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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 NTRS1984

Dynamical relations for left ventricular ejection - Flow rate, momentum, force and impulse

An investigation was carried out to quantitatively evaluate left ventricular volume flow rate, momentum, force and impulse derived from application of conservation principles for mass and momentum of blood within the ventricle during the ejection phase. An automated digital image processing system was developed and applied to left ventricular angiograms which are computer processed and analyzed frame by frame to determine the dynamical relations by numerical methods. The initial experience with force and impulse has indicated that neither quantity seemed to be a sensitive indicator of coronary artery disease as evaluated by qualitative angiography for the particular patient group studied. Utilization of the dynamical relations in evaluating human left ventricular performance requires improved means of measurement and interpretation of clinical studies.

Back, L. H.↗

NASA NTRS1978

Experiments on the dynamic behavior of cavitating pumps

This paper describes experiments performed to measure the dynamic transfer matrices for cavitating (and noncavitating) pumps. These transfer matrices describe the relationship between small linear oscillatory perturbations in the pressures and mass flow rates at inlet and discharge from the hydraulic machine. The matrices were deduced from direct measurements of these fluctuating quantities for different modes of excitation of the machine. Results for a cavitating inducer are presented as functions of frequency and mean operating state. Though some of the trends in the data are consistent with existing theoretical models of inducer dynamics, others are not, indicating a need for further theoretical investigation of the dynamic characteristics of such flows. The results exhibit increasingly complex dynamics with increasing cavitation; it appears that the hydraulic machine deviates from an essentially passive response without cavitation to an increasingly active response as the cavitation number is reduced.

Ng, S. L.↗

NASA NTRS1978

A three-dimensional model of corotating streams in the solar wind. I - Theoretical foundations

The paper is concerned with the development of the theoretical and mathematical background pertinent to the study of steady, corotating solar wind structure in all three spatial dimensions. The dynamical evolution of the plasma in interplanetary space (defined as the region beyond roughly 35 Rs where the flow is supersonic) is approximately described by the nonlinear, single-fluid, polytropic magnetohydrodynamic or hydrodynamic equations. Efficient numerical techniques are outlined for solving this complex system of coupled, hyperbolic partial differential equations. The present formulation is inviscid and nonmagnetic, but the methods used allow for the potential inclusion of both features with only modest modifications. A simple, highly idealized hydrodynamic model stream is examined to illustrate the fundamental processes involved in the three-dimensional dynamics of stream evolution. It is found that spatial variations in the rotational stream interaction mechanism produce small nonradial flows on a global scale that lead to the transport of mass, energy, and momentum away from regions of relative compression and into regions of relative rarefaction. Comparison with simpler models demonstrates the essential nonlinear, multidimensional nature of the interplanetary dynamics.

Pizzo, V.↗

NASA NTRS1999

What is the Relationship between the Solar Wind and Storms/Substorms?

The interplanetary magnetic field (IMF) carried past the Earth by the solar wind has long been known to be the principal quantity that controls geomagnetic storms and substorms. Intervals of strong southward IMF with durations of at least a significant fraction of a day produce storms, while more typical, shorter intervals of less-intense southward fields produce substorms. The strong, long-duration southward fields are generally associated with coronal mass ejections and magnetic clouds or else they are produced by interplanetary dynamics initiated by fast solar wind flows that compress preexisting southward fields. Smaller, short-duration southward fields that occur on most days are related to long period waves, turbulence, or random variations in the IMF. Southward IMF enhances dayside reconnection between the IMF and the Earth's dipole with the reconnected field lines supplementing open field lines of the geomagnetic tail and producing an expanded polar cap and increased tail energy. Although the frequent storage of solar wind energy and its release during substorms is the most common mode of solar wind/magnetosphere interaction, under certain circumstances, steady southward IMF seems to produce intervals of relatively steady magnetosphere convection without substorms. During these latter times, the inner magnetosphere remains in a stressed tail-like state while the more distant magnetotail has larger northward field and more dipolar-like field lines. Recent evidence suggests that enhanced magnetosphere particle densities associated with enhanced solar wind densities allow more particles to be accelerated for the ring current, thus creating larger storms.

