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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Blade row interaction effects on flutter and forced response

In the flutter or forced response analysis of a turbomachine blade row, the blade row in question is commonly treated as if it is isolated from the neighboring blade rows. Disturbances created by vibrating blades are then free to propagate away from this blade row without being disturbed. In reality, neighboring blade rows will reflect some portion of this wave energy back toward the vibrating blades, causing additional unsteady forces on them. It is of fundamental importance to determine whether or not these reflected waves can have a significant effect on the aeroelastic stability or forced response of a blade row. Therefore, a procedure to calculate intra-blade-row unsteady aerodynamic interactions has been developed which relies upon results available from isolated blade row unsteady aerodynamic analyses. In addition, an unsteady aerodynamic influence coefficient technique is used to obtain a model for the vibratory response in which the neighboring blade rows are also flexible. The flutter analysis shows that interaction effects can be destabilizing, and the forced response analysis shows that interaction effects can result in a significant increase in the resonant response of a blade row.

Buffum, Daniel H.↗
NASA NTRS1993

Blade row interaction effects on flutter and forced response

In the flutter or forced response analysis of a turbomachine blade row, the blade row in question is commonly treated as if it is isolated from the neigboring blade rows. Disturbances created by vibrating blades are then free to propagate away from this blade row without being disturbed. In reality, neighboring blade rows will reflect some portion of this wave energy back toward the vibrating blades, causing additional unsteady forces on them. It is of fundamental importance to determine whether or not these reflected waves can have a significant effect on the aeroelastic stability or forced response of a blade row. Therefore, a procedure to calculate intra-blade-row unsteady aerodynamic interactions was developed which relies upon results available from isolated blade row unsteady aerodynamic analyses. In addition, an unsteady aerodynamic influence coefficient technique is used to obtain a model for the vibratory response in which the neighboring blade rows are also flexible. The flutter analysis shows that interaction effects can be destabilizing, and the forced response analysis shows that interaction effects can result in a significant increase in the resonant response of a blade row.

Buffum, Daniel H.↗
DOE OSTI2019

Nuclear physics without high-momentum potentials: Constructing the nuclear effective interaction directly from scattering observables

The traditional approach to nuclear physics encodes phase shift information in a nucleon-nucleon (NN) potential, producing a nucleon-level interaction that captures the sub-GeV consequences of QCD. A further reduction to the nuclear scale is needed to produce an effective interaction for soft Hilbert spaces, such as those employed in the shell model. Here we describe an alternative construction of the effective interaction that is simple and quite precise, proceeding from the QCD scale directly to the nuclear scale. This eliminates the need for constructing and renormalizing the high-momentum NN potential. Instead, continuum phase shifts and mixing angles are used directly at the nuclear scale. The method exploits the analytic continuity in energy of HOBET (Harmonic-Oscillator-Based Effective Theory) to connect bound states to continuum solutions at specific energies. The procedure is systematic, cutoff independent, and convergent, yielding keV accuracy at NNLO or N 3 LO, depending on the channel. Lepage plots are provided.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1984

Impact of atmospheric uncertainties and viscous interaction effects on the performance of aeroassisted orbital transfer vehicles

Simulations of aerobraking trajectories of aeroassisted orbital transfer vehicles (AOTV's) returning from geosynchronous orbit were analyzed to examine the effects of high-altitude viscous interactions and off-nominal atmospheres on AOTV return weight, heating, and loads performance. Viscous interaction effects encountered at high altitudes had little detrimental effect on the return weight capabilities for AOTV's representing a range of lift/drag ratios. Most of the AOTV return weight increase over an all-propulsive OTV occurred for a low lift/drag ratio. Smaller increases in return weight were observed for higher lift/drag ratios, at the expense of significantly higher heating and aerodynamic loads. Off-nominal atmospheres based on Shuttle-derived data and multipliers on a U.S. Standard Atmosphere were considered. AOTV's intended for entry under standard atmospheric conditions either deorbited during the pass through the off-nominal atmospheres or missed the target phasing orbit by wide margins. The AOTV's could successfully negotiate these atmospheres when new bank-angle histories were implemented with little loss and sometimes with a gain in return weight.

