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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 847 records · Page 47

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NASA NTRS1975

NASA aircraft noise reduction research and technology program overview

A brief outline of the chief areas where NASA is making efforts in aircraft noise research is given. This includes studies of the physical basis of aircraft noise and methods for accurately predicting it, the development of practical technologies for noise reduction, and the subjective response of people when exposed to aircraft noise. The JT8D Refan Program was to explore whether the noise reduction design concepts used effectively in modern high-bypass engines could also be applied practically and effectively as retrofittable modifications to existing older, low-bypass JT8D engines. A program has been completed on developing and demonstrating safe and acceptable flight procedures together with necessary airborne electronics to permit two-segment approaches under either VFR or IFR conditions.

Johnson, H. W.↗

NASA NTRS1983

Mobile radio alternative systems study, executive summary

Present day mobile communication technologies, systems and equipment are described from background in evaluating the concepts generated in the study. Average propagation ranges are calculated for terrestrial installations in each of seven physiographic areas of the contiguous states to determine the number of installations that would be required for nationwide coverage. Four system concepts are defined and analyzed to determine how well terrestrial systems can fulfill the requirements at acceptable costs.

Anderson, R. E.↗

NASA NTRS2008

Science Goals in Radiation Protection for Exploration

Space radiation presents major challenges to future missions to the Earth s moon or Mars. Health risks of concern include cancer, degenerative and performance risks to the central nervous system, heart and lens, and the acute radiation syndromes. The galactic cosmic rays (GCR) contain high energy and charge (HZE) nuclei, which have been shown to cause qualitatively distinct biological damage compared to terresterial radiation, such as X-rays or gamma-rays, causing risk estimates to be highly uncertain. The biological effects of solar particle events (SPE) are similar to terresterial radiation except for their biological dose-rate modifiers; however the onset and size of SPEs are difficult to predict. The high energies of GCR reduce the effectiveness of shielding, while SPE s can be shielded however the current gap in radiobiological knowledge hinders optimization. Methods used to project risks on Earth must be modified because of the large uncertainties in projecting health risks from space radiation, and thus impact mission requirements and costs. We describe NASA s unique approach to radiation safety that applies probabilistic risk assessments and uncertainty based criteria within the occupational health program for astronauts and to mission design. The two terrestrial criteria of a point estimate of maximum acceptable level of risk and application of the principle of As Low As Reasonably Achievable (ALARA) are supplemented by a third requirement that protects against risk projection uncertainties using the upper 95% confidence level (CL) in radiation risk projection models. Exploration science goals in radiation protection are centered on ground-based research to achieve the necessary biological knowledge, and in the development of new technologies to improve SPE monitoring and optimize shielding. Radiobiology research is centered on a ground based program investigating the radiobiology of high-energy protons and HZE nuclei at the NASA Space Radiation Laboratory (NSRL) located at DoE s Brookhaven National Laboratory in Upton, NY. We describe recent NSRL results that are closing the knowledge gap in HZE radiobiology and improving exploration risk estimates. Linking probabilistic risk assessment to research goals makes it possible to express risk management objectives in terms of quantitative metrics, which include the number of days in space without exceeding a given risk level within well defined confidence limits, and probabilistic assessments of the effectiveness of design trade spaces such as material type, mass, solar cycle, crew selection criteria, and biological countermeasures. New research in SPE alert and risk assessment, individual radiation sensitivity, and biological countermeasure development are described.

Cucinotta, Francs A.↗

NASA NTRS2010

Functional Allocation for Ground-Based Automated Separation Assurance in NextGen

As part of an ongoing research effort into functional allocation in a NextGen environment, a controller-in-the-loop study on ground-based automated separation assurance was conducted at NASA Ames' Airspace Operations Laboratory in February 2010. Participants included six FAA front line managers, who are currently certified professional controllers and four recently retired controllers. Traffic scenarios were 15 and 30 minutes long where controllers interacted with advanced technologies for ground-based separation assurance, weather avoidance, and arrival metering. The automation managed the separation by resolving conflicts automatically and involved controllers only by exception, e.g., when the automated resolution would have been outside preset limits. Results from data analyses show that workload was low despite high levels of traffic, Operational Errors did occur but were closely tied to local complexity, and safety acceptability ratings varied with traffic levels. Positive feedback was elicited for the overall concept with discussion on the proper allocation of functions and trust in automation.