Fairfield, D. H.↗

NASA NTRSDate not supplied

Comparisons of CFD Simulations of Icing Wind Tunnel Clouds with Experiments Conducted at the NASA Propulsions Systems Laboratory

This paper evaluates simulation predictions against experimental test data of icing clouds that were produced during 2018 ice crystal icing physics tests conducted at the NASA Propulsion Systems Laboratory icing wind tunnel. Aero-thermal and cloud parameters are set and known upstream at the tunnel inlet and spray system, but change as the cloud and air thermodynamically interact as the flowing masses reach the tunnel test section. Utilizing the ANSYS Fluent Discrete Phase Model function, 3D computational fluid dynamics (CFD) simulations were performed, capturing the thermodynamic interactions between the test parameters, and providing predictions of the aero thermal and cloud conditions at the tunnel test section. Simulation predictions were compared with test data that were measured at the tunnel exit plane. Evaluations focused on the cloud concentration (total water content), humidity content, and air temperature. CFD simulation predictions showed areas of agreement and disagreement. Simulations showed that cloud concentration profiles at the test section are strongly related to the initial spray nozzle pattern used at the tunnel inlet. Experimental data suggest that greater dispersion of the cloud occurred as the simulated cloud predicted areas of high and low cloud concentration compared to test data profiles. Simulations, however, captured the magnitude and location of the change in humidity content and the change in air temperature due to the presence of the cloud reasonably well, when compared to test data. This result would suggest that while the ANSYS simulation did not fully predict the spreading of the cloud as measured during experiment, it did capture evaporation and the molecular movements of air and vapor relatively well.

CFD↗

NASA NTRSDate not supplied

Comparisons of CFD Simulations of Icing Wind Tunnel Clouds with Experiments Conducted at the NASA Propulsions Systems Laboratory

CFD↗

NASA NTRS2004

Properties of Longitudinal Flux Tube Waves: Wave Propagation in Solar and Stellar Wind Flows - III

We discuss the analytic properties of longitudinal tube waves taking into account ambient wind flows. This is an extension of the studies of Papers I and II, which assumed a mean flow speed of zero and also dealt with a simplified horizontal pressure balance. Applications include the study of longitudinal flux tube waves in stars with significant mass loss and heating and dynamics of plumes in the solar wind. Slow magnetosonic waves, also called longitudinal waves, have been observed in solar plumes and are likely an important source of heating. We show that the inclusion of ambient wind flows considerably alters the limiting shock strength as well as the energy damping length of waves.

Cuntz, M.↗

NASA NTRS2019

Observations of Surface Mass Balance on Pine Island Glacier, West Antarctica, and the Effect of Strain History in Fast-Flowing Sections

Surface mass balance (SMB) is the net input of mass on a glacier's upper surface, composed of snow deposition, melt and erosion processes, and is a major contributor to the overall mass balance. Pine Island Glacier (PIG) in West Antarctica has been dynamically imbalanced since the early 1990s, indicating that discharge of solid ice into the oceans exceeds snow deposition. However, observations of the SMB pattern on the fast flowing regions are scarce, and are potentially affected by the firn's strain history. Here, we present new observations from radar-derived stratigraphy and a relatively dense network of firn cores, collected along a ~900 km traverse of PIG. Between 1986 and 2014, the SMB along the traverse was 0.505 m w.e. a−1 on average with a gradient of higher snow deposition in the South-West compared with the North-East of the catchment. We show that along ~80% of the traverse the strain history amounts to a misestimation of SMB below the nominal uncertainty, but can exceed it by a factor 5 in places, making it a significant correction to the SMB estimate locally. We find that the strain correction changes the basin-wide SMB by ~0.7 Gt a−1 and thus forms a negligible (1%) correction to the glacier's total SMB.

ice core↗

NASA NTRS1972

Dynamics of stratified liquids in the presence of space charge.

The dispersion characteristics of small signal electrohydrodynamic space charge and polarization waves in continuously and discretely stratified liquids are developed. The liquids, modeled as incompressible, inviscid, and perfectly insulating have distributions of mass density, charge density, permittivity, and electric field. A general set of relations for perturbation field and flow variables defined for a prototype layer are used to describe the dynamics of many superposed planar layers. It is shown that the general relations can be used to represent systems of coupled layers which approximate continuous distributions by a series of step functions. Specific examples of weak gradient and exponential distributions are presented showing that the solution found directly from the distributed theory is approached by the system of coupled layers, if the limit is taken in which the number of layers become large while each layer thickness approaches zero.

