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At least 559 records · Page 31

All sources NASA NTRS DOE OSTI

NASA NTRS1995

Design and development of a high-speed bearing test rig

The development of a high-speed test rig, to be used for compiling an experimental data base of bearing signatures for bearings with known faults, is described. This bearing test rig can be adapted to test oil-film bearings as well as rolling element bearings. This is achieved by mounting the test bearing in one of two special test housings, either of which can be mounted onto a common test shaft which can be driven up to 30,000 rpm. The test bearing housing for rolling element bearings can accommodate proximity displacement transducers, accelerometers, thermocouples, and acoustic emission sensors. The test bearing housing for the fluid-film bearings can accommodate the same instrumentation as well as Bourdon tube-type transducers for measuring oil film pressures around the bearing circumference.

Cockburn, J. A.↗

NASA NTRS1997

Three-Wave Gas Journal Bearing Behavior With Shaft Runout

Experimental orbits of a free-mounted, three-wave gas journal bearing housing were recorded and compared to transient predicted orbits. The shaft was mounted eccentric with a fixed runout. Experimental observations for both the absolute bearing housing center orbits and the relative bearing housing center to shaft center orbits are in good agreement with the predictions. The sub-synchronous whirl motion generated by the fluid film was found experimentally and predicted theoretically for certain speeds. A three-wave journal bearing can run stably under dynamic loads with orbits well inside the bearing clearance. Moreover, the orbits are almost circular free of the influence of bearing wave shape.

Dimofte, Florin↗

NASA NTRS1994

Development of an Advanced Animal Habitat for Spaceflight

It is necessary to fly a group-housed animals for many Life Science spaceflight studies. Currently, group-housed rodents are flown aboard the shuttle in the Animal Enclosure Module (AEM). Although the AEM has been used successfully for a number of flights, it has significant limitations in the number of animals it can accommodate, limited flight duration, passive temperature control and limited in flight data acquisition capability. An Advanced Animal Habitat (AAH) is being developed, which can be flown on the shuttle middeck, both spacelab and spacehab shuttle payload modules, and the space station. The AAH is designed to house 12 rats or 30 mice for up to 30 days. The AAH will have active temperature control, a window mechanism to facilitate video monitoring/recording of the animals, and biotelemetry capabilities. In addition, the design will permit access to the animals for experimental manipulations in space. The AAH can be refitted to experiment-specific requirements as needed. In initial 7-day hardware tests 12 male rats and 10 female mice show no adverse affects with respect to final body and organ weights as compared to vivarium. controls. The Advanced Animal Habitat will provide the science community opportunities to perform a greater variety of studies for longer duration in the microgravity environment than the current Animal Enclosure Module.

Baer, L.↗

NASA NTRS1994

Navier-Stokes Flowfield Simulation of Boeing 747-200 as Platform for SOFIA

Steady and unsteady viscous, three-dimensional flowfields are calculated using a thin layer approximation of Navier-Stokes equations in conjunction with Chimera overset grids. The finite-difference numerical scheme uses structured grids and a pentadiagonal flow solver called "OVERFLOW". The configuration of Boeing 747-200 has been chosen as one of configurations to be used as a platform for the SOFIA (Stratospheric Observatory For Infrared Astronomy). Initially, the steady flowfield of the full aircraft is calculated for the clean configuration (without a cavity to house telescope). This solution is then used to start the unsteady flowfield of a configuration containing cavity housing the observation telescope and its peripheral units. Analysis of unsteady flowfield in the cavity and its influence on the tail empennage, as well as the noise due to turbulence and optical quality of the flow are the main focus of this study. For the configuration considered here, the telescope housing cavity is located slightly downstream of the portwing. The entire flow-field is carefully constructed using 45 overset grids and consists of nearly 4 million grid points. All the computations axe done at one freestream flow condition of M(sub infinity) = 0.85, alpha = 2.5deg, and a Reynolds of Re = 1.85x10deg

