ESA Parabolic Flight, Drop Tower and Centrifuge Opportunities for University Students

NASA Astrophysics Data System (ADS)

Callens, Natacha; Ventura-Traveset, Javier; Zornoza Garcia-Andrade, Eduardo; Gomez-Calero, Carlos; van Loon, Jack J. W. A.; Pletser, Vladimir; Kufner, Ewald; Krause, Jutta; Lindner, Robert; Gai, Frederic; Eigenbrod, Christian

The European Space Agency (ESA) Education Office was established in 1998 with the purpose of motivating young people to study science, engineering and technology subjects and to ensure a qualified workforce for ESA and the European space sector in the future. To this end the ESA Education Office is supporting several hands-on activities including small student satellites and student experiments on sounding rockets, high altitude balloons as well as microgravity and hypergravity platforms. This paper is intended to introduce three new ESA Education Office hands-on activities called "Fly Your Thesis!", "Drop Your Thesis!" and "Spin Your Thesis!". These activities give re-spectively access to aircraft parabolic flight, drop tower and centrifuge campaigns to European students. These educational programmes offer university students the unique opportunity to design, build, and eventually perform, in microgravity or hypergravity, a scientific or techno-logical experiment which is linked to their syllabus. During the "Fly Your Thesis!" campaigns, the students accompany their experiments onboard the A300 Zero-G aircraft, operated by the company Novespace, based in Bordeaux, France, for a series of three flights of 30 parabolas each, with each parabola providing about 20s of microgravity [1]. "Drop Your Thesis!" campaigns are held in the ZARM Drop Tower, in Bremen, Germany. The installation delivers 4.74s of microgravity in dropping mode and 9.3s in the catapulting mode [2]. Research topics such as fluid physics, fundamental physics, combustion, biology, material sciences, heat transfer, astrophysics, chemistry or biochemistry can greatly benefit from using microgravity platforms. "Spin Your Thesis!" campaigns take place in the Large Diameter Centrifuge (LDC) facility, at ESTEC, Noordwijk, in the Netherlands. This facility offers an acceleration from 1 to 20 times Earth's gravity [3]. The use of hypergravity allows completing the scientific picture of how gravity has an impact on a system over the whole acceleration spectrum, but can address as well specifically problems which require these high g-levels. A wide range of hypergravity exper-iments can be performed in the LDC facility, including biological, biochemical, microbiological, opto-physical, physical, material and fluid sciences, geology or plasma physics. ESA Education Office financially supports the cost of the campaigns, part of the hardware development, as well as necessary travel and accommodation of the student selected teams. An ELGRA (European Low Gravity Research Association) mentor, i.e. a scientist specialized in gravity-related research, support each student team throughout these education programmes. [1] Pletser V., Gharib T., Gai F., Mora C., Rosier P. "The 50 parabolic flight campaigns of the European Space Agency to conduct short duration microgravity research experimentation", Paper IAC-09-A2.5.1, 60th International Astronautical federation Congress, Daejeon, Korea, October 2009. [2] von Kampen P., Kaczmarczik U., Rath H.J. The new Drop Tower catapult system", Acta Astronautica, 59, 1-5, 278-283, 2006. [3] van Loon J. W. A. , Krause J., Cunha H., Goncalves J., Almeida H., Schiller P. "The Large Diameter Centrifuge, LDC, for life and physical sciences and technology", Proc. of the 'Life in Space for Life on Earth Symposium', Angers, France, 22-27 June 2008. (ESA SP-663, December 2008)

Increasing the sensitivity of the visual system reduces kinetotic behaviour of fish under microgravity

NASA Astrophysics Data System (ADS)

Anken, Ralf; Hilbig, Reinhard; Knie, Miriam; Weigele, Jochen; Anken, Ralf

We have shown earlier that some fish of a given batch reveal motion sickness (a kinetosis) at the transition from earth gravity to diminished gravity. The percentual ratios of the various types of behaviour (normal swimming and kinetotic swimming; kinetotic specimens revealed looping responses or spinning movements) highly differed depending on the quality of diminished gravity. At high quality microgravity (HQM, 10-6 g, ZARM drop-tower, Bremen, Germany), kinetoses were exhibited by some 90% of the animals, whereas kinetoses were not as frequently seen at higher G-levels (at 0.03-0.05g during parabolic aircraft flights or during centrifugation in the drop-capsule, only some 15-25% of the animals show kinetoses). In the course of the present study, we further assessed the role of the visual system in maintaining postural control under HQM, when the remaining level of gravity is too low to be used as a vestibular cue. Therefore, larval cichlid fish siblings (Oreochromis mossambicus) were subjected to drop-tower flights at HQM and different kinds of illumination were used. Applying blue light (which leads to an increase of the sensitivity of the visual system and to a general arousal of the animal) resulted in a decrease of kinetotically swimming specimens as compared to white and red light (red light is almost invisible for fish). The final data as well as results from analyses of inner ear otoliths will be communicated at the meeting. We expect that the few fish, which swam normally under white or red light, will have a very low otolith asymmetry (differences in the size of the right versus the left otoliths). Asymmetry may be considerably higher in animals swimming normally under blue light, since these specimens are presumed to rely entirely on visual input; an otolith asymmetry will thus not lead to a computation of erroneous vestibular cues. Acknowledgement: This work was financially supported by the German Aerospace Center (DLR) (FKZ: 50 WB 0527). The excellent technical assistance of Sandra Schroer is highly appreciated.

The United Nations Human Space Technology Initiative

NASA Astrophysics Data System (ADS)

Balogh, Werner; Miyoshi, Takanori

2016-07-01

The United Nations Office for Outer Space Affairs (OOSA) launched the Human Space Technology Initiative (HSTI) in 2010 within the United Nations Programme on Space Applications, based on relevant recommendations of the Third United Nations Conference on the Exploration and Peaceful Uses of Outer Space (UNISPACE III). The activities of HSTI are characterized by the following "Three Pillars": International Cooperation, Outreach, and Capacity-building. For International Cooperation, OOSA and the Japan Aerospace Exploration Agency (JAXA) jointly launched a new programme entitled "KiboCUBE". KiboCUBE aims to provide educational or research institutions located in developing countries with opportunities to deploy cube satellites of their own design and manufacture from Japanese Experiment Module "Kibo" on-board the International Space Station (ISS). The Announcement of Opportunity was released on 8 September 2015 and the selected institution is to be announced by 1 August 2016. OOSA is also collaborating with WHO and with the COPUOS Expert Group on Space and Global Health to promote space technologies and ground- and space-based research activities that can contribute to improving global health. For Outreach, OOSA and the government of Costa Rica are jointly organising the United Nations/Costa Rica Workshop on Human Space Technology from 7 to 11 March 2016. Participants will exchange information on achievements in human space programmes and discuss how to promote international cooperation by further facilitating the participation of developing countries in human space exploration-related activities. Also, it will address the role of space industries in human space exploration and its related activities, considering that they have become significant stakeholders in this field. For Capacity-building, OOSA has been carrying out two activities: the Zero-Gravity Instrument Project (ZGIP) and the Drop Tower Experiment Series (DropTES). In ZGIP, OOSA has annually distributed clinostats (microgravity simulation instruments) worldwide. ZGIP has been providing students and teachers with the opportunity to study gravitational effects on samples such as plant seeds in a simulated microgravity condition. Currently, second and third cycles are on-going. DropTES is a fellowship programme, in which OOSA and the Centre of Applied Space Technology and Microgravity (ZARM) jointly provide one student team annually with the opportunity to conduct their own microgravity experiment at the Bremen Drop Tower, Germany. In 2015, in the DropTES second cycle, Universidad Católica Boliviana "San Pablo" was given the fellowship. DropTES has been extended to the third cycle for 2016.

Electrostatic Positioning System for a free fall test at drop tower Bremen and an overview of tests for the Weak Equivalence Principle in past, present and future

NASA Astrophysics Data System (ADS)

Sondag, Andrea; Dittus, Hansjörg

2016-08-01

The Weak Equivalence Principle (WEP) is at the basis of General Relativity - the best theory for gravitation today. It has been and still is tested with different methods and accuracies. In this paper an overview of tests of the Weak Equivalence Principle done in the past, developed in the present and planned for the future is given. The best result up to now is derived from the data of torsion balance experiments by Schlamminger et al. (2008). An intuitive test of the WEP consists of the comparison of the accelerations of two free falling test masses of different composition. This has been carried through by Kuroda & Mio (1989, 1990) with the up to date most precise result for this setup. There is still more potential in this method, especially with a longer free fall time and sensors with a higher resolution. Providing a free fall time of 4.74 s (9.3 s using the catapult) the drop tower of the Center of Applied Space Technology and Microgravity (ZARM) at the University of Bremen is a perfect facility for further improvements. In 2001 a free fall experiment with high sensitive SQUID (Superconductive QUantum Interference Device) sensors tested the WEP with an accuracy of 10-7 (Nietzsche, 2001). For optimal conditions one could reach an accuracy of 10-13 with this setup (Vodel et al., 2001). A description of this experiment and its results is given in the next part of this paper. For the free fall of macroscopic test masses it is important to start with precisely defined starting conditions concerning the positions and velocities of the test masses. An Electrostatic Positioning System (EPS) has been developed to this purpose. It is described in the last part of this paper.

