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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 1,315 records · Page 73

All sources NASA NTRS DOE OSTI

NASA NTRS2001

Reynolds Number Effects on a Supersonic Transport at Transonic Conditions

A High Speed Civil Transport configuration was tested in the National Transonic Facility at the NASA Langley Research Center as part of NASA's High Speed Research Program. The primary purposes of the tests were to assess Reynolds number scale effects and the high Reynolds number aerodynamic characteristics of a realistic, second generation supersonic transport while providing data for the assessment of computational methods. The tests included longitudinal and lateral/directional studies at low speed high-lift and transonic conditions across a range of Reynolds numbers from that available in conventional wind tunnels to near flight conditions. Results are presented which focus on both the Reynolds number and static aeroelastic sensitivities of longitudinal characteristics at Mach 0.90 for a configuration without an empennage.

Wahls, R. N.↗

NASA NTRS2002

Reynolds Number Effects on the Stability and Control Characteristics of a Supersonic Transport

A High Speed Civil Transport (HSCT) configuration was tested in the National Transonic Facility at the NASA Langley Research Center as part of NASA's High Speed Research Program. A series of tests included longitudinal and lateral/directional studies at transonic and low speed, high-lift conditions across a range of Reynolds numbers from that available in conventional wind tunnels to near flight conditions. Results presented focus on Reynolds number sensitivities of the stability and control characteristics at Mach 0.30 and 0.95 for a complete HSCT aircraft configuration including empennage. The angle of attack where the pitching-moment departure occurred increased with higher Reynolds numbers for both the landing and transonic configurations. The stabilizer effectiveness increased with Reynolds number for both configurations. The directional stability also increased with Reynolds number for both configurations. The landing configuration without forebody chines exhibited a large yawing-moment departure at high angles of attack and zero sideslip that varied with increasing Reynolds numbers. This departure characteristic nearly disappeared when forebody chines were added. The landing configuration's rudder effectiveness also exhibited sensitivities to changes in Reynolds number.

Owens, L. R.↗

DOE OSTI2022

Testing and Simulation of an Updated Cartridge Loop Vehicle

The Versatile Test Reactor (VTR) is a sodium-cooled, fast-spectrum test reactor that is being developed in the United States and will support a variety of irradiation test vehicle configurations, including cartridge loops. This work includes out-of-pile experimental results from a single-phase, natural circulation cartridge loop vehicle with geometry relevant to VTR irradiation sites, as well as comparisons between the experimental results and results predicted using the TRAC/RELAP Advanced Computational Engine (TRACE) modeling tool. The experiments were conducted in the thermosyphon test loop (TSTL) facility at Oak Ridge National Laboratory. Comparisons are also made between the current experimental data and results from natural circulation experiments previously conducted in the TSTL in a cartridge vehicle that is similar in design but has smaller flow areas. This cartridge vehicle and the experimental program were developed to add to the single-phase, natural circulation data collected in the previous iteration of the cartridge loop design, which supports future irradiation experiments and adds to a database that is useful for validating computer models. Comparisons of experimental results to TRACE model predictions is a pertinent step in validating the computational tool for supporting future irradiation experiment design and safety calculations, and comparisons to previous cartridge loop results highlight the impact of the design changes made to the test vehicle. The experiments conducted include several steady state tests and transients, including power ramp, loss of offsite power, and loss of external flow scenarios. This work shows that TRACE can accurately predict temperatures and flow conditions in the cartridge loop and the updated vehicle design achieves higher mass flow rates at the same steady state power levels.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

NASA NTRS1974

LST secondary mirror articulation mechanism

The analysis, design, manufacture, test, and delivery of one secondary mirror articulation mechanism for the large space telescope (LST) are reported. The mechanism provides angular freedom about two axes that are perpendicular to the optical axis of the secondary mirror. Motion in each axis is controlled from two sources; one source provides alignment, the other source provides stabilization. Two articulation mechanism configurations were evaluated. In one configuration the stabilization system was assembled with piezoelectric actuators. In the second configuration the stabilization system utilized flexure torque motor actuators. The alignment system was the same for both configurations. System testing confirmed performance that met or exceeded all operational requirements. The two types of stabilization actuators had different performance characteristics. Both types demonstrated position resolution and frequency response better than specified limits.