Srinivasan, G.R.↗

NASA NTRS2001

Effects of Cage Type and NASA Rodent Food Bar in Male Sprague-Dawley Rats

Early prototype caging for the rodent Advanced Animal Habitat (P-AAH) for the International Space Station (ISS) is currently being tested. In this five week study, effects of the wire-bottom P-AAH cages and specialized NASA rodent food bars (FB) were compared to standard vivarium cages (VIV) with corn-cob, litter-filled bottoms, and standard Purina rat chow (CH). Ninety-six male Sprague-Dawley rats were divided into four treatment groups (24 rats/treatment): Group 1) VIV+CH, Group 2) P-AAH+CH, Group 3) VIV+FB, and Group 4) P-AAH+FB. Each VIV and P-AAH cage housed three and six rats, respectively. After five weeks of treatment rats were weighed, euthanized, and blood samples were collected. Weights of liver (LIV), kidney (KID), brain (BRN), epididymal fat (EPI), and perirenal fat (PERI) were also measured. Statistical analysis to compare differences between groups was performed by standard analysis of variance procedures (ANOVA) with a significance level of pLO.05. Results indicated P-AAH housed rats had significantly lower body weights (BW), LIV weights, and LIV/BW than VIV housed rats. FB fed rats had significantly lower blood urea nitrogen (BUN) levels and LIV/BW than CH fed rats. In addition, FB fed rats had significantly higher cholesterol (CHOL) levels, EPI/BW, PERI/BW, and total fat (EPI+PERI)/BW than CH fed rats. The P-AAH+FB group had significantly lower EPI, BRN, and total fat than VIV+FB rats. VIV+FB rats had significantly higher BRN, EPI, PERI, and total fat than VIV+CH rats. Triglycerides (TG), KID, KID/BW, and BRN/BW were not significantly different among treatment groups. These findings provide valuable information regarding cage design and food bar suitability for long-term use on the ISS.

Lau, Angela↗

NASA NTRS2002

Blood Pump Having a Magnetically Suspended Rotor

A blood pump preferably has a magnetically suspended rotor that rotates within a housing. The rotor may rotate about a stator disposed within the housing. Radial magnetic bearings may be defined within the stator and the rotor in order to suspend the rotor. The radial magnetic bearings may be passive magnetic bearings that include permanent magnets disposed within the stator and the rotor or active magnetic bearings. The pump may further include an axial magnetic bearing that may be either a passive or an active magnetic bearing. A motor that drives the rotor may be disposed within the housing in order to more easily dissipate heat generated by the motor. A primary flow path is defined between the rotor and the stator, and a secondary flow path is defined between the stator and the rotor. Preferably, a substantial majority of blood passes through the primary flow path. The secondary flow path is large enough so that it provides adequate flushing of the secondary flow path while being small enough to permit efficient operation of the radial magnet bearings across the secondary flow path.

James F Antaki↗

NASA NTRS2001

Blood Pump Having a Magnetically Suspended Rotor

James F Antaki↗

NASA NTRS2002

Status of Nozzle Aerodynamic Technology at MSFC

This viewgraph presentation provides information on the status of nozzle aerodynamic technology at MSFC (Marshall Space Flight Center). The objectives of this presentation were to provide insight into MSFC in-house nozzle aerodynamic technology, design, analysis, and testing. Under CDDF (Center Director's Discretionary Fund), 'Altitude Compensating Nozzle Technology', are the following tasks: Development of in-house ACN (Altitude Compensating Nozzle) aerodynamic design capability; Building in-house experience for all aspects of ACN via End-to-End Nozzle Test Program; Obtaining Experimental Data for Annular Aerospike: Thrust eta, TVC (thrust vector control) capability and surface pressures. To support selection/optimization of future Launch Vehicle propulsion we needed a parametric design and performance tool for ACN. We chose to start with the ACN Aerospike Nozzles.

