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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1997

West-Antarctic Ice Streams: Analog to Ice Flow in Channels on Mars

Sounding of the sea floor in front of the Ross Ice Shelf in Antarctica recently revealed large persistent patterns of longitudinal megaflutes and drumlinoid forms, which are interpreted to have formed at the base of ice streams during the list glacial advance. The flutes bear remarkable resemblance to longitudinal grooves and highly elongated streamlined islands found on the floors of some large martian channels, called outflow channels. ln addition, other similarities exist between Antarctic ice streams and outflow channels. Ice streams are 30 to 80 km wide and hundreds of kilometers long, as are the martian channels. Ice stream beds are below sea level. Floors of many martian outflow channels lie below martian datum, which may have been close to or below past martian sea levels. The Antarctic ice stream bed gradient is flat and locally may go uphill, and surface slopes are exceptionally low. So are gradients of martian channels. The depth to the bed in ice streams is 1 to 1.5 km. At bankful stage, the depth of the fluid in outflow channels would have been 1 to 2 km. These similarities suggest that the martian outflow channels, whose origin is commonly attributed to gigantic catastrophic floods, were locally filled by ice that left a conspicuous morphologic imprint. Unlike the West-Antarctic-ice streams, which discharge ice from an ice sheet, ice in the martian channels came from water erupting from the ground. In the cold martian environment, this water, if of moderate volume, would eventually freeze. Thus it may have formed icings on springs, ice dams and jams on constrictions in the channel path, or frozen pools. Given sufficient thickness and downhill surface gradient, these ice masses would have moved; and given the right conditions, they could have moved like Antarctic ice streams.

Lucchitta, B. K.↗
NASA NTRS1992

Possible recent and ancient glacial ice flow in the south polar region of Mars

Martian polar science began almost as soon as small telescopes were trained on the planet. The seasonal expansion and contraction of the polar caps and their high albedoes led most astronomers to think that water ice is the dominant constituent. In 1911 Lowell perceived a bluish band around the retreating edge of the polar caps, and interpreted it as water from melting polar ice and seasonal snow. An alternative idea in his time was that the polar caps consist of frozen carbonic acid. Lowell rejected the carbonic acid hypothesis on account of his blue band. He also pointed out that carbonic acid would sublimate rather than melt at confining pressures near and below one bar, hence, carbonic acid could not account for the blue band. In comparing Lowell's theories with today's knowledge, it is recognized that (1) sublimation is mainly responsible for the growth and contraction of Mars' polar caps, (2) carbon dioxide is a major component of the southern polar cap, and (3) Lowell's blue band was probably seasonal dust and/or clouds. Geomorphic evidence that glacial ice and glacial melt waters once flowed over broad areas of the southern polar region. Two aspects of the south polar region suggest possible glacial processes during two distinct eras in Mars' history.

Kargel, J. S.↗
NASA NTRS2014

Tidal Modulation of Ice-shelf Flow: a Viscous Model of the Ross Ice Shelf

Three stations near the calving front of the Ross Ice Shelf, Antarctica, recorded GPS data through a full spring-neap tidal cycle in November 2005. The data revealed a diurnal horizontal motion that varied both along and transverse to the long-term average velocity direction, similar to tidal signals observed in other ice shelves and ice streams. Based on its periodicity, it was hypothesized that the signal represents a flow response of the Ross Ice Shelf to the diurnal tides of the Ross Sea. To assess the influence of the tide on the ice-shelf motion, two hypotheses were developed. The first addressed the direct response of the ice shelf to tidal forcing, such as forces due to sea-surface slopes or forces due to sub-ice-shelf currents. The second involved the indirect response of ice-shelf flow to the tidal signals observed in the ice streams that source the ice shelf. A finite-element model, based on viscous creep flow, was developed to test these hypotheses, but succeeded only in falsifying both hypotheses, i.e. showing that direct tidal effects produce too small a response, and indirect tidal effects produce a response that is not smooth in time. This nullification suggests that a combination of viscous and elastic deformation is required to explain the observations.

