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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS2007

Os-186 and Os-187 Enrichments and High-He-3/He-4 sources in the Earth's Mantle: Evidence from Icelandic Picrites

Picrites from the neovolcanic zones in Iceland display a range in Os-187/Os-188O from 0.1297 to 0.1381 ((gamma)Os = 0.0 to 6.5) and uniform Os-186/Os-188 of 0.1198375+/-32 (2 (sigma)). The value for Os-186/Os-188 is within uncertainty of the present-day value for the primitive upper mantle of 0.1198398+/-16. These Os isotope systematics are best explained by ancient recycled crust or melt enrichment in the mantle source region. If so, then the coupled enrichments displayed in Os-186/Os-188 and Os-187/Os-188 from lavas of other plume systems must result from an independent process, the most viable candidate at present remains core-mantle interaction. While some plumes with high He-3/He-4, such as Hawaii, appear to have been subjected to detectable addition of Os (and possibly He) from the outer core, others such as Iceland do not. A positive correlation between Os-187/Os-188 and He-3/He-4 from 9.6 to 19 RA in Iceland picrites is best modeled as mixtures of 500 Ma or older ancient recycled crust mixed with primitive mantle, creating a hybrid source region that subsequently mixes with the convecting MORB mantle during ascent and melting. This multistage mechanism to explain these isotope systematics is consistent with ancient recycled crust juxtaposed with more primitive, relatively He-rich mantle, in convective isolation from the upper mantle, most likely in the lowermost mantle. This is inconsistent with models that propose random mixing between heterogeneities in the convecting upper mantle as a mechanism to explain the observed isotopic variation in oceanic lavas or models that produce a high He-3/He-4 signature in melt depleted and strongly outgassed, He-poor mantle. Instead these systematics require a deep mantle source to explain the 3He/4He signature in Iceland lavas. The He-3/He-4 of lavas derived from the Iceland plume changed over time, from a maximum of 50 RA at 60 Ma, to approximately 25-27 RA at present. The changes are coupled with distinct compositional gaps between the different aged lavas when H-3/He-4 is plotted versus various geochemical parameters such as Nd-143/Nd-144 and La/Sm. These relationships can be interpreted as an increase in the proportion of ancient recycled crust in the upwelling plume over this time period.

Brandon, Alan D.↗
NASA NTRS1998

Ion Propulsion Plasma Interactions in the Solar Wind

This paper focuses on the plasma physics issues related to ion propulsion. We present an overview of our current understanding of ion thruster plume induced plasma interactions and discuss the planned investigations of such interactions form the DS1 mission.

Solar↗
NASA NTRS1973

RCS jet-flow field interaction effects on the aerodynamics of the space shuttle orbiter

A study was conducted to determine the external effects caused by operation of the reaction control system during entry of the space shuttle orbiter. The effects of jet plume-external flow interactions were emphasized. Force data were obtained for the basic airframe characteristics plus induced effects when the reaction control system is operating. Resulting control amplification and/or coupling were derived and their effects on the aerodynamic stability and control of the orbiter and the reaction control system thrust were determined.

Rausch, J. R.↗
NASA NTRS2006

Space Shuttle and Launch Pad Computational Fluid Dynamics Model for Lift-off Debris Transport Analysis

This paper discusses the Space Shuttle Lift-off CFD model developed for potential Lift-off Debris transport for return-to-flight. The Lift-off portion of the flight is defined as the time starting with tanking of propellants until tower clear, approximately T0+6 seconds, where interactions with the launch pad cease. A CFD model containing the Space Shuttle and launch Pad geometry has been constructed and executed. Simplifications required in the construction of the model are presented and discussed. A body-fitted overset grid of up to 170 million grid points was developed which allowed positioning of the Vehicle relative to the Launch Pad over the first six seconds of Climb-Out. The CFD model works in conjunction with a debris particle transport model and a debris particle impact damage tolerance model. These models have been used to assess the interactions of the Space Shuttle plumes, the wind environment, and their interactions with each other and the Launch Pad and their ultimate effect on potential debris during Lift-off.