Experiments on Nitrogen Oxide Production of Droplet Arrays Burning under Microgravity Conditions

NASA Astrophysics Data System (ADS)

Moesl, Klaus; Sattelmayer, Thomas; Kikuchi, Masao; Yamamoto, Shin; Yoda, Shinichi

The optimization of the combustion process is top priority in current aero-engine and aircraft development, particularly from the perspectives of high efficiency, minimized fuel consumption, and a sustainable exhaust gas production. Aero-engines are exclusively liquid-fueled with a strong correlation between the combustion temperature and the emissions of nitric oxide (NOX ). Due to safety concerns, the progress in NOX reduction has been much slower than in stationary gas turbines. In the past, the mixing intensity in the primary zone of aero-engine combustors was improved and air staging implemented. An important question for future aero-engine combustors, consequently, is how partial vaporization influences the NOX emissions of spray flames? In order to address this question, the combustion of partially vaporized, linear droplet arrays was studied experimentally under microgravity conditions. The influence of fuel pre-vaporization on the NOX emissions was assessed in a wide range. The experiments were performed in a drop tower and a sounding rocket campaign. The microgravity environment provided ideal experiment conditions without the disturbing ef-fect of natural convection. This allowed the study of the interacting phenomena of multi-phase flow, thermodynamics, and chemical kinetics. This way the understanding of the physical and chemical processes related to droplet and spray combustion could be improved. The Bremen drop tower (ZARM) was utilized for the precursor campaign in July 2008, which was com-prised of 30 drops. The sounding rocket experiments, which totaled a microgravity duration of 6 minutes, were finally performed on the flight of TEXUS-46 in November 2009. On both campaigns the "Japanese Combustion Module" (JCM) was used. It is a cooperative experi-ment on droplet array combustion between the Japan Aerospace Exploration Agency (JAXA) and ESA's (European Space Agency) research team, working on the combustion properties of partially premixed sprays. One droplet array consisted of five droplets (for sounding rocket) and 9 -17 droplets (for drop tower) of the hydrocarbon n-decane (C10 H22 ). While keeping the pressure at 1.0 bar (+/-20 mbar), the combustion chamber temperature and the fuel vaporization time were varied in the range of 300 -500 K and 0.5 -18 s, respectively. Consequently, the total amount of fuel, the local equivalence ratio Φ along the droplet array, and the dimensionless droplet spacing S/d0 , with d0 being the initial droplet diameter, were adapted. Ignition was initiated by a hot-wire igniter from one end of the droplet array. Representative gas samples were collected from every single combustion sequence after flame extinction and stored in specially treated gas sampling cylinders for their succeeding analysis on ground. Visual observation of the combustion process, as well as temperature and pressure logging, supported the scientific interpretation of the gas analysis. With an increase of the preheating temperature, NOX emissions increase due to a higher effec-tive flame temperatures. However, with an increasing pre-vaporization, NOX emissions become lower due to the dropping number and the dropping size of burning droplets, acting as hot spots. A correction for the effect of the preheating temperature was developed. It reveals the effect of pre-vaporization and shows that the NOX emissions are almost independent of it for near-stoichiometric operation. At overall lean conditions the NOX emissions drop non-linearly with the degree of vaporization. Up to now, this leads to the conclusion that a high degree of vaporization is required in order to achieve substantial NOX abatement.

Drop Tower tests in preparation of a Tethered Electromagnetic Docking space demonstration

NASA Astrophysics Data System (ADS)

Olivieri, Lorenzo; Francesconi, Alessandro; Antonello, Andrea; Bettiol, Laura; Branz, Francesco; Duzzi, Matteo; Mantellato, Riccardo; Sansone, Francesco; Savioli, Livia

2016-07-01

A group of students of the University of Padova is recently developing some technologies to implement a Tethered Electromagnetic Docking (TED) experiment, a novel system for close rendezvous and mating manoeuvres between two spacecraft, consisting in a small tethered probe ejected by the chaser and magnetically guided by a receiving electromagnet mounted on the target. Because of the generated magnetic field, automatic self-alignment and mating are possible; then, as the tether is rewinded, the chaser is able to dock with the target. This concept allows to simplify standard docking procedures, thanks to the reduction of proximity navigation and guidance requirements, as well as consequent fuel reduction. Other interesting applications are expected, from active debris removal to space tugging; in particular, the utilization of the tethered connection for detumbling operations is considered. The realization of a space demonstrator requires a preliminary verification of the critical technologies employed in TED, in particular the magnetic guidance and the probe deploy and retrieve; in the framework of ESA "Drop your Thesis!" 2014 and 2016 campaigns the experiments FELDs (Flexible Electromagnetic Leash Docking system) and STAR (System for Tether Automatic Retrieval) have been focused on the test of such critical elements in the relevant microgravity environment of ZARM Drop Tower in Bremen. In particular, FELDs consisted in a simplified model of TED with a magnetic target interface, a passive tethered probe and its launch system: the experiment allowed to assess the passive self-alignment of the probe with respect to the target and to study the effect of friction between the tether and the release system. Similarly, STAR is investigating the tether actively controlled deployment and retrieval, with the experiment campaign planned on November 2016. In addition, another microgravity experiment is in preparation for the investigation of active magnetic navigation: PACMAN (Position and Attitude Control with MAgnetic Navigation) will consist in a CubeSat-sized spacecraft mock-up using on-board actively-controlled electromagnetic coils for guidance This paper describes the TED concept and presents the evaluation its performances with respect to standard docking procedure. The roadmap in TED development is then introduced, focusing on the importance of microgravity tests in the assessment of its critical technologies and discussing the influence of the collected data on the design drivers of the proposed space demonstrator.

Effects of drop acceleration and deceleration on particle capture in a cross-flow gravity tower at intermediate drop Reynolds numbers.

PubMed

Kumar, Anoop; Gupta, S K; Kale, S R

2007-04-01

Cross-flow gravity towers are particle scrubbing devices in which water is sprayed from the top into particle-laden flow moving horizontally. Models for predicting particle capture assume drops traveling at terminal velocity and potential flow (ReD > 1000) around it, however, Reynolds numbers in the intermediate range of 1 to 1000 are common in gravity towers. Drops are usually injected at velocities greater than their terminal velocities (as in nozzles) or from near rest (perforated tray) and they accelerate/decelerate to their terminal velocity in the tower. Also, the effects of intermediate drop Reynolds number on capture efficiency have been simulated for (a) drops at their terminal velocity and (b) drops accelerating/decelerating to their terminal velocity. Tower efficiency based on potential flow about the drop is 40%-50% greater than for 200 mm drops traveling at their terminal velocity. The corresponding values for 500 mm drops are about 10%-20%. The drop injection velocity is important operating parameter. Increase in tower efficiency by about 40% for particles smaller than 5 mm is observed for increase in injection velocity from 0 to 20 m/s for 200 and 500mm drops.

Droplet combustion experiment drop tower tests using models of the space flight apparatus

NASA Technical Reports Server (NTRS)

Haggard, J. B.; Brace, M. H.; Kropp, J. L.; Dryer, F. L.

1989-01-01

The Droplet Combustion Experiment (DCE) is an experiment that is being developed to ultimately operate in the shuttle environment (middeck or Spacelab). The current experiment implementation is for use in the 2.2 or 5 sec drop towers at NASA Lewis Research Center. Initial results were reported in the 1986 symposium of this meeting. Since then significant progress was made in drop tower instrumentation. The 2.2 sec drop tower apparatus, a conceptual level model, was improved to give more reproducible performance as well as operate over a wider range of test conditions. Some very low velocity deployments of ignited droplets were observed. An engineering model was built at TRW. This model will be used in the 5 sec drop tower operation to obtain science data. In addition, it was built using the flight design except for changes to accommodate the drop tower requirements. The mechanical and electrical assemblies have the same level of complexity as they will have in flight. The model was tested for functional operation and then delivered to NASA Lewis. The model was then integrated into the 5 sec drop tower. The model is currently undergoing initial operational tests prior to starting the science tests.

Small-scale impacts as potential trigger for landslides on small Solar system bodies

NASA Astrophysics Data System (ADS)

Hofmann, Marc; Sierks, Holger; Blum, Jürgen

2017-07-01

We conducted a set of experiments to investigate whether millimetre-sized impactors impinging on a granular material at several m s-1 are able to trigger avalanches on small, atmosphereless planetary bodies. These experiments were carried out at the Zentrum für angewandte Raumfahrttechnologie und Mikrogravitation (ZARM) drop tower facility in Bremen, Germany to facilitate a reduced gravity environment. Additional data were gathered at Earth gravity levels in the laboratory. As sample materials we used a ground Howardites, Eucrites and Diogenites (HED) meteorite and the Johnson Space Center (JSC) Mars-1 Martian soil simulant. We found that this type of small-scale impact can trigger avalanches with a moderate probability, if the target material is tilted to an angle close to the angle of repose. We additionally simulated a small-scale impact using the discrete element method code esys-particle. These simulations show that energy transfer from impactor to the target material is most efficient at low- and moderate-impactor inclinations and the transferred energy is retained in particles close to the surface due to a rapid dissipation of energy in lower material layers driven by inelastic collisions. Through Monte Carlo simulations we estimate the time-scale on which small-scale impacts with the observed characteristics will trigger avalanches covering all steep slopes on the surface of a small planetary body to be of the order 105 yr.

Drop Tower Physics

ERIC Educational Resources Information Center

Dittrich, William A.

2014-01-01

The drop towers of yesteryear were used to make lead shot for muskets, as described in "The Physics Teacher" in April 2012. However, modern drop towers are essentially elevators designed so that the cable can "break" on demand, creating an environment with microgravity for a short period of time, currently up to nine seconds at…

Short Duration Reduced Gravity Drop Tower Design and Development

NASA Astrophysics Data System (ADS)

Osborne, B.; Welch, C.

The industrial and commercial development of space-related activities is intimately linked to the ability to conduct reduced gravity research. Reduced gravity experimentation is important to many diverse fields of research in the understanding of fundamental and applied aspects of physical phenomena. Both terrestrial and extra-terrestrial experimental facilities are currently available to allow researchers access to reduced gravity environments. This paper discusses two drop tower designs, a 2.0 second facility built in Australia and a proposed 2.2 second facility in the United Kingdom. Both drop towers utilise a drag shield for isolating the falling experiment from the drag forces of the air during the test. The design and development of The University of Queensland's (Australia) 2.0 second drop tower, including its specifications and operational procedures is discussed first. Sensitive aspects of the design process are examined. Future plans are then presented for a new short duration (2.2 sec) ground-based reduced gravity drop tower. The new drop tower has been designed for Kingston University (United Kingdom) to support teaching and research in the field of reduced gravity physics. The design has been informed by the previous UQ drop tower design process and utilises a catapult mechanism to increase test time and also incorporates features to allow participants for a variety of backgrounds (from high school students through to university researchers) to learn and experiment in reduced gravity. Operational performance expectations for this new facility are also discussed.