Source record↗

NASA NTRS1979

Experimental investigation of effects of blade tip geometry on loads and performance for an articulated rotor system

Wind-tunnel tests of an aeroelastically designed helicopter rotor model were carried out to determine the effects on dynamic response and aerodynamic performance of varying the design of the outboard 8 percent of the blade lengths. Four different blade tip geometries or shapes having different amounts of planform sweep, thickness and chordwise taper, and anhedral angle were studied. Each configuration was tested at several shaft angles of attack for advance ratios of 0.20, 0.30, 0.35, and 0.40. For each combination of shaft angle and advance ratio, rotor lift was varied over a wide range to include high lift conditions.

Weller, W. H.↗

NASA NTRS2009

Supersonic Testing of 0.8 m Disk Gap Band Parachutes in the Wake of a 70 Deg Sphere Cone Entry Vehicle

Supersonic wind tunnel testing of Viking-type 0.8 m Disk-Gap-Band (DGB) parachutes was conducted in the NASA Glenn Research Center 10'x10' wind-tunnel. The tests were conducted in support of the Mars Science Laboratory Parachute Decelerator System development and qualification program. The aerodynamic coupling of the entry-vehicle wake to parachute flow-field is under investigation to determine the cause and functional dependence of a supersonic canopy breathing phenomenon referred to as area oscillations, characteristic of DGB's above Mach 1.5 operation. Four percent of full-scale parachutes (0.8 m) were constructed similar to the flight-article in material and construction techniques. The parachutes were attached to a 70-deg sphere-cone entry-vehicle to simulate the Mars flight configuration. The parachutes were tested in the wind-tunnel from Mach 2 to 2.5 in a Reynolds number range of 2x105 to 1x106, representative of a Mars deployment. Three different test configurations were investigated. In the first two configurations, the parachutes were constrained horizontally through the vent region to measure canopy breathing and wake interaction for fixed trim angles of 0 and 10 degrees from the free-stream. In the third configuration the parachute was unconstrained, permitted to trim and cone, similar to free-flight (but capsule motion is constrained), varying its alignment relative to the entry-vehicle wake. Non-intrusive test diagnostics were chosen to quantify parachute performance and provide insight into the flow field structure. An in-line loadcell provided measurement of unsteady and mean drag. Shadowgraph of the upstream parachute flow field was used to capture bow-shock motion and wake coupling. Particle image velocimetry provided first and second order flow field statistics over a planar region of the flow field, just upstream of the parachute. A photogrammetric technique was used to quantify fabric motion using multiple high speed video cameras to record the location in time and space of reflective targets placed on the canopy interior. The experimental findings including an updated drag model and the physical basis of the area oscillation phenomenon will be discussed.

EDL↗

NASA NTRS2003

Stage Separation Wind Tunnel Tests of a Generic Two-Stage-to-Orbit Launch Vehicle

In support of NASA s Space Launch Initiative Program, stage separation wind tunnel tests of a generic two-stage-to-orbit (TSTO) launch vehicle were conducted to determine the interference aerodynamic forces and moments and to determine the proximity flow environment. The tests were conducted in the NASA Marshall Space Flight Center s Aerodynamic Research Facility using a manual separation fixture for a Mach number range of 2.74 to 4.96 and separation distances up to 80 percent and 35 percent of the body length in the vehicle X and Z coordinates, respectively. For the TSTO bimese, winged-body vehicle configuration, both wing-to-wing and wing-to-fuselage configurations were tested. Individual-body force and moment, schlieren, and surface pressure data were acquired. The results showed that the proximity aerodynamics were dominated by complex bow shock interactions, and that he booster was statically unstable at several separation positions. As compared to the isolated body, the proximity normal force change with pitch angle was found to be nearly the same, and the proximity axial force increased, in general, by 3% for both bodies.

Bordelon, Wayne J., Jr.↗

NASA NTRS1984

Analysis and testing of a new method for drop size measurement using laser scatter interferometry

Research was conducted on a laser light scatter detection method for measuring the size and velocity of spherical particles. The method is based upon the measurement of the interference fringe pattern produced by spheres passing through the intersection of two laser beams. A theoretical analysis of the method was carried out using the geometrical optics theory. Experimental verification of the theory was obtained by using monodisperse droplet streams. Several optical configurations were tested to identify all of the parametric effects upon the size measurements. Both off-axis forward and backscatter light detection were utilized. Simulated spray environments and fuel spray nozzles were used in the evaluation of the method. The measurements of the monodisperse drops showed complete agreement with the theoretical predictions. The method was demonstrated to be independent of the beam intensity and extinction resulting from the surrounding drops. Signal processing concepts were considered and a method was selected for development.

