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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Limited Impact of Thwaites Ice Shelf on Future Ice Loss From Antarctica

Abstract Thwaites Ice Shelf (TWIS), the floating extension of Thwaites Glacier, West Antarctica, is changing rapidly and may completely disintegrate in the near future. Any buttressing that the ice shelf provides to the upstream grounded Thwaites glacier will then be lost. Previously, it has been argued that this could lead to onset of dynamical instability and the rapid demise of the entire glacier. Here we provide the first systematic quantitative assessment of how strongly the upstream ice is buttressed by TWIS and how its collapse affects future projections. By modeling the stresses acting along the current grounding line, we show that they deviate insignificantly from the stresses after ice shelf collapse. Using three ice‐flow models, we furthermore model the transient evolution of Thwaites Glacier and find that a complete disintegration of the ice shelf will not substantially impact future mass loss over the next 50 years.

Gudmundsson, G. H.↗
DOE OSTI2024

Ice-slurry production for solar-ice systems using supercooling with an in-stream crystallizer

Using ice slurry produced from supercooled water with an in-stream crystallizer opens a new path for solarice systems, increasing efficiency and reducing investment cost compared to ice-on-coil systems. Power needs are decoupled from the stored energy since the heat exchangers are not evenly distributed in the ice storage vessel but directly placed as the heat pump evaporator, which depends on the heat pump capacity and not on the ice storage volume. The novel ice storage design can serve as a heat source for a heat pump, where its evaporator is used to supercool water below 0 °C, or for refrigeration. The supercooled water at a temperature around −2 °C, maintained in a meta-stable liquid state, is triggered to nucleate in an in-stream crystallizer. The current design of the ice crystallizer allows for continuous operation of the system and scalability. Experimental results obtained with a gasketed plate heat exchanger used to supercool water and an in-stream crystallizer operated at a power of up to 6.5 kW are presented.

Thamm, Ann-Katrin↗
DOE OSTI2021

Secondary ice production during the break-up of freezing water drops on impact with ice particles

Abstract. We provide the first dedicated laboratory study of collisions of supercooled water drops with ice particles as a secondary ice production mechanism. We experimentally investigated collisions of supercooled water drops (∼ 5 mm in diameter) with ice particles of a similar size (∼ 6 mm in diameter) placed on a glass slide at temperatures >-12 ∘C. Our results showed that secondary drops were generated during both the spreading and retraction phase of the supercooled water drop impact. The secondary drops generated during the spreading phase were emitted too fast to quantify. However, quantification of the secondary drops generated during the retraction phase with diameters >0.1 mm showed that 5–10 secondary drops formed per collision, with approximately 30 % of the secondary drops freezing over a temperature range between −4 and −12 ∘C. Our results suggest that this secondary ice production mechanism may be significant for ice formation in atmospheric clouds containing large supercooled drops and ice particles.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1979

Low-velocity impact craters in ice and ice-saturated sand with implications for Martian crater count ages

The paper reports on a series of low-velocity impact experiments performed in ice and ice-saturated sand. It is found that crater diameters in ice-saturated sand were about 2 times larger than in the same energy and velocity range in competent blocks of granite, basalt and cement, while craters in ice were 3 times larger. It is shown that if this dependence of crater size on strength persists to large hypervelocity impact craters, then surface of geologic units composed of ice or ice-saturated soil would have greater crater count ages than rocky surfaces with identical influx histories. Among the conclusions are that Martian impact crater energy versus diameter scaling may also be a function of latitude.

