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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Reynolds Number Effects on a 5.2%-Scale High Lift Common Research Model

A 5.2%-scale High Lift Common Research Model (CRM-HL) semispan wind tunnel model was tested at the National Transonic Facility (NTF) wind tunnel in Hampton, VA. One of the primary objectives of the NTF test was to determine the effect of varying Reynolds number on the configuration. The test used a combination of air and cryogenic nitrogen testing to obtain up to flight-like Reynolds numbers. The landing and takeoff configurations of the model were tested at speeds ranging from Mach 0.2 to 0.35. The Reynolds numbers based on the mean aerodynamic chord of the model ranged from 1.6 to 30 million. Overall, the lift increased and drag decreased with increasing Reynolds number for chord Reynolds numbers less than 16 million, following well-established trends. However, some anomalies in the force and moment data were observed in the linear region of the angle of attack range that did not follow expected trends. The force and moment results for both the landing and takeoff configurations are presented, along with surface pressure data for the landing configuration. Incremental effects from the landing gear, nacelle, and horizontal tail on the landing configuration are also presented.

CRM-HL↗
NASA NTRSDate not supplied

Reynolds Number Effects on a 5.2%-Scale High Lift Common Research Model

A 5.2%-scale High Lift Common Research Model (CRM-HL) semispan wind tunnel model was tested at the National Transonic Facility (NTF) wind tunnel in Hampton, VA. One of the primary objectives of the NTF test was to determine the effect of varying Reynolds number on the configuration. The test used a combination of air and cryogenic nitrogen testing to obtain up to flight-like Reynolds numbers. The landing and takeoff configurations of the model were tested at speeds ranging from Mach 0.2 to 0.35. The Reynolds numbers based on the mean aerodynamic chord of the model ranged from 1.6 to 30 million. Overall, the lift increased and drag decreased with increasing Reynolds number for chord Reynolds numbers less than 16 million, following well-established trends. However, some anomalies in the force and moment data were observed in the linear region of the angle of attack range that did not follow expected trends. The force and moment results for both the landing and takeoff configurations are presented, along with surface pressure data for the landing configuration. Incremental effects from the landing gear, nacelle, and horizontal tail on the landing configuration are also presented.

CRM-HL↗
NASA NTRS2002

Simulated Space Vacuum Ultraviolet (VUV) Exposure Testing for Polymer Films

Vacuum ultraviolet (VUV) radiation of wavelengths between 115 and 200 nm produced by the sun in the space environment can cause degradation to polymer films producing changes in optical, mechanical, and chemical properties. These effects are particularly important for thin polymer films being considered for ultra-lightweight space structures, because, for most polymers, VUV radiation is absorbed in a thin surface layer. NASA Glenn Research Center has developed facilities and methods for long-term ground testing of polymer films to evaluate space environmental VUV radiation effects. VUV exposure can also be used as part of sequential simulated space environmental exposures to determine combined damaging effects. This paper will describe the effects of VUV on polymer films and the necessity for ground testing. Testing practices used at Glenn Research Center for VUV exposure testing will be described including characterization of the VUV radiation source used, calibration procedures traceable to the National Institute of Standards and Technology (NIST), and testing techniques for VUV exposure of polymer surfaces.

Dever, Joyce A.↗
NASA NTRS2000

FDNS CFD Code Benchmark for RBCC Ejector Mode Operation: Continuing Toward Dual Rocket Effects

Computational Fluid Dynamics (CFD) analysis results are compared with benchmark quality test data from the Propulsion Engineering Research Center's (PERC) Rocket Based Combined Cycle (RBCC) experiments to verify fluid dynamic code and application procedures. RBCC engine flowpath development will rely on CFD applications to capture the multi -dimensional fluid dynamic interactions and to quantify their effect on the RBCC system performance. Therefore, the accuracy of these CFD codes must be determined through detailed comparisons with test data. The PERC experiments build upon the well-known 1968 rocket-ejector experiments of Odegaard and Stroup by employing advanced optical and laser based diagnostics to evaluate mixing and secondary combustion. The Finite Difference Navier Stokes (FDNS) code [2] was used to model the fluid dynamics of the PERC RBCC ejector mode configuration. Analyses were performed for the Diffusion and Afterburning (DAB) test conditions at the 200-psia thruster operation point, Results with and without downstream fuel injection are presented.