Talay, T. A.↗
DOE OSTI2017

Perturbation theory of nuclear matter with a microscopic effective interaction

Here, an updated and improved version of the effective interaction based on the Argonne-Urbana nuclear Hamiltonian, derived using the formalism of correlated basis functions and the cluster expansion technique, is employed to obtain a number of properties of cold nuclear matter at arbitrary neutron excess within the formalism of many-body perturbation theory. The numerical results, including the ground-state energy per nucleon, the symmetry energy, the pressure, the compressibility, and the single-particle spectrum, are discussed in the context of the available empirical information, obtained from measured nuclear properties and heavy-ion collisions.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Differential charge radii: Proton-neutron interaction effects

The analysis of self-consistency and proton-neutron interaction effects in the buildup of differential charge radii were carried out in covariant density functional theoretical calculations without pairing interaction on the example of selected configurations in the Pb isotopes. The proton-neutron interaction of neutron(s) added to the neutron 𝑁 = 126 core and the protons forming the 𝑍 = 82 proton core is responsible for a major contribution to the buildup of differential charge radii. It depends on the products of proton and neutron wave functions and thus on their nodal structure. This interaction leads to a redistribution of single-particle density of occupied proton states which in turn modifies the charge radii. Furthermore, the microscopic origin of this redistribution and its consequences for differential charge radii were investigated for the first time. Self-consistency effects affecting the shape of proton potential, total proton densities and the energies of the single-particle proton states provide only minor contribution to differential charge radii.

190 ≤ A ≤ 219↗
NASA NTRS1994

Wall interaction effects for a full-scale helicopter rotor in the NASA Ames 80- by 120-foot wind tunnel

A full-scale helicopter rotor test was conducted in the NASA Ames 80- by 120-Foot Wind Tunnel with a four-bladed S-76 rotor system. This wind tunnel test generated a unique and extensive data base covering a wide range of rotor shaft angles-of-attack and rotor thrust conditions from 0 to 100 knots. Three configurations were tested: (1) empty tunnel; (2) test stand body (fuselage) and support system; and (3) fuselage and support system with rotor installed. Empty tunnel wall pressure data are evaluated as a function of tunnel speed to understand the baseline characteristics. Aerodynamic interaction effects between the fuselage and the walls of the tunnel are investigated by comparing wall, ceiling, and floor pressures for various tunnel velocities and fuselage angles-of-attack. Aerodynamic interaction effects between the rotor and the walls of the tunnel are also investigated by comparing wall, ceiling, and floor pressures for various rotor shaft angles, rotor thrust conditions, and tunnel velocities. Empty tunnel wall pressure data show good repeatability and are not affected by tunnel speed. In addition, the tunnel wall pressure profiles are not affected by the presence of the fuselage apart from a pressure shift. Results do not indicate that the tunnel wall pressure profiles are affected by the presence of the rotor. Significant changes in the wall, ceiling, and floor pressure profiles occur with changing tunnel speeds for constant rotor thrust and shaft angle conditions. Significant changes were also observed when varying rotor thrust or rotor shaft angle-of-attack. Other results indicate that dynamic rotor loads and blade motion are influenced by the presence of the tunnel walls at very low tunnel velocity and, together with the wall pressure data, provide a good indication of flow breakdown.

Shinoda, Patrick M.↗
NASA NTRS2008

Experimental Measurement of RCS Jet Interaction Effects on a Capsule Entry Vehicle

