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NASA NTRS1994

Optimized design of a hypersonic nozzle

Conventional procedures for designing nozzles involve the design of an inviscid contour (using the method of characteristics) that is corrected with a displacement thickness calculated from boundary-layer theory. However, nozzles designed using this classical procedure have been shown to exhibit poor flow quality at Mach numbers characteristic of hypersonic applications. The nozzle to be designed will be a part of the NASA HYPULSE facility which is being used for hypervelocity flight research. Thus, the flow quality of the nozzle is a critical question that needs to be addressed. Design of nozzles for hypersonic applications requires a proper assessment of the effects of the thick boundary layer on the inviscid flowfield. Since the flow field is largely supersonic, the parabolized form of the Navier-Stokes (PNS) equations can be used. The requirement of a uniform flow at the exit plane of the nozzle can be used to define an objective function as part of an optimization procedure. The design procedure used in this study involves the coupling of a nonlinear (least-squares) optimization algorithm with an efficient, explicit PNS solver. The thick boundary layers growing on the walls of the nozzle limit the extent of the usable core region (region with uniform flow) for testing models (especially rectangular). In order to maximize the region of uniform flow, it was decided to have the exit plane of this nozzle to be (nearly) rectangular. Thus, an additional constraint on the nozzle shape resulted, namely the nozzle will have a shape transitioning from a circular one at the inlet to that of a rectangle at the exit. In order to provide for a smooth shape transition, the cross sectional contour of the nozzle is defined by a superellipse. The nozzle is taken to be a meter in length. The axial variations of the major and minor radii of the superellipse are governed by cubic splines. The design parameters are the coefficients of the splines associated with the local nozzle wall slopes. Extensive calculations have been made (with a three-dimensional Euler code) to understand the effects of various parameters such as location of the knot points of the spline function, different ways of characterizing the uniformity of the flow in the exit plane, as well as the effect of constraining the area of the nozzle to be invariant. Turbulent flow (measurements indicate that the flow at the nozzle inlet is turbulent) calculations are now being performed (with the inviscidly designed nozzle contours) to assess the flow quality.

Krishnamurthy, Ramesh↗

NASA NTRS1987

Low speed wind tunnel test of a propulsive wing/canard concept in the STOL configuration. Volume 1: Test description and discussion of results

A propulsive wing/canard model was tested at STOL operating conditions in the NASA Langley Research Center 4 x 7 meter wind tunnel. Longitudinal and lateral/directional aerodynamic characteristics were measured for various flap deflections, angles of attack and sideslip, and blowing coefficients. Testing was conducted for several model heights to determine ground proximity effects on the aerodynamic characteristics. Flow field surveys of local flow angles and velocities were performed behind both the canard and the wing. This is volume 1 of a 2 volume report. The model, instrumentation, and test procedures are described. An analysis of the data is included.

Stewart, V. R.↗

NASA NTRS1987

Low speed wind tunnel test of a propulsive wing/canard concept in the STOL configuration. Volume 2: Test data

A propulsive wind/canard model was tested at STOL operating conditions in the NASA Langley Research Center 4 x 7 meter wind tunnel. Longitudinal and lateral/directional aerodynamic characteristics were measured for various flap deflections, angles of attack and sideslip, and blowing coefficients. Testing was conducted for several model heights to determine ground proximity effects on the aerodynamic characteristics. Flow field surveys of local flow angles and velocities were performed behind both the canard and the wing. This is volume 2 of a 2 volume report. All of the test data in three appendices are presented. Appendix A presented tabulated six component force and moment data, Appendix B presents tabulated wing pressure coefficients, and Appendix C presents the flow field data.

Stewart, V. R.↗

NASA NTRS1988

Mass and energy flow near sunspots

Sunspots block the flow of energy to the solar surface. The blocked energy heats the volume beneath the spot, producing a pressure excess which drives an outflow of mass. Linear numerical models of the mass and energy flow around spots were constructed to estimate the predictions of this physical picture against the observed properties of sunspot bright rings and moat flows. The width of the bright ring and moat are predicted to be proportional to the depth of the spot penumbra, in conflict with the observed proportionality of the moat width to the spot diameter. Postulating that spot depths are proportional to spot diameters would bury the moat flow too deeply to be observed, because the radial velocity at the surface is found to be inversely proportional to the depth of the spot penumbra. The radial velocity at the surface is of order a few hundred meters per second after 1 day, in agreement with the observed excess of moat velocities over supergranule velocities.