West, Jeff↗
NASA NTRS2016

Wind Tunnel Test of Subscale Ringsail and Disk-Gap-Band Parachutes

A subsonic wind tunnel test was conducted to determine the drag and static aerodynamic coefficients, as well as to capture the dynamic motions of a new Supersonic Ringsail parachute developed by the Low Density Supersonic Decelerator Project. To provide a comparison against current Mars parachute technology, the Mars Science Laboratory's Disk-Gap-Band parachute was also included in the test. To account for the effect of fabric permeability, two fabrics ("low" and "standard" permeability) were used to fabricate each parachute canopy type, creating four combinations of canopy type and fabric material. A wide range of test conditions were covered during the test, spanning Mach numbers from 0.09 to 0.5, and static pressures from 103 to 2116 pounds per square inch (psf) (nominal values). The fabric permeability is shown to have a first-order effect on the aerodynamic coefficients and dynamic motions of the parachutes. For example, for a given parachute type and test condition, models fabricated from "low" permeability fabric always have a larger drag coefficient than models fabricated from "standard" permeability material. This paper describes the test setup and conditions, how the results were analyzed, and presents and discusses a sample of the results. The data collected during this test is being used to create and improve parachute aerodynamic databases for use in flight dynamics simulations for missions to Mars.

Zumwalt, Carlie H.↗
NASA NTRS1957

Static Longitudinal and Lateral Stability Characteristics at Low Speed of 45 Degree Sweptback-midwing Models Having Wings with an Aspect Ratio of 2, 4, or 6

Results are presented of tests conducted in the Langley stability tunnel to determine the effects of various components and combinations of components on the static longitudinal and lateral stability characteristics at low speed of a series of 45 degree sweptback-midwing-airplane configurations having wings with an aspect ratio of 2, 4, or 6. The tests were made at a dynamic pressure of 24.9 pounds per square foot which corresponds to a Mach number of 0.13 and Reynolds numbers of 1.00 x 10(exp 6), 0.71 x 10 (exp 6), and 0.58 x 10 (exp 6) based on the respective wing mean aerodynamic chords. The angle-of-attack range covered was from -4 degrees to 32 degrees and the sideslip angles used for the lateral-derivative tests were 5 degrees and -5 degrees. An increasing loss in tail contribution to directional stability both with increasing wing aspect ratio and increasing angle of attack was found to be a principal cause of all the complete models becoming directionally unstable in the high angle-of-attack range.

STABILITY, LONGITUDINAL - STATIC↗
NASA NTRS2016

Capabilities of the Environmental Effects Branch at Marshall Space Flight Cente

The Environmental Effects Branch at the Marshall Space Flight Center supports a myriad array of programs for NASA, DoD, and commercial space including human exploration, advanced space propulsion, improving life on Earth, and the study of the Sun, the Earth, and the solar system. The branch provides testing, evaluation, and qualification of materials for use on external spacecraft surfaces and in contamination-sensitive systems. Space environment capabilities include charged particle radiation, ultraviolet radiation, atomic oxygen, impact, plasma, and thermal vacuum, anchored by flight experiments and analysis of returned space hardware. These environmental components can be combined for solar wind or planetary surface environment studies or to evaluate synergistic effects. The Impact Testing Facility allows simulation of impacts ranging from sand and rain to micrometeoroids and orbital debris in order to evaluate materials and components for flight and ground-based systems. The Contamination Control Team is involved in the evaluation of environmentally-friendly replacements for HCFC-225 for use in propulsion oxygen systems, developing cleaning methods for additively manufactured hardware, and reducing risk for the Space Launch System.

Rogers, Jan↗
NASA NTRS2004

Real-Time Measurements of Aft Dome Insulation Erosion on Space Shuttle Reusable Solid Rocket Motor

Real-time erosion of aft dome internal insulation was measured with internal instrumentation on a static test of a lengthened version of the Space Shuffle Reusable Solid Rocket Motor (RSRM). This effort marks the first time that real-time aft dome insulation erosion (Le., erosion due to the combined effects of thermochemical ablation and mechanical abrasion) was measured in this kind of large motor static test [designated as Engineering Test Motor number 3 (ETM3)I. This paper presents data plots of the erosion depth versus time. The data indicates general erosion versus time behavior that is in contrast to what would be expected from earlier analyses. Engineers have long known that the thermal environment in the aft dome is severe and that the resulting aft dome insulation erosion is significant. Models of aft dome erosion involve a two-step process of computational fluid dynamics (CFD) modeling and material ablation modeling. This modeling effort is complex. The time- dependent effects are difficult to verify with only prefire and postfire insulation measurements. Nozzle vectoring, slag accumulation, and changing boundary conditions will affect the time dependence of aft dome erosion. Further study of this data and continued measurements on future motors will increase our understanding of the aft dome flow and erosion environment.