An investigation was made in NASA Langley Research Center s 31-Inch Mach 10 Tunnel to determine the effects of reaction-control system (RCS) jet interactions on the aft-body of a capsule entry vehicle. The test focused on demonstrating and improving advanced measurement techniques that would aid in the rapid measurement and visualization of jet interaction effects for the Orion Crew Exploration Vehicle while providing data useful for developing engineering models or validation of computational tools used to assess actual flight environments. Measurements included global surface imaging with pressure and temperature sensitive paints and three-dimensional flow visualization with a scanning planar laser induced fluorescence technique. The wind tunnel model was fabricated with interchangeable parts for two different aft-body configurations. The first, an Apollo-like configuration, was used to focus primarily on the forward facing roll and yaw jet interactions which are known to have significant aft-body heating augmentation. The second, an early Orion Crew Module configuration (4-cluster jets), was tested blowing only out of the most windward yaw jet, which was expected to have the maximum heating augmentation for that configuration. Jet chamber pressures and tunnel flow conditions were chosen to approximate early Apollo wind tunnel test conditions. Maximum heating augmentation values measured for the Apollo-like configuration (>10 for forward facing roll jet and 4 for yaw jet) using temperature sensitive paint were shown to be similar to earlier experimental results (Jones and Hunt, 1965) using a phase change paint technique, but were acquired with much higher surface resolution. Heating results for the windward yaw jet on the Orion configuration had similar augmentation levels, but affected much less surface area. Numerical modeling for the Apollo-like yaw jet configuration with laminar flow and uniform jet outflow conditions showed similar heating patterns, qualitatively, but also showed significant variation with jet exit divergence angle, with as much as 25 percent variation in heat flux intensity for a 10 degree divergence angle versus parallel outflow. These results along with the fabrication methods and advanced measurement techniques developed will be used in the next phase of testing and evaluation for the updated Orion RCS configuration.

Buck, Gregory M.↗
NASA NTRS2003

Blade Row Interaction Effects on the Performance of a Moderately Loaded NASA Transonic Compressor Stage

Blade row interaction effects on loss generation in compressors have received increased attention as compressor work-per-stage and blade loading have increased. Two dimensional Laser Doppler Velocimeter measurements of the velocity field in a NASA transonic compressor stage show the magnitude of interactions in the velocity field at the peak efficiency and near stall operating conditions. The experimental data are presented along with an assessment of the velocity field interactions. In the present study the experimental data are used to confirm the fidelity of a three-dimensional, time-accurate, Navier Stokes calculation of the stage using the MSU-TURBO code at the peak efficiency and near stall operating conditions. The simulations are used to quantify the loss generation associated with interaction phenomena. At the design point the stator pressure field has minimal effect on the rotor performance. The rotor wakes do have an impact on loss production in the stator passage at both operating conditions. A method for determining the potential importance of blade row interactions on performance is presented.

VanZante, Dale E.↗
DOE OSTI2019

Effective interactions in the s d shell

We perform here a quantitative study of the microscopic effective shell-model interactions in the valence sd shell, obtained from modern nucleon-nucleon potentials, chiral N3LO, JISP16 and Daejeon16, using No-Core Shell-Model wave functions and the Okubo-Lee-Suzuki transformation. We investigate the monopole properties of those interactions in comparison with the phenomenological universal sd-shell interaction, USDB. Theoretical binding energies and low-energy spectra of O isotopes and of selected sd-shell nuclei, are presented. We conclude that there is a noticeable improvement in the quality of the effective interaction when it is derived from the Daejeon16 potential. We show that its proton-neutron centroids are consistent with those from USDB. We then propose monopole modifications of the Daejeon16 centroids in order to provide an adjusted interaction yielding significantly improved agreement with the experiment. A spin-tensor decomposition of two-body effective interactions is applied in order to extract more information on the structure of the centroids and to understand the reason for deficiencies arising from our current theoretical approximations. The concern of the possible role of the three-nucleon forces is addressed.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Interaction Effects on the Dynamical Anderson Metal-Insulator Transition Using Kicked Quantum Gases

Understanding the interplay of interaction and disorder in quantum transport poses long-standing scientific challenges for theory and experiment. While highly controlled ultracold atomic platforms combining atomic interactions with spatially disordered lattices have led to remarkable advances, the extension of such controlled studies to phenomena in high-dimensional disordered systems, such as the three-dimensional Anderson metal-insulator transition has been limited. Kicked quantum gases provide an alternate experimental platform that captures the Anderson model in momentum space and features dynamical localization as the analog of Anderson localization. Here, we utilize a momentum space lattice platform using quasiperiodically kicked ultracold atomic gases to experimentally investigate interaction effects on the three-dimensional dynamical Anderson metal-insulator transition. Here, we observe interaction-driven subdiffusion and a divergence of delocalization onset time on approaching the phase boundary. Mean-field numerical simulations show qualitative agreement with experimental observations, but with significant quantitative deviations.

