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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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NASA NTRS2016

Analysis and Prediction of Ice Shedding for a Full-Scale Heated Tail Rotor

When helicopters are to fly in icing conditions, it is necessary to consider the possibility of ice shed from the rotor blades. In 2013, a series of tests were conducted on a heated tail rotor at NASA Glenn's Icing Research Tunnel (IRT). The tests produced several shed events that were captured on camera. Three of these shed events were captured at a sufficiently high frame rate to obtain multiple images of the shed ice in flight that had a sufficiently long section of shed ice for analysis. Analysis of these shed events is presented and compared to an analytical Shedding Trajectory Model (STM). The STM is developed and assumes that the ice breaks off instantly as it reaches the end of the blade, while frictional and viscous forces are used as parameters to fit the STM. The trajectory of each shed is compared to that predicted by the STM, where the STM provides information of the shed group of ice as a whole. The limitations of the model's underlying assumptions are discussed in comparison to experimental shed events.

rotorcraft↗
NASA NTRS2016

Analysis and Prediction of Ice Shedding for a Full-Scale Heated Tail Rotor

When helicopters are to fly in icing conditions, it is necessary to consider the possibility of ice shed from the rotor blades. In 2013, a series of tests were conducted on a heated tail rotor at NASA Glenn's Icing Research Tunnel (IRT). The tests produced several shed events that were captured on camera. Three of these shed events were captured at a sufficiently high frame rate to obtain multiple images of the shed ice in flight that had a sufficiently long section of shed ice for analysis. Analysis of these shed events is presented and compared to an analytical Shedding Trajectory Model (STM). The STM is developed and assumes that the ice breaks off instantly as it reaches the end of the blade, while frictional and viscous forces are used as parameters to fit the STM. The trajectory of each shed is compared to that predicted by the STM, where the STM provides information of the shed group of ice as a whole. The limitations of the model's underlying assumptions are discussed in comparison to experimental shed events.

icing↗
NASA NTRS1993

An overview of shed ice impact in the NASA Lewis Icing Research Tunnel

One of the areas of active research in commercial and military rotorcraft is directed toward developing the capability of sustained flight in icing conditions. The emphasis to date has been on the accretion and subsequent shedding of ice in an icing environment, where the shedding may be natural or induced. Historically, shed-ice particles have been a problem for aircraft, particularly rotorcraft. Because of the high particle velocities involved, damage to a fuselage or other airframe component from a shed-ice impact can be significant. Design rules for damage tolerance from shed-ice impact are not well developed because of a lack of experimental data. Thus, NASA Lewis (LeRC) has begun an effort to develop a database of impact force and energy resulting from shed ice. This effort consisted of a test of NASA LeRC's Model Rotor Test Rig (MRTR) in the Icing Research Tunnel (IRT). Both natural shedding and forced shedding were investigated. Forced shedding was achieved by fitting the rotor blades with Small Tube Pneumatic (STP) deicer boots manufactured by BF Goodrich. A detailed description of the test is given as well as the design of a new impact sensor which measures the force-time history of an impacting ice fragment. A brief discussion of the procedure to infer impact energy from a force-time trace are required for the impact-energy calculations. Recommendations and future plans for this research area are also provided.

Bond, Thomas H.↗
NASA NTRS1993

An overview of shed ice impact studies in the NASA Lewis Icing Research Tunnel

One of the areas of active research in commercial and military rotorcraft is directed toward developing the capability of sustained flight in icing conditions. The emphasis to date has been on the accretion and subsequent shedding of ice in an icing environment, where the shedding may be natural or induced. Historically, shed-ice particles have been a problem for aircraft, particularly rotorcraft. Because of the high particle velocities involved, damage to a fuselage or other airframe component from a shed-ice impact can be significant. Design rules for damage tolerance from shed-ice impact are not well developed because of a lack of experimental data. Thus, NASA Lewis (LeRC) has begun an effort to develop a database of impact force and energy resulting from shed ice. This effort consisted of a test of NASA LeRC's Model Rotor Test Rig (MRTR) in the Icing Research Tunnel (IRT). Both natural shedding and forced shedding were investigated. Forced shedding was achieved by fitting the rotor blades with Small Tube Pneumatic (STP) deicer boots manufactured by BF Goodrich. A detailed description of the test is given as well as the design of a new impact sensor which measures the force-time history of an impacting ice fragment. A brief discussion of the procedure to infer impact energy from a force-time trace are required for the impact-energy calculations. Recommendations and future plans for this research area are also provided.