Bachalo, W. D.↗

NASA NTRS1968

Aerodynamic Characteristics of Several Hypersonic Boost-Glide-Type Configurations at Mach Numbers from 2.30 to 4.63

An investigation has been conducted at Mach numbers from 2.30 to 4.63 to determine the static aerodynamic characteristics of several configurations designed for flight at hypersonic Mach numbers. Two all-wing and three wing-body configurations were tested through an angle-of-attack range from about -4 degrees to 33 degrees and an angle-of-sideslip range from about -4 degrees to 8 degrees at a Reynolds number of 3 times 10 (sup 6) per foot (9.84 times 10 (sup 6) per meter). The results of the investigation indicated that the wing-body configurations produced higher values of maximum lift-drag ratio than those produced by the all-wing models. The high wing-body configurations tend to have a self-trimming capability as opposed to that for the low wing-body configurations. Each of the configurations produced a positive dihedral effect that increased with increasing angle of attack and decreased with increasing Mach number. The high wing-body models produced decreasing values of directional stability with increase in angle of attack, whereas the low wing-body models provided increasing values of directional stability with increase in angle of attack.

Graves, Ernald B.↗

NASA NTRS2006

Designing and Testing a Blended Wing Body with Boundary Layer Ingestion Nacelles

A knowledge-based aerodynamic design method coupled with an unstructured grid Navier-Stokes flow solver was used to improve the propulsion/airframe integration for a Blended Wing Body with boundary-layer ingestion nacelles. A new zonal design capability was used that significantly reduced the time required to achieve a successful design for each nacelle and the elevon between them. A wind tunnel model was built with interchangeable parts reflecting the baseline and redesigned configurations and tested in the National Transonic Facility (NTF). Most of the testing was done at the cruise design conditions (Mach number = 0.85, Reynolds number = 75 million). In general, the predicted improvements in forces and moments as well as the changes in wing pressures between the baseline and redesign were confirmed by the wind tunnel results. The effectiveness of elevons between the nacelles was also predicted surprisingly well considering the crudeness in the modeling of the control surfaces in the flow code.

Carter, Melissa B.↗

NASA NTRS1975

Hypersonic engine airplane integration

A summary of the research activities is presented along with the design and analysis of an integrated scramjet engine which utilizes heat conduction flames. The scramjet engine model described was tested at a freestream Mach number of 4.0 by personnel at the General Applied Science Laboratory. The research effort was primarily concerned with the interpretation and analysis of the experimental data. The mixing tests were conducted with cold ambient air, while the combustion tests were conducted with hot vitiated air. The purpose of the cold mixing tests was to determine the degree of mixedness of the fuel at the ignitor station so as to certify if the fuel injection conditions and fuel injectors locations were properly selected to give a uniform fuel concentration profile at the ignitor station. A second objective was to assess the influence of the fuel injection on the inlet flow. Several fuel injection configurations were tested.

Source record↗

NASA NTRS1984

Wind-Tunnel Investigation of an Advanced General Aviation Canard Configuration

Wind-tunnel tests of a model of an advanced canard configuration designed for general aviation were conducted in the Langley 30- by 60-Foot Tunnel. The objective of the tests was to determine the aerodynamic stability and control characteristics of the configuration for a large range of angles of attack and sideslip at several power conditions. Analysis of the aerodynamic data indicates significant effects of power and of center-of-gravity location. For forward center-of-gravity locations, the configuration had extremely stall-resistant stability and control characteristics. For aft center-of-gravity locations and high-power conditions, the combined effects of increased pitch control and reduced longitudinal stability overpowered the stall resistance provided by the canard, which led to a high-angle-of-attack, deep-stall trim condition. Other aspects of the aerodynamic characteristics studied include the following: flow-visualization study, effect of negative angles of attack, lateral-directional characteristics, and comparison of the stall characteristics with another canard configuration.

Chambers, J. R.↗

NASA NTRS2005

Design and Testing of a Blended Wing Body With Boundary Layer Ingestion Nacelles at High Reynolds Numbers