Dougherty, Sam↗
NASA NTRS1992

The effects of 1 kW class arcjet thruster plumes on spacecraft charging and spacecraft thermal control materials

Arcjet thrusters are soon to be used for north/south stationkeeping on commercial communications satellites. A series of tests was performed to evaluate the possible effects of these thrusters on spacecraft charging and the degradation of thermal control material. During the tests the interaction between arcjet plumes and both charged and uncharged surfaces did not cause any significant material degradation. In addition, firing an arcjet thruster benignly reduced the potential of charged surfaces to near zero.

Bogorad, A.↗
NASA NTRS1983

Space Shuttle third flight /STS-3/ entry RCS analysis

Flight data obtained from three Space Transportation System orbiter entries (STS-1, 2, and 3) are processed and analyzed to determine the roll interactions caused by the firing of the entry reaction control system (RCS). Comparisons between the flight-derived parameters and the predicted derivatives without interaction effects are made. The flight-derived RCS Plume flow-field interaction effects are independently deduced by direct integration of the incremental changes in the wing upper surface pressures induced by RCS side thruster firings. The separately obtained interaction effects are compared to the predicted values and the differences are discussed.

Scallion, W. I.↗
NASA NTRS1988

Aeroacoustics of advanced STOVL aircraft plumes

This paper summarizes a basic and well-controlled experimental study involving flow visualization and noise measurements to define the acoustic and flow fields of single plumes impinging on a simulated ground plane. The flow visualization was made by strobing a laser light source at the discrete frequencies generated by the impingement of the jets and measured by a nearfield microphone. This enabled visualization of instability waves generated by the interaction between the plumes and the sound generated during impingement, and also by dynamic coupling between the two plumes. These data were acquired as a function of distance between the ground and the nozzle exit. Nearfield acoustic data were acquired simultaneously. Data for nozzle diameters of 0.265 in. and 0.4 in. are described. For selected nozzles, effects of exit boundary layer characteristics and nozzle protrusion through a simulated aircraft body are also presented.

Ahuja, K. K.↗
NASA NTRS1990

Influence of local configuration on the backflow from small rocket thrusters

A numerical study has been made of the low density plume flow from a small thruster motor. For the case studied, the addition of a thin plume shield with a diameter 1.67 times the nozzle exit diameter was found to lead to a reduction in the backflow by several orders of magnitude. Calculations were also made for the three-dimensional flow produced by a pair of motors, in order to determine the increase in the backflow due to the interaction of the plumes. The calculations were made with the direct simulation Monte Carlo (DSMC) method, and one of the purposes of the work was to test a new and faster set of algorithms for this method.

Bird, G. A.↗
NASA NTRS1986

Tactical missile aerodynamics

The present conference on tactical missile aerodynamics discusses autopilot-related aerodynamic design considerations, flow visualization methods' role in the study of high angle-of-attack aerodynamics, low aspect ratio wing behavior at high angle-of-attack, supersonic airbreathing propulsion system inlet design, missile bodies with noncircular cross section and bank-to-turn maneuvering capabilities, 'waverider' supersonic cruise missile concepts and design methods, asymmetric vortex sheding phenomena from bodies-of-revolution, and swept shock wave/boundary layer interaction phenomena. Also discussed are the assessment of aerodynamic drag in tactical missiles, the analysis of supersonic missile aerodynamic heating, the 'equivalent angle-of-attack' concept for engineering analysis, the vortex cloud model for body vortex shedding and tracking, paneling methods with vorticity effects and corrections for nonlinear compressibility, the application of supersonic full potential method to missile bodies, Euler space marching methods for missiles, three-dimensional missile boundary layers, and an analysis of exhaust plumes and their interaction with missile airframes.

