Three-Dimensional Measurement of the Crater Formation During Plume-Surface Interactions Using Stereo-Photogrammetry

The present investigation focused on adapting and validating stereo-photogrammetry for obtaining three-dimensional, time-resolved, nonintrusive, full-domain measurements of crater evolution during the plume-surface interaction (PSI) process. An atmospheric experimental facility was designed and constructed to facilitate the development of the stereo-photogrammetry technique for PSI applications. Stereo-photogrammetry was then used to measure the dynamic crater evolution process at nozzle heights of 25, 40, 55, and 70 nozzle diameters above the sand simulant bed. From the stereo-photogrammetry data, time-resolved three-dimensional reconstructions of the crater geometry were generated, and crater depth, radius, and volume time histories were extracted. Crater depth was observed to grow logarithmically for the two highest nozzle heights, and the depth growth rate for the lower two nozzle heights was more rapid. Crater volume growth was well characterized by a power law fit. The post-nozzle-flow slope of the collapsed crater was found to increase with nozzle height, along with the final crater volume. The results show that stereo-photogrammetry can be used to successfully measure the crater geometry in cases where optical access to the crater is not completely degraded by ejected particles.