Search NASA⌕ Search

SEARCH · Search NASA

Results for “Icing conditions”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

Gulf of Mexico Helicopter Offshore System Technologies Engineering Needs Assessment

The National Aeronautics and Space Administration (NASA), in partnership with the Federal Aviation Administration (FAA), is conducting a research and development program to modernize the National Airspace System (NAS). The mission of NASA's Advanced Air Transportation Technologies (AATT) project is to develop advanced Air Traffic Management (ATM) concepts and decision support tools for eventual deployment and implementation by the FAA and the private sector. One major objective of the NASA AATT project is to understand and promote the needs of all user classes. The Gulf of Mexico (GoMex) airspace has unique needs. A large number of helicopters operate in this area with only limited surveillance and sometimes-severe environmental conditions. Thunderstorms are the most frequent weather hazard during the spring, summer, and fall. In winter, reduced hours of daylight, low ceilings, strong winds, and icing conditions may restrict operations. Hurricanes impose the most severe weather hazard. The hurricane season, from June through October, normally requires at least one mass evacuation of all offshore platforms.

Edmund J. Koenke↗
NASA NTRS2019

An Investigation into the Grain Structure of Impact Ice

To design effective anti-icing and de-icing technology for aircraft, scientists and engineers must obtain a fundamental understanding of the microstructural characteristics of impact ice. This study investigates the effects of icing parameters, such as airspeed and liquid water content (LWC), on impact ice microstructure near the interface to a metal substrate. Ice samples were accreted in the NASA Glenn Icing Research Tunnel and tested in the NASA Revolutionary Icing Materials Evaluation Laboratory. A microtome was used to shave down the ice to a thickness of < 1 mm for examination under a microscope. Samples were imaged at multiple magnifications using bright field imaging. The average grain size was determined for each sample in accordance with ASTM standard methods, and relationships between airspeed, LWC, and grain size were identified. It was observed that the average grain area in a given cross-section was linearly related to the distance of the cross-section from the metal surface. Finally, the effects of annealing and sublimation on the microstructure were also explored. Results show significant variation in the grain structure, suggesting a means by which icing condition influences adhesion strength.

grain↗
NASA NTRS1991

Icing simulation: A survey of computer models and experimental facilities

A survey of the current methods for simulation of the response of an aircraft or aircraft subsystem to an icing encounter is presented. The topics discussed include a computer code modeling of aircraft icing and performance degradation, an evaluation of experimental facility simulation capabilities, and ice protection system evaluation tests in simulated icing conditions. Current research focussed on upgrading simulation fidelity of both experimental and computational methods is discussed. The need for increased understanding of the physical processes governing ice accretion, ice shedding, and iced airfoil aerodynamics is examined.

Potapczuk, M. G.↗
NASA NTRS2002

Icing Sensor Probe

Aircraft icing is a serious safety problem for the general aviation and some commuter transport airplanes. There has been tremendous growth in the commuter aviation industry in the last few years, Since these type of aircraft generally operate at lower altitudes they consequently spend a far greater proportion of their time operating in icing conditions. For the past thirty years airborne and ground based facilities have relied primarily on two types of cloud physics instrumentation to measure the characteristics of icing clouds: hot wire liquid water content probes and laser based particle sizing probes for the measurement of water droplet size. The instrumentation is severely limited by the technology that was developed during the 1970's and is quite large in size. The goal of this research is to develop one instrument with a wide bandwidth, better response time, higher resolution, user selectability, and small and lightweight. NASA Glenn Research Center, Droplet Measurement Technology, and Meteorology Society of Canada have developed a collaborative effort to develop such an instrument. This paper describes the development and test results of the prototype Icing Sensor Probe.