Zahn, M.↗

NASA NTRS1997

Gas Dynamics, Characterization, and Calibration of Fast Flow Flight Cascade Impactor Quartz Crystal Microbalances (QCM) for Aerosol Measurements

During recent high altitude flights, we have tested the aerosol section of the fast flow flight cascade impactor quartz crystal microbalance (QCM) on loan to Howard University from NASA. The aerosol mass collected during these flights was disappointingly small. Increasing the flow through the QCM did not correct the problem. It was clear that the instrument was not being operated under proper conditions for aerosol collect ion primarily because the gas dynamics is not well understood. A laboratory study was therefore undertaken using two different fast flow QCM's in an attempt to establish the gas flow characteristics of the aerosol sections and its effect on particle collection, Some tests were made at low temperatures but most of the work reported here was carried out at room temperature. The QCM is a cascade type impactor originally designed by May (1945) and later modified by Anderson (1966) and Mercer et al (1970) for chemical gas analysis. The QCM has been used extensively for collecting and sizing stratospheric aerosol particles. In this paper all flow rates are given or corrected and referred to in terms of air at STP. All of the flow meters were kept at STP. Although there have been several calibration and evaluation studies of moderate flow cascade impactors of less than or equal to 1 L/rein., there is little experimental information on the gas flow characteristics for fast flow rates greater than 1 L/rein.

Grant, J.R.↗

NASA NTRS2004

Properties of Longitudinal Flux Tube Waves: Wave Propagation in Solar and Stellar Wind FLows - III

We discuss the analytic properties of longitudinal tube waves taking into account ambient wind flows. This is an extension of the studies of Papers I and II, which assumed a mean flow speed of zero and also dealt with a simplified horizontal pressure balance. Applications include the study of longitudinal flux tube waves in stars with significant mass loss and the heating and dynamics of plumes in the solar wind. Slow magnetosonic waves, also called longitudinal waves, have been observed in solar plumes and are likely an important source of heating. We show that the inclusion of ambient wind flows considerably alters the limiting shock strength as well as the energy damping length of the waves.

Cuntz, M.↗

NASA NTRS1980

Prediction of noise constrained optimum takeoff procedures

An optimization method is used to predict safe, maximum-performance takeoff procedures which satisfy noise constraints at multiple observer locations. The takeoff flight is represented by two-degree-of-freedom dynamical equations with aircraft angle-of-attack and engine power setting as control functions. The engine thrust, mass flow and noise source parameters are assumed to be given functions of the engine power setting and aircraft Mach number. Effective Perceived Noise Levels at the observers are treated as functionals of the control functions. The method is demonstrated by applying it to an Advanced Supersonic Transport aircraft design. The results indicate that automated takeoff procedures (continuously varying controls) can be used to significantly reduce community and certification noise without jeopardizing safety or degrading performance.

Padula, S. L.↗

NASA NTRS1989

A search for X-ray emission associated with the great attractor

A search is reported for X-ray emission associated with the object, dubbed the 'great attractor', which has been postulated as the cause of the coherent deviations from the Hubble flow which are observed in nearby parts of the universe. The hypothesis that a substantial fraction of the dynamical mass of the great attractor exists in the form of rich clusters of galaxies is ruled out. The possibility is considered that a substantial fraction of the mass of the great attractor could exist in a form which would increase the apparently diffuse X-ray surface brightness. The observational upper limit to the diffuse X-ray sky surface brightness enhancement in the general direction of the great attractor allows interesting limits to be set on the fraction of the dynamical mass of the great attractor which can exist in the form of X-ray-luminous material.

Jahoda, Keith↗

NASA NTRS1990

Nonlinear evolution of protostellar disks and light modulations in young stellar objects

An evolutionary model of dynamical processes in protostellar disks is described and illustrated with graphs of typical results. The effective transport mechanisms are discussed, including thermal convection, nonaxisymmetric gravitational instabilities in the outer regions of disks, and wave propagation. Consideration is then given to the stages of dynamical evolution, FU Ori outburst phenomena, unsteady accretion-disk flows, and nonlinear feedback as a mechanism to modulate mass transfer. The simulations show that mass redistribution is determined by angular-momentum transfer, which in turn is regulated by the effective viscosity generated by convectively driven turbulence. Significant mass transfer occurs as a result of mixing of infalling material with disk gas and is affected by the tidal torque associated with the growth of nonaxisymmetric disturbances in the outer disk. The time scale for disk evolution is found to be about 1 Myr.

Lin, D. N. C.↗

NASA NTRS1992

Full-scale high angle-of-attack tests of an F/A-18

This paper presents an overview of high angle-of-attack tests of a full-scale F/A-18 in the 80- by 120-Foot Wind Tunnel of the National Full-Scale Aerodynamic Complex at NASA Ames Research Center at Moffett Field, California. A production aircraft was tested over an angle-of-attack range of 18 to 50 deg and at wind speeds of up to 100 knots. These tests had three primary test objectives. Pneumatic and mechanical forebody flow control devices were tested at full-scale and shown to produce significant yawing moments for lateral control of the aircraft at high angles of attack. Mass flow requirements for the pneumatic system were found to scale with freestream density and speed rather than freestream dynamic pressure. Detailed measurements of the pressures buffeting the vertical tail were made and spatial variations in the buffeting frequency were found. The LEX fence was found to have a significant effect on the frequency distribution on the outboard surface of the vertical fin. In addition to the above measurements, an extensive set of data was acquired for the validation of computational fluid dynamics codes and for comparison with flight test and small-scale wind tunnel test results.