Croft, S. K.↗
NASA NTRS1981

Satellite-derived ice data sets no. 1: Antarctic monthly average microwave brightness temperatures and sea-ice concentrations, 1973 - 1976

A summary data set concerning 4 years of Antarctic sea-ice conditions was created and is available on magnetic tape. The data were derived from electrically scanning microwave radiometer brightness temperatures and were mapped into a polar stereographic grid enclosing the 50 deg S latitude circle. The grid size varies from about 32 by 32 sq km at the poles to about 28 by 28 sq km at 50 deg S. The microwave brightness temperatures of Antarctic sea ice are predominantly characteristic of first-year ice with an emissivity of 0.92 at 19 GHz frequency. Sea ice concentrations were calculated from the brightness temperature data for each grid element with an algorithm that uses an emissivity value of 0.92 and an ice physical temperature estimate from climatological surface air temperatures. Monthly, multiyear monthly, and yearly maps of brightness temperatures and sea ice concentrations were created for the 4 years, except for 7 months for which useable data were insufficient.

Zwally, H. J.↗
NASA NTRS1982

Ice crystal and ice nucleus measurements in cap clouds

Ice nucleation in cap clouds over a mountain in Wyoming was examined with airborne instrumentation. Crosswind and wind parallel passes were made through the clouds, with data being taken on the ice crystal concentrations and sizes. A total of 141 penetrations of 26 separate days in temperatures ranging from -7 to -24 C were performed. Subsequent measurements were also made 100 km away from the mountain. The ice crystal concentrations measured showed good correlation with the ice nucleus content in winter time, midcontinental air masses in Wyoming. Further studies are recommended to determine if the variations in the ice nucleus population are the cause of the variability if ice crystal content.

Vali, G.↗
NASA NTRS1987

Shuttle Imaging Radar B (SIR-B) Weddell Sea ice observations - A comparison of SIR-B and scanning multichannel microwave radiometer ice concentrations

Ice concentrations over the Weddell Sea were studied using SIR-B data obtained during the October 1984 mission, with special attention given to the effect of ocean waves on the radar return at the ice edge. Sea ice concentrations were derived from the SIR-B data using two image processing methods: the classification scheme at JPL and the manual classification method at Scott Polar Research Institute (SPRI), England. The SIR ice concentrations were compared with coincident concentrations from the Nimbus-7 SMMR. For concentrations greater than 40 percent, which was the smallest concentration observed jointly by SIR-B and the SMMR, the mean difference between the two data sets for 12 points was 2 percent. A comparison between the JPL and the SPRI SIR-B algorithms showed that the algorithms agree to within 1 percent in the interior ice pack, but the JPL algorithm gives slightly greater concentrations at the ice edge (due to the fact that the algorithm is affected by the wind waves in these areas).

Martin, Seelye↗
NASA NTRS1987

Evaluation of icing drag coefficient correlations applied to iced propeller performance prediction

Evaluation of three empirical icing drag coefficient correlations is accomplished through application to a set of propeller icing data. The various correlations represent the best means currently available for relating drag rise to various flight and atmospheric conditions for both fixed-wing and rotating airfoils, and the work presented here ilustrates and evaluates one such application of the latter case. The origins of each of the correlations are discussed, and their apparent capabilities and limitations are summarized. These correlations have been made to be an integral part of a computer code, ICEPERF, which has been designed to calculate iced propeller performance. Comparison with experimental propeller icing data shows generally good agreement, with the quality of the predicted results seen to be directly related to the radial icing extent of each case. The code's capability to properly predict thrust coefficient, power coefficient, and propeller efficiency is shown to be strongly dependent on the choice of correlation selected, as well as upon proper specificatioon of radial icing extent.

Miller, Thomas L.↗
NASA NTRS1987

Ice dynamics at the mouth of ice stream B, Antarctica

Data collected in the region of the mouth of ice stream B, West Antarctica, during three field seasons are presented. The physical characteristics of the mouth of ice stream B are described, and the dynamics in the vicinity of the DNB network are discussed. The dynamics of ice stream B from DNB to the grounding line is briefly considered, and a force analysis of the grounding line region is made. The results demonstrate that the dynamic situation of the region at the mouth of ice stream B is distinctly different from either the greater portion of the ice stream upstream or the Ross ice shelf downstream.

