High accuracy variable area meter calibrations with multiple gases.
High accuracy variable area meter calibrations with multiple gases
CALIBRATION↗
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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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Preliminary study of the minimum temperatures for valid testing in a cryogenic wind tunnel
The minimum operating temperature which avoids real-gas effects, such as condensation, was determined for M sub infinity = 0.85 flow over a 0.137-meter NACA 0012-64 airfoil mounted in the Langley 1/3-meter transonic cryogenic tunnel. For temperatures within 5 K of reservoir saturation and total pressures from 1.2 to 4.5 atmospheres, the pressure distributions over the airfoil are not altered by real-gas effects. This ability to test at total temperatures below those which avoid saturation over the airfoil allows an increase in Reynolds number capability of at least 17 percent for a constant tunnel total pressure. Similarly, 17 percent less total pressure is required to obtain a given Reynolds number.
Hall, R. M.↗
An analysis of data related to the minimum temperatures for valid testing in cryogenic wind tunnels using nitrogen as the test gas
The minimum operating temperature which avoids adverse low temperature effects, such as condensation, has been determined at a free stream Mach number of 0.85 for flow over a 0.137 meter airfoil mounted at zero incidence in the Langley 1/3 meter transonic cryogenic tunnel. The onset of low temperature effects is established by comparing the pressure coefficient measured at a given orifice for a particular temperature with those measured at temperatures sufficiently above where low temperature effects might be expected to occur. The pressure distributions over the airfoil are presented in tabular form. In addition, the comparisons of the pressure coefficient as a function of total temperature are presented graphically for chord locations of 0, 25, 50, and 75 percent. Over the 1.2 to 4.5 atmosphere total pressure range investigated, low temperature effects are not detected until total temperatures are 2 K, or more, below free stream saturation temperatures.
Hall, R. M.↗
Radiative properties of a nickel based superalloy: Inconel 617 - After simulated earth reentry
Experimental results are presented to show the effect of environmental simulation exposures of convective heating and of radiant heating on the spectral (1.0 to 14 micrometers) and total emittance of oxidized Inconel 617. Convective heating exposures were conducted in an arc heated supersonic wind tunnel using a wedge-shaped specimen configuration. Radiant tests were conducted in dry air at a flow velocity of several meters per second. Convective heating specimens were subjected to 8, 20 and 38 heating cycles of 15-minutes duration and radiant heating specimens were tested for 10, 20, 50 and 100 one-half hour heating cycles. Changes in radiative properties are discussed in terms of changes in composition and morphology resulting from the exposure tests. Total normal emittance did not significantly change from the statically oxidized condition after either type of exposure, and it remained above 0.80 at 1260K for all cases. Although spectral changes were observed on post exposure specimens at wavelengths less than 2.0 micrometers and greater than 15 micrometers, these changes have no influence on total emittance at 1260K.
Cunnington, G. R.↗
Radiative properties of advanced spacecraft heat shield materials
Experimental results are presented to show the effects of simulated reentry exposure by convective heating and by radiant heating on spectral and total emittance of statically oxidized Inconel 617 and Haynes HS188 superalloys to 1260 K and a silicide coatea (R512E) columbium 752 alloy to 1590 K. Convective heating exposures were conducted in a supersonic arc plasma wind tunnel using a wedge-shaped specimen configuration. Radiant tests were conducted at a pressure of .003 atmospheres of dry air at a flow velocity of several meters per second. Convective heating specimens were subjected to 8, 20, and 38 15-min heating cycles, and radiant heating specimens were tested for 10, 20, 50, and 100 30-min heating cycles. Changes in radiative properties are explained in terms of changes in composition resulting from simulated reentry tests. The methods used to evaluate morphological, compositional and crystallographic changes include: Auger electron spectroscopy; scanning electron microscopy; X-ray diffraction analysis; and electron microprobe analysis.