McWhorter, Bruce↗
NASA NTRS1989

Sliding seal materials for low heat rejection engines

Sliding friction coefficients and wear rates of promising piston seal materials were measured under temperature, environmental, velocity, and loading conditions that are representative of the low heat rejection (LHR) diesel engine environment. These materials included carbides, oxides, and nitrides. In addition, silicon nitride and partially stablized zirconia disks (cylinder liners) were ion-implanted with TiNi, Ni, Co, and Cr, and subsequently run against carbide pins (piston rings), with the objective of producing reduced friction via solid lubrication at elevated temperature. Friction and wear measurements were obtained using pin-on-disk laboratory experiments and a unique engine friction test rig. Unmodified ceramic sliding couples were characterized at all temperatures by friction coefficients of 0.24 and above during the pin-on-disk tests. The coefficient at 800 C in an oxidizing environment was reduced to below 0.1, for certain material combination, by the ion-implantation of TiNi or Co. This beneficial effect was found to derive from the lubricious Ti, Ni, and Co oxides. Similar results were demonstrated on the engine friction test rig at lower temperatures. The structural integrity and feasibility of engine application with the most promising material combination were demonstrated during a 30-hour single-cylinder, direct-injection diesel engine test.

Beaty, Kevin↗
NASA NTRS1980

Experimental determination of pure rotary stability derivatives using curved and rolling flow wind tunnel

The technique of using a curved and rolling flow wind tunnel to extract pure rotary stability derivatives is presented. Descriptions of the curved flow and the rolling flow test sections of the Virginia Tech Stability Wind Tunnel are given including methods for obtaining the proper velocity profiles and correcting the data acquired. Results of testing current fighter configurations in this facility are presented with particular attention given to comparing pure rotary derivatives with combined rotary and unsteady derivatives obtained by standard oscillation tests. Also the effect of curved and rolling flow on lateral static stability derivatives is examined.

Lutze, F. H.↗
NASA NTRS1992

Scaling Of Responses Of Composite Beams

Report describes series of experiments in which scale-model composite beams made of matrix/fiber composite materials tested to failure under combined axial compressive and bending loads. Discusses scaling effects in static large-deflection response of composite beams.

Jackson, Karen E.↗
NASA NTRS2007

Viability of NLCD Products From IRS-P6, And From Landsat 7 Scan-gap Data

Landcover test on Salt Lake test site illustrates potential issues with AWiFS/LISS-III for classification of certain land cover classes (evergreen, shrub/scrub, woody wetlands, emergent wetlands). Canopy and impervious graphs of product differences from source indicate slightly lower overall accuracies (shorter peaks, wider bases) for AWiFS/LISS-III, compared to L5/L7. Inspection of individual products from canopy and impervious estimate tests revealed issues with combining AWifs quadrants, and similar but less severe effects with combining multiple dates of L7 scan gap data.

Coan, Michael↗
NASA NTRS2020

An Over-the-Rotor Liner Investigation with Configurations Enabled by Additive Manufacturing

This paper presents the results of an investigation of over-the-rotor acoustic liner configurations enabled by additive manufacturing. NASA Langley and Glenn Research Centers have collaborated on the usage of acoustic liners in the turbofan aircraft engine nacelle wall at or very near the tip of the rotor. These liners absorb rotor-alone and rotor-stator interaction noise and, due to their proximity to the rotor tips, serve as a pressure release to inhibit the amount of generated noise. Initial tests with a metallic foam liner demonstrated good acoustic results, but there was concern regarding the durability of the material. NASA then decided to explore configurations enabled by additive manufacturing via tests in the NASA Langley Normal Incidence Tube. Measured data for uniform-depth and variable-depth cores with narrow and wide chambers were compared with predictions via the NASA Langley impedance prediction model. As these configurations were intended for eventual use in an over-the-rotor application, it was necessary to add facesheets to the wide-chamber cores to avoid deleterious flow effects caused by open cavities. A number of facesheets were tested in combination with each wide-chamber core. Finally, it has been shown that grooves near the rotor tips cause an improvement in aerodynamic performance. A small set of grooves were fabricated such that they could be combined with the wide-chamber configurations. The results of these tests were subsequently used to guide designs for further testing in higher technology readiness level test rigs at NASA Glenn Research Center.