Nye, Alan↗

NASA NTRS1989

Large velocity shears and associated electrostatic waves and turbulence in the auroral F region

Broadband electrostatic waves at 10-1000 Hz have been observed with very large shears in the plasma flow velocity transverse to the ambient magnetic field in the auroral F region. The shears were detected through their perpendicular electric field signatures, which changed by as much as 200 mV/m over distances of only a few hundred meters. Transverse shears can be uniquely related to field-aligned currents through the current continuity equation, and the resulting field-aligned drift exceeds the threshold for excitation of current-driven electrostatic ion-cyclotron waves. A numerical simulation of this instability has been used to generate electric-field spectra in the rocket frame of reference, and these spectra are similar to the spectra generated form the actual rocket data.

Earle, G. D.↗

NASA NTRS1990

Laser skin friction measurements and CFD comparison of weak-to-strong swept shock/boundary-layer interactions

A joint experimental and computational study of skin friction in weak-to-strong swept shock wave/turbulent boundary-layer interactions has been carried out. A planar shock wave is generated by a sharp fin at angles of attack alpha = 10 deg and 16 deg at M(infinity) = 3 and 16 and 20 deg at M(infinity) = 4. Measurements are made using the Laser Interferometer Skin Friction meter, which optically detects the rate of thinning of an oil film applied to the test surface. The results show a systematic rise in the peak c(f) at the rear part of the interaction, where the separated flow atttaches. For the stronget case studied, this peak is an order of magnitude higher than the incoming freestream c(f)level.

Kim, K.-S.↗

NASA NTRS2015

Boundary Layer Instabilities Generated by Freestream Laser Perturbations

A controlled, laser-generated, freestream perturbation was created in the freestream of the Boeing/AFOSR Mach-6 Quiet Tunnel (BAM6QT). The freestream perturbation convected downstream in the Mach-6 wind tunnel to interact with a flared cone model. The geometry of the flared cone is a body of revolution bounded by a circular arc with a 3-meter radius. Fourteen PCB 132A31 pressure transducers were used to measure a wave packet generated in the cone boundary layer by the freestream perturbation. This wave packet grew large and became nonlinear before experiencing natural transition in quiet flow. Breakdown of this wave packet occurred when the amplitude of the pressure fluctuations was approximately 10% of the surface pressure for a nominally sharp nosetip. The initial amplitude of the second mode instability on the blunt flared cone is estimated to be on the order of 10 −6 times the freestream static pressure. The freestream laser-generated perturbation was positioned upstream of the model in three different configurations: on the centerline, offset from the centerline by 1.5 mm, and offset from the centerline by 3.0 mm. When the perturbation was offset from the centerline of a blunt flared cone, a larger wave packet was generated on the side toward which the perturbation was offset. The offset perturbation did not show as much of an effect on the wave packet on a sharp flared cone as it did on a blunt flared cone.

Chou, Amanda↗

DOE OSTI2021

Hydraulic Response to Thermal Stimulation Efforts at Raft River Based on Stepped Rate Injection Testing

