.005
January 26, 2018
Two new articles were recently presented at the AIAA Aerospace Science Meeting (SciTech 2018):
Sparks, J. D., Whitmer, E. C., Myers, G. I., Montague, C. C., Dietz, C. J., Khouri, N., Nichols, J. T., Smith, S. W., and Martin, A., “Overview of the first test-flight of the Kentucky re-entry universal payload system (KRUPS),” 56th AIAA Aerospace Sciences Meeting, AIAA Paper 2018-1720, Kissimmee, FL, January 2018.
doi: 10.2514/6.2018-1720
Duzel, U., Schroeder, O. M., and Martin, A., “Computational prediction of nasa langley hymets arc jet flow with KATS,” 56th AIAA Aerospace Sciences Meeting, AIAA 2018-1719, Kissimmee, FL, January 2018.
doi: 10.2514/6.2018-1719
December 13, 2017
Louisville main newspaper, the Courier-Journal, recently published an article about the research of the Gas-Surface Interaction Lab: https://www.courier-journal.com/story/tech/science/2017/09/14/kentucky-scientists-help-nasa-prepare-deep-space-missions/525000001/