Drop Tower Workshop

NASA Technical Reports Server (NTRS)

Urban, David

2013-01-01

Ground based microgravity facilities are an important proving ground for space experiments, ground-based research and space hardware risk mitigation. An overview of existing platforms will be discussed with an emphasis on drop tower capabilities. The potential for extension to partial gravity conditions will be discussed. Input will be solicited from attendees for their potential to use drop towers in the future and the need for enhanced capabilities (e.g. partial gravity)

Aerodynamic and engineering design of a 1.5 s high quality microgravity drop tower facility

NASA Astrophysics Data System (ADS)

Belser, Valentin; Breuninger, Jakob; Reilly, Matthew; Laufer, René; Dropmann, Michael; Herdrich, Georg; Hyde, Truell; Röser, Hans-Peter; Fasoulas, Stefanos

2016-12-01

Microgravity experiments are essential for research in space science, biology, fluid mechanics, combustion, and material sciences. One way to conduct microgravity experiments on Earth is by using drop tower facilities. These facilities combine a high quality of microgravity, adequate payload masses and have the advantage of virtually unlimited repeatability under same experimental conditions, at a low cost. In a collaboration between the Institute of Space Systems (IRS) at the University of Stuttgart and Baylor University (BU) in Waco, Texas, a new drop tower is currently under development at the Center for Astrophysics, Space Physics and Engineering Research (CASPER). The design parameters of the drop tower ask for at least 1.5 s in free fall duration while providing a quality of at least 10-5 g. Previously, this quality has only been achieved in vacuum drop tower facilities where the capsule experiences virtually zero aerodynamic drag during its free fall. Since this design comes at high costs, a different drop tower design concept, which does not require an evacuated drop shaft, was chosen. It features a dual-capsule system in which the experiment capsule is shielded from aerodynamic forces by surrounding it with a drag shield during the drop. As no other dual-capsule drop tower has been able to achieve a quality as good as or better than 10-5 g previous work optimized the design with an aerodynamic perspective by using computational fluid dynamics (CFD) simulations to determine the ideal shape and size of the outer capsule and to specify the aerodynamically crucial dimensions for the overall system. Experiments later demonstrated that the required quality of microgravity can be met with the proposed design. The main focus of this paper is the mechanical realization of the capsule as well as the development and layout of the surrounding components, such as the release mechanism, the deceleration device and the drop shaft. Because the drop tower facility is a complex system with many interdependencies between all of the components, several engineering challenges had to be addressed. For example, initial disturbances that are caused by the release mechanism are a common issue that arises at drop tower facilities. These vibrations may decrease the quality of microgravity during the initial segment of free fall. Because this would reduce the free fall time experiencing high quality microgravity, a mechanism has been developed to provide a soft release. Challenges and proposed solutions for all components are highlighted in this paper.

Critical point wetting drop tower experiment

NASA Technical Reports Server (NTRS)

Kaukler, W. F.; Tcherneshoff, L. M.; Straits, S. R.

1984-01-01

Preliminary results for the Critical Point Wetting CPW Drop Tower Experiment are produced with immiscible systems. Much of the observed phenomena conformed to the anticipated behavior. More drops will be needed to test the CPW theory with these immiscible systems.

Combat Helmet-Headform Coupling Characterized from Blunt Impact Events

DTIC Science & Technology

2011-11-01

Testing was completed on a monorail drop tower to analyze the effect of helmet/headform coupling on the blunt impact behavior of ACH helmets using FMVSS...designates its own methods and test equipment: a drop tower ( monorail or twin- wire), headform (DOT, ISO, NOCSAE), headform CG accelerometer (single or...the more anthropomorphic International Standard Organization (ISO) half headform. Testing was completed on a monorail drop tower to analyze the effect

Enhancing Injury Protection Capabilities of Army Combat Helmets

DTIC Science & Technology

2006-11-01

rate on each material’s energy attenuation characteristics, dynamic compression tests were conducted using a monorail drop tower conforming to ANSI...equipment. An Army combat helmet is fitted to the monorail drop tower (left). The variable weight, flat impactor (right) is fitted to the monorail ...3.3.1 Impact attenuation All impact tests were conducted using the USAARL vertical monorail drop tower (Figure 1, left). Impact sites along with

Kinetotic behaviour and otolith asymmetry of fish under "low quality microgravity" - a drop-tower experiment at 0.03-0.05g

NASA Astrophysics Data System (ADS)

Anken, Ralf; Knie, Miriam; Hilbig, Reinhard; Anken, Ralf

We have shown earlier that some fish of a given batch reveal motion sickness (a kinetosis) at the transition from earth gravity to diminished gravity. The percentual ratios of the various types of behaviour (normal swimming and kinetotic swimming; kinetotic specimens revealed looping responses/LR or spinning movements/SM), however, highly differed depending on the quality of diminished gravity. Whereas kinetoses were exhibited by some 90 In striking contrast to the results gained using PF specimens, according to which otolith asymmetry (differences in the size and calcium incorporation of the inner ear stones between the left and right side of the body) was significantly higher in kinetotic specimens as compared to normally swimming fish, a comparable asymmetry between kinetotically and normally swimming drop-tower samples (HQM) could statistically not be verified. The present study was designed to further elucidate the role of otolith asymmetry concerning an individually different susceptibility to kinetoses. In order to test, whether the differing results between the PF and the drop-tower experiment were based exclusively on the differing quality of diminished gravity, or, if further parameters of the PF and the drop-tower environment (e.g., vibrations and changing accelerations during PFs or the brisk compression of the drop-capsule at its release) need to be taken into consideration to explain the earlier results, drop-tower flights were performed at LQM. This simulation of PF "micro"gravity was carried out in housing larval cichlid fish (Oreochromis mossambicus) within a centrifuge at 0.03-0.05g during the drop-tower flights. The percentual ratios of the swimming behaviour at drop-tower LQM ranged between those of PF LQM and (drop-tower) HQM. This indicates that many normally swimming fish during PFs use cues other than the residual gravity (e.g., vibrations detected by the lateral line organ) for orientation. Furthermore, looping responses seem to be transitional behaviour depending on the developmental stage, whereas spinning movements occur stage-independently. Details as well as data on otoliths will be communicated at the meeting. Acknowledgement: This work was financially supported by the German Aerospace Center (DLR) (FKZ: 50 WB 0527).

Small Liquid Hydrogen Tank for Drop Tower Tests

NASA Image and Video Library

1964-11-21

A researcher fills a small container used to represent a liquid hydrogen tank in preparation for a microgravity test in the 2.2-Second Drop Tower at the National Aeronautics and Space Administration (NASA) Lewis Research Center. For over a decade, NASA Lewis endeavored to make liquid hydrogen a viable propellant. Hydrogen’s light weight and high energy made it very appealing for rocket propulsion. One of the unknowns at the time was the behavior of fluids in the microgravity of space. Rocket designers needed to know where the propellant would be inside the fuel tank in order to pump it to the engine. NASA Lewis utilized sounding rockets, research aircraft, and the 2.2 Second Drop Tower to study liquids in microgravity. The drop tower, originally built as a fuel distillation tower in 1948, descended into a steep ravine. By early 1961 the facility was converted into an eight-floor, 100-foot tower connected to a shop and laboratory space. Small glass tanks, like this one, were installed in experiment carts with cameras to film the liquid’s behavior during freefall. Thousands of drop tower tests in the early 1960s provided an increased understanding of low-gravity processes and phenomena. The tower only afforded a relatively short experiment time but was sufficient enough that the research could be expanded upon using longer duration freefalls on sounding rockets or aircraft. The results of the early experimental fluid studies verified predictions made by Lewis researchers that the total surface energy would be minimized in microgravity.

Drop tower with no aerodynamic drag

NASA Technical Reports Server (NTRS)

Kendall, J. M., Jr.

1981-01-01

Cooling air accelerated to match velocity of falling object eliminates drag. 3 meter drop tower with suction fan and specific geometry causes air to accelerate downward at 1 g. Although cooling of molten material released from top is slow because surrounding air moves with it, drop remains nearly spherical.

The Tower and Glass Marbles Problem

ERIC Educational Resources Information Center

Denman, Richard T.; Hailey, David; Rothenberg, Michael

2010-01-01

The Catseye Marble company tests the strength of its marbles by dropping them from various levels of their office tower, to find the highest floor from which a marble will not break. We find the smallest number of drops required and from which floor each drop should be made. We also find out how these answers change if a restriction is placed on…

9. BUILDING NO. 620B, FRICTION PENDULUM BUILDING. 29FOOT DROP TOWER ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

9. BUILDING NO. 620-B, FRICTION PENDULUM BUILDING. 29-FOOT DROP TOWER SITS BEHIND BLAST SHIELD IN FRONT OF BUILDING. - Picatinny Arsenal, 600 Area, Test Areas District, State Route 15 near I-80, Dover, Morris County, NJ

Microgravity Level Measurement of the Beijing Drop Tower Using a Sensitive Accelerometer

PubMed Central

Liu, T. Y.; Wu, Q. P.; Sun, B. Q.; Han, F. T.

2016-01-01

Drop tower is the most common ground-based facility to provide microgravity environment and widely used in many science experiments. A differential space accelerometer has been proposed to test the spin-gravity interaction between rotating extended bodies onboard a drag-free satellite. In order to assist design and test of this inertial sensor in a series of ground- based pre-flight experiments, it is very important to know accurately the residual acceleration of drop towers. In this report, a sensitive instrument for this purpose was built with a high-performance servo quartz accelerometer, and the dedicated interface electronics design providing small full-scale range and high sensitivity, up to 136.8 V/g0. The residual acceleration at the Beijing drop tower was measured using two different drop capsules. The experimental result shows that the microgravity level of the free-falling double capsule is better than 2 × 10−4g0 (Earth’s gravity). The measured data in this report provides critical microgravity information for design of the following ground experiments. PMID:27530726

Thermosolutal Marangoni convection short-time regimes - Proposals for drop tower experiments and real time computer simulation

NASA Astrophysics Data System (ADS)

Polezhaev, V. I.; Ermakov, M. K.