The injection well stimulation project at the Raft River geothermal field tests the effect of long-term cold water injection and high pressure injection on well injectivity, improvements to which could reduce operating costs. The primary data for analysis and interpretation of the injection test are step-rate flow tests run before each new phase of the injection. These tests were analyzed using a combination of standard pump-test analytical solution methods and methods developed expressly for the observed conditions. The stepped rate injection tests, combined with long-term flow and pressure response data suggest that the well is located within a fractured formation of low transmissivity but high storativity. These calculated parameters appeared to increase with pressure during the first injection test and the higher values were reproduced during the second stepped rate test. Calculated transmissivity and storativity are on the order of 4E-5 m cm 2 and 1E-4 m Pa -1 , respectively. The apparent pressure dependence of fitted hydraulic parameters may reflect near-well fracture compliance that increased the effective radius of the wellbore during the first test. While the type curve fit analysis also suggests that the reservoir behaves as a uniformly fractured reservoir with a radial flow regime, the hydraulic parameters indicate that condition may exist only a very limited distance (<10 m) from the well. Longer-term pressure response suggests that flow in the system effectively reaches steady state in a period of less than a day, which may reflect pressure stabilization resulting from pressure-dependent permeability or a region of much higher permeability located with a few meters of the well. The transmissivity estimates obtained from this analysis, converted to approximate fracture density and aperture, provide useful constraints on the distance to which the thermal front may migrate from the well during the cold water injection phase of the stimulation project. We estimate that the cooling front will migrate less than a tenth of a kilometer over an approximately one-year injection period. Here, the effects of that cooling, however, may be substantial, because increases in permeability have maximum effect nearest the well.

cold water injection↗

DOE OSTI2024

EPCAPE-PT-LANL Measurements: Single Particle Soot Photometer

Coastal cities offer a unique environment for studying aerosol-cloud interactions and the effects of urban emissions on cloud properties. As part of the Eastern Pacific Cloud Aerosol Precipitation Experiment (EPCAPE), the Partitioning Thrust by Los Alamos National Laboratory (EPCAPE-PT-LANL) was conducted. Our campaign focused on measuring the optical and chemical properties of aerosols and their interactions within marine stratocumulus clouds in La Jolla, California. EPCAPE-PT-LANL enhances the primary goals of EPCAPE through innovative observations of vapor-phase transitions between aerosols and cloud droplets, the impact of black carbon on aerosol-cloud dynamics, and the effects of cloud processing on aerosol optical properties. Instrument: Single Particle Soot Photometer (Droplet Measurements Technology) Data Notes: Contact us if you want additional data products from this instrument. Reported data is the black carbon (rBC) number and mass concentration with diagnostic flags. The SP2 measures incandescence from particles that is induced with a 1064 Nd-YAG laser. Particles that absorb the laser energy and then emit radiation is assumed to contain black carbon. The amount of intensity of radiation is related to the mass of absorbing material in the particle. Here, we calibrate the incandescence intensity to size selected Regal Black (Cabot) nebulized from solution. Data provided for the EPCAPE campaign used the combined broadband high-gain + low-gain channels (BHBL). Each channel has a lower threshold of detection equivalent to 2-s of the respective channel noise. Thresholding has been applied to select between the high-gain and low-gain channels. The detection limit is 80-540 nm (Deq) or 0.36- 55 fg. It is assumed that rBC is the only aerosol type that is in significant concentration in the sampled atmosphere that absorbs the laser energy. Particle data are integrated over 10 second windows to calculate a rBC number and mass concentration. QC/QA: • Diagnostic flags that impacted measured concentration: - Sample, Sheath, and Purge Flow Rates: Despite observing fluctuations in all flows, the rBC detection and mass quantification are generally observed to be stable, although large changes in sample flow rate did impact detection efficiency. A flag was implemented for sample flow deviations >12 cm3/min from the set point averaged over 30 seconds - Laser Power: Detection efficiency decreases with laser power and deviations in laser power also affect mass quantification. Flag for laser power is set for deviations in laser current from the set value >5 mA. - Primary Detector Threshold: Primary thresholding is the signal value which determines whether a “particle” is recorded. Thresholding errors occur when the threshold value is too HIGH and real particles are ignored. • Several periods without data: - 16-18 Nov: Ultra Zero Air generator failure, flows deviated significantly from set points. rBC # conc recovered but questionable. - 20-21 Nov: Offline for calibrations for several hours each day. - 25-27 Nov: Data is missing. - 30 Nov: Power outage 3 Dec: SP2 hard-drive full. - 3 Dec: Power Outage Header: - BHBL_NumbConc[#/cc]: Refers to the number concentration of refractory black carbon (rBC) measured from combined broadband high-gain and low-gain channels, expressed in particles per cubic centimeter. - BHBL_BCMass_Conc[ug/m3]: Refers to the mass concentration of refractory black carbon (rBC) measured from combined broadband high-gain and low-gain channels, expressed in micrograms per cubic meter. - NoData_Flag[bool]: A boolean flag that indicates whether no data was recorded during a measurement. - NoBC_Flag[bool]: A boolean flag indicating whether no black carbon particles were recorded during the measurement. - Laser_Flag[bool]: A boolean flag indicating deviations in laser current during the measurement. - SampleFlow_Flag[bool]: A boolean flag indicating deviations from the set sample flow rate during the measurement. - PrimThresh_Flag[bool]: A boolean flag indicating deviations from the set primary threshold during the measurement, potentially ignoring real particles. - Manual_Flag[bool]: A boolean flag indicating manual intervention or adjustments during the measurement. - CVI_Flag[bool]: A boolean flag indicating whether the Counterflow Virtual Impactor (CVI) was active or inactive during the measurement.

