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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 1,351 records · Page 75
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Performance and Wake Characterization of a Model Hydrokinetic Turbine: The Reference Model 1 (RM1) Dual Rotor Tidal Energy Converter

The mechanical power and wake flow field of a 1:40 scale model of the US Department of Energy’s Reference Model 1 (RM1) dual rotor tidal energy converter are characterized in an open-channel flume to evaluate power performance and wake flow recovery. The NACA-63(4)-24 hydrofoil profile in the original RM1 design is replaced with a NACA-4415 profile to minimize the Reynolds dependency of lift and drag characteristics at the test chord Reynolds number. Precise blade angular position and torque measurements were synchronized with three acoustic Doppler velocimeters (ADV) aligned with each rotor centerline and the midpoint between the rotor axes. Flow conditions for each case were controlled to maintain a hub height velocity, uhub= 1.04 ms−1, a flow Reynolds number, ReD= 4.4 × 105, and a blade chord length Reynolds number, Rec= 3.1 × 105. Performance was measured for a range of tip-speed ratios by varying rotor angular velocity. Peak power coefficients, CP= 0.48 (right rotor) and CP= 0.43 (left rotor), were observed at a tip speed ratio, λ= 5.1. Vertical velocity profiles collected in the wake of each rotor between 1 and 10 rotor diameters are used to estimate the turbulent flow recovery in the wake, as well as the interaction of the counter-rotating rotor wakes. The observed performance characteristics of the dual rotor configuration in the present study are found to be similar to those for single rotor investigations in other studies. Similarities between dual and single rotor far-wake characteristics are also observed.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2021

Impact of Rheology Models on Horizontal Well Polymer Flooding in a Heavy Oil Reservoir on Alaska North Slope: A Simulation Study

Polymer rheology can have either a positive or a negative effect on polymer flooding performance under varied circumstances. Many researchers have studied the effect of polymer rheology in a vertical well, but no field scale studies have been conducted to investigate whether polymer rheology is beneficial to polymer flooding in heavy oil reservoirs developed by horizontal wells. In this paper, we conducted a numerical simulation study to examine the effect of HPAM polymer rheology on a polymer flooding pilot, which is the first-ever project conducted on a heavy oil reservoir from Alaska North Slope (ANS) developed by horizontal wells. Three rheology types were considered in the study including the apparent viscosity measured during coreflooding of using a HPAM polymer, the bulk viscosity measured with a viscometer, and a Newtonian flow model. The results suggest that using the bulk viscosity in simulation underestimates the conformance control and the water-oil-ratio reduction capability of the HPAM polymer solution. When the apparent viscosity is used, the incremental oil and sweep were largely increased, and the optimal recovery period of polymer flooding was extended greatly, especially for the heterogeneous formations. Therefore, the rheology type of polymer plays a significant role in the incremental oil recovery and injection profile of the horizontal well system given the pilot test conditions. This study has provided practical guidance to field operators for the ongoing polymer flooding pilot on ANS and will also provide valuable information for other polymer projects conducted in similar conditions.

Leng, Jianqiao↗
DOE OSTI2020

Modelling mixed-phase clouds with the large-eddy model UCLALES–SALSA

The large-eddy model UCLALES–SALSA, with an exceptionally detailed aerosol description for both aerosol number and chemical composition, has been extended for ice and mixed-phase clouds. Comparison to a previous mixed-phase cloud model intercomparison study confirmed the accuracy of newly implemented ice microphysics. A further simulation with a heterogeneous ice nucleation scheme, in which ice-nucleating particles (INPs) are also a prognostic variable, captured the typical layered structure of Arctic mid-altitude mixed-phase cloud: a liquid layer near cloud top and ice within and below the liquid layer. In addition, the simulation showed a realistic freezing rate of droplets within the vertical cloud structure. The represented detailed sectional ice microphysics with prognostic aerosols is crucially important in reproducing mixed-phase clouds.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1967

Application of distorted models in developing scaled structural models

In the design and development of dynamically similar structural models a distorted model of the panel is used. The panel thickness is made larger than that dictated by geometric scaling, and the mass of the panel is decreased by adding mass to the surface of the panel to counteract the additional stiffness obtained by the thickness increase.

White, R. W.↗
NASA NTRS1973

V/STOL tilt rotor study. Volume 6: Hover, low speed and conversion tests of a tilt rotor aeroelastic model (Model 300)

Stability and control tests of a scale model of a tilt rotor research aircraft were conducted. The characteristics of the model for hover, low speed, and conversion flight were analyzed. Hover tests were conducted in a rotor whirl cage. Helicopter and conversion tests were conducted in a low speed wind tunnel. Data obtained from the tests are presented as tables and graphs. Diagrams and illustrations of the test equipment are provided.

Marr, R. L.↗
NASA NTRS1975

Radiation cooler for 10 micrometer wavelength engineering model receiver model no. 7172, serial no. 201

The design, fabrication, and testing of a radiative cooler are described. This cooler is an engineering model suitable for bench testing in the laboratory as a part of the 10-micrometer wavelength engineering model receiver, and conforms to the standard radiative cooler configuration, except that the inner stage and its support system were redesigned to accommodate the larger, heavier SAT detector. This radiative cooler will cool the detector to cryogenic temperature levels when the receiver is in a space environment or in a suitable thermal vacuum chamber. Equipment specifications are given along with the results of thermal tests, vibration tests, and electrical integrity tests.