Tidal↗
NASA NTRS1987

Icing of flow conditioners in a closed-loop wind tunnel

Described are the results of an experiment which determined whether flow conditioning screens and honeycombs would ice up in a closed-loop icing wind tunnel when placed downstream of the heat exchanger and upstream of the spray bars. The experiment was performed in the Icing Research Tunnel (IRT) at NASA Lewis Research Center. The investigation involved two separate tests: one to find the icing characteristics of flow conditioners in the IRT, and the second to find the icing characteristics of flow conditioners in the proposed rehabilitation of the Altitude Wind Tunnel (AWT). Both experiments showed that the heat exchanger removed nearly all of the icing cloud so that icing of the flow conditioners would cause no serious tunnel performance degradation during the course of a day's run. Only extremely cold conditions caused frost formation on the flow conditioners. The significance of this frost formation was minimized because frost buildup on the heat exchanger caused a much more severe pressure drop than did icing of the flow conditioners.

Newton, James E.↗
DOE OSTI2025

Computationally efficient subglacial drainage modelling using Gaussian process emulators: GlaDS-GP v1.0

Subglacial drainage models represent water flow at the ice–bed interface through coupled distributed and channelized systems to determine water pressure, discharge, and drainage system geometry. While they are used to understand processes such as the relationship between surface melt and ice flow, the number of uncertain model parameters and the computational cost of running models makes it difficult to adequately explore the high-dimensional parameter space and evaluate uncertainty in model predictions. Here, we develop Gaussian process (GP) emulators that make fast predictions with associated uncertainty of subglacial drainage model outputs. Using a truncated principal component (PC) basis representation, we construct a GP emulator for diurnally averaged subglacial water pressure. We also explore emulation of scalar variables describing drainage efficiency and configuration. We train the emulators using ensembles of up to 512 simulations varying eight parameters of the Glacier Drainage System (GlaDS) model on a synthetic domain intended to represent an ice-sheet margin. The emulators make predictions ∼ 1000 times faster than GlaDS simulations, with errors <3 % for the water pressure field and ∼ 5 %–9 % for drainage efficiency and configuration. We apply the emulators to explore the eight-dimensional parameter space by computing variance-based parameter sensitivity indices, finding that three parameters (ice flow coefficient, bed bump aspect ratio, and the subglacial cavity system conductivity) explain 90 % of the variance in modelled water pressure in response to parameter changes. The GP emulator approach described here is well suited to integrating observational data with models to make calibrated, credible predictions of subglacial drainage.

58 GEOSCIENCES↗
NASA NTRS2001

Overview of the Icing and Flow Quality Improvements Program for the NASA Glenn Icing Research Tunnel

Major upgrades were made in 1999 to the 6- by 9-Foot (1.8- by 2.7-m) Icing Research Tunnel (IRT) at the NASA Glenn Research Center. These included replacement of the electronic controls for the variable-speed drive motor, replacement of the heat exchanger, complete replacement and enlargement of the leg of the tunnel containing the new heat-exchanger, the addition of flow-expanding and flow-contracting turning vanes upstream and downstream of the heat exchanger, respectively, and the addition of fan outlet guide vanes (OGV's). This paper describes the rationale behind this latest program of IRT upgrades and the program's requirements and goals. An overview is given of the scope of work undertaken by the design and construction contractors, the scale-model IRT (SMIRT) design verification program, the comprehensive reactivation test program initiated upon completion of construction, and the overall management approach followed.

Irvine, Thomas B.↗
NASA NTRS2002

Concentrating Antarctic Meteorites on Blue ice Fields: The Frontier Mountain Meteorite Trap

The collection of meteorites in Antarctica has greatly stimulated advancement in the field of meteoritics by providing the community with significant numbers of rare and unique meteorites types and by yielding large numbers of meteorites that sample older infall epochs (Grady et al., 1998). The majority of Antarctic meteorites are found on blue ice fields, where they are thought to be concentrated by wind and glacial drift (cf. Cassidy et al., 1992). The basic "ice flow model" describes the concentration of meteorites by the stagnation or slowing of ice as it moves against a barrier located in a zone with low snow accumulation. However, our limited knowledge of the details of the actual concentration mechanisms prevents establishing firm conclusions concerning the past meteorite flux from the Antarctic record (Zolensky, 1998). The terrestrial ages of Antarctic meteorites indicate that their concentration occurs on time scales of tens to hundreds of thousands of years (Nishiizumi et al., 1989). It is a challenge to measure a mechanism that operates so slowly, and since such time scales can span more than one glacial epoch one cannot assume that the snow accumulation rates, ice velocities and directions, etc. that are measured today are representative of those extant over the age of the trap. Testing the basic "ice flow model" therefore requires the careful measurement of meteorite locations, glacialogical ice flow data, ice thicknesses, bedrock and surface topology, ice ablation and snow accumulation rates, and mass transport by wind over an extended period of time in a location where these quantities can be interpreted in the context of past glacialogical history.