1992-12-01

Results are presented of a parametrical study of flow patterns, heat transfer, and time scales of thermosolutal Marangoni convection in a cavity with temperature and solutal gradients along the free surface and adiabatic bottom for the case of zero gravity. Nusselt number, concentration difference across the cavity, and flow/temperature fields for the different regimes are presented; they show the possibility to use Drop Tower 'Bremen' for measuring the developed secondary flow and heat/mass transfer due to thermosolutal Marangoni convection as well as the possibility to analyze and plan the drop tower for such experiments using the COMGA PC-based system.

Reusable Material for Drop Tower

DTIC Science & Technology

2011-08-01

R3 Buna-N Rubber ............................................................................................... 32 B-3. R5 EPDM Rubber ...Butyl Rubber . Figure B-2. R3 Buna-N Rubber . Figure B-3. R5 EPDM Rubber . Figure B-4. R6 Gel Rubber . UNCLASSIFIED 33...11 Current Drop Tower Material & Setup .......................................................... 11 Bowling Ball Rubber Material Sample Test

Interest of the MICROSTAR Accelerometer to improve the GRASP Mission.

NASA Astrophysics Data System (ADS)

Perrot, E.; Lebat, V.; Foulon, B.; Christophe, B.; Liorzou, F.; Huynh, P. A.

2015-12-01

The Geodetic Reference Antenna in Space (GRASP) is a micro satellite mission concept proposed by JPL to improve the definition of the Terrestrial Reference Frame (TRF). GRASP collocates GPS, SLR, VLBI, and DORIS sensors on a dedicated spacecraft in order to establish precise and stable ties between the key geodetic techniques used to define and disseminate the TRF. GRASP also offers a space-based reference antenna for the present and future Global Navigation Satellite Systems (GNSS). By taking advantage of the new testing possibilities offer by the catapult facility at the ZARM drop tower, the ONERA's space accelerometer team proposes an up-dated version, called MICROSTAR, of its ultra sensitive electrostatic accelerometers which have contributed to the success of the last Earth's gravity missions GRACE and GOCE. Built around a cubic proof-mass, it provides the 3 linear accelerations with a resolution better than 10-11 ms-2/Hz1/2 into a measurement bandwidth between 10-3 Hz and 0.1 Hz and the 3 angular accelerations about its 3 orthogonal axes with 5´10-10 rad.s-2/Hz1/2 resolution. Integrated at the centre of mass of the satellite, MICROSTAR improves the Precise Orbit Determination (POD) by accurate measurement of the non-gravitational force acting on the satellite. It offers also the possibility to calibrate the change in the position of the satellite center of mass with an accuracy better than 100 μm as demonstrated in the GRACE mission. Assuming a sufficiently rigid structure between the antennas and the accelerometer, its data can participate to reach the mission objective of 1 mm precision for the TRF position.

Advancements in the Quantification of the Crystal Structure of ZNS Materials Produced in Variable Gravity

NASA Astrophysics Data System (ADS)

Castillo, Martin

2016-07-01

Screens and displays consume tremendous amounts of power. Global trends to significantly consume less power and increase battery life have led to the reinvestigation of electroluminescent materials. The state of the art in ZnS materials has not been furthered in the past 30 years and there is much potential in improving electroluminescent properties of these materials with advanced processing techniques. Self-propagating high temperature synthesis (SHS) utilises a rapid exothermic process involving high energy and nonlinearity coupled with a high cooling rate to produce materials formed outside of normal equilibrium boundaries thus possessing unique properties. The elimination of gravity during this process allows capillary forces to dominate mixing of the reactants which results in a superior and enhanced homogeneity in the product materials. ZnS type materials have been previously conducted in reduced gravity and normal gravity. It has been claimed in literature that a near perfect phases of ZnS wurtzite was produced. Although, the SHS of this material is possible at high pressures, there has been no quantitative information on the actual crystal structures and lattice parameters that were produced in this work. Utilising this process with ZnS doped with Cu, Mn, or rare earth metals such as Eu and Pr leads to electroluminescence properties, thus making this an attractive electroluminescent material. The work described here will revisit the synthesis of ZnS via high pressure SHS and will re-examine the work performed in both normal gravity and in reduced gravity within the ZARM drop tower facility. Quantifications in the lattice parameters, crystal structures, and phases produced will be presented to further explore the unique structure-property performance relationships produced from the SHS of ZnS materials.

Drop-tower experiments for capillary surfaces in an exotic container

NASA Technical Reports Server (NTRS)

Concus, Paul; Finn, Robert; Weislogel, Mark

1991-01-01

Low-gravity drop-tower experiments are carried out for an 'exotic' rotationally-symmetric container, which admits an entire continuum of distinct equilibrium symmetric capillary free surfaces. It is found that an initial equilibrium planer interface, a member of the continuum, will reorient toward a non-symmetric interface, as predicted by recent mathematical theory.

DIME Students Discuss Final Drop Tower Experiment Design

NASA Technical Reports Server (NTRS)

2002-01-01

Students discuss fine points of their final design for the Drop Tower experiment during the second Dropping in a Microgravity Environment (DIME) competition held April 23-25, 2002, at NASA's Glenn Research Center. Competitors included two teams from Sycamore High School, Cincinnati, OH, and one each from Bay High School, Bay Village, OH, and COSI Academy, Columbus, OH. DIME is part of NASA's education and outreach activities. Details are on line at http://microgravity.grc.nasa.gov/DIME_2002.html.

DIME Participant Builds a Potential Drop Tower Candidate

NASA Technical Reports Server (NTRS)

2002-01-01

A student assembles a Lego (TM) Challenge device designed to operate in the portable drop tower demonstrator as part of the second Dropping in a Microgravity Environment (DIME) competition held April 23-25, 2002, at NASA's Glenn Research Center. Competitors included two teams from Sycamore High School, Cincinnati, OH, and one each from Bay High School, Bay Village, OH, and COSI Academy, Columbus, OH. DIME is part of NASA's education and outreach activities. Details are on line at http://microgravity.grc.nasa.gov/DIME_2002.html.

Student Drop Tower Competitions: Dropping In a Microgravity Environment (DIME) and What If No Gravity? (WING)

NASA Technical Reports Server (NTRS)

Hall, Nancy R.; Stocker, Dennis P.; DeLombard, Richard

2011-01-01

This paper describes two student competition programs that allow student teams to conceive a science or engineering experiment for a microgravity environment. Selected teams design and build their experimental hardware, conduct baseline tests, and ship their experiment to NASA where it is operated in the 2.2 Second Drop Tower. The hardware and acquired data is provided to the teams after the tests are conducted so that the teams can prepare their final reports about their findings.

Research approach and first results on agglomerate compaction in protoplanetary dust simulation in the Cloud Manipulation System

NASA Astrophysics Data System (ADS)

Vedernikov, Andrei; Blum, Jurgen; Ingo Von Borstel, Olaf; Schraepler, Rainer; Balapanov, Daniyar; Cecere, Anselmo

2016-07-01

Nanometre and micrometre-sized solid particles are ubiquitous in space and on Earth - from galaxies, interstellar space, protoplanetary and debris disks to planetary rings and atmospheres, planetary surfaces, comets, interplanetary space, Earth's atmosphere. Apparently, the most intriguing problem in the picture of the formation of planets is the transition from individual microscopic dust grains to kilometre-sized planetesimals. Revealing the mechanisms of this transition is one of the main tasks of the European Space Agency's project Interaction in Cosmic and Atmospheric Particle Systems (ICAPS). It was found that Brownian motion driven agglomeration could not provide the transition within reasonable time scale. As a result, at this stage top scientific goals shifted towards forced agglomeration and concentration of particles, targeting revealing the onset of compaction, experimental study of the evolution of fractal dimensions, size and mass distribution, occurrence of bouncing. The main tasks comprise 1) development of the rapid agglomeration model 2) development of the experimental facilities creating big fractal-type agglomerates from 10 to 1000 μm from a cloud of micrometre-size grains; 3) experimental realization of the rapid agglomeration in microgravity and ground conditions; and 4) in situ investigation of the morphology, mobility, mechanical and optical properties of the free-floating agglomerates, including investigation of thermophoresis, photophoresis of the agglomerates and of the two-phase flow phenomena. To solve the experimental part of the tasks we developed a Cloud Manipulation System, realized as a breadboard (CMS BB) for long duration microgravity platforms and a simplified laboratory version (CMS LV) mostly oriented on short duration microgravity and ground tests. The new system is based on the use of thermophoresis, most favourable for cloud manipulation without creating additional particle-particle forces in the cloud with a possibility of growing single agglomerate out of the whole cloud. The cloud manipulation system additionally provides temperature stabilization or, on the contrary, high temperature variation in the observation volume; formation of controlled temperature gradients, intensive three-dimensional periodic shear flow or three-dimensional gas density pulsations of the contraction-expansion type; application of electrostatic gradients including electro dynamic balancing; imposing of photophoretic force, etc. Their choice and/or combination depend upon particular experimental task. Experiments on forced agglomeration in short duration microgravity conditions of the Bremen drop tower succeeded in rapid growth of extended agglomerates, formation of complex three-dimensional cloud patterns, allowed observing controlled cloud displacement, cloud trapping, particle separation with respect to their electrical charge. The breadboard (CMS BB) and the laboratory version of the Cloud Manipulation System (CMS LV) are new types of scientific instrument with high scientific potential. ESA PRODEX program, the Belgian Federal Science Policy Office, DLR project 50WM1223, ZARM Drop Tower Operation and Service Company Ltd. are greatly acknowledged.