Source record↗
NASA NTRS1974

CNO abundances and hydrodynamic models of the nova outburst. II - 1.00 solar mass models with enhanced carbon and oxygen

Results of a computation of a variety of evolutionary sequences involving thermonuclear runaways in the hydrogen-rich envelopes of 1.00-solar-mass carbon-oxygen white dwarfs. The evidence concerning the location of the outburst in the nova system is reexamined, and it is concluded that the white dwarf is the seat of the outburst. An order-of-magnitude argument is presented which indicates that for a 1.00-solar-mass white dwarf it is impossible to achieve mass ejection without an energy generation of approximately 10 to the 16th ergs/g/sec. A description is given of models with low nuclear enhancements that do not produce an outburst, although their evolution has certain implications for the cause of the dwarf-nova outburst. The results for models that produced a nova outburst are then presented, and on the basis of these results it is found possible to explain continuous ejection, Kukarkin and Parenago's (1934) relationship, and other gross features of the nova phenomena.

Starrfield, S.↗
NASA NTRS1975

Mated aerodynamic characteristics investigation for 0.04-scale model Boeing 747 CAM/external tank (model AX1284 E-5) combination in the University of Washington Aeronautical Laboratory F. K. Kirsten Wind Tunnel (CA11)

Experimental investigations of the aerodynamic characteristics of a 0.04-scale external tank (ET) force model in combination with a 0.04-scale Boeing 747 force model were conducted. Test purposes were: (1) to determine ET airloads for selected configurations and (2) to determine the effectiveness of ET position, incidence, and support structure and 747 vertical stabilizing surfaces on stability, control, and performance of 747/ET combinations. The 747 was tested alone to establish baseline data and to verify test results. Six-component aerodynamic force and moment data were recorded for the 747 CAM and ET combination. Six-component force and moment data were also recorded for the ET, which was mounted on an internal balance supported by the 747. Data were recorded for angles of attack from -4 deg to +24 deg in 2 deg increments and angles of sideslip of - deg to + or - 20 deg. Testing was conducted at Mach 0.15 with dynamic pressure deg at 36 psf and unit Reynolds number of 1.3 million per foot. Photographs of test configurations are shown.

Source record↗
NASA NTRS1976

Encounters of spherical galaxies. I - Galaxy models with one stellar population. II - Galaxy models with two stellar populations

Close encounters between two spherical galaxies of equal size and consisting of only one stellar population are calculated using models of elliptical galaxies constructed according to King's (1966) method. The mass loss and the change in internal energy are computed under the assumption that the stars do not change their velocity or density distributions during the encounters. The results for a specific case are compared with the calculations of Gallagher and Ostriker (1972), who employed the observed brightness distribution and the derived density distribution of the E1 galaxy NGC 3379. For models with one stellar population, the results suggest that the radius of a galactic halo would have to be at least 200 kpc for appreciable mass loss to occur over the history of a galaxy in a rich cluster. The calculations are then extended to include a halo population characterized by a high central velocity dispersion. In this case, it is found that the halo population of sufficiently large galaxies can be dispersed without appreciably affecting the main population. It is suggested that the missing mass of many clusters of galaxies may be located in an intergalactic sea of faint stars making up an envelope for the centrally located gE galaxies.

Biermann, P.↗
NASA NTRS1976

A low speed wind tunnel test of a 0.050 scale model of shuttle orbiter (model 089B) to investigate the longitudinal and lateral directional effects of canard and tail configurational modifications in the LTV LSWT (MA14)

A low speed wind tunnel test was conducted to determine the effects of 6 canard configurations on the 0.050 scale model of shuttle orbiter 089B. In addition, two horizontal tail configurations were tested at two positions on the model as were two wing configurations. Since this test was restricted to 103 runs, only a limited number of permutations of the configurational changes could be tested. The testing was done in the 15 by 20 foot section of the LSWT and consisted of pitch polars, one yawed polar and several yaw runs. The pitch polars encompassed an alpha range from 0 to 28 deg; the yawed polar was run at beta = +2 degrees and the yaw runs covered a beta range from -6 to +6 deg at angles-of-attack of 0, 4, 10, 16, and 20 deg.

Chambliss, E. B.↗
NASA NTRS1977

Remote sensing inputs to landscape models which predict future spatial land use patterns for hydrologic models

A tropical forest area of Northern Thailand provided a test case of the application of the approach in more natural surroundings. Remote sensing imagery subjected to proper computer analysis has been shown to be a very useful means of collecting spatial data for the science of hydrology. Remote sensing products provide direct input to hydrologic models and practical data bases for planning large and small-scale hydrologic developments. Combining the available remote sensing imagery together with available map information in the landscape model provides a basis for substantial improvements in these applications.

Miller, L. D.↗