Hemsch, Michael J.↗
NASA NTRS2016

Wind Tunnel Model Design for Sonic Boom Studies of Nozzle Jet Flows with Shock Interactions

NASA and the U.S. aerospace industry are performing studies of supersonic aircraft concepts with low sonic boom pressure signatures. The computational analyses of modern aircraft designs have matured to the point where there is confidence in the prediction of the pressure signature from the front of the vehicle, but uncertainty remains in the aft signatures due to boundary layer and nozzle exhaust jet effects. Wind tunnel testing without inlet and nozzle exhaust jet effects at lower Reynolds numbers than in-flight make it difficult to accurately assess the computational solutions of flight vehicles. A wind tunnel test in the NASA Ames 9- by 7-Foot Supersonic Wind Tunnel is planned for February 2016 to address the nozzle jet effects on sonic boom. The experiment will provide pressure signatures of test articles that replicate waveforms from aircraft wings, tails, and aft fuselage (deck) components after passing through cold nozzle jet plumes. The data will provide a variety of nozzle plume and shock interactions for comparison with computational results. A large number of high-fidelity numerical simulations of a variety of shock generators were evaluated to define a reduced collection of suitable test models. The computational results of the candidate wind tunnel test models as they evolved are summarized, and pre-test computations of the final designs are provided.

Wind Tunnel↗
NASA NTRS1992

Acoustic interactions between an altitude test facility and jet engine plumes: Theory and experiments

The overall objective of the described effort was to develop an understanding of the physical mechanisms involved in the flow/acoustic interactions experienced in full-scale altitude engine test facilities. This is done by conducting subscale experiments and through development of a theoretical model. Model cold jet experiments with an axisymmetric convergent nozzle are performed in a test setup that stimulates a supersonic jet exhausting into a cylindrical diffuser. The measured data consist of detailed flow visualization data and acoustic spectra for a free and a ducted plume. It is shown that duct resonance is most likely responsible by theoretical calculations. Theoretical calculations also indicate that the higher discrete tones observed in the measurements are related to the screech phenomena. Limited experiments on the sensitivity of a free 2-D, C-D nozzle to externally imposed sound are also presented. It is shown that a 2-D, C-D nozzle with a cutback is less excitable than a 2-D C-D nozzle with no cutback. At a pressure ratio of 1.5 unsteady separation from the diverging walls of the nozzle is noticed. This separation switches from one wall to the opposite wall thus providing an unsteady deflection of the plume. It is shown that this phenomenon is related to the venting provided by the cutback section.

Ahuja, K. K.↗
NASA NTRS1989

Dynamical characteristics of tropical plumes

The effect of the barotropic interaction of tropical waves on the initial development of tropical plumes is investigated. A tropical plume from January 1979 is studied using FGGE data. The zonal wind, planetary-scale features, and relative vorticity are analyzed. An one-layer, shallow water, grid point model is utilized to examine the stability of inviscid, horizontally-sheared, barotropic basic states with respect to synoptic-scale perturbation. The data reveal a localized strengthening of cross-equatorial flow in some regions.

Askue, C. A.↗
NASA NTRS1975

NO sub X Deposited in the Stratosphere by the Space Shuttle Solid Rocket Motors

The possible effects of the interaction of the plumes from the two solid rocket motors (SRM) from the space shuttles and mixing of the rocket exhaust products and ambient air in the base recirculation region on the total nitrous oxide deposition rate in the stratosphere were investigated. It was shown that these phenomena will not influence the total NOx deposition rate. It was also shown that uncertainties in the particle size of Al2O3, size distributions and particle/gas drag and heat transfer coefficients will not have a significant effect on the predicted NOx deposition rate. The final results show that the total mass flow of NOx leaving the plume at 30 km altitude is 4000 g./sec with a possible error factor of 3. For a vehicle velocity of 1140 meter/sec this yields an NOx deposition rate of about 3.5 g./meter. The corresponding HCl deposition rate at this altitude is about a factor of 500 greater than this value.