Compound Capillary Flows in Complex Containers: Drop Tower Test Results

NASA Astrophysics Data System (ADS)

Bolleddula, Daniel A.; Chen, Yongkang; Semerjian, Ben; Tavan, Noël; Weislogel, Mark M.

2010-10-01

Drop towers continue to provide unique capabilities to investigate capillary flow phenomena relevant to terrestrial and space-based capillary fluidics applications. In this study certain `capillary rise' flows and the value of drop tower experimental investigations are briefly reviewed. A new analytic solution for flows along planar interior edges is presented. A selection of test cell geometries are then discussed where compound capillary flows occur spontaneously and simultaneously over local and global length scales. Sample experimental results are provided. Tertiary experiments on a family of asymmetric geometries that isolate the global component of such flows are then presented along with a qualitative analysis that may be used to either avoid or exploit such flows. The latter may also serve as a design tool with which to assess the impact of inadvertent container asymmetry.

Low Gravity Freefall Facilities

NASA Technical Reports Server (NTRS)

1981-01-01

Composite of Marshall Space Flight Center's Low-Gravity Free Fall Facilities.These facilities include a 100-meter drop tower and a 100-meter drop tube. The drop tower simulates in-flight microgravity conditions for up to 4.2 seconds for containerless processing experiments, immiscible fluids and materials research, pre-flight hardware design test and flight experiment simulation. The drop tube simulates in-flight microgravity conditions for up to 4.6 seconds and is used extensively for ground-based microgravity convection research in which extremely small samples are studied. The facility can provide deep undercooling for containerless processing experiments that require materials to remain in a liquid phase when cooled below the normal solidification temperature.

Microgravity

NASA Image and Video Library

1981-03-30

Composite of Marshall Space Flight Center's Low-Gravity Free Fall Facilities.These facilities include a 100-meter drop tower and a 100-meter drop tube. The drop tower simulates in-flight microgravity conditions for up to 4.2 seconds for containerless processing experiments, immiscible fluids and materials research, pre-flight hardware design test and flight experiment simulation. The drop tube simulates in-flight microgravity conditions for up to 4.6 seconds and is used extensively for ground-based microgravity convection research in which extremely small samples are studied. The facility can provide deep undercooling for containerless processing experiments that require materials to remain in a liquid phase when cooled below the normal solidification temperature.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, Murray E.

The Los Alamos RP-SVS Radiation Protection Services group designed and constructed a drop tower facility for TA- 55 support work. The drop mechanism was supplied by the Lansmont company in Monterey CA. Los Alamos staffers Murray Moore and Yong Tao have noticed that the system is not dropping loads correctly, and they have photographed aspects of the PDT- 80 model system. The first 10 photos show the platen loaded with a cylindrical steel bar. The next 10 photos are of the roller-cam mechanism in the drop tower, and the last 2 photos indicate the amount of looseness in the platenmore » when it is being pulled by a person.« less

Surface tension propellant control for Viking 75 Orbiter

NASA Technical Reports Server (NTRS)

Dowdy, M. W.; Hise, R. E.; Peterson, R. G.; Debrock, S. C.

1976-01-01

The paper describes the selection, development and qualification of the surface tension system and includes results of low-g drop tower tests of scale models, 1-g simulation tests of low-g large ullage settling and liquid withdrawal, structural qualification tests, and propellant surface tension/contact angle studies. Subscale testing and analyses were used to evaluate the ability of the system to maintain or recover the desired propellant orientation following possible disturbances during the Viking mission. This effort included drop tower tests to demonstrate that valid wick paths exist for moving any displaced propellant back over the tank outlet. Variations in surface tension resulting from aging, temperature, and lubricant contamination were studied and the effects of surface finish, referee fluid exposure, aging, and lubricant contamination on contact angle were assessed. Results of movies of typical subscale drop tower tests and full scale slosh tests are discussed.

Dropping In a Microgravity Environment (DIME) contest

NASA Technical Reports Server (NTRS)

2001-01-01

The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. Here, students are briefed by NASA engineer Daniel Dietrich at the top of the drop tower. This image is from a digital still camera; higher resolution is not available.

New student-designed research and demonstration drop tower

NASA Astrophysics Data System (ADS)

Bell, Donald; Weislogel, Mark

A new drop tower has been designed and constructed at Portland State University. The ap-proach incorporates innovative features to increase throughput and microgravity quality in a highly public facility. Push button operation with full wireless CCTV coverage and passive magnetic deceleration provides quiet, safe operation from a single control station with low re-cycle time. A two-stage coaxial release mechanism decouples the payload from the drag shield to minimize disturbances to the experiment during release. This is especially important for fluids experiments that are highly sensitive to initial conditions. Performance of the new tower is presented including release, free fall, and deceleration accelerometer data. The two second tower is used for research and educational outreach. The research efforts focus on capillary flows and phenomena relevant to spacecraft fluid systems. The outreach efforts utilize partnerships with local primary, secondary and post-secondary institutions to promote the fields of science, technology, engineering and mathematics.

Dropping In a Microgravity Environment (DIME) contest

NASA Technical Reports Server (NTRS)

2001-01-01

The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. NASA and contractor personnel who conducted the DIME activity with the students. Shown (L-R) are: Eric Baumann (NASA, 2.2-second Drop Tower Facility manager), Daniel Dietrich (NASA) mentor for Sycamore High School team), Carol Hodanbosi (National Center for Microgravity Research; DIME staff), Richard DeLombard (NASA; DIME staff), Jose Carrion (GRC Akima, drop tower technician), Dennis Stocker (NASA; DIME staff), Peter Sunderland (NCMR, mentor for COSI Academy student team), Sandi Thompson (NSMR sabbatical teacher; DIME staff), Dan Woodard (MASA Microgravity Outreach Program Manager), Adam Malcolm (NASA co-op student; DIME staff), Carla Rosenberg (NCMR; DIME staff), and Twila Schneider (Infinity Technology; NASA Microgravity Research program contractor). This image is from a digital still camera; higher resolution is not available.

Dropping In a Microgravity Environment (DIME) contest

NASA Technical Reports Server (NTRS)

2001-01-01

The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. Here students from Sycamore High School in Cincinnati, Ohio, talk with Dr. Dennis Stocker, one of Glenn's lead microgravity scientists, about the uses of the drop tower. This image is from a digital still camera; higher resolution is not available.

Drop Tower and Aircraft Capabilities

NASA Technical Reports Server (NTRS)

Urban, David L.

2015-01-01

This presentation is a brief introduction to existing capabilities in drop towers and low-gravity aircraft that will be presented as part of a Symposium: Microgravity Platforms Other Than the ISS, From Users to Suppliers which will be a half day program to bring together the international community of gravity-dependent scientists, program officials and technologists with the suppliers of low gravity platforms (current and future) to focus on the future requirements and use of platforms other than the International Space Station (ISS).

Blast Mitigation Seat Analysis - Assessment of the Effect of Personal Protective Equipment on the 5th Percentile Female Anthropomorphic Test Devices Performance in Drop Tower Evaluations (Briefing Charts)

DTIC Science & Technology

2015-08-01

for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data ...sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden...UNCLASSIFIED UNCLASSIFIED • Baseline drop tower data collected from Anthropomorphic Test Devices (ATDs) seated in 12 models of Commercial Off-The-Shelf

Results and perspectives of particle transport measurements in gases in microgravity

NASA Astrophysics Data System (ADS)

Vedernikov, Andrei; Balapanov, Daniyar; Beresnev, Sergey

2016-07-01

Solid or liquid particles floating in a gas belong to dispersed systems, most often referred to as aerosols or dust clouds. They are widely spread in nature, involving both environmental and technological issues. They attract growing attention in microgravity, particularly in complex plasma, simulation of protoplanetary dust clouds, atmospheric aerosol, etc. Brownian random walk, motion of particles in gravity, electrostatic and magnetic fields, are well defined. We present the survey showing that the quantitative description of a vast variety of other types of motion is much less accurate, often known only in a limited region of parameters, sometimes described by the contradictory models, poorly verified experimentally. It is true even for the most extensively investigated transport phenomena - thermophoresis and photophoresis, not to say about diffusiophoresis, gravito-photophoresis, various other types of particle motion driven by physicochemical transformation and accommodation peculiarities on the particle-gas interface, combination of different processes. The number of publications grow very quickly, only those dealing with thermophoresis exceeded 300 in 2015. Hence, there is a strong need in high quality experimental data on particle transport properties with growing interest to expand the scope for non-isometric particles, agglomerates, dense clouds, interrelation with the two-phase flow dynamics. In most cases, the accuracy and sometimes the entire possibility of the measurement is limited by the presence of gravity. Floating particles have the density considerably different from that of the gas. They sediment, often with gliding and tumbling, that perturbs the motion trajectory, local hydrodynamic environment around particles, all together complicating definition of the response. Measurements at very high or very low Knudsen numbers (rarefied gas or too big particles) are of particular difficulty. Experiments assume creating a well-defined force, i.e. certain potential gradient. Most often, it results in the gas density non-uniformity and thus in perturbations from gravitational convection on the Earth. The advantages of microgravity in measurements of kinetic properties are well admitted since long ago. There are quite many experiments on this subject, well presented and referenced by the scientific community, however, sporadic and statistically not sufficiently worked out. It is timely and there is all the necessary components to getting crucial experimental data using microgravity, especially short duration drop tower flights. Of particular interest is the concurrent use of different set-up, their miniaturisation, combination of calibrated powders, coatings, introducing tracers, extreme particle thermal conductivities and gas accommodation coefficients that broaden the range of the parameters by several decimal orders of magnitude. This will provide the crucial accuracy and reliability to get reference data, to judge existing experimental results and to make the choice among controversial theoretical models. In the coming years, we anticipate the genuine break-through in high-quality particle transport measurements resulting in substantial advancement in aerosol microphysics and rarefied gas dynamics. ESA PRODEX program, the Belgian Federal Science Policy Office, ZARM Drop Tower Operation and Service Company Ltd. are greatly acknowledged.