Bindschadler, R. A.↗
NASA NTRS1989

The influence of ice accretion physics on the forecasting of aircraft icing conditions

The physics which control aircraft ice accretion are reviewed in the context of identifying and forecasting hazardous icing conditions. The severity of aircraft icing is found to be extremely sensitive to temperature, liquid water content and droplet size distribution particularly near the transition between rime and mixed icing. The difficulty in measurement and the variability of these factors with altitude, position and time coupled with variable aircraft sensitivity make forecasting and identifying icing conditions difficult. Automated Pilot Reports (PIREPS) are suggested as one mechanism for improving the data base necessary to forecast icing conditions.

Hansman, R. John, Jr.↗
NASA NTRS1990

The influence of ice accretion physics on the forecasting of aircraft icing conditions

The physics which control aircraft ice accretion are reviewed in the context of identifying and forecasting hazardous icing conditions. The severity of aircraft icing is found to be extremely sensitive to temperature, liquid water content and droplet size distribution particularly near the transition between rime and mixed icing. The difficulty in measurement and the variability of these factors with altitude, position and time coupled with variable aircraft sensitivity make forecasting and identifying icing conditions difficult. Automated Pilot Reports (PIREPS) are suggested as one mechanism for improving the data base necessary to forecast icing conditions.

Hansman, R. John, Jr.↗
NASA NTRS1991

Advanced ice protection systems test in the NASA Lewis icing research tunnel

Tests of eight different deicing systems based on variations of three different technologies were conducted in the NASA Lewis Research Center Icing Research Tunnel (IRT) in June and July 1990. The systems used pneumatic, eddy current repulsive, and electro-expulsive means to shed ice. The tests were conducted on a 1.83 m span, 0.53 m chord NACA 0012 airfoil operated at a 4 degree angle of attack. The models were tested at two temperatures: a glaze condition at minus 3.9 C and a rime condition at minus 17.2 C. The systems were tested through a range of icing spray times and cycling rates. Characterization of the deicers was accomplished by monitoring power consumption, ice shed particle size, and residual ice. High speed video motion analysis was performed to quantify ice particle size.

Bond, Thomas H.↗
NASA NTRS1992

Results of an Icing test on a NACA 0012 airfoil in the NASA Lewis Icing Research Tunnel

Tests were conducted in the Icing Research Tunnel (IRT) at the NASA Lewis Research Center to document the current capability of the IRT, focused mainly on the repeatability of the ice shape over a range of icing conditions. Measurements of drag increase due to the ice accretion were also made to document the repeatability of drag. Surface temperatures of the model were obtained to show the effects of latent-heat release by the freezing droplets and heat transfer through the ice layer. The repeatability of the ice shape was very good at low temperatures, but only fair at near freezing temperatures. In general, drag data shows good repeatability.

Shin, Jaiwon↗
NASA NTRS1991

Advanced ice protection systems test in the NASA Lewis Icing Research Tunnel

Tests of eight different deicing systems based on variations of three different technologies were conducted in the NASA Lewis Research Center Icing Research Tunnel (IRT) in June and July 1990. The systems used pneumatic, eddy current repulsive, and electroexpulsive means to shed ice. The tests were conducted on a 1.83 m span, 0.53 m chord NACA 0012 airfoil operated at a 4 degree angle of attack. The models were tested at two temperatures: a glaze condition at minus 3.9 C and a rime condition at minus 17.2 C. The systems were tested through a range of icing spray times and cycling rates. Characterization of the deicers was accomplished by monitoring power consumption, ice shed particle size, and residual ice. High speed video motion analysis was performed to quantify ice particle size.