Cunnington, G. R.↗
Reconstruction of the dynamics of the 1800-1801 Hualalai eruption: Implications for planetary lava flows
The 1800-1801 eruption of alkalic basalt from the Hualalai volcano, Hawaii provides a unique opportunity for investigating the dynamics of lava flow emplacement with eruption rates and compositions comparable to those that have been suggested for planetary eruptions. Field observations suggest new considerations must be used to reconstruct the emplacement of these lava flows. These observations are: (1) the flow traversed the 15 km from the vent to the sea so rapidly that no significant crust formed and an observation of the eruption reported that the flow reach the sea from the vent in approximately 1 hour; (2) the drainage of beds of xenolith nodules indicates a highly fluid, low viscosity lava; (3) overspills and other morphologic evidence for a very low viscosity host fluid; (4) no significant longitudinal increase in flow thickness that might be associated with an increase in the rheological properties of the lava; and (5) the relatively large size of channels associated with the flow, up to 80 meters across and several km long. Models for many geologic mass movements and fast moving fluids with various loadings and suspensions are discussed.
Baloga, Stephen↗
CATS-based Air Traffic Controller Agents
This report describes intelligent agents that function as air traffic controllers. Each agent controls traffic in a single sector in real time; agents controlling traffic in adjoining sectors can coordinate to manage an arrival flow across a given meter fix. The purpose of this research is threefold. First, it seeks to study the design of agents for controlling complex systems. In particular, it investigates agent planning and reactive control functionality in a dynamic environment in which a variety perceptual and decision making skills play a central role. It examines how heuristic rules can be applied to model planning and decision making skills, rather than attempting to apply optimization methods. Thus, the research attempts to develop intelligent agents that provide an approximation of human air traffic controller behavior that, while not based on an explicit cognitive model, does produce task performance consistent with the way human air traffic controllers operate. Second, this research sought to extend previous research on using the Crew Activity Tracking System (CATS) as the basis for intelligent agents. The agents use a high-level model of air traffic controller activities to structure the control task. To execute an activity in the CATS model, according to the current task context, the agents reference a 'skill library' and 'control rules' that in turn execute the pattern recognition, planning, and decision-making required to perform the activity. Applying the skills enables the agents to modify their representation of the current control situation (i.e., the 'flick' or 'picture'). The updated representation supports the next activity in a cycle of action that, taken as a whole, simulates air traffic controller behavior. A third, practical motivation for this research is to use intelligent agents to support evaluation of new air traffic control (ATC) methods to support new Air Traffic Management (ATM) concepts. Current approaches that use large, human-in-the-loop simulations are unquestionably valuable for this purpose, but pose considerable logistical, fiscal, and experimental control problems. First, data analysis is extremely complicated, owing simply to the large number of participants and data sources in such simulations. In addition, experienced human air traffic controllers working adjacent sectors tend to flexibly adapt to the evolving control problem - potentially shifting to other strategies than those under investigation. In addition, their performance is tightly coupled to the control interface, which in the development phase may support some concepts and supporting strategies better than others. A simple shift in strategy by one controller can change the character of a particular traffic scenario dramatically, which makes experimental comparison of ATC performance under different traffic scenarios difficult. Training a given team of controllers on operations under a new ATM concept for a sufficient period of time could avert such difficulties, but instituting an adequate training program is expensive and logistically difficult.
Callantine, Todd J.↗
Software for Simulating Air Traffic
Future Air Traffic Management Concepts Evaluation Tool (FACET) is a system of software for performing computational simulations for evaluating advanced concepts of advanced air-traffic management. FACET includes a program that generates a graphical user interface plus programs and databases that implement computational models of weather, airspace, airports, navigation aids, aircraft performance, and aircraft trajectories. Examples of concepts studied by use of FACET include aircraft self-separation for free flight; prediction of air-traffic-controller workload; decision support for direct routing; integration of spacecraft-launch operations into the U.S. national airspace system; and traffic- flow-management using rerouting, metering, and ground delays. Aircraft can be modeled as flying along either flight-plan routes or great-circle routes as they climb, cruise, and descend according to their individual performance models. The FACET software is modular and is written in the Java and C programming languages. The architecture of FACET strikes a balance between flexibility and fidelity; as a consequence, FACET can be used to model systemwide airspace operations over the contiguous U.S., involving as many as 10,000 aircraft, all on a single desktop or laptop computer running any of a variety of operating systems. Two notable applications of FACET include: (1) reroute conformance monitoring algorithms that have been implemented in one of the Federal Aviation Administration s nationally deployed, real-time, operational systems; and (2) the licensing and integration of FACET with the commercially available Flight Explorer, which is an Internet- based, real-time flight-tracking system.