Prevot, Thomas↗

NASA NTRS2016

Space Suit Portable Life Support System (PLSS) 2.0 Unmanned Vacuum Environment Testing

For the first time in more than 30 years, an advanced space suit Portable Life Support System (PLSS) design was operated inside a vacuum chamber representative of the flight operating environment. The test article, PLSS 2.0, was the second system-level integrated prototype of the advanced PLSS design, following the PLSS 1.0 Breadboard that was developed and tested throughout 2011. Whereas PLSS 1.0 included five technology development components with the balance the system simulated using commercial-off-the-shelf items, PLSS 2.0 featured first generation or later prototypes for all components less instrumentation, tubing and fittings. Developed throughout 2012, PLSS 2.0 was the first attempt to package the system into a flight-like representative volume. PLSS 2.0 testing included an extensive functional evaluation known as Pre-Installation Acceptance (PIA) testing, Human-in-the-Loop testing in which the PLSS 2.0 prototype was integrated via umbilicals to a manned prototype space suit for 19 two-hour simulated EVAs, and unmanned vacuum environment testing. Unmanned vacuum environment testing took place from 1/9/15-7/9/15 with PLSS 2.0 located inside a vacuum chamber. Test sequences included performance mapping of several components, carbon dioxide removal evaluations at simulated intravehicular activity (IVA) conditions, a regulator pressure schedule assessment, and culminated with 25 simulated extravehicular activities (EVAs). During the unmanned vacuum environment test series, PLSS 2.0 accumulated 378 hours of integrated testing including 291 hours of operation in a vacuum environment and 199 hours of simulated EVA time. The PLSS prototype performed nominally throughout the test series, with two notable exceptions including a pump failure and a Spacesuit Water Membrane Evaporator (SWME) leak, for which post-test failure investigations were performed. In addition to generating an extensive database of PLSS 2.0 performance data, achievements included requirements and operational concepts verification, as well as demonstration of vehicular interfaces, consumables sizing and recharge, and water quality control.

Watts, Carly↗

NASA NTRS1979

Development of non-volatile semiconductor memory

A 256 word by 8-bit random access memory chip was developed utilizing p channel, metal gate metal-nitride-oxide-silicon (MNOS) technology; with operational characteristics of a 2.5 microsecond read cycle, a 6.0 microsecond write cycle, 800 milliwatts of power dissipation; and retention characteristics of 10 to the 8th power read cycles before data refresh and 5000 hours of no power retention. Design changes were implemented to reduce switching currents that caused parasitic bipolar transistors inherent in the MNOS structure to turn on. Final wafer runs exhibited acceptable yields for a die 250 mils on a side. Evaluation testing was performed on the device in order to determine the maturity of the device. A fixed gate breakdown mechanism was found when operated continuously at high temperature.

Heikkila, W. W.↗

NASA NTRS1982

Hot isostatically pressed manufacture of high strength MERL 76 disk and seal shapes

The feasibility of using MERL 76, an advanced high strength direct hot isostatic pressed powder metallurgy superalloy, as a full scale component in a high technology, long life, commercial turbine engine were demonstrated. The component was a JT9D first stage turbine disk. The JT9D disk rim temperature capability was increased by at least 22 C and the weight of JT9D high pressure turbine rotating components was reduced by at least 35 pounds by replacement of forged Superwaspaloy components with hot isostatic pressed (HIP) MERL 76 components. The process control plan and acceptance criteria for manufacture of MERL 76 HIP consolidated components were generated. Disk components were manufactured for spin/burst rig test, experimental engine tests, and design data generation, which established lower design properties including tensile, stress-rupture, 0.2% creep and notched (Kt = 2.5) low cycle fatigue properties, Sonntag, fatigue crack propagation, and low cycle fatigue crack threshold data. Direct HIP MERL 76, when compared to conventionally forged Superwaspaloy, is demonstrated to be superior in mechanical properties, increased rim temperature capability, reduced component weight, and reduced material cost by at least 30% based on 1980 costs.