Meyn, Larry A.↗

NASA NTRSDate not supplied

Calorimeter Heat Flux Trends in NASA’s Subscale Rotating Detonation Rocket Engine

A calorimeter-style rotating detonation rocket engine (RDRE) outer chamber body was designed, additively manufactured in GRCop-42, and hot-fire tested in test cell 105 at NASA Marshall Space Flight Center (MSFC) in Huntsville, AL in August 2024. Steady-state, spatially resolved heat flux and chamber pressure were measured at 13 and 9 locations from the injector face, respectively, for a variety of test conditions and hardware configurations with gaseous methane and oxygen propellants. The 2-in. diameter highly instrumented design, enabled by metal additive manufacturing (AM), allowed for simultaneous measurement of heat flux and chamber pressure through 44 long duration hot-fire tests without failure. Of the 44 tests, only 3 of the tests featured chamber pressures below 100 psia and are discussed in this work. Heat flux trends for this subscale hardware are explored with respect to local propellant mass flux for several different injectors, chamber lengths, and chamber “subsonic” area ratios (contraction ratios). Results show that for increasing chamber pressure, a reduced amount of energy per kilogram of propellant is transferred to the wall. Switching injectors affects the near-face heat flux and chamber pressure profiles. Chamber length does not noticeably affect the heat flux profile but increases bulk heat load. A subsonic area ratio greater than 1 reduces heat losses to the wall compared to a straight annulus case. Equivalence ratio shift did not significantly affect heat flux. Computational fluid dynamics (CFD) and conjugate heat transfer (CHT) analyses were performed to delineate 3-D heat transfer and coolant mass flow maldistribution effects and create a calorimeter transfer function to transform heat flux data and mitigate the profile distortions. Additional CFD/CHT simulations were performed using experimental data as boundary conditions to assess local nucleate boiling propensity during testing and to assess projected hot wall temperatures for future fatigue assessment. Vapor fractions were observed locally for several cases. It is anticipated that this effort will provide a common framework for coolant system design/analysis in calorimeter systems for rocket-based and air-breathing combustors, ensuring greater repeatability in calorimetry measurements across the research community.

Joseph Hernandez-McCloskey↗

NASA NTRS2015

Arc Jet Facility Test Condition Predictions Using the ADSI Code

The Aerothermal Design Space Interpolation (ADSI) tool is used to interpolate databases of previously computed computational fluid dynamic solutions for test articles in a NASA Ames arc jet facility. The arc jet databases are generated using an Navier-Stokes flow solver using previously determined best practices. The arc jet mass flow rates and arc currents used to discretize the database are chosen to span the operating conditions possible in the arc jet, and are based on previous arc jet experimental conditions where possible. The ADSI code is a database interpolation, manipulation, and examination tool that can be used to estimate the stagnation point pressure and heating rate for user-specified values of arc jet mass flow rate and arc current. The interpolation is performed in the other direction (predicting mass flow and current to achieve a desired stagnation point pressure and heating rate). ADSI is also used to generate 2-D response surfaces of stagnation point pressure and heating rate as a function of mass flow rate and arc current (or vice versa). Arc jet test data is used to assess the predictive capability of the ADSI code.

fluid dynamics↗

NASA NTRS2011

Experimental Determination of the Dynamic Hydraulic Transfer Function for the J-2X Oxidizer Turbopump: Methodology - Part One

An advanced methodology for extracting the hydraulic dynamic pump transfer matrix (Yp) for a cavitating liquid rocket engine turbopump inducer+impeller has been developed. The transfer function is required for integrated vehicle pogo stability analysis as well as optimization of local inducer pumping stability. Laboratory pulsed subscale waterflow test of the J-2X oxygen turbo pump is introduced and our new extraction method applied to the data collected. From accurate measures of pump inlet and discharge perturbational mass flows and pressures, and one-dimensional flow models that represents complete waterflow loop physics, we are able to derive Yp and hence extract the characteristic pump parameters: compliance, pump gain, impedance, mass flow gain. Detailed modeling is necessary to accurately translate instrument plane measurements to the pump inlet and discharge and extract Yp. We present the MSFC Dynamic Lump Parameter Fluid Model Framework and describe critical dynamic component details. We report on fit minimization techniques, cost (fitness) function derivation, and resulting model fits to our experimental data are presented. Comparisons are made to alternate techniques for spatially translating measurement stations to actual pump inlet and discharge.

Zoladz, Tom↗