Britton, Randall K.↗
NASA NTRS1996

Further evaluation of traditional icing scaling methods

This report provides additional evaluations of two methods to scale icing test conditions; it also describes a hybrid technique for use when scaled conditions are outside the operating envelope of the test facility. The first evaluation is of the Olsen method which can be used to scale the liquid-water content in icing tests, and the second is the AEDC (Ruff) method which is used when the test model is less than full size. Equations for both scaling methods are presented in the paper, and the methods were evaluated by performing icing tests in the NASA Lewis Icing Research Tunnel (IRT). The Olsen method was tested using 53 cm diameter NACA 0012 airfoils. Tests covered liquid-water-contents which varied by as much as a factor of 1.8. The Olsen method was generally effective in giving scale ice shapes which matched the reference shapes for these tests. The AEDC method was tested with NACA 0012 airfoils with chords from 18 cm to 53 cm. The 53 cm chord airfoils were used in reference tests, and 1/2 and 1/3 scale tests were made at conditions determined by applying the AEDC scaling method. The scale and reference airspeeds were matched in these tests. The AEDC method was found to provide fairly effective scaling for 1/2 size tests, but for 1/3 size models, scaling was generally less effective. In addition to these two scaling methods, a hybrid approach was also tested in which the Olsen method was used to adjust the LWC after size was scaled using the constant Weber number method. This approach was found to be an effective way to test when scaled conditions would otherwise be outside the capability of the test facility.

Anderson, David N.↗
NASA NTRSDate not supplied

NASA Icing Update – May 2024

This presentation provides a status update on select NASA icing research activities for the SAE AC-9C Icing Technical Committee Meeting on May 6, 2024. The updates include the following topics: (1) Propulsion Systems Lab (PSL), (2) Adaptive Icing Tunnel (AIT), (3) Ice Adhesion / Deformed Skin Adhesion Test, (4) GlennICE, (5) Efficient Quiet Integrated Propulsor, (6) Icing Research Tunnel (IRT) CFD Characterization, and (7) Supercooled Large Droplet (SLD) Research.

Icing↗
NASA NTRS1996

Validation of NASA Thermal Ice Protection Computer Codes: Program Overview - Part 1

The Icing Technology Branch at NASA Lewis has been involved in an effort to validate two thermal ice protection codes developed at the NASA Lewis Research Center. LEWICE/Thermal (electrothermal deicing & anti-icing), and ANTICE (hot-gas & electrothermal anti-icing). The Thermal Code Validation effort was designated as a priority during a 1994 'peer review' of the NASA Lewis Icing program, and was implemented as a cooperative effort with industry. During April 1996, the first of a series of experimental validation tests was conducted in the NASA Lewis Icing Research Tunnel(IRT). The purpose of the April 96 test was to validate the electrothermal predictive capabilities of both LEWICE/Thermal, and ANTICE. A heavily instrumented test article was designed and fabricated for this test, with the capability of simulating electrothermal de-icing and anti-icing modes of operation. Thermal measurements were then obtained over a range of test conditions, for comparison with analytical predictions. This paper will present an overview of the test, including a detailed description of: (1) the validation process; (2) test article design; (3) test matrix development; and (4) test procedures. Selected experimental results will be presented for de-icing and anti-icing modes of operation. Finally, the status of the validation effort at this point will be summarized. Detailed comparisons between analytical predictions and experimental results are contained in the following two papers: 'Validation of NASA Thermal Ice Protection Computer Codes: Part 2- The Validation of LEWICE/Thermal' and 'Validation of NASA Thermal Ice Protection Computer Codes: Part 3-The Validation of ANTICE'

Miller, Dean↗
NASA NTRS1996

Laser Sheet Flow Visualization Developed for Lewis' Icing Research Tunnel

A new flow-visualization technique has been developed for use in the NASA Lewis Research Center's Icing Research Tunnel (IRT). This technique uses a sheet of light shining across the wind tunnel to illuminate a mist of water droplets in the air and display any organized flow patterns. Since the IRT already has the special water spray system required for aircraft icing experiments, no special visualization seeding material is required. The system has been used to visualize the changes in tip and leading edge vortices caused by ice accretion. Because the IRT's icing spray is used as part of the visualization technique, changes in the flow patterns about a wing can be observed and measured during the ice accretion process.