Sridhar, Banavar↗
How do Air Traffic Controllers Use Automation and Tools Differently During High Demand Situations?
In a human-in-the-loop simulation, two air traffic controllers managed identical airspace while burdened with higher than average workload, and while using advanced tools and automation designed to assist with scheduling aircraft on multiple arrival flows to a single meter fix. This paper compares the strategies employed by each controller, and investigates how the controllers' strategies change while managing their airspace under more normal workload conditions and a higher workload condition. Each controller engaged in different methods of maneuvering aircraft to arrive on schedule, and adapted their strategies to cope with the increased workload in different ways. Based on the conclusions three suggestions are made: that quickly providing air traffic controllers with recommendations and information to assist with maneuvering and scheduling aircraft when burdened with increased workload will improve the air traffic controller's effectiveness, that the tools should adapt to the strategy currently employed by a controller, and that training should emphasize which traffic management strategies are most effective given specific airspace demands.
ATC↗
ATD-3 Dynamic Routes for Arrivals in Weather (DRAW) Operational Concept, V2.0
NASA's Airspace Technology Demonstration-3 (ATD-3) is the applied traffic flow management activity, and third in the series of ATD projects. ATD-3 provides a suite of en route automation tools, both ground and flight-deck based, that focus on improving the efficiency of en route operation from initial cruise to arrival into the Terminal Radar Approach Control (TRACON). Dynamic Routes for Arrivals in Weather (DRAW) is a technology in the ATD-3 suite that is designed to provide Traffic Managers with a capability to efficiently manage arrival traffic flow and help sustain metering operations when weather is impacting arrivals into major airports. DRAW mitigates convective weather impact on arrival metering operations by providing tools to Traffic Managers that enable efficient reroutes free of convective weather conflicts, and integrated with the arrival metering schedule(s).
terminal airspace↗
AC adapter for fuel-flow sensor
Readily-available fuel meters can be used to aid in fuel oil conservation in homes and commercial buildings. Device also includes failure monitor that activates warning light and horn if meter fails.
Millman, L. L.↗
Flow Visualization of Density in a Cryogenic Wind Tunnel Using Planar Rayleigh and Raman Scattering
Using a pulsed Nd:YAG laser (532 nm) and a gated, intensified charge-coupled device, planar Rayleigh and Raman scattering techniques have been used to visualize the unseeded Mach 0.2 flow density in a 0.3-meter transonic cryogenic wind tunnel. Detection limits are determined for density measurements by using both unseeded Rayleigh and Raman (N2 vibrational) methods. Seeding with CO2 improved the Rayleigh flow visualization at temperatures below 150 K. The seeded Rayleigh version was used to demonstrate the observation of transient flow features in a separated boundary layer region, which was excited with an oscillatory jet. Finally, a significant degradation of the laser light sheet, in this cryogenic facility, is discussed.
Herring, Gregory C.↗
Laser Doppler velocimetry application in the Langley 0.3-meter Transonic Cryogenic Tunnel
The problems and the potential use of a nonintrusive flow velocity measuring technique in the Langley 0.3 meter transonic cryogenic tunnel (TCT) were investigated. A laser velocimeter (LV) was used. It was concluded that free-stream velocity measurements can be successfully made in the Langley 0.3-m TCT using a low-power (15-mW) LV system. The measured and calculated mean velocities typically agreed within one percent. The overall normalized standard deviation was less than one percent. Tunnel vibration and temperature had no detrimental effects on the optical system. It is recommended that the LV work should be further investigated for future use in the Langley 0.3-m TCT.