Emery, Edward↗
NASA NTRS1988

Ultrasonic techniques for aircraft ice accretion measurement

Ultrasonic pulse-echo measurements of ice growth on cylinders and airfoils exposed to both artificial (icing wind tunnel) and natural (flight) icing conditions are presented. An accuracy of + or - 0.5 mm is achieved with the present method. The ultrasonic signal characteristics associated with each of the two types of icing regimes identified, wet and dry ice growth, are discussed. Heat transfer coefficients are found to be higher in the wind tunnel environment than in flight. Results for ice growth on airfoils have also been obtained using an array of ultrasonic transducers. Icing profiles obtained during flight are compared with mechanical and stereo image measurements.

Hansman, R. John, Jr.↗
NASA NTRS1991

Icing simulation: A survey of computer models and experimental facilities

A survey of the current methods for simulation of the response of an aircraft or aircraft subsystem to an icing encounter is presented. The topics discussed include a computer code modeling of aircraft icing and performance degradation, an evaluation of experimental facility simulation capabilities, and ice protection system evaluation tests in simulated icing conditions. Current research focused on upgrading simulation fidelity of both experimental and computational methods is discussed. The need for the increased understanding of the physical processes governing ice accretion, ice shedding, and iced aerodynamics is examined.

Potapczuk, M. G.↗
NASA NTRS2015

NASA,FAA,ONERA Swept-Wing Icing and Aerodynamics: Summary of Research and Current Status

NASA, FAA, ONERA, and other partner organizations have embarked on a significant, collaborative research effort to address the technical challenges associated with icing on large scale, three-dimensional swept wings. These are extremely complex phenomena important to the design, certification and safe operation of small and large transport aircraft. There is increasing demand to balance trade-offs in aircraft efficiency, cost and noise that tend to compete directly with allowable performance degradations over an increasing range of icing conditions. Computational fluid dynamics codes have reached a level of maturity that they are being proposed by manufacturers for use in certification of aircraft for flight in icing. However, sufficient high-quality data to evaluate their performance on iced swept wings are not currently available in the public domain and significant knowledge gaps remain.

Aircraft Icing↗
NASA NTRS2015

Initial Low-Reynolds Number Iced Aerodynamic Performance for CRM Wing

NASA, FAA, ONERA, and other partner organizations have embarked on a significant, collaborative research effort to address the technical challenges associated with icing on large scale, three-dimensional swept wings. These are extremely complex phenomena important to the design, certification and safe operation of small and large transport aircraft. There is increasing demand to balance trade-offs in aircraft efficiency, cost and noise that tend to compete directly with allowable performance degradations over an increasing range of icing conditions. Computational fluid dynamics codes have reached a level of maturity that they are being proposed by manufacturers for use in certification of aircraft for flight in icing. However, sufficient high-quality data to evaluate their performance on iced swept wings are not currently available in the public domain and significant knowledge gaps remain.

Ice Formation↗
NASA NTRS1998

Process Developed for Forming Urethane Ice Models

A new process for forming ice shapes on an aircraft wing was developed at the NASA Lewis Research Center. The innovative concept was formed by Lewis' Icing Research Tunnel (IRT) team, and the hardware was manufactured by Lewis' Manufacturing Engineering Division. This work was completed to increase our understanding of the stability and control of aircraft during icing conditions. This project will also enhance our evaluation of true aerodynamic wind tunnel effects on aircraft. In addition, it can be used as a design tool for evaluating ice protection systems.

Vannuyen, Thomas↗
NASA NTRS1953

Effect of Ice and Frost Formations on Drag of NACA 65(sub 1) -212 Airfoil for Various Modes of Thermal Ice Protection

The effects of primary and. runback icing and frost formations on the drag of an 8-foot-chord NACA 651-212 airfoil section were investigated over a range of angles of attack from 20 to 80 and airspeeds up to 260 miles per hour for icing conditions with liquid-water contents ranging from 0.25 to 1.4 grams per cubic meter and datum air temperatures of -30 to 30 F. The results showed that glaze-ice formations, either primary or runback, on the upper surface near the leading edge of the airfoil caused large and rapid increases in drag, especially at datum air temperatures approaching 32 F and in the presence of high rates of water catch. Ice formations at lower temperatures (rime ice) did not appreciably increase the drag coefficient over the initial (standard roughness) drag coefficient. Cyclic de-icing of the primary Ice formations on the airfoil leading-edge section permitted the drag coefficient to return almost to the bare airfoil drag value. Runback icing on the lower surface did not present a serious drag problem except when heavy spanwise ridges of runback ice occurred aft of the heatable area. Frost formations caused rapid and large increases in drag with incipient stalling of the airfoil.