Eng, R. D.↗

NASA NTRS1988

Space Station propulsion system test bed

The test bed to study H2/O2 propulsion technology for the Space Station is discussed. The test bed consists of propellant accumulators, valving, instrumentation, and controls configured in a 9-ft cube. A water electrolysis module was added to simulate the baseline propulsion system configuration. The activation of the test bed is described, and results are presented from tests of the system, including verification of the control system, thruster tests, electrolysis system testing, and acceptance test, oxidizer system, and fuel system blowdowns.

Norman, A. M.↗

NASA NTRS2001

Institutionalizing Lessons Learned

The NASA Integrated Action Team (NIAT) was formed by the NASA Administrator in March 2000. The purpose of this team was to identify the actions that NASA must take to address systemic findings reported in 4 different anomaly investigations. Team membership represented senior managers from all the field centers and NASA Headquarters. NIAT report addressed 165 findings and developed 17 action plans that are described in five themes: people and teams, technology, risk, formulation rigor, and communications. The NIAT actions present a systems solution for strengthening formulation and implementation of programs and improving the environment for their support. NIAT results included: enhancing success by avoiding failures that could have been prevented through good planning and sound practice; ensuring that prudent risks do not compromise safety; and ensuring that mission risks are objectively assessed, appropriately mitigated and consciously accepted by the program team and customers. Definitions of Faster, Better, Cheaper and Success Criteria were also developed and included as part of the NIAT report. As a result of the NIAT report, program and project management process changes were incorporated into NASA's quality system documentation, including NPG 7120.513, "NASA Program and Project Management Processes and Requirements. This paper describes the NIAT results and the resulting updates to NPG 7120.5 that keep this program and project management description a living process.

McBrayer, Robert O.↗

NASA NTRS2004

A Study on the Requirements for Fast Active Turbine Tip Clearance Control Systems

This paper addresses the requirements of a control system for active turbine tip clearance control in a generic commercial turbofan engine through design and analysis. The control objective is to articulate the shroud in the high pressure turbine section in order to maintain a certain clearance set point given several possible engine transient events. The system must also exhibit reasonable robustness to modeling uncertainties and reasonable noise rejection properties. Two actuators were chosen to fulfill such a requirement, both of which possess different levels of technological readiness: electrohydraulic servovalves and piezoelectric stacks. Identification of design constraints, desired actuator parameters, and actuator limitations are addressed in depth; all of which are intimately tied with the hardware and controller design process. Analytical demonstrations of the performance and robustness characteristics of the two axisymmetric LQG clearance control systems are presented. Takeoff simulation results show that both actuators are capable of maintaining the clearance within acceptable bounds and demonstrate robustness to parameter uncertainty. The present model-based control strategy was employed to demonstrate the tradeoff between performance, control effort, and robustness and to implement optimal state estimation in a noisy engine environment with intent to eliminate ad hoc methods for designing reliable control systems.