Ruf, Joseph H.↗

NASA NTRS2004

Probabilistic Assessment of a CMC Turbine Vane

In order to demonstrate the advanced CMC technology under development within the Ultra Efficient Engine Technology (UEET) program, it has been planned to fabricate, test and analyze an all CMC turbine vane made of a SiC/SiC composite material. The objective was to utilize a 5-II Satin Weave SiC/CVI SiC/ and MI SiC matrix material that was developed in-house under the Enabling Propulsion Materials (EPM) program, to design and fabricate a stator vane that can endure successfully 1000 hours of engine service conditions operation. The design requirements for the vane are to be able to withstand a maximum of 2400 F within the substrate and the hot surface temperature of 2700 F with the aid of an in-house developed Environmental/Thermal Barrier Coating (EBC/TBC) system. The vane will be tested in a High Pressure Burner Rig at NASA Glenn Research Center facility. This rig is capable of simulating the engine service environment. The present paper focuses on a probabilistic assessment of the vane. The material stress/strain relationship shows a bilinear behavior with a distinct knee corresponding to what is often termed as first matrix cracking strength. This is a critical life limiting consideration for these materials. The vane is therefore designed such that the maximum stresses are within this limit so that the structure is never subjected to loads beyond the first matrix cracking strength. Any violation of this design requirement is considered as failure. Probabilistic analysis is performed in order to determine the probability of failure based on this assumption. In the analysis, material properties, strength, and pressures are considered random variables. The variations in properties and strength are based on the actual experimental data generated in house. The mean values for the pressures on the upper surface and the lower surface are known but their distributions are unknown. In the present analysis the pressures are considered normally distributed with a nominal variation. Temperature profile on the vane is obtained by performing a CFD analysis and is assumed to be deterministic.

Murthy, Pappu L. N.↗

NASA NTRS2005

Development of Particulates and Aerosols Research

During the past year several accomplishments were made for both the Particulate Matter Characterization and Measurement System, (PMCMS) and PAGEMS projects. The PAGEMS focus is to measure particulate emissions as a function of combustor parameters such as inlet temperature, inlet pressure and fuel air ratio. These measurements are used to evaluate combustor performance in hopes of correlating particulate emissions with engine conditions. These measurements have taken place at in-house NASA combustor facilities and off-site facilities. Ths work is unique because particulate measurements at high- pressure conditions are not commonly made. Some calibration of the PAGEMS instrumentation was done as well as minor modifications to the PAGEMS plumbing setup. These led to measurement improvements. The instrumentation and measurement process for PAGEMS was assessed and new instruments such as a thermodenuder, thermal mass flow meters and a cyclone separator were purchased to improve the PAGEMS instrumentation and measurement process. A worksheet was created to simulate varying inlet conditions to the DMA. This worksheet allows the user to assess the error in the measurements when certain conditions exist. Two technical papers were written with the PAGEMS team for the EXCAVATE field project. A paper was also reviewed for an in house publication. Also data was processed and analyzed for another field project (PAX) and will be part of a third PAGEMS paper. Accomplishments were also made with the PMCMS project. The calibration of the radial differential mobility analyzer, (RDMA) in the particle sizing system in the PMCMS was completed and provided satisfactory results. The voltages used for the RDMA depending on the particle of interest were corrected. The measurement capability of the PMCMS was increased by replacing the MetOne CPC with a TSI CPC. Lastly, assistance was provided to three college summer students with calibration of their particulate equipment and Monica Rivera shared her understanding of the aerosol technology with them. She also provided input for their end of the summer presentations. And attended the Aviation and Particle Emissions workshop. This workshop brought together experts in the aircraft particulate emissions field. As a result Ms. Rivera made two significant contacts with academia (UMR) and government (WPAFB) which could lead to future collaboration. She also attended the Aerosol and Particle Measurement Class held at the University of Minnesota. This class refreshed her particulate knowledge and introduced her to new aerosol applications and technology. Furthermore at the class contacts were made with private industry (TSI) and government (WPAFB). Ms. Rivera also enhanced her education by taking an in-house class on aircraft design and operation.