Gray, V. H.↗
NASA NTRS1994

Role of Wind Tunnels and Computer Codes in the Certification and Qualification of Rotorcraft for Flight in Forecast Icing

The cost and time to certify or qualify a rotorcraft for flight in forecast icing has been a major impediment to the development of ice protection systems for helicopter rotors. Development and flight test programs for those aircraft that have achieved certification or qualification for flight in icing conditions have taken many years, and the costs have been very high. NASA, Sikorsky, and others have been conducting research into alternative means for providing information for the development of ice protection systems, and subsequent flight testing to substantiate the air-worthiness of a rotor ice protection system. Model rotor icing tests conducted in 1989 and 1993 have provided a data base for correlation of codes, and for the validation of wind tunnel icing test techniques. This paper summarizes this research, showing test and correlation trends as functions of cloud liquid water content, rotor lift, flight speed, and ambient temperature. Molds were made of several of the ice formations on the rotor blades. These molds were used to form simulated ice on the rotor blades, and the blades were then tested in a wind tunnel to determine flight performance characteristics. These simulated-ice rotor performance tests are discussed in the paper. The levels of correlation achieved and the role of these tools (codes and wind tunnel tests) in flight test planning, testing, and extension of flight data to the limits of the icing envelope are discussed. The potential application of simulated ice, the NASA LEWICE computer, the Sikorsky Generalized Rotor Performance aerodynamic computer code, and NASA Icing Research Tunnel rotor tests in a rotorcraft certification or qualification program are also discussed. The correlation of these computer codes with tunnel test data is presented, and a procedure or process to use these methods as part of a certification or qualification program is introduced.

Flemming, Robert J.↗
NASA NTRS1998

Satellite Microwave Radar Observations of Antarctic Sea Ice

Historical data on Antarctic sea ice extent and concentration have traditionally been derived from visible and near-infrared images acquired by the polar-orbiting National Oceanic and Atmospheric Agency's (NOAA) meteorological satellites, using the Advanced Very High Resolution Radiometer (AVHRR), and more recently by the Defense Meteorological Satellite Program's Operational Linescan System (OLS). The limitation of these systems is that the majority of energy imparted to the Antarctic sea-ice system is transferred during b6y fast-moving low pressure systems. Since the Southern Ocean sea-ice cover is completely bounded at its lower latitude limit by open ocean, these "polar lows" transport large amounts of moisture (contained in warm air masses) over the outer ice cover. The result is that most, if not all, noteworthy periods of wind- and temperature-driven dynamic changes in the ice cover are accompanied by periods where the region is blanketed by cloud, and when the atmosphere is inherently more electromagnetically opaque. During storms, the probability with which the area is cloud covered is extremely high, thereby ruling out use of visible or near-infrared images as a practical method of monitoring the associated changes in ice conditions. Instead, Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) and DMSP Special Sensor Microwave/imager (SSM/I) have been the primary workhorses to build up a microwave record of Antarctic sea-ice characteristics. Similar problems, however, occur in passive microwave retrievals of sea-ice concentration, and the algorithms are called into question during these periods of change. The influence of water vapor in the atmosphere alone can modify the ice concentration retrievals by fractions exceeding 105, and that retrievals of ice concentration must compensate for the atmospheric water vapor and liquid water contents.