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS1981

Electromagnetic measurement of lightning strikes to aircraft

Recent in-flight direct-strike lightning research, using an NASA F-1068 aircraft, is reviewed. The instrumentation system which records the rates of change of electric and magnetic flow density at several locations on the aircraft and rate of change of strike current to the boom is described. The measurement parameters are: rate of change of electric flux density over a range of 50 amperes per square meter, rate of change of magnetic flux density over a range of 20,000 tesla per second, and rate of change of strike current over a range of 100 kilo-amperes per microsecond. The isolated and shielded instrumentation system employs high-sample-rate digital transient recorders with augmented memory capacity and a wideband analog recorder for data acquisition and recording. The data obtained during the 1980 flight test program are presented and the data significance is discussed.

Pitts, F. L.↗

NASA NTRS1984

Nighttime observations of thunderstorm electrical activity from a high altitude airplane

Nocturnal thunderstorms were observed from above and features of cloud structure and lightning which are not generally visible from the ground are discussed. Most, lightning activity seems to be associated with clouds with strong convective cauliflower tops. In both of the storms lightning channels were visible in the clear air above the cloud. It is shown that substances produced by thunderstorm electrical discharges can be introduced directly into the stratosphere. The cause and nature of the discharges above the cloud are not clear. They may be produced by accumulations of space charge in the clear air above the cloud. The discharges may arise solely because of the intense electric fields produced by charges within the cloud. In the latter case the ions introduced by these discharges will increase the electrical conductivity of the air above the cloud and increase the conduction current that flows from the cloud to the electrosphere. More quantitative data at higher resolution may show significant spectral differences between cloud to ground and intracloud strokes. It is shown that electric field change data taken with an electric field change meter mounted in an airplane provide data on lightning discharges from above that are quite similar to those obtained from the ground in the past. The optical signals from dart leaders, from return strokes, and from continuing currents are recognizable, can be used to provide information on the fine structure of lightning, and can be used to distinguish between cloud to ground and intracloud flashes.

Brook, M.↗

NASA NTRS1996

Development of Uniform Microstructures in Immiscible Alloys by Processing in a Low-Gravity Environment

Highly segregated macrostructures tend to develop during processing of hypermonotectic alloys because of the density difference existing between the two liquid phases. The approximately 4.6 seconds of low-gravity provided by Marshall Space Flight Center's 105 meter drop tube was utilized to minimize density-driven separation and promote uniform microstructures in hypermonotectic Ag-Ni and Ag-Mn alloys. For the Ag-Ni alloys a numerical model was developed to track heat flow and solidification of the bi-metal drop configuration. Results, potential applications, and future work are presented.