DeCastro, Jonathan A.↗

NASA NTRS1981

Advanced oxygen-hydrocarbon rocket engine study

This study identifies and evaluates promising LO2/HC rocket engine cycles, produces a consistent and reliable data base for vehicle optimization and design studies, demonstrates the significance of propulsion system improvements, and selects the critical technology areas necessary to realize an improved surface to orbit transportation system. Parametric LO2/HC engine data were generated over a range of thrust levels from 890 to 6672 kN (200K to 1.5M 1bF) and chamber pressures from 6890 to 34500 kN (1000 to 5000 psia). Engine coolants included RP-1, refined RP-1, LCH4, LC3H8, LO2, and LH2. LO2/RP-1 G.G. cycles were found to be not acceptable for advanced engines. The highest performing LO2/RP-1 staged combustion engine cycle utilizes LO2 as the coolant and incorporates an oxidizer rich preburner. The highest performing cycle for LO2/LCH4 and LO2/LC3H8 utilizes fuel cooling and incorporates both fuel and oxidizer rich preburners. LO2/HC engine cycles permitting the use of a third fluid LH2 coolant and an LH2 rich gas generator provide higher performance at significantly lower pump discharge pressures. The LO2/HC dual throat engine, because of its high altitude performance, delivers the highest payload for the vehicle configuration that was investigated.

Obrien, C. J.↗

NASA NTRS1982

Possible safety hazards associated with the operation of the 0.3-m transonic cryogenic tunnel at the NASA Langley Research Center

The 0.3 m Transonic Cryogenic Tunnel (TCT) at the NASA Langley Research Center was built in 1973 as a facility intended to be used for no more than 60 hours in order to verify the validity of the cryogenic wind tunnel concept at transonic speeds. The role of the 0.3 m TCT has gradually changed until now, after over 3000 hours of operation, it is classified as a major NASA research facility and, under the administration of the Experimental Techniques Branch, it is used extensively for the testing of airfoils at high Reynolds numbers and for the development of various technologies related to the efficient operation and use of cryogenic wind tunnels. The purpose of this report is to document the results of a recent safety analysis of the 0.3 m TCT facility. This analysis was made as part of an on going program with the Experimental Techniques Branch designed to ensure that the existing equipment and current operating procedures of the 0.3 m TCT facility are acceptable in terms of today's standards of safety for cryogenic systems.

Webster, T. J.↗

NASA NTRS1996

Sensors for Environmental Control

Under a Kennedy Space Center Small Business Innovation Research contract, GEO-CENTERS, Inc. developed a sensing element or 'optrode,' which NASA needed for space life support research to measure a hydroponic culture's pH factor. The company then commercialized the technology in the PC Based pH Monitoring System. The system employs the optrode to enable long term continuous monitoring of the pH level of fluids in standing and flowing conditions, an optoelectronic board with light sensors and detectors that fits into a desktop computer, and a fiber optic cable that connects the two. The system is effective in monitoring the pH output of industries to maintain ranges acceptable to the Environmental Protection Agency.

Source record↗

NASA NTRS2005

Overview of 10 inch Diameter HTPB Hybrid Motor Testing with Liquid Oxygen at Stennis Space Center

To further explore the operation of hybrid rocket motors and to demonstrate the performance characteristics of the motor design Lockheed Martin funded research on a series of 10 inch diameter hybrid motors that produce less than 10 klbf sea level thrust. This test series was given the name "Hybrid Technology Test Program." These motors were fired in the existing test stand at the SSC E-3 complex Cell 1. The fuel and oxidizer for these 10 inch diameter motors are HTPB and LO2, respectively. The original goal of the testing was to verify that the predicted performance matched the actual performance of these 10 inch motors (ref. figure 1) and then confirm that the motors performed acceptably. For this element of testing horizontally fired hybrid motors will be tested using LO2 supplied from the existing facility 100 gallon LO2 tank that is pressurized with facility GN2. The thrust produced by the motor will be measured by a Lockheed Martin supplied load cell.