DeWitt, Kenneth↗

NASA NTRS2004

Security Management and Safeguards Office

The Security Management and Safeguards Office at NASA is here to keep the people working in a safe environment. They also are here to protect the buildings and documents from sabotage, espionage, and theft. During the summer of 2004, I worked with Richard Soppet in Physical Security. While I was working here I helped out with updating the map that we currently use at NASA Glenn Research Center, attended meetings for homeland security, worked with the security guards and the locksmith. The meetings that I attended for homeland security talked about how to protect ourselves before something happened, they told us to always be on the guard and look for anything suspicious, and the different ways that terrorist groups operate. When I was with the security guards I was taught how to check someone into the base, showed how to use a radar gun, observed a security guard make a traffic stop for training and was with them while they patrolled NASA Glenn Research Center to make sure things were running smooth and no one was in danger. When I was with the lock smith I was taught how to make keys and locks for the employees here at NASA. The lock smith also showed me that he had inventory cabinets of files that show how many keys were out to people and who currently has access to the rooms that they keys were made for. I also helped out the open house at NASA Glenn Research Center. I helped out by showing the Army Reserves, and Brook Park's SWAT team where all the main events were going to take place a week before the open house was going to begin. Then during the open house I helped out by making sure people had there IDS, checked through there bags, and handed out a map to them that showed where the different activities were going to take place. So the main job here at NASA Glenn Research Center for the Security Management and Safeguards Office is to make sure that nothing is stolen, sabotaged, and espionaged. Also most importantly make sure all the employees here at NASA are in a safe environment.

Bewley, Nathaniel M.↗

NASA NTRS2005

STS-114: Discovery Impromptu Briefing

Dr. Griffin, NASA Administrator, is accompanied by members of The U.S. House of Representatives in this STS-114 Discovery Impromptu briefing. The U.S. House of Representatives present include: Sherwood Boehlert, House Science Committee Chairman, Senator Hutchinson, Sheila Jackson, 18th Congressional District Texas, Al Green, 9th Congressional District, Representative Jim Davis, Florida, and Gene Green, 29th District, Texas. Griffin talks about the problem that occurred with the external fuel tank sensor of the Space Shuttle Discovery and the effort NASA is pursuing to track the problem, and identify the root cause. He answers questions from the news media about the next steps for the Space Shuttle Discovery, time frame for the launch, and activities for the astronauts for the next few days.

Source record↗

NASA NTRS2003

Noninterference Systems Developed for Measuring and Monitoring Rotor Blade Vibrations

In the noninterference measurement of blade vibrations, a laser light beam is transmitted to the rotor blade tips through a single optical fiber, and the reflected light from the blade tips is collected by a receiving fiber-optic bundle and conducted to a photodetector. Transmitting and receiving fibers are integrated in an optical probe that is enclosed in a metal tube which also houses a miniature lens that focuses light on the blade tips. Vibratory blade amplitudes can be deduced from the measurement of the instantaneous time of arrival of the blades and the knowledge of the rotor speed. The in-house noninterference blade-vibration measurement system was developed in response to requirements to monitor blade vibrations in several tests where conventional strain gauges could not be installed or where there was a need to back up strain gauges should critical gauges fail during the test. These types of measurements are also performed in the aircraft engine industry using proprietary in-house technology. Two methods of measurement were developed for vibrations that are synchronous with a rotor shaft. One method requires only one sensor; however, it is necessary to continuously record the data while the rotor is being swept through the resonance. In the other method, typically four sensors are employed and the vibratory amplitude is deduced from the data by performing a least square fit to a harmonic function. This method does not require continuous recording of data through the resonance and, therefore, is better suited for monitoring. The single-probe method was tested in the Carl facility at the Wright- Patterson Air Force Base, and the multiple-probe method was tested in NASA Glenn Research Center's Spin Rig facility, which uses permanent magnets to excite synchronous vibrations. Representative results from this test are illustrated in the bar chart. Nonsynchronous vibrations were measured online during testing of the Quiet High Speed Fan in Glenn s 9- by 15-Foot Low-Speed Wind Tunnel. Three sensors were employed, enabling a reconstruction of the vibratory patterns at the leading and trailing edges at the tip span, as well as a determination of vibratory amplitudes for every blade.

Kurkov, Anatole P.↗

NASA NTRS2005

ORTHOPEDIC LEG BRACE

Knee braces generally have been rigid in both the knee bending direction and in the knee straightening direction unless a manually operated release is incorporated in them to allow the knee to bend. Desirably a braced knee joint should effectively duplicate the compound, complex, actions of a normal knee. The key to knee braces is the knee joint housing. The housing herein carries a number of cam action pawls. with teeth adapted to engage the internal teeth of a ratchet ring mounted in the housing. Cam action return springs and the shape of the cam action pawl teeth allow rotation of the ratchet ring in a leg straightening direction while still supporting a load. The leg can then be extended during walking while at the same time being prevented by the cam action pawls from buckling in the knee bending direction.