Sandford, Scott A.↗
NASA NTRS1997

Meteorite Infall and Transport in Antarctica: An Analysis of Icefields as Accumulation Surfaces

Over 10,000 meteorite fragments have been collected on only a dozen or so small icefields in Antarctica. The terrestrial history of these meteorites is important, both from the perspective of the effects of their ambient environment on the meteorites themselves, and on the information that can be derived in relation to ice flow and ice stability over periods of time up to 1 million years. We discuss the relative importance of meteorite infall, and ice and aeolian transport in creating meteorite accumulations and the importance of ice and aeolian transport and weathering in removing meteorites at various icefields in Antarctica. The present analysis is confined to equibrated ordinary chondrites. We use the natural thermoluminescence (TL) to to examine the effects of weathering. Natural TL is used in combination with size analysis to gauge the effects of aeolian transport. Some icefields, especially the Lewis Cliff Ice Tongue, are dominated by wind-transported fragments, while others, including the Far Western field at Allan Hills, have lost fragments. It appears that most Antarctic icefields preserve meteorite collections on time scales of a few tens of thousands of years.

Benoit, P. H.↗
NASA NTRS2023

Greenland and Canadian Arctic Ice Temperature Profiles Database

Here, we present a compilation of 95 ice temperature profiles from 85 boreholes from the Greenland ice sheet and peripheral ice caps, as well as local ice caps in the Canadian Arctic. Profiles from only 31 boreholes (36 %) were previously available in open-access data repositories. The remaining 54 borehole profiles (64 %) are being made digitally available here for the first time. These newly available profiles, which are associated with pre-2010 boreholes, have been submitted by community members or digitized from published graphics and/or data tables. All 95 profiles are now made available in both absolute (meters) and normalized (0 to 1 ice thickness) depth scales and are accompanied by extensive metadata. These metadata include a transparent description of data provenance. The ice temperature profiles span 70 years, with the earliest profile being from 1950 at Camp VI, West Greenland. To highlight the value of this database in evaluating ice flow simulations, we compare the ice temperature profiles from the Greenland ice sheet with an ice flow simulation by the Parallel Ice Sheet Model (PISM). We find a cold bias in modeled near-surface ice temperatures within the ablation area, a warm bias in modeled basal ice temperatures at inland cold-bedded sites, and an apparent underestimation of deformational heating in high-strain settings. These biases provide process level insight on simulated ice temperatures.

Greenland↗
NASA NTRS2019

Total Temperature Measurements in Icing Cloud Flows Using a Rearward Facing Probe

This paper reports on temperature and humidity measurements from a series of ice-crystal icing tunnel experiments conducted in June 2018 at the Propulsion Systems Laboratory at the NASA Glenn Research Center. The tests were fundamental in nature and were aimed at investigating the icing processes on a two-dimensional NACA0012 airfoil subjected to artificially generated icing clouds. Prior to the tests on the airfoil, a suite of instruments, including total temperature and humidity probes, were used to characterize the thermodynamic flow and icing cloud conditions of the facility. Two different total temperature probes were used in these tests which included a custom designed rearward facing probe and a commercial self-heating total temperature probe. The rearward facing probe, the main total temperature probe, was designed to reduce and mitigate the contaminating effects of icing and ingestion of ice crystals and water droplets at the probe's inlet. The probe also serves as an air-sample inlet for a light absorption based humidity measurement. The paper includes a section which discusses total temperature and humidity measurement considerations, and another section which provides an analysis of the main probe's performance characteristics. A computational fluid dynamic model of the flow around the probe was also conducted to gain insight into the trajectory of the flow entering the probe inlet. The experiments included a series of tests in which the relative humidity of the facility flow was swept through with increasingly larger values. The data showed that the rearward facing probe can reasonably capture the flow's total temperature and humidity under mild to moderate icing conditions but produces anomalous results under more intense icing conditions. The experimental data was also compared to an in-house developed thermodynamic model which takes into account the interaction of the main flow with the icing cloud. Comparison to the thermodynamic model showed that the rearward facing probe measured the predicted trends.

Agui, Juan H.↗