Development of Active Learning Curriculum for CASPER's Microgravity Drop Tower

NASA Astrophysics Data System (ADS)

Carmona-Reyes, Jorge; Wang, Li; York, Judy; Matthews, Lorin; Laufer, Rene; Cook, Mike; Schmoke, Jimmy; Hyde, Truell

2016-10-01

As CASPER's new drop tower comes on line, plans for correlated educational research curricula are underway. CASPER's educational research team is working on developing curricula specific to the CASPER drop tower, modeled on a contest currently in use by (BEST) Robotics Inc. within central Texas independent school districts. The curricula integrates age specific use of computer programming software packages such as ``Scratch'' with industry standard communication protocols and augmented reality applications. Content is constructed around an earth and space science framework, covering subjects such as stars and galaxies, matter and energy, fusion and fission at a middle school level. CASPER faculty are partnering with the Region 12 Service Center; this combination provides a wide range of expertise that includes professional development, pedagogical methods, computational thinking in addition to microgravity and space science research expertise. The details of this work will be presented and samples of the manner in which it is impacting the CASPER research and educational outreach partnership will be discussed.

Microgravity

NASA Image and Video Library

2001-04-26

The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. Here, students are briefed by NASA engineer Daniel Dietrich at the top of the drop tower. This image is from a digital still camera; higher resolution is not available.

Microgravity

NASA Image and Video Library

2001-04-26

The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. NASA and contractor personnel who conducted the DIME activity with the students. Shown (L-R) are: Eric Baumann (NASA, 2.2-second Drop Tower Facility manager), Daniel Dietrich (NASA) mentor for Sycamore High School team), Carol Hodanbosi (National Center for Microgravity Research; DIME staff), Richard DeLombard (NASA; DIME staff), Jose Carrion (GRC Akima, drop tower technician), Dennis Stocker (NASA; DIME staff), Peter Sunderland (NCMR, mentor for COSI Academy student team), Sandi Thompson (NSMR sabbatical teacher; DIME staff), Dan Woodard (MASA Microgravity Outreach Program Manager), Adam Malcolm (NASA co-op student; DIME staff), Carla Rosenberg (NCMR; DIME staff), and Twila Schneider (Infinity Technology; NASA Microgravity Research program contractor). This image is from a digital still camera; higher resolution is not available.

The Physics of Shot Towers

ERIC Educational Resources Information Center

Lipscombe, Trevor C.; Mungan, Carl E.

2012-01-01

In the late 18th and throughout the 19th century, lead shot for muskets was prepared by use of a shot tower. Molten lead was poured from the top of a tower and, during its fall, the drops became spherical under the action of surface tension. In this article, we ask and answer the question: "How does the size of the lead shot depend on the height…

Dropping In a Microgravity Environment (DIME) contest

NASA Technical Reports Server (NTRS)

2001-01-01

The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. Here Jose Carrion, a lab mechanic with AKAC, starts the orange-colored drag shield, and the experiment apparatus inside, on the hoist upward to the control station at the top of the drop tower. This image is from a digital still camera; higher resolution is not available.

Development of the West Virginia University Small Microgravity Research Facility (WVU SMiRF)

NASA Astrophysics Data System (ADS)

Phillips, Kyle G.

West Virginia University (WVU) has created the Small Microgravity Research Facility (SMiRF) drop tower through a WVU Research Corporation Program to Stimulate Competitive Research (PSCoR) grant on its campus to increase direct access to inexpensive and repeatable reduced gravity research. In short, a drop tower is a tall structure from which experimental payloads are dropped, in a controlled environment, and experience reduced gravity or microgravity (i.e. "weightlessness") during free fall. Currently, there are several methods for conducting scientific research in microgravity including drop towers, parabolic flights, sounding rockets, suborbital flights, NanoSats, CubeSats, full-sized satellites, manned orbital flight, and the International Space Station (ISS). However, none of the aforementioned techniques is more inexpensive or has the capability of frequent experimentation repeatability as drop tower research. These advantages are conducive to a wide variety of experiments that can be inexpensively validated, and potentially accredited, through repeated, reliable research that permits frequent experiment modification and re-testing. Development of the WVU SMiRF, or any drop tower, must take a systems engineering approach that may include the detailed design of several main components, namely: the payload release system, the payload deceleration system, the payload lifting and transfer system, the drop tower structure, and the instrumentation and controls system, as well as a standardized drop tower payload frame for use by those researchers who cannot afford to spend money on a data acquisition system or frame. In addition to detailed technical development, a budgetary model by which development took place is also presented throughout, summarized, and detailed in an appendix. After design and construction of the WVU SMiRF was complete, initial calibration provided performance characteristics at various payload weights, and full-scale checkout via experimentation provided repeatability characteristics of the facility. Based on checkout instrumentation, Initial repeatability results indicated a drop time of 1.26 seconds at an average of 0.06g, with a standard deviation of 0.085g over the period of the drop, and a peak impact load of 28.72g, with a standard deviation of 10.73g, for a payload weight of 113.8 lbs. In order to thoroughly check out the facility, a full-scale, fully operational experiment was developed to create an experience that provides a comprehensive perspective of the end-user experience to the developer, so as to incorporate the details that may have been overlooked to the designer and/or developer, in this case, Kyle Phillips. The experiment that was chosen was to determine the effects of die swell, or extrudate swell, in reduced gravity. Die swell is a viscoelastic phenomenon that occurs when a dilatant, or shear-thickening substance is forced through a sufficient constriction, or "die," such that the substance expands, or "swells," downstream of the constriction, even while forming and maintaining a free jet at ambient sea level conditions. A wide range of dilatants exhibit die swell when subjected to the correct conditions, ranging from simple substances such as ketchup, oobleck, and shampoo to complex specially-formulated substances to be used for next generation body armor and high performance braking systems. To date, very few, if any, have researched the stabilizing effect that gravity may have on the phenomenon of die swell. By studying a fluid phenomenon in a reduced gravity environment, both the effect of gravity can be studied and the predominant forces acting on the fluid can be concluded. Furthermore, a hypothesis describing the behavior of a viscoelastic fluid particle employing the viscous Navier-Stokes Equations was derived to attempt to push the fluid mechanics community toward further integrating more fluid behavior into a unified mathematical model of fluid mechanics. While inconclusive in this experiment, several suggestions for future research were made in order to further the science behind die swell, and a comprehensive checkout of the facility and its operations were characterized. As a result of this checkout experience, several details were modified or added to the facility in order for the drop tower to be properly operated and provide the optimal user experience, such that open operation of the WVU SMiRF may begin in the Fall of 2014.

Microgravity

NASA Image and Video Library

2001-04-26

The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. Here students from Sycamore High School in Cincinnati, Ohio, talk with Dr. Dennis Stocker, one of Glenn's lead microgravity scientists, about the uses of the drop tower. This image is from a digital still camera; higher resolution is not available.

Study of the production of some superconducting and magnetic materials by solidification in the drop tube and drop tower

NASA Technical Reports Server (NTRS)

Wu, M. K.

1987-01-01

A systematic study on the relationship between the microstructure and physical properties of several superconducting materials prepared by solidification in low gravity was conducted. Further study of the materials, such as the applications of hydrostatic pressure which is known to be an effective mean to vary the electronic structure of materials, in conjunction with the detailed microstructure analysis of the samples was also performed to better understand the low gravity effects on the enhancement of the electronic properties. Results of the studies on the directionally solidified AlInSn alloys processed in the KC-135 aircraft and immiscible GaBi alloy prepared during free fall in the Marshall Space Flight Center Drop Tower are presented.

Drop Tower Facility at Queensland University of Technology

NASA Astrophysics Data System (ADS)

Plagens, Owen; Castillo, Martin; Steinberg, Theodore; Ong, Teng-Cheong

The Queensland University of Technology (QUT) Drop Tower Facility is a {raise.17exscriptstyle˜}2.1 second, 21.3 m fall, dual capsule drop tower system. The dual capsule comprises of an uncoupled exterior hollow drag shield that experiences drag by the ambient atmosphere with the experimental capsule falling within the drag shield. The dual capsule system is lifted to the top of the drop tower via a mechanical crane and the dropping process is initiated by the cutting of a wire coupling the experimental package and suspending the drag shield. The internal experimental capsule reaches the bottom of the drag shield floor just prior to the deceleration stage at the air bag and during this time experience gravity levels of {raise.17exscriptstyle˜}10textsuperscript{-6} g. The deceleration system utilizes an inflatable airbag where experimental packages can be designed to experience a maximum deceleration of {raise.17exscriptstyle˜}10textsuperscript{18} g for {raise.17exscriptstyle˜}0.1 seconds. The drag shield can house experimental packages with a maximum diameter of 0.8 m and height of 0.9 m. The drag shield can also be used in foam mode, where the walls are lined with foam and small experiments can be dropped completely untethered. This mode is generally used for the study of microsatellite manipulation. Payloads can be powered by on-board power systems with power delivered to the experiment until free fall occurs. Experimental data that can be collected includes but is not limited to video, temperature, pressure, voltage/current from the power supply, and triggering mechanisms outputs which are simultaneously collected via data logging systems and high speed video recording systems. Academic and commercial projects are currently under investigation at the QUT Drop Tower Facility and collaboration is openly welcome at this facility. Current research includes the study of heterogeneously burning metals in oxygen which is aimed at fire safety applications and identifying size distributions and morphologies of particles produced during the combustion of bulk metals. Materials produced via self-propagating high-temperature synthesis in microgravity are investigated to produce high electroluminescent materials and high efficient dye sensitized electrolyte materials. The rapid cooling and quenching of ZBLAN glass in a microgravity environment is studied to reduce crystallization in the glass. Convective pool boiling and nucleate bubble formation in nano-fluids is aimed at investigating heat transfer properties in these new materials which are masked by gravity. Novel carbon nanotubes are produced in low gravity via an arch discharge to investigate the formation mechanisms of these materials.