Myers, William Neil↗

NASA NTRS2006

Development of the Gecko (Pachydactylus turneri) Animal Model during Foton M-2 to Study Comparative Effects of Microgravity in Terrestrial and Aquatic Organisms

Terrestrial organisms exposed to microgravity during spaceflight experience degeneration in bone, muscle, and possibly other tissues that require gravity-mediated mechanical stimulation for normal regenerative growth. In the Gecko experiment aboard Foton M-2, we flew for the first time, five terrestrial Pachydactylus turneri specimens to develop a model of microgravity effects comparable to the newt Pleurodeles waltl, a well-established model organism for spaceflight. These lower vertebrate species have similar body plans and size, are poikilothermic, have tissue regenerative ability, and are adapted to moderate periods of fasting. Furthermore the gecko (Pachydactylus) can also survive prolonged periods without water. In pre-flight control experiments and after a 16-day Foton M-2 spaceflight without food or water, the geckos were recovered and showed no apparent negative health effects. However, detailed analysis of bone mass and architecture by micro Computed Tomography { pCT), showed that both synchronous control and spaceflight animals lost significant amounts of cancellous bone in the distal femur and humerus relative to basal controls. In addition, cell cycle analysis of 30h post-flight liver tissue reveals a shift of DNA content from G2 and S to G1, both in spaceflight and synchronous controls. Together, these results suggest that housing conditions alone induce rapid catabolism of cancellous bone and reduced normal tissue regeneration. Further use of the gecko Puchydactylus turneri as a spaceflight model requires modification of housing conditions, possibly by including water and food, or changing other factors such as eliminating housing stresses to obtain stable bone structure and tissue regeneration during spaceflight experiments.

Almeida, E. A.↗

NASA NTRS1994

Yarn carrier with clutch

A yarn carrier apparatus particularly suited for use in braiding machinery or the like due to its capability of continuous yarn feeding and retraction of long lengths of yarn. The yarn carrier apparatus comprises a yarn supply spool which is rotatably mounted within the housing, a spring motor also mounted within the housing and operatively connected to the yarn supply spool through a mechanical transmission assembly which is adapted to multiply rotational movement between the first element of the gear assembly operatively connected to the spring motor and the final element of the gear assembly operatively connected to the yarn supply spool. The spring motor is adapted to tension the yarn during both feeding and retraction thereof, and it is further adapted to periodically rotatably slip within the housing and partially unwind so as to allow for continuous withdrawal of a long length of yarn without the spring motor becoming fully wound and preventing further yarn retraction.

Doyne, Richard A.↗

NASA NTRS1994

High temperature turbine engine structure

A high temperature ceramic/metallic turbine engine includes a metallic housing which journals a rotor member of the turbine engine. A ceramic disk-like shroud portion of the engine is supported on the metallic housing portion and maintains a close running clearance with the rotor member. A ceramic spacer assembly maintains the close running clearance of the shroud portion and rotor member despite differential thermal movements between the shroud portion and metallic housing portion.

Carruthers, William D.↗

NASA NTRS2000

Scan mirror remote temperature sensing system and method

A remote temperature sensing system (10) for a scanning mirror (7). The system (10) includes a sensor which detects heat radiated by the mirror and provides a signal in response thereto. In the illustrative implementation, the system (10) includes a thermistor mounted within a housing. The housing is contoured to maximize the receipt of thermal energy thereby. A mounting assembly maintains the thermistor a predetermined nonzero distance from the scanning mirror (7). The invention includes a shroud (12) mounted on the mirror (7) for shielding the thermistor and a support tube connected to the thermistor housing on a first end and to a base on the second end thereof. The support tube is adapted to remain stationary within the shroud as the scanning mirror and the shroud rotate due to the scanning of the mirror. Wires are connected to the thermistor on a first end thereof and are wrapped around the support tube. The wires include a length of electrically conductive material having a resistivity which has a low sensitivity to temperature variations. The sensor output is processed in a conventional manner to provide an output indicative of the temperature of the mirror.

VanDyk, Steven G.↗