Source record↗
NASA NTRS2018

An Investigation of Glaciated Cloud Capabilities in the NASA Glenn Icing Research Tunnel

In 2015 the FAA added Appendix D to Part 33 engine certification requirements that included Mixed Phase and Ice Crystal Icing to aircraft engine certification. Replicating the ice crystal environment that is seen in nature has proven to be a challenge, which multiple engine ground testing facilities and icing wind tunnels have achieved to varying degrees. The Icing Research Tunnel (IRT) at NASA Glenn has always been focused on super-cooled liquid water to produce FAA Part 23 and Part 25 regulations, targeting Appendix C and lately also Appendix O. However, due to a growing interest in the field of ice crystals and the high cost of operating engine icing facilities, the IRT staff have recently completed testing using the Multi-Element Sensor (also known as the multi-wire) to measure glaciated cloud conditions. Results indicate that turning off the heat to the nozzle air and water supply can create a stable, fully glaciated cloud in the test section for a small range of conditions: drop-size distribution values below 20 microns (median volumetric diameter), air temperatures as warm as -7 deg C, and airspeeds between 100 and 250 knots. These tests also revealed how varying the total temperature, airspeed, nozzle air pressure, and nozzle water pressure affect the glaciation of the IRT cloud.

ice water content↗
NASA NTRSDate not supplied

Computational Icing Analysis on NASA’s SIDRM Geometry to Investigate Collection Efficiency

Computational icing analysis results were compared to experimental icing tunnel data including aerothermal (e.g. dry air) and supercooled water droplet rime-ice conditions from tests conducted in early 2022 at the NASA Icing Research Tunnel (IRT). The Simulated Intercompressor Duct Research Model (SIDRM) test article was used in this study, and its geometry represents the inter-compressor duct region of a turbofan engine. The test article’s purpose is to study the physics of supercooled water icing and ice crystal icing. This study compared three different icing codes: FENSAP-ICE (Eulerian approach), LEWICE3D (Lagrangian approach), and GlennICE (Lagrangian approach). All three icing codes were conducted on SIDRM’s complex body flow-field and compared to different experimental supercooled water rime runs. The test article instrumentation (pressure taps, thermocouples, etc.) and 3D laser scans of final ice shapes were used to compare against the different icing code simulations. The overall objectives are to understand how the icing codes handle capturing collection efficiency on the complex test article’s unheated surfaces. In the aerothermal cases, pressure tap readings matched the CFD results, but dry air CFD underpredicted thermocouple readings. Collection efficiency results from all three icing codes matched well together on the main body leading edge, main body slope, and the strut leading edges. All three icing codes underpredicted the final ice shape using a single-shot constant ice density approach, with more difficulty coming from the strut leading edge ice shape due to the swept wing like flow field. NASA’s overall goal for this effort is to develop computational icing tools to assist in the design and certification of engines for flight in icing conditions.

Supercooled icing, SIDRM, aerodynamics, computatio↗
NASA NTRS2008

IceVal DatAssistant: An Interactive, Automated Icing Data Management System

As with any scientific endeavor, the foundation of icing research at the NASA Glenn Research Center (GRC) is the data acquired during experimental testing. In the case of the GRC Icing Branch, an important part of this data consists of ice tracings taken following tests carried out in the GRC Icing Research Tunnel (IRT), as well as the associated operational and environmental conditions during those tests. Over the years, the large number of experimental runs completed has served to emphasize the need for a consistent strategy to manage the resulting data. To address this situation, the Icing Branch has recently elected to implement the IceVal DatAssistant automated data management system. With the release of this system, all publicly available IRT-generated experimental ice shapes with complete and verifiable conditions have now been compiled into one electronically-searchable database; and simulation software results for the equivalent conditions, generated using the latest version of the LEWICE ice shape prediction code, are likewise included and linked to the corresponding experimental runs. In addition to this comprehensive database, the IceVal system also includes a graphically-oriented database access utility, which provides reliable and easy access to all data contained in the database. In this paper, the issues surrounding historical icing data management practices are discussed, as well as the anticipated benefits to be achieved as a result of migrating to the new system. A detailed description of the software system features and database content is also provided; and, finally, known issues and plans for future work are presented.

Levinson, Laurie H.↗
NASA NTRS2008

IceVal DatAssistant: An Interactive, Automated Icing Data Management System

As with any scientific endeavor, the foundation of icing research at the NASA Glenn Research Center (GRC) is the data acquired during experimental testing. In the case of the GRC Icing Branch, an important part of this data consists of ice tracings taken following tests carried out in the GRC Icing Research Tunnel (IRT), as well as the associated operational and environmental conditions documented during these tests. Over the years, the large number of experimental runs completed has served to emphasize the need for a consistent strategy for managing this data. To address the situation, the Icing Branch has recently elected to implement the IceVal DatAssistant automated data management system. With the release of this system, all publicly available IRT-generated experimental ice shapes with complete and verifiable conditions have now been compiled into one electronically-searchable database. Simulation software results for the equivalent conditions, generated using the latest version of the LEWICE ice shape prediction code, are likewise included and are linked to the corresponding experimental runs. In addition to this comprehensive database, the IceVal system also includes a graphically-oriented database access utility, which provides reliable and easy access to all data contained in the database. In this paper, the issues surrounding historical icing data management practices are discussed, as well as the anticipated benefits to be achieved as a result of migrating to the new system. A detailed description of the software system features and database content is also provided; and, finally, known issues and plans for future work are presented.