Microgravity experiment study on the vane type surface tension tank

NASA Astrophysics Data System (ADS)

Kang, Qi; Duan, Li; Rui, Wei

Having advantages of low cost, convenience and high level of microgravity, the drop tower has become a significant microgravity experiment facility. National Microgravity Laboratory/CAS(NMLC) drop tower has 3.5s effective microgravity time, meanwhile the level of microgravity can reach 10 (-5) g. And the impact acceleration is less than 15g in the recovery period. The microgravity experiments have been conducted on the scaling model of vane type surface tension tank in NMLC’s drop tower. The efficiency of Propellant Management Devices (PMDs) was studied, which focus on the effects of Propellant Management Devices (PMDs), numbers of PMDs, contact angle, and liquid viscosity on the flow rate. The experimental results shown that the numbers of PMDs have little or no effect on the flow rate while the liquid is sufficient. The experiments about the influence of different charging ratio have been carried out while tank is placed positively and reversely, and we find the charging ratio has less effect on the capillary flow rate when the charging ratio is greater than 2%.

Preliminary Design, Feasibility and Cost Evaluation of 1- to 15-Kilometer Height Steel Towers

NASA Technical Reports Server (NTRS)

Shanker, Ajay

2003-01-01

Design and construction of tall towers is an on-going research program of NASA. The agency has already done preliminary review in this area and has determined that multi-kilometer height towers are technically and economically feasible. The proposed towers will provide high altitude launch platforms reaching above eighty percent of Earth's atmosphere and provide tremendous gains in the potential energy as well as substantial reduction in aerodynamic drag. NASA has also determined that a 15-KM tower will have many useful applications in: (i)Meteorology,(ii)Oceanography, (iii)Astronomy, (iv)High Altitude Launch, (v)Physics Drop Tower, (vi) Biosphere Research, (vii) Nanotechnology, (viii) Energy/Power, (ix)Broadband Wireless Technology, (x)Space Transportation and (xi)Space Tourism.

Blast Mitigation Sea Analysis - Evaluation of Lumbar Compression Data Trends in 5th Percentile Female Anthropomorphic Test Device Performance Compared to 50th Percentile Male Anthropomorphic Test Device in Drop Tower Testing

DTIC Science & Technology

2016-08-21

less pronounced for pelvis velocity • Seat velocity and dynamic displacement not recorded for this test series – Would provide key information for...effectiveness of seat – Displacement /time history data should be recorded for all future test series UNCLASSIFIED UNCLASSIFIED Conclusions/Future...interfacing with seat manufacturers to broaden occupant protection range – Record dynamic stroke on all drop tower tests to evaluate correlation between displacement rate and lumbar compression UNCLASSIFIED UNCLASSIFIED 17

Microgravity

NASA Image and Video Library

2001-04-26

The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. Here Jose Carrion, a lab mechanic with AKAC, starts the orange-colored drag shield, and the experiment apparatus inside, on the hoist upward to the control station at the top of the drop tower. This image is from a digital still camera; higher resolution is not available.

How to Make a Microgravity Drop Tower for Your Classroom

NASA Technical Reports Server (NTRS)

DeLombard, Richard; Hall, Nancy R.

2014-01-01

Microgravity is quite often seen as exotic and special as astronauts float around in the International Space Station, eating MM's in mid-air, and performing science experiments, all done seemingly without gravity being present. Surprisingly enough, up on the ISS there is about 90 of the same gravity that holds you to the floor in your classroom or museum exhibit hall. Participate in this session and you will understand that and more. You can use simple devices to demonstrate microgravity conditions in your classroom or museum exhibit hall. This will be the same microgravity condition that astronauts experience on the ISS, just for a much shorter period of time. Contrary to popular opinion of some people, microgravity is NOT caused by zero gravity up there. Microgravity on the ISS is due to free fall within the Earth's gravitational field. That means you can drop an item in free fall in your classroom and museum exhibit hall and that item will experience microgravity. In this session, a short theory segment will explain and reinforce these concepts so that you may explain to others. The session will concentrate on showing the session participants how to make an effective, but inexpensive, drop tower for use in the classroom. Such a drop tower may be used to reinforce classroom instruction in physics and forces motion as well as serve as a platform for student investigations, classroom competitions, and student science or technology fair entries. Session participants will build their own simple microgravity experiment and operate them in a drop tower, compare results, and modify their experiment based on results. This material is also useful for public demonstrations at school open houses, travelling museum exhibits, fixed museum exhibits, and independent student projects or experiments. These free fall concepts also connect terrestrial demonstrations with planetary moon motion, comet trajectory, and more.

Sandia National Laboratories, Tonopah Test Range Askania Tower (Building 02-00): Photographs and Written Historical and Descriptive Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ullrich, Rebecca A.

The Askania Tower (Building 02-00) was built in 1956 as part of the first wave of construction at the newly established Tonopah Test Range (TTR). Located at Station 2, near the primary target area at the range, the tower was one of the first four built to house Askania phototheodolites used in tracking test units dropped from aircraft. This report includes historical information, architectural information, sources of information, project information, maps, blueprints, and photographs.

Diode pumped solid state kilohertz disk laser system for time-resolved combustion diagnostics under microgravity at the drop tower Bremen

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wagner, Volker; Paa, Wolfgang; Triebel, Wolfgang

We describe a specially designed diode pumped solid state laser system based on the disk laser architecture for combustion diagnostics under microgravity (μg) conditions at the drop tower in Bremen. The two-stage oscillator-amplifier-system provides an excellent beam profile (TEM{sub 00}) at narrowband operation (Δλ < 1 pm) and is tunable from 1018 nm to 1052 nm. The laser repetition rate of up to 4 kHz at pulse durations of 10 ns enables the tracking of processes on a millisecond time scale. Depending on the specific issue it is possible to convert the output radiation up to the fourth harmonic aroundmore » 257 nm. The very compact laser system is integrated in a slightly modified drop capsule and withstands decelerations of up to 50 g (>11 ms). At first the concept of the two-stage disk laser is briefly explained, followed by a detailed description of the disk laser adaption to the drop tower requirements with special focus on the intended use under μg conditions. In order to demonstrate the capabilities of the capsule laser as a tool for μg combustion diagnostics, we finally present an investigation of the precursor-reactions before the droplet ignition using 2D imaging of the Laser Induced Fluorescence of formaldehyde.« less

Experimental measurement of cooling tower emissions using image processing of sensitive papers

NASA Astrophysics Data System (ADS)

Ruiz, J.; Kaiser, A. S.; Ballesta, M.; Gil, A.; Lucas, M.

2013-04-01

Cooling tower emissions are harmful for several reasons such as air polluting, wetting, icing and solid particle deposition, but mainly due to human health hazards (i.e. Legionella). There are several methods for measuring drift drops. This paper is focussed on the sensitive paper technique, which is suitable in low drift scenarios and real conditions. The lack of an automatic classification method motivated the development of a digital image process algorithm for the Sensitive Paper method. This paper presents a detailed description of this method, in which, drop-like elements are identified by means of the Canny edge detector combined with some morphological operations. Afterwards, the application of a J48 decision tree is proposed as one of the most relevant contributions. This classification method allows us to discern between stains whose origin is a drop and stains whose origin is not a drop. The method is applied to a real case and results are presented in terms of drift and PM10 emissions. This involves the calculation of the main features of the droplet distribution at the cooling tower exit surface in terms of drop size distribution data, cumulative mass distribution curve and characteristic drop diameters. The Log-normal and the Rosin-Rammler distribution functions have been fitted to the experimental data collected in the tests and it can been concluded that the first one is the most suitable for experimental data among the functions tested (whereas the second one is less suitable). Realistic PM10 calculations include the measurement of drift emissions and Total Dissolved Solids as well as the size and number of drops. Results are compared to the method proposed by the U.S. Environmental Protection Agency assessing its overestimation. Drift emissions have found to be 0.0517% of the recirculating water, which is over the Spanish standards limit (0.05%).

Preliminary drop-tower experiments on liquid-interface geometry in partially filled containers at zero gravity

NASA Technical Reports Server (NTRS)

Smedley, G.

1990-01-01

Plexiglass containers with rounded trapezoidal cross sections were designed and built to test the validity of Concus and Finn's existence theorem (1974, 1983) for a bounded free liquid surface at zero gravity. Experiments were carried out at the NASA Lewis two-second drop tower. Dyed ethanol-water solutions and three immiscible liquid pairs, with one liquid dyed, were tested. High-speed movies were used to record the liquid motion. Liquid rose to the top of the smaller end of the containers when the contact angle was small enough, in agreement with the theory. Liquid interface motion demonstrated a strong dependence on physical properties, including surface roughness and contamination.

75 FR 65669 - Notice of Information Collection

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-26

... INFORMATION: I. Abstract DIME & WING are components of a NASA competition program which allows teams to design and build a science experiment which will then be operated in a NASA microgravity drop tower facility. Teams of 4 students are selected to come to GRC and drop their experiment and will be required to...

75 FR 54189 - Notice of Information Collection

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-03

... INFORMATION: I. Abstract DIME & WING are components of a NASA competition program which allows teams to design and build a science experiment which will then be operated in a NASA microgravity drop tower facility. Teams of 4 students are selected to come to GRC and drop their experiment and will be required to...

Dropping In a Microgravity Environment (DIME) Contest

NASA Technical Reports Server (NTRS)

2001-01-01

The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. NASA and contractor personnel who conducted the DIME activity with the students. Shown (L-R) are: Daniel Dietrich (NASA) mentor for Sycamore High School team), Carol Hodanbosi (National Center for Microgravity Research; DIME staff), Jose Carrion (GRC Akima, drop tower technician), Dennis Stocker (NASA; DIME staff), Richard DeLombard (NASA; DIME staff), Sandi Thompson (NSMR sabbatical teacher; DIME staff), Peter Sunderland (NCMR, mentor for COSI Academy student team), Adam Malcolm (NASA co-op student; DIME staff). This image is from a digital still camera; higher resolution is not available.

Modified Drop Tower Impact Tests for American Football Helmets.