Knowles, Timothy E.↗

NASA NTRS2017

Development of Reliable Life Support Systems

The life support systems on the International Space Station (ISS) are the culmination of an extensive effort encompassing development, design, and test to provide the highest possible confidence in their operation on ISS. Many years of development testing are initially performed to identify the optimum technology and the optimum operational approach. The success of this development program depends on the accuracy of the system interfaces. The critical interfaces include the specific operational environment, the composition of the waste stream to be processed and the quality of the product. Once the development program is complete, a detailed system schematic is built based on the specific design requirements, followed by component procurement, assembly, and acceptance testing. A successful acceptance test again depends on accurately simulating the anticipated environment on ISS. The ISS Water Recovery System (WRS) provides an excellent example of where this process worked, as well as lessons learned that can be applied to the success of future missions. More importantly, ISS has provided a test bed to identify these design issues. Mechanical design issues have included an unreliable harmonic drive train in the Urine Processor's fluids pump, and seals in the Water Processor's Catalytic Reactor with insufficient life at the operational temperature. Systems issues have included elevated calcium in crew urine (due to microgravity effect) that resulted in precipitation at the desired water recovery rate, and the presence of an organosilicon compound (dimethylsilanediol) in the condensate that is not well removed by the water treatment process. Modifications to the WRS to address these issues are either complete (and now being evaluated on ISS) or are currently in work to insure the WRS has the required reliability before embarking on a mission to Mars.

Carter, Layne↗

NASA NTRS2017

Development of Reliable Life Support Systems

Carter, Layne↗

NASA NTRS1999

Investigation of Wake-Vortex Aircraft Encounters

The National Aeronautics and Space Administration is addressing airport capacity enhancements during instrument meteorological conditions though the Terminal Area Productivity (TAP) program. The major goal of the TAP program is to develop the technology that will allow air traffic levels during instrument meteorological condition to approach those achieved during visual operations. The Reduced Spacing Operations (RSO) subelement of TAP at the NASA Langley Research Center (LaRC) will develop the Aircraft Vortex Spacing System (AVOSS). The purpose of the AVOSS is to integrate current and predicted weather conditions, wake vortex transport and decay knowledge, wake vortex sensor data, and operational definitions of acceptable strengths for vortex encounters to produce dynamic wake vortex separation criteria. The proposed research is in support of the wake vortex hazard definition component of the LaRC AVOSS development research. The research program described in the next section provided an analysis of the static test data and uses this data to evaluate the accuracy vortex/wake-encounter models. The accuracy of these models has not before been evaluated using experimental data. The research results also presented the first analysis of the forces and moments imparted on an airplane during a wake vortex encounter using actual flight test data.

Smith, Sonya T.↗

NASA NTRS1997

Application of Laser Based Ultrasound for NDE of Damage in Thick Stitched Composites

As design engineers implement new composite systems such as thick, load bearing composite structures, they must have certifiable confidence in structure s durability and worthiness. This confidence builds from understanding the structural response and failure characteristics of simple components loaded in testing machines to tests on full scale sections. Nondestructive evaluation is an important element which can provide quantitative information on the damage initiation, propagation, and final failure modes for the composite structural components. Although ultrasound is generally accepted as a test method, the use of conventional ultrasound for in-situ monitoring of damage during tests of large structures is not practical. The use of lasers to both generate and detect ultrasound extends the application of ultrasound to in- situ sensing of damage in a deformed structure remotely and in a non-contact manner. The goal of the present research is to utilize this technology to monitor damage progression during testing. The present paper describes the application of laser based ultrasound to quantify damage in thick stitched composite structural elements to demonstrate the method. This method involves using a Q-switched laser to generate a rapid, local linear thermal strain on the surface of the structure. This local strain causes the generation of ultrasonic waves into the material. A second laser used with a Fabry-Perot interferometer detects the surface deflections. The use of fiber optics provides for eye safety and a convenient method of delivering the laser over long distances to the specimens. The material for these structural elements is composed of several stacks of composite material assembled together by stitching through the laminate thickness that ranging from 0.5 to 0.8 inches. The specimens used for these nondestructive evaluation studies had either impact damage or skin/stiffener interlaminar failure. Although little or no visible surface damage existed, internal damage was detected by laser based ultrasound.

Anastasi, Robert F.↗