acoustic↗
NASA NTRS2003

Graphite/Ultra-High Modulus Polyethylene Hybrid Fiber Composites with Epoxy and Polyethylene Matrices for Cosmic Radiation Shielding

One of the most significant technical challenges in long-duration space missions is that of protecting the crew from harmful radiation. Protection against such radiation on a manned Mars mission will be of vital importance both during transit and while on the surface of the planet. The development of multifunctional materials that serve as integral structural members of the space vehicle and provide the necessary radiation shielding for the crew would be both mission enabling and cost effective. Additionally, combining shielding and structure could reduce total vehicle mass. Hybrid laminated composite materials having both ultramodulus polyethylene (PE) and graphite fibers in epoxy and PE matrices could meet such mission requirements. PE fibers have excellent physical properties, including the highest specific strength of any known fiber. Moreover, the high hydrogen (H) content of polyethylene makes the material an excellent shielding material for cosmic radiation. When such materials are incorporated into an epoxy or PE matrix a very effective shielding material is expected. Boron (B) may be added to the matrix resin or used as a coating to further increase the shielding effectiveness due to B s ability to slow thermal neutrons. These materials may also serve as micrometeorites shields due to PE s high impact energy absorption properties. It should be noted that such materials can be fabricated by existing equipment and methods. It is the objective of this work therefore to: (a) perform preliminary analysis of the radiation transport within these materials; (b) fabricate panels for mechanical property testing before and after radiation exposure. Preliminary determination on the effectiveness of the combinations of material components on both shielding and structural efficiency will be made.

Source record↗
NASA NTRS1975

On the effect of emotional states on operator thinking

A combination sonic and electrical skin stimuli stress test is reported that is suitable for the psychological selection of individuals to perform operator functions. The behavior of these people is characterized by a fighting spirit, increased work capacity, minimum expenditure of strength and insignificant fatigue.

Solodkova, A. V.↗
NASA NTRS2014

Preliminary Analysis of Aircraft Loss of Control Accidents: Worst Case Precursor Combinations and Temporal Sequencing

Aircraft loss of control (LOC) is a leading cause of fatal accidents across all transport airplane and operational classes, and can result from a wide spectrum of hazards, often occurring in combination. Technologies developed for LOC prevention and recovery must therefore be effective under a wide variety of conditions and uncertainties, including multiple hazards, and their validation must provide a means of assessing system effectiveness and coverage of these hazards. This requires the definition of a comprehensive set of LOC test scenarios based on accident and incident data as well as future risks. This paper defines a comprehensive set of accidents and incidents over a recent 15 year period, and presents preliminary analysis results to identify worst-case combinations of causal and contributing factors (i.e., accident precursors) and how they sequence in time. Such analyses can provide insight in developing effective solutions for LOC, and form the basis for developing test scenarios that can be used in evaluating them. Preliminary findings based on the results of this paper indicate that system failures or malfunctions, crew actions or inactions, vehicle impairment conditions, and vehicle upsets contributed the most to accidents and fatalities, followed by inclement weather or atmospheric disturbances and poor visibility. Follow-on research will include finalizing the analysis through a team consensus process, defining future risks, and developing a comprehensive set of test scenarios with correlation to the accidents, incidents, and future risks. Since enhanced engineering simulations are required for batch and piloted evaluations under realistic LOC precursor conditions, these test scenarios can also serve as a high-level requirement for defining the engineering simulation enhancements needed for generating them.

Belcastro, Christine M.↗
NASA NTRS1993

What LDEF means for development and testing of materials

The Long Duration Exposure Facility (LDEF) served as the ultimate laboratory to provide combined space environmental effects on materials. The LDEF structure and its 57 experiments contained an estimated 12,000 to 14,000 specimens of materials and materials processes. It not only provided information about the resistance of these materials to the space environment but gives us direction into future needs for spacecraft materials development and testing. This paper provides an overview of the materials effects observed on the satellite and suggests recommendations for the future work in space-qualified materials development and space environmental simulation.

Whitaker, Ann F.↗