74 ATOMIC AND MOLECULAR PHYSICS↗
NASA NTRS1979

The analysis of propellers including interaction effects

Analytical and experimental studies were undertaken on propellers operating in the unsteady flow field produced by interaction effects due to the fuselage, wing, and nacelles. Methods were developed and verified experimentally for determining the velocity field in which a propeller operates as well as its aerodynamic and dynamic response to this unsteady environment. Methods are presented for predicting and net thrust of a propeller-wing-body combination as well as the unsteady thrust and torque acting on the propeller. Sample calculations as well as wind tunnel and flight test results are presented which illustrate the sensitivity of a propeller to the flow field in which it is operating.

Mccormick, B. W.↗
NASA NTRS1959

Interaction Effects Produced by Jet Exhausting Laterally Near Base of Ogive-Cylinder Model in Supersonic Main Stream

The experimentally determined interaction effects of a side jet exhausting near the base of an ogive-cylinder model are presented and discussed. The interaction force appears to be independent of main-stream Mach number, boundary-layer condition (laminar or turbulent), angle of attack, and forebody length. The ratio of interaction force to jet force is found to be inversely proportional to the square root of the product of jet stagnation-to-free-stream pressure ratio and jet-to-body diameter ratio.

Vinson, P. W.↗
NASA NTRS1994

Interactive effects of growth hormone and exercise on muscle mass in suspended rats

Measures to attenuate muscle atrophy in rats in response to simulated microgravity (hindlimb suspension (HS)) have been only partially successful. In the present study, hypophysectomized rats were in HS for 7 days, and the effects of recombinant human growth hormone (GH), exercise (Ex), or GH+Ex on the weights, protein concentrations, and fiber cross-sectional areas (CSAs) of hindlimb muscles were determined. The weights of four extensor muscles, i.e., the soleus (Sol), medial (MG) and lateral (LG) gastrocnemius, and plantaris (Plt), and one adductor, i.e., the adductor longus (AL), were decreased by 10-22% after HS. Fiber CSAs were decreased by 34% in the Sol and by 1 17% in the MG after HS. In contrast, two flexors, i.e., the tibialis anterior (TA) and extensor digitorum longus (EDL), did not atrophy. In HS rats, GH treatment alone maintained the weights of the fast extensors (MG, LG, Plt) and flexors (TA, EDL) at or above those of control rats. This effect was not observed in the slow extensor (Sol) or AL. Exercise had no significant effect on the weight of any muscle in HS rats. A combination of GH and Ex treatments yielded a significant increase in the weights of the fast extensors and in the CSA of both fast and slow fibers of the MG and significantly increased Sol weight and CSA of the slow fibers of the Sol. The AL was not responsive to either GH or Ex treatments. Protein concentrations of the Sol and MG were higher only in the Sol of Ex and GH+Ex rats. These results suggest that while GH treatment or intermittent high intensity exercise alone have a minimal effect in maintaining the mass of unloaded muscle, there is a strong interactive effect of these two treatments.

Grindeland, Richard E.↗
NASA NTRS1976

Gas interaction effects on lunar bonded particles and their implications

Results are reported for an experimental investigation of gas-interaction effects on different Apollo 11 and Apollo 12 lunar-soil samples containing bonded particles. In the experiments, lunar fines were exposed to pure O2, pure water vapor, HCl, NH3, N2, HCOOH, and CH3NH2, in order to observe whether bonded particles would separate. In addition, repeated gas adsorption/desorption measurements were performed to determine the nature and reactive properties of the particle surfaces, and surface areas were measured for comparison with analogous terrestrial samples to determine whether the surface areas of highly radiation-damaged particles were larger or smaller. It is found that N2 is apparently ineffective in separating bonded particles and that the ratio of Apollo 11 to Apollo 12 bonded particles separated by a particular gas exposure ranges from 2.5 to 3.0. Possible reasons for differences in material surface properties at the two Apollo sites are considered, and it is concluded that material from a certain depth at some other site was transported to the Apollo 12 site and mixed with the original material in recent years (considerably less than 2000 years ago).

Mukherjee, N. R.↗