Bond, Thomas H.↗
NASA NTRS1992

Results of an icing test on a NACA 0012 airfoil in the NASA Lewis Icing Research Tunnel

Tests were conducted in the Icing Research Tunnel (IRT) at the NASA Lewis Research Center to document the current capability of the IRT, focused mainly on the repeatability of the ice shape over a range of icing conditions. Measurements of drag increase due to the ice accretion were also made to document the repeatability of drag. Surface temperatures of the model were obtained to show the effects of latent-heat release by the freezing droplets and heat transfer through the ice layer. The repeatability of the ice shape was very good at low temperatures, but only fair at near freezing temperatures. In general, drag data shows good repeatability.

Shin, Jaiwon↗
NASA NTRS1994

An overview of a model rotor icing test in the NASA Lewis Icing Research Tunnel

During two entries in late 1989, a heavily instrumented sub-scale model of a helicopter main rotor was tested in the NASA LeRC Icing Research Tunnel (IRT). The results of this series of tunnel tests were published previously. After studying the results from the 1989 test and comparing them to predictions, it became clear that certain test conditions still needed investigation. Therefore, a re-entry of the Sikorsky Aircraft Powered Force Model (PFM) in the IRT was instituted in order to expand upon the current rotor craft sub-scale model experimental database. The major areas of interest included expansion of the test matrix to include a larger number of points in the FAA AC 29-2 icing envelope, inclusion of a number of high power rotor performance points, close examination of warm temperature operations, operation of the model in constant lift mode, and testing for conditions for icing test points in the full scale helicopter database. The expanded database will allow further and more detailed examination and comparison with analytical models. Participants in the test were NASA LeRC, the U.S. Army Vehicle Propulsion Directorate based at LeRC, and Sikorsky Aircraft. The model rotor was exposed to a range of icing conditions (temperature, liquid water content, median droplet diameter) and was operated over ranges of shaft angle, rotor tip speed, advance ratio, and rotor lift. The data taken included blade strain gage and balance data, as well as still photography, video, ice profile tracings, and ice molds. A discussion of the details of the test is given herein. Also, a brief examination of a subset of the data taken is also given.

Britton, Randall K.↗
NASA NTRS1994

Ice-atmosphere interactions in the central Arctic: Remotely-sensed and simulated ice concentration and motion

The response of the Beaufort Sea ice pack to the passage of strong low pressure systems is studied using SAR (synthetic aperture radar), AVHRR (advanced very high resolution radiometer), and SSM/I (special sensor microwave/imager) data combined with model simulations. The SAR, AVHRR, and modeled concentrations concur generally in showing a 1 to 5 percent decrease in ice fraction during the passage of the lows. SSM/I derived concentrations appear to underestimate overall concentration and overestimate the opening of the pack relative to the other data sets. Ice motion derived from SAR and AVHRR and model simulations using two ice rheologies agree reasonably well in direction and magnitude, although the cavitating fluid approximation tends to overestimate ice motion compared to a viscous plastic rheology. Ice motions from SAR, AVHRR, and buoy observations can be merged to yield uniform grids particularly well suited to synoptic scale studies and model validation.

Maslanik, J. A.↗
NASA NTRS1995

Ice flow dynamics of the Greenland ice sheet from SAR interferometry

Synthetic-aperture radar (SAR) interferograms produced from ESA's ERS-1 satellite, provide the first synoptic view of ice flow dynamics of the western sector of the Greenland Ice Sheet. Glacial motion is detected in the radar ranging direction at millimetric scales, across a complete sequence of snow accumulation and melting regimes, despite significant varations in their radar scattering properties. Ice flow evolves from a slow, regular motion at the higher elevations. At lower elevations, motion is strongly convoluted by meter-scale undulations in surface topography, which have a unique interferometric signature that enables a novel approach for retrieving flow direction. Inferred flow directions, combined with surface displacements in the radar ranging direction, yield ice velocity estimates that are within 6% of in-situ measurements gathered along a 40 km survey line. Application of repeat-pass SAR interferometry to the entire Greenland Ice Sheet should enable precise mapping of its ice flow dynamics at an unprecedented level of spatial detail.

Rignot, E.↗