Grugel, R. N.↗

NASA NTRSDate not supplied

Viability of Small Dimension Crew Quarters for Surface Habitation

During early planning for the Artemis program’s sustained phase of lunar activity, NASA planners have been held to work towards a NASA reference lunar lander concept. With this activity taking place prior to the awarding of a lander contract, NASA planners cannot assume which of several potential landers will be available. This has limited habitation team engineers to a 12-metric ton mass limit for the reference concept of the lunar Surface Habitat. Consequently, minimal approaches have been applied to many habitat systems and it is important to determine acceptable volume for crew quarters. A number of both NASA and non-NASA surface habitat concepts have proposed relatively small crew quarters due to this constraint. Consequently, there is a need to collect objective test data to confirm or refute the validity of small crew quarters. NASA-STD-3001 is looked to for guidance in its many standards but offers little to no help. While prior versions called for private habitation, the current version – Revision B – calls for “individual privacy” to “accommodate social retreat.” Proposed Revision C modifications change the language slightly to “accommodate sleep and social retreat.” This is not enough guidance to determine the size of a crew quarters or even its capabilities. Unfortunately, only a small number of US spacecraft have included crew quarters, primarily the International Space Station and the Skylab Space Station. The space shuttle orbiter sometimes flew a set of private bunks that some might consider a crew quarters. All of these are dramatically smaller than US standards for minimum jail cells. The first opportunity for NASA to test a small crew quarters in a surface habitat application has been created through the Exploration Atmospheres test series, which is evaluating human performance under reduced cabin pressures. The test is converting the 20-Foot Vacuum Chamber at Johnson Space Center into a habitat, with the lower level outfitted as an EVA test area and the upper two levels for human habitation. The test will place eight people (six test subjects and two technicians) inside the chamber for eleven days. All eight will sleep in private quarters during the test. Volume limitations in the chamber forced extremely small crew quarters, measuring approximately 2 meters in length, 0.85 meters in height, and 0.9 meters in width. The test cabin pressure of 8.2 psi and elevated oxygen also introduces significant material limitations, limiting outfitting options. Nonetheless, the crew quarters design requirements were to accommodate visual separation, auditory separation, olfactory separation, tactile separation, air flow control, lighting control, single person personal computing, physical work surface access, sleep accommodations, non-sleep rest/relaxation, meditation, stretching, two-person meetings, snacking, changing clothes, viewing appearance, video communication, and audio communication. This paper will detail the acceptability of the crew quarters as measured in the October 2021 Exploration Atmosphere test. Based on this data, the viability of the type of crew quarters used in the 20 Foot Chamber will be assessed. Design recommendations for a 30-60-day Surface Habitat crew quarters will be provided, along with recommendations for future testing.

Crew Quarters↗

NASA NTRS1986

Containerless processing of hypermonotectic and glass forming alloys using the Marshall Space Flight Center 100 meter drop tube facility

Two separate projects were carried out to study alloys whose solidification structures can be strongly influenced by the presence of a container during melting and solidifications. One project involved containerless solidification of hypermonotectic Au35Rh65 alloys. This alloy exhibits liquid immiscibility over a temperature range. It has been suggested that containerless melting might be one solution to the problem of sedimentation in the dispersions of immiscible liquid phases. However, surface tension driven flows could also lead to accumulation of the minority liquid phase at the external surface of a containerlessly melted alloy. The research underway is a first step in determining the influence of containerless, microgravity processing on immiscible alloys. Nickel-niobium alloys were studied using the drop tube facility. One alloy in this system, a Ni60Nb40 alloy, is a good candidate for the formation of a bulk metallic glass. Amorphous alloys of this composition were produced using thin film and mechanical alloying techniques. However, theory indicates that if heterogeneous nucleation can be avoided, it should be possible to produce an amorphous structure in this system using a moderate cooling rate from the melt. The containerless melting and solidification capabilities of the drop tube faciltiy provide ideal conditions for a study of this type. To date, several Ni60Nb40 samples have been levitated, melted and cooled during 4.6 seconds of free fall in the 100 meter drop tube. Structures obtained are discussed.

Andrews, J. B.↗

NASA NTRS1981

Circulation in the Chesapeake Bay entrance region: Estuary-shelf interaction

Current meters and temperature-salinity recorders confirm the assumption that the upper layers of the continental shelf waters off Chesapeake Bay can be banded in summer, such that the coastal boundary layer (consisting of the Bay outflow) and the outer shelf flow southward while the inner shelf flows to the north, driven by the prevailing southerly winds. These measurements show that the estuary itself may also be banded in its lower reaches such that the inflow is confined primarily to the deep channel, while the upper layer outflow is split into two flow maxima on either side of this channel.