Levinson, Laurie H.↗
NASA NTRSDate not supplied

Isokinetic Probe Total Water Content Measurements in the NASA Icing Research Tunnel with Supercooled Large Drop Conditions

An Isokinetic Total Water Content Evaporator (IKP2) was used to measure liquid water content (LWC) in the NASA Icing Research Tunnel (IRT) with spray conditions that ranged in LWC and cloud drop size spectra as characterized by the median volumetric diameter (MVD). The IKP2 measurements were made as part of an international collaborative effort to investigate the measurement of supercooled large drop (SLD) conditions in several icing wind tunnels. This report focuses on the IKP2 and background water vapor (BWV) measurements made within the NASA IRT during the October 2017 test entry. The IKP2 TWC results are compared to the IRT LWC calibration values for a range of LWC and MVD values. The IRT LWC calibration is based on measurements from a multi-element hot-wire probe. In general, the IKP2 TWC values were approximately 9% greater than the IRT LWC calibration values over a range of LWC from 0.4 g/m3 to 3.0 g/m3. The ratio of IKP2 TWC to IRT LWC calibration ranged from approximately 0.9 to 1.27 over a range of MVD from 15µm to 460 µm. Comparisons of this data set to IKP2 data from a 2014 IRT test entry show similar results in the regions where overlaps occurred. The results support the theory and observations of water mass loss from hot-wire TWC sensors when subjected to large MVD conditions.

Icing cloud instruments↗
NASA NTRSDate not supplied

Isokinetic Probe Total Water Content Measurements in the NASA Icing Research Tunnel with Supercooled Large Drop Conditions

An Isokinetic Total Water Content Evaporator (IKP2) was used to measure liquid water content (LWC) in the NASA Icing Research Tunnel (IRT) with spray conditions that ranged in LWC and cloud drop size spectra as characterized by the median volumetric diameter (MVD). The IKP2 measurements were made as part of an international collaborative effort to investigate the measurement of supercooled large drop (SLD) conditions in several icing wind tunnels. This report focuses on the IKP2 and background water vapor (BWV) measurements made within the NASA IRT during the October 2017 test entry. The IKP2 TWC results are compared to the IRT LWC calibration values for a range of LWC and MVD values. The IRT LWC calibration is based on measurements from a multi-element hot-wire probe. In general, the IKP2 TWC values were approximately 9% greater than the IRT LWC calibration values over a range of LWC from 0.4 g/m3 to 3.0 g/m3. The ratio of IKP2 TWC to IRT LWC calibration ranged from approximately 0.9 to 1.27 over a range of MVD from 15m to 460 m. Comparisons of this data set to IKP2 data from a 2014 IRT test entry show similar results in the regions where overlaps occurred. The results support the theory and observations of water mass loss from hot-wire TWC sensors when subjected to large MVD conditions.

o Aircraft Icing↗
NASA NTRS2021

Isokinetic Probe Total Water Content Measurements in the NASA Icing Research Tunnel with Supercooled Large Drop Conditions

An Isokinetic Total Water Content Evaporator (IKP2) was used to measure liquid water content (LWC) in the NASA Icing Research Tunnel (IRT) with spray conditions that ranged in LWC and cloud drop size spectra as characterized by the median volumetric diameter (MVD). The IKP2 measurements were made as part of an international collaborative effort to investigate the measurement of supercooled large drop (SLD) conditions in several icing wind tunnels. This report focuses on the IKP2 and background water vapor (BWV) measurements made within the NASA IRT during the October 2017 test entry. The IKP2 TWC results are compared to the IRT LWC calibration values for a range of LWC and MVD values. The IRT LWC calibration is based on measurements from a multi-element hot-wire probe. In general, the IKP2 TWC values were approximately 9% greater than the IRT LWC calibration values over a range of LWC from 0.4 g/m3 to 3.0 g/m3. The ratio of IKP2 TWC to IRT LWC calibration ranged from approximately 0.9 to 1.27 over a range of MVD from 15um to 460 um. Comparisons of this data set to IKP2 data from a 2014 IRT test entry show similar results in the regions where overlaps occurred. The results support the theory and observations of water mass loss from hot-wire TWC sensors when subjected to large MVD conditions.