Pergament, H. S.↗
NASA NTRS1991

Tropical Pacific moisture variability

The research objectives were to describe synoptic scale variability of moisture over the tropical Pacific Ocean and the systems leading to this variability, to implement satellite analysis procedures to accomplish that objective, to incorporate additional satellite information into operational analysis/forecast systems at the National Meteorological Center (NMC), and to synthesize knowledge gained from satellite observations through diagnosis and numerical models. In the past year, three significant satellite data analysis tasks were accomplished: comparisons for upwelling radiance fields for 1983 and 1984 were completed for the purpose of testing the sensitivity of water vapor/greenhouse feedback to local sea surface temperature variations; the interaction between tropical plumes, wave features over Central America, traveling waves in the upper tropospheric tropics, and the tropical interseasonal oscillation was examined; and planning and early efforts on the construction of a model and the infrared based climatology of daily precipitable water was completed. Research on tropical plume mechanisms included is briefly discussed.

Mcguirk, James P.↗
NASA NTRS1993

Workshop on Solar Electric Propulsion

A summary of the discussion at the workshop on solar electric propulsion (SEP) is presented. The purpose of ELITE SEP flight experiment is to demonstrate operation of solar array powered electric thrusters for raising spacecraft from parking orbit to higher altitudes, leading to definition of an operational SEP orbit transfer vehicles (OTV) for Air Force missions. Many of the problems or potential problems that may be associated with SEP are not well understood nor clearly identified, and system level phenomena such as interaction of thruster plume with the solar arrays cannot be simulated in a ground test. Therefore, an end-to-end system flight test is required to demonstrate solar electric propulsion.

Bents, David↗
NASA NTRS2004

The Electric Propulsion Interactions Code (EPIC)

Science Applications International Corporation is currently developing the Electric Propulsion Interactions Code, EPIC, as part of a project sponsored by the Space Environments and Effects Program at the NASA Marshall Space Flight Center. Now in its second year of development, EPIC is an interactive computer tool that allows the construction of a 3-D spacecraft model, and the assessment of a variety of interactions between its subsystems and the plume from an electric thruster. These interactions may include erosion of surfaces due to sputtering and re-deposition of sputtered materials, surface heating, torque on the spacecraft, and changes in surface properties due to erosion and deposition. This paper describes the overall capability of EPIC and provides an outline of the physics and algorithms that comprise many of its computational modules.

Mikellides, I. G.↗
NASA NTRS2005

Volcanism and Volatile Recycling on Venus from Lithospheric Delamination

Venus has an unmoving lithosphere, a young surface indicative of volcanic resurfacing, and a wide variety of volcanic and tectonic features. The planet s ubiquitous magmatic features include 100,000 small shield volcanoes as well as the descriptively named pancakes, ticks, and arachnoids [1]. Coronae, volcanic and tectonic features up to 2,600 km in diameter, have been attributed to lithospheric interactions with upwelling plumes [e.g., 2], but more recently to delamination of the lower lithosphere with [3] or without [4] a central upwelling. Lavas issuing from different volcanic features appear to have a range of compositions, as evidenced by their apparent viscosities and by data from Soviet landers. Steep-sided or "pancake" domes [e.g., 5] appear to consist of more viscous magma [6], perhaps silicic compositions created by remelting basaltic crust [7]. These steep-sided domes are associated with coronae and with shield volcanoes effusing basaltic magmas [7,8] with apparently low viscosities (low enough to allow fluid flow for hundreds of km, creating channels reminiscent of water rivers on Earth). Pancake domes, in contrast, can be up to 3 km in height and have volumes from 30 to approx.3,000 km3 [calculated from data in 8], and hundreds dot the planet [6-8].

Elkins-Tanton, L. T.↗
NASA NTRS2006

NASA/MSFC's Calculation for Test Case 1a of ATAC-FSDC Workshop on After-body and Nozzle Flows

Mr. Ruf of NASA/MSFC executed the CHEM computational fluid dynamics (CFD) code to provide a prediction of the test case 1 a for the ATAC-FSDC Workshop on After-body and Nozzle Flows. CHEM is used extensively at MSFC for a wide variety of fluid dynamic problems. These problems include; injector element flows, nozzle flows, feed line flows, turbomachinery flows, solid rocket motor internal flows, plume vehicle flow interactions, etc.

Ruf, Joseph H.↗