Boicourt, W. C.↗

NASA NTRS1980

Synoptic thermal and oceanographic parameter distribution in the New York Bight Apex on June 23, 1977

Concurrent surface water measurements made from a moving oceanographic research vessel were used to calibrate and interpret remotely sensed data collected over a plume in the New York Bight Apex on June 23, 1977. Multiple regression techniques were used to develop equations to subsequently map synoptic distributions of water quality parameters, chlorophyll A and total suspended matter, in the remotely sensed scene. Thermal (which did not have surface calibration values) and water quality parameter distributions indicated a cold mass of upwelled water in the Bight Apex with an overflowing nutrient-rich warm water plume that originated in the Sandy Hook Bay and flowed south near the New Jersey shoreline. Additional comparison of remotely sensed thermal and optical properties of the water with shipboard measurements indicated that remotely sensed data may be particularly useful for studying physical and biological processes in the top several meters of surface water at the plume boundaries.

Johnson, R. W.↗

NASA NTRS2014

Global Distribution of Lunar Impact Melt Flows

In this study, we analyzed the distribution and properties of 146 craters with impact melt deposits exterior to their rims. Many of these craters were only recently discovered due to their unusual radar properties in the near-global Mini-RF data set. We find that most craters with exterior deposits of impact melt are small, less than 20 kilometers, and that the smallest craters have the longest melt flows relative to their size. In addition, exterior deposits of impact melt are more common in the highlands than the mare. This may be the result of differing target properties in the highlands and mare, the difference in titanium content, or the greater variation of topography in the highlands. We find that 80 percent of complex craters and 60 percent of simple craters have melt directions that are coincident or nearly coincident with the lowest point in their rim, implying that pre-existing topography plays a dominant role in melt emplacement. This is likely due to movement during crater modification (complex craters) or breached crater rims (simple craters). We also find that impact melt flows have very high circular polarization ratios compared to other features on the Moon. This suggests that their surfaces are some of the roughest material on the Moon at the centimeter to decimeter scale, even though they appear smooth at the meter scale.

Cratering↗

DOE OSTI2021

Quantity of 135I Released from the AGR 5/6/7 Experiment

A series of four Advanced Reactor Technologies (ART) experiments have been conducted in the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL). From 2006 through 2020, these experiments supported the development and qualification of the new U.S. tristructural isotropic (TRISO) particle fuel for Very High Temperature Reactors (VHTR). Each Advanced Gas Reactor (AGR) experiment consisted of multiple fueled capsules, each plumbed for independent temperature control using a mix of helium and neon gases. The gas leaving a capsule was routed to individual Fission Product Monitor (FPM) detectors. For intact fuel particles, the TRISO particle coatings provide a substantial barrier to fission product release. However, particles with failed coatings, whether because of a minute percentage of initially defective particles, those which fail during irradiation, or those designed to fail (DTF) particles, can release fission products to the flowing gas stream. Because reactive fission product elements like iodine and cesium quickly deposit on cooler capsule components and piping structures as the effluent gas leaves the reactor core, only the noble fission gas isotopes of Kr and Xe tend to reach FPM detectors. The FPM system utilizes High Purity Germanium (HPGe) detectors coupled with a thallium activated sodium iodide NaI(Tl) scintillator. The HPGe detector provides individual isotopic information, while the NaI(Tl) scintillator is used as a gross count rate meter. During irradiation, the 135mXe concentration reaching the FPM detectors is from both direct fission and by decay of the accumulated 135I. About 2.5 hours after irradiation (ten 15.3 minute 135mXe half lives) the directly produced 135mXe has decayed and only the longer lived 135I remains as a source. Decay systematics dictate that 135mXe will be in secular equilibrium with its 135I parent, such that its production rate very nearly equals the decay rate of the parent, and its concentration in the flowing gas stream will appear to decay with the parent half life. This equilibrium condition enables the determination of the amount of 135I released from the fuel particles by measurement of the 135mXe at the FPM following reactor shutdown. In this paper, the 135I released will be reported.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