o Aircraft Icing↗
NASA NTRSDate not supplied

Influence of Airfoil Angle of Attack on Ice Accretion Roughness

The influence of airfoil angle attack on roughness evolution and spatial variation was investigated in the Icing Research Tunnel (IRT) at the NASA Glenn Research Center. Two airfoil models were used for the study: a 53.34-cm (21-in.) NACA 0012 model and a 152.4-cm (60-in.) HAARP-II model. For the NACA 0012, the angle of attack was varied from 0° to 3°, and the ice accretion roughness was characterized while keeping the other icing parameters such as freestream velocity, freestream stagnation temperature, accumulation parameter, and median volumetric diameter (MVD) constant. For the HAARP-II, the angle of attack was varied from -1.9°, which is the non-lifting angle of attack for the airfoil, to 3°. A series of accumulation time progression cases for the HAARP-II at 2.3° angle of attack was also performed in Appendix C and Appendix O conditions and compared to the measurements presented by McClain et al. (2018) for the non-lifting angle of attack condition. The results demonstrate the strong influence of the changing local static pressure along the surface influencing the roughness characteristics. A correlation approach for the maximum equivalent sand-grain roughness along the surface of an airfoil is presented and considers the scaled accumulation time, the stagnation point freezing fraction, and the surface pressure relative to the static and stagnation pressures of the flow. Finally, an attempt to relate the maximum roughness quantities to local pressure coefficients and local icing quantities is presented and discussed.

Icing↗
NASA NTRS2005

Validation Results for LEWICE 3.0

A research project is underway at NASA Glenn to produce computer software that can accurately predict ice growth under any meteorological conditions for any aircraft surface. This report will present results from version 3.0 of this software, which is called LEWICE. This version differs from previous releases in that it incorporates additional thermal analysis capabilities, a pneumatic boot model, interfaces to computational fluid dynamics (CFD) flow solvers and has an empirical model for the supercooled large droplet (SLD) regime. An extensive comparison of the results in a quantifiable manner against the database of ice shapes and collection efficiency that have been generated in the NASA Glenn Icing Research Tunnel (IRT) has also been performed. The complete set of data used for this comparison will eventually be available in a contractor report. This paper will show the differences in collection efficiency between LEWICE 3.0 and experimental data. Due to the large amount of validation data available, a separate report is planned for ice shape comparison. This report will first describe the LEWICE 3.0 model for water collection. A semi-empirical approach was used to incorporate first order physical effects of large droplet phenomena into icing software. Comparisons are then made to every single element two-dimensional case in the water collection database. Each condition was run using the following five assumptions: 1) potential flow, no splashing; 2) potential flow, no splashing with 21 bin drop size distributions and a lift correction (angle of attack adjustment); 3) potential flow, with splashing; 4) Navier-Stokes, no splashing; and 5) Navier-Stokes, with splashing. Quantitative comparisons are shown for impingement limit, maximum water catch, and total collection efficiency. The results show that the predicted results are within the accuracy limits of the experimental data for the majority of cases.

Wright, William B.↗
NASA NTRSDate not supplied

A Model for Ice Accretion Roughness Evolution and Spatial Variations

Over the past decade, multiple investigations of ice accretion roughness and spatial variations have been performed in the Icing Research Tunnel (IRT) at the NASA Glenn Research Center. The early investigations used models of NACA 0012 airfoils with different chord sizes and focused on temporal scaling and primary cloud scaling parameters such as stagnation point collection efficiency. Subsequent investigations included the effects of model sweep, airfoil shape, airfoil lifting condition, and freestream static temperature. To develop a predictive model for roughness evolution in generalized icing situations, the maximum roughness values for the airfoils and conditions used in the angle of attack and freestream temperature investigations were scaled to eliminate the temporal variations. LEWICE simulations were employed to identify the local collection efficiency at the locations of maximum roughness, and a two-dimensional panel-method code was used to identify the local static pressure at the location of the maximum roughness. Because of the stochastic nature of ice accretion roughness, a physics-directed approach was employed to develop a multi-dimensional correlation based on the local pressure coefficient, the local total temperature, the cloud properties, and the cloud exposure time. The resulting correlation predictions are compared to ice shapes measured in the IRT for both a 21-in. NACA 0012 airfoil model and a 60-in. HAARP-II model. The resulting predictions indicate that the local freezing fraction must be included in the roughness predictive model. Implications regarding icing heat transfer predictions using the resulting roughness model are also discussed.

Icing↗