Campbell, Richard L.↗

NASA NTRS2010

HOPE: An On-Line Piloted Handling Qualities Experiment Data Book

A novel on-line database for capturing most of the information obtained during piloted handling qualities experiments (either flight or simulated) is described. The Hyperlinked Overview of Piloted Evaluations (HOPE) web application is based on an open-source object-oriented Web-based front end (Ruby-on-Rails) that can be used with a variety of back-end relational database engines. The hyperlinked, on-line data book approach allows an easily-traversed way of looking at a variety of collected data, including pilot ratings, pilot information, vehicle and configuration characteristics, test maneuvers, and individual flight test cards and repeat runs. It allows for on-line retrieval of pilot comments, both audio and transcribed, as well as time history data retrieval and video playback. Pilot questionnaires are recorded as are pilot biographies. Simple statistics are calculated for each selected group of pilot ratings, allowing multiple ways to aggregate the data set (by pilot, by task, or by vehicle configuration, for example). Any number of per-run or per-task metrics can be captured in the database. The entire run metrics dataset can be downloaded in comma-separated text for further analysis off-line. It is expected that this tool will be made available upon request

Jackson, E. B.↗

NASA NTRSDate not supplied

Testing of a Multi-Stringer Post-Buckled Panel with Incremental Damage Detection

A multi-stringer panel was designed and tested to produce a failure mode of skin-stiffener delamination due to compression loading of a post-buckled skin to support the validation of high-fidelity progressive damage failure analysis modeling. The test procedure included multiple methods of data acquisition ranging from multiple strain gages, front and back digital image correlation, passive thermography, acoustic emission, and ultrasonic inspection to capture key events and damage progression prior to catastrophic failure. Detailed data showing the initial stiffness, onset of skin buckling, buckled mode shape, damage initiation load, damage propagation morphology, and peak load was captured. Two panel configurations were tested. The first had a Teflon insert placed in the interface between the skin and the stiffener flanges adjacent to the center skin bay. The second was subjected to impact damage to the skin-stiffener flange. In each case, continuously-loaded-to-failure tests were conducted first with passive thermography being used exclusively to determine key damage events. Then, incrementally loaded tests were completed where ultrasonic inspections were conducted between each increment. The amount of load applied between each increment was determined based on the in-situ damage detection provided by the passive thermography system. The results of the testing showed a complex delamination growth pattern which migrated between ply interfaces through matrix splits in the upper skin ply of the panel. The result of the testing produced very detailed data which will prove to be useful for validation of delamination growth and migration predictions from progressive damage failure analysis methods.

Jason Action↗

NASA NTRS1990

Flow visualization in a simulated brush seal

A method to visualize and characterize the complex flow fields in simulated brush seals is presented. The brush seal configuration was tested in a water and then in an oil tunnel. The visualization procedure revealed typical regions that are rivering, jetting, vortical or lateral flows and exist upstream, downstream or within the seal. Such flows are engendered by variations in fiber void that are spatial and temporal and affect changes in seal leakage and stability. While the effects of interface motion for linear or cylindrical configurations have not been considered herein, it is believed that the observed flow fields characterize flow phenomenology in both circular and linear brush seals. The axial pressure profiles upstream, across and downstream of the brush in the oil tunnel have been measured under a variety of inlet pressure conditions and the ensuing pressure maps are presented and discussed.

Braun, M. J.↗

NASA NTRS1983

Large-area sheet task advanced dendritic web growth development

The thermal stress models were used to test the effect of melt level on stress generation and growth velocity. The results indicate that melt level has only small effects on stresses but significant effects on growth velocity. These results are consistent with experimental growth from measured melt levels. A new low-stress design concept is being evaluated with the models. A width-limiting version of the low-stress J460 configuration was tested experimentally with results consistent with the design goals.

Duncan, C. S.↗

NASA NTRS1987

Aerothermal evaluation of a spherically blunted body with a trapezoidal cross section in the Langley 8-foot high-temperature tunnel

A model to be used in the flow studies and curved Thermal Protection System (TPS) evaluations was tested in the Langley 8 Foot High-Temperature Tunnel at a nominal Mach number of 6.8. The purpose of the study was to define the surface pressure and heating rates at high angles of attack (in support of curved metallic TPS studies) and to determine the conditions for which the model would be suitable as a test bed for aerothermal load studies. The present study was conducted at a nominal total temperature of 2400 and 3300 R, dynamic pressures from 2.3 to 10.9 psia, and free-stream Reynolds numbers from 4000,000 to 1,700,000/ft. The measurements consisted primarily of surface pressure and cold-wall (530 R) heating rates. Qualitative comparisons between predictions and data show that for this configuration, aerothermal tests should be limited to angles of attack between 10 and -10 degrees. Outside this range, the effects of free-stream flow nonuniformity appear in the data, as a result of the long length of the model. However, for TPS testing, this is not a concern and tests can be performed at angles of attack ranging from 20 to -20 degrees. Laminar and naturally turbulent boundary layers are available over limited ranges of conditions.

Albertson, Cindy W.↗