Drinkwater, Mark R.↗
NASA NTRS2010

Envelope Protection for In-Flight Ice Contamination

Fatal loss-of-control (LOC) accidents have been directly related to in-flight airframe icing. The prototype system presented in this paper directly addresses the need for real-time onboard envelope protection in icing conditions. The combinations of a-priori information and realtime aerodynamic estimations are shown to provide sufficient input for determining safe limits of the flight envelope during in-flight icing encounters. The Icing Contamination Envelope Protection (ICEPro) system has been designed and implemented to identify degradations in airplane performance and flying qualities resulting from ice contamination and provide safe flight-envelope cues to the pilot. Components of ICEPro are described and results from preliminary tests are presented.

Gingras, David R.↗
NASA NTRS2011

Development and Implementation of a Model-Driven Envelope Protection System for In-Flight Ice Contamination

Fatal loss-of-control (LOC) accidents have been directly related to in-flight airframe icing. The prototype system presented in this paper directly addresses the need for real-time onboard envelope protection in icing conditions. The combinations of a-priori information and realtime aerodynamic estimations are shown to provide sufficient input for determining safe limits of the flight envelope during in-flight icing encounters. The Icing Contamination Envelope Protection (ICEPro) system has been designed and implemented to identify degradations in airplane performance and flying qualities resulting from ice contamination and provide safe flight-envelope cues to the pilot. Components of ICEPro are described and results from preliminary tests are presented.

Gingras, David R.↗
NASA NTRSDate not supplied

Computational Heat Flux Analysis for HEATheR Electric Aircraft Wing Ice Protection Systems

Increased electrification of aircraft systems, a growing trend in the aircraft industry, affects subsystems that have historically been pneumatically driven by the engine. Optimized design of propulsion and power systems must account for the requirements of these subsystems. One such subsystem, the wing ice protection system, is the focus of this paper. A preliminary computational icing analysis has been conducted using the LEWICE and ANSYS FENSAP-ICE software to characterize the requirements of a thermal ice protection system for three More Electric Aircraft concepts. This paper summarizes the methodology, simulation execution, and icing conditions used for the analysis as well as discusses the results, observed trends, and impacts to system design. This initial analysis indicates that the computed heat requirements for the wing ice protection systems are not within the capabilities of known traditional systems. A discussion of potential methods for reducing the heat flow requirement by the ice protection system is included. Potential refinements to the analysis to improve the accuracy are also discussed.

Nic Heersema↗
NASA NTRS1985

A new characterization of the icing environment below 10,000 feet AGL from 7,000 miles of measurements in supercooled clouds

A growing requirement over the past decade for a new assessment of aircraft icing conditions in wintertime clouds at altitudes up to about 10,000 feet is discussed. The requirement was documented in past workshops and comes primarily from the helicopter community which wants ice-protected rotorcraft to meet increasing demands for all-weather operations. Currently, only a few of the larger helicopters are equipped with certification of ice-protection devices. This is because the current FAA criteria for design and certification of ice-protection equipment results in power and payload penalties that smaller rotorcraft cannot tolerate. The FAA criteria were actually designed for large, transport-category aircraft capable of flying to 20,000 feet or more. For this reason, there have been concerns that the current criteria may be too severe for low-performance aircraft, such as helicopters, which generally operate at altitudes below 10,000 feet.

Jeck, R. K.↗
NASA NTRS1981

Oceanographic influences on the sea ice cover in the Sea of Okhotsk

Sea ice conditions in the Sea of Okhotsk, as determined by satellite images from the electrically scanning microwave radiometer on board Nimbus 5, were analyzed in conjunction with the known oceanography. In particular, the sea ice coverage was compared with the bottom bathymetry and the surface currents, water temperatures, and salinity. It is found that ice forms first in cold, shallow, low salinity waters. Once formed, the ice seems to drift in a direction approximating the Okhotsk-Kuril current system. Two basic patterns of ice edge positioning which persist for significant periods were identified as a rectangular structure and a wedge structure. Each of these is strongly correlated with the bathymetry of the region and with the known current system, suggesting that convective depth and ocean currents play an important role in determining ice patterns.

Gratz, A. J.↗