Gartrell, L. R.↗
Portable Dew Point Mass Spectrometry System for Real-Time Gas and Moisture Analysis
A portable instrument incorporates both mass spectrometry and dew point measurement to provide real-time, quantitative gas measurements of helium, nitrogen, oxygen, argon, and carbon dioxide, along with real-time, quantitative moisture analysis. The Portable Dew Point Mass Spectrometry (PDP-MS) system comprises a single quadrupole mass spectrometer and a high vacuum system consisting of a turbopump and a diaphragm-backing pump. A capacitive membrane dew point sensor was placed upstream of the MS, but still within the pressure-flow control pneumatic region. Pressure-flow control was achieved with an upstream precision metering valve, a capacitance diaphragm gauge, and a downstream mass flow controller. User configurable LabVIEW software was developed to provide real-time concentration data for the MS, dew point monitor, and sample delivery system pressure control, pressure and flow monitoring, and recording. The system has been designed to include in situ, NIST-traceable calibration. Certain sample tubing retains sufficient water that even if the sample is dry, the sample tube will desorb water to an amount resulting in moisture concentration errors up to 500 ppm for as long as 10 minutes. It was determined that Bev-A-Line IV was the best sample line to use. As a result of this issue, it is prudent to add a high-level humidity sensor to PDP-MS so such events can be prevented in the future.
Arkin, C.↗
Impact of Janssen effect on thermal transport in granular flow
Using a modulated photothermal radiometry (MPR) technique capable of measuring thermal transport in particle beds, we find asymptotically increasing effective thermal conductivity and decreasing near-wall thermal resistance along gravity-driven downward granular flows through a 1-meter-long narrow vertical channel owing to the Janssen effect. The Janssen effect is confirmed by similar asymptotic trends from particle bed apparent mass measurements as well as separate MPR heat transfer measurements on stationary particle beds under compression at different heights of the channel with and without pressure screening. Furthermore, local heat transfer coefficient along the 1-meter-long channel was modeled based on measured spatially resolved thermal conductivity and near-wall thermal resistance due to the Janssen effect. This work reveals for the first time the impact of the over century-old Janssen effect on heat transfer in granular media. Furthermore, the results from this work can lead to a better understanding of heat transfer in granular flow.
14 SOLAR ENERGY↗
An analysis of maximum vertical gusts recorded at NASA's 150-meter ground winds tower facility at Kennedy Space Center, Florida
A statistical summary is presented of vertical wind speed data recorded at NASA's 150-Meter Ground Winds Tower Facility on Merritt Island, Kennedy Space Center, Florida. One year of continuous around-the-clock vertical wind speed measurements processed by the Automatic Data Acquisition System (ADAS) is classified as a function of tower level (10, 18, 60, and 150 meters) and period of reference day, month, season: winter (October through March) and summer (April through September), and annual. Intensity, frequency, time of occurrence, prevailing conditions, etc., of the daily maximum vertical gusts (i.e., updraft and downdraft) are determined. The results are compared with the vertical gusts associated with the daily maximum horizontal gust. The intent of this summarization of vertical wind speed data is to provide a general description of wind flow in the lower 150 meters of the atmosphere for the identification of hazards involved in wind shear encounters relative to ascent and descent of the Space Shuttle and conventional aircraft.
Alexander, M. B.↗
Analysis of altitude compensation systems for aircraft carburetors
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FLOW - JETS↗
Volcanic recycling of carbonate deposits on Mars
One question of great interest to those who study the evolution of the Martian atmosphere is: if there was an early, dense atmosphere that was removed, is there any mechanism that could restore it? In the case of an atmosphere removed largely by the formation of carbonates, the only obvious means of restoring it is by the thermal decomposition of the carbonates. Decomposition of carbonates under turbulently flowing lava holds great promise as a means of resupplying the atmosphere with CO2. Huppert and colleagues have modeled the emplacement of terrestrial komatiite flows and found that komatiites, even when flowing over previously emplaced and cooled komatiite flows, could melt and erode this rock to a significant depth. Based on this work, I have begun modeling the erosion of Martian carbonate deposits under turbulently flowing, komatiitic lava. Initial results from this modeling indicate that a high-volume lava flow, emerging at a temperature of, say, 1600 degrees, is capable of eroding several meters of carbonate deposits per day. If such a flow is active for a hundred days, several hundreds of meters of carbonate could be decomposed. If this process occurred over a large area, a bar or more of CO2 could be injected back into the atmosphere over an extremely short period of time. The implications of such an occurrence are intriguing. For instance, if a relatively late pulse of volcanism (such as is suggested by Frey) were to cause a large flow of lava over carbonate deposits in the northern lowlands, the resulting pulse of CO2 into the atmosphere could conceivably restore the climate to one in which liquid water could exist on the surface, or ice could flow.
Schaefer, M. W.↗