PubMed

Rush, G Alston; Prabhu, R; Rush, Gus A; Williams, Lakiesha N; Horstemeyer, M F

2017-02-19

A modified National Operating Committee on Standards for Athletic Equipment (NOCSAE) test method for American football helmet drop impact test standards is presented that would provide better assessment of a helmet's on-field impact performance by including a faceguard on the helmet. In this study, a merger of faceguard and helmet test standards is proposed. The need for a more robust systematic approach to football helmet testing procedures is emphasized by comparing representative results of the Head Injury Criterion (HIC), Severity Index (SI), and peak acceleration values for different helmets at different helmet locations under modified NOCSAE standard drop tower tests. Essentially, these comparative drop test results revealed that the faceguard adds a stiffening kinematic constraint to the shell that lessens total energy absorption. The current NOCSAE standard test methods can be improved to represent on-field helmet hits by attaching the faceguards to helmets and by including two new helmet impact locations (Front Top and Front Top Boss). The reported football helmet test method gives a more accurate representation of a helmet's performance and its ability to mitigate on-field impacts while promoting safer football helmets.

Review on drop towers and long drop tubes

NASA Technical Reports Server (NTRS)

Bayuzick, R. J.; Hofmeister, W. H.; Robinson, M. B.

1987-01-01

A drop tube is an enclosure in which a molten sample can be solidified while falling; three such large tubes are currently in existence, all at NASA research facilities, and are engaged in combustion and fluid physics-related experiments rather than in materials research. JPL possesses smaller tubes, one of which can be cryogenically cooled to produce glass and metal microshells. A new small drop tube will soon begin operating at NASA Lewis that is equipped with four high-speed two-color pyrometers spaced equidistantly along the column.

Droplet combustion at reduced gravity

NASA Technical Reports Server (NTRS)

Dryer, F. L.; Williams, F. A.

1988-01-01

The current work involves theoretical analyses of the effects identified, experiments in the NASA Lewis drop towers performed in the middeck areas of the Space Shuttle. In addition, there is laboratory work associated with the design of the flight apparatus. Calculations have shown that some of the test-matrix data can be obtained in drop towers, and some are achievable only in the space experiments. The apparatus consists of a droplet dispensing device (syringes), a droplet positioning device (opposing, retractable, hollow needles), a droplet ignition device (two matched pairs of retractable spark electrodes), gas and liquid handling systems, a data acquisition system (mainly giving motion-picture records of the combustion in two orthogonal views, one with backlighting for droplet resolution), and associated electronics.

Development of PIV for Microgravity Diffusion Flames

NASA Technical Reports Server (NTRS)

Greenberg, Paul S.; Wernet, Mark P.; Yanis, William; Urban, David L.; Sunderland, Peter B.

2003-01-01

Results are presented from the application of Particle Image Velocimetry(PIV) to the overfire region of a laminar gas jet diffusion flame in normal gravity. A methane flame burning in air at 0.98 bar was considered. The apparatus demonstrated here is packaged in a drop rig designed for use in the 2.2 second drop tower.

Short Shot Tower for Silicon

NASA Technical Reports Server (NTRS)

Bates, H. E.; Hill, D. M.; Jewett, D. N.

1983-01-01

Drop length necessary to convert molten silicon to shot reduced by proposed new process. Conversion of silicon from powder or chunks to shot often simplifies processing. Shot is more easily handled in most processing equipment. Drops of liquid silicon fall through protective cloud of argon, then through rapidly cooling bath of methanol, where they quickly turn into solid shot.

Multi-Terrain Vertical Drop Tests of a Composite Fuselage Section

NASA Technical Reports Server (NTRS)

Kellas, Sotiris; Jackson, Karen E.

2008-01-01

A 5-ft-diameter composite fuselage section was retrofitted with four identical blocks of deployable honeycomb energy absorber and crash tested on two different surfaces: soft soil, and water. The drop tests were conducted at the 70-ft. drop tower at the Landing and Impact Research (LandIR) Facility of NASA Langley. Water drop tests were performed into a 15-ft-diameter pool of water that was approximately 42-in. deep. For the soft soil impact, a 15-ft-square container filled with fine-sifted, unpacked sand was located beneath the drop tower. All drop tests were vertical with a nominally flat attitude with respect to the impact surface. The measured impact velocities were 37.4, and 24.7-fps for soft soil and water, respectively. A fuselage section without energy absorbers was also drop tested onto water to provide a datum for comparison with the test, which included energy absorbers. In order to facilitate this type of comparison and to ensure fuselage survivability for the no-energy-absorber case, the velocity of the water impact tests was restricted to 25-fps nominal. While all tests described in this paper were limited to vertical impact velocities, the implications and design challenges of utilizing external energy absorbers during combined forward and vertical impact velocities are discussed. The design, testing and selection of a honeycomb cover, which was required in soft surface and water impacts to transmit the load into the honeycomb cell walls, is also presented.

An Experimental Study of the Structure of Turbulent Non-Premixed Jet Flames in Microgravity

NASA Astrophysics Data System (ADS)

Boxx, Isaac; Idicheria, Cherian; Clemens, Noel

2000-11-01

The aim of this work is to investigate the structure of transitional and turbulent non-premixed jet flames under microgravity conditions. The microgravity experiments are being conducted using a newly developed drop rig and the University of Texas 1.5 second drop tower. The rig itself measures 16”x33”x38” and contains a co-flowing round jet flame facility, flow control system, CCD camera, and data/image acquisition computer. These experiments are the first phase of a larger study being conducted at the NASA Glenn Research Center 2.2 second drop tower facility. The flames being studied include methane and propane round jet flames at jet exit Reynolds numbers as high as 10,000. The primary diagnostic technique employed is emission imaging of flame luminosity using a relatively high-speed (350 fps) CCD camera. The high-speed images are used to study flame height, flame tip dynamics and burnout characteristics. Results are compared to normal gravity experimental results obtained in the same apparatus.

The Effects of Buoyancy on Characteristics of Turbulent Nonpremixed Jet Flames

NASA Astrophysics Data System (ADS)

Idicheria, Cherian; Boxx, Isaac; Clemens, Noel

2002-11-01

This work addresses the influence of buoyant forces on the underlying structure of turbulent nonpremixed jet flames. Buoyancy effects are investigated by studying transitional and turbulent propane and ethylene flames (Re_D=2500-10500) at normal, low and microgravity conditions. The reduced gravity experiments are conducted by dropping a combustion rig in the University of Texas 1.25-second drop tower and the NASA Glenn 2.2-second drop tower. The diagnostic employed is high-speed luminosity imaging using a CCD camera. The images obtained are used to compare flame length, mean, RMS and flame tip oscillation characteristics The results showed that, in contrast to previous studies, the high Reynolds number flames at all gravity levels were essentially identical. Furthermore, the parameter ξL (Becker and Yamazaki, 1978) is sufficient for quantifying the effects of buoyancy on the flame characteristics. The large-scale structure and flame tip dynamics are essentially identical to those of purely momentum driven flames provided ξL is less than approximately 3.

Microgravity

NASA Image and Video Library

2001-04-26

The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. NASA and contractor personnel who conducted the DIME activity with the students. Shown (L-R) are: Daniel Dietrich (NASA) mentor for Sycamore High School team), Carol Hodanbosi (National Center for Microgravity Research; DIME staff), Jose Carrion (GRC Akima, drop tower technician), Dennis Stocker (NASA; DIME staff), Richard DeLombard (NASA; DIME staff), Sandi Thompson (NSMR sabbatical teacher; DIME staff), Peter Sunderland (NCMR, mentor for COSI Academy student team), Adam Malcolm (NASA co-op student; DIME staff). This image is from a digital still camera; higher resolution is not available.

Comparison of explicit finite element and mechanical simulation of the proximal femur during dynamic drop-tower testing.

PubMed

Ariza, O; Gilchrist, S; Widmer, R P; Guy, P; Ferguson, S J; Cripton, P A; Helgason, B

2015-01-21

Current screening techniques based on areal bone mineral density (aBMD) measurements are unable to identify the majority of people who sustain hip fractures. Biomechanical examination of such events may help determine what predisposes a hip to be susceptible to fracture. Recently, drop-tower simulations of in-vitro sideways falls have allowed the study of the mechanical response of the proximal human femur at realistic impact speeds. This technique has created an opportunity to validate explicit finite element (FE) models against dynamic test data. This study compared the outcomes of 15 human femoral specimens fractured using a drop tower with complementary specimen-specific explicit FE analysis. Correlation coefficient and root mean square error (RMSE) were found to be moderate for whole bone stiffness comparison (R(2)=0.3476 and 22.85% respectively). No correlation was found between experimentally and computationally predicted peak force, however, energy absorption comparison produced moderate correlation and RMSE (R(2)=0.4781 and 29.14% respectively). By comparing predicted strain maps to high speed video data we demonstrated the ability of the FE models to detect vulnerable portions of the bones. Based on our observations, we conclude that there exists a need to extend the current apparent level material models for bone to cover higher strain rates than previously tested experimentally. Copyright © 2014 Elsevier Ltd. All rights reserved.

DIME Students Waiting for Their Turn to Drop Experiment

NASA Technical Reports Server (NTRS)

2002-01-01

Students pause while waiting their turn at the 2.2-second Drop Tower during the second Dropping in a Microgravity Environment (DIME) competition held April 23-25, 2002, at NASA's Glenn Research Center. Competitors included two teams from Sycamore High School, Cincinnati, OH, and one each from Bay High School, Bay Village, OH, and COSI Academy, Columbus, OH. DIME is part of NASA's education and outreach activities. Details are on line at http://microgravity.grc.nasa.gov/DIME_2002.html.

High-school Student Teams in a National NASA Microgravity Science Competition

NASA Technical Reports Server (NTRS)

DeLombard, Richard; Hodanbosi, Carol; Stocker, Dennis

2003-01-01

The Dropping In a Microgravity Environment or DIME competition for high-school-aged student teams has completed the first year for nationwide eligibility after two regional pilot years. With the expanded geographic participation and increased complexity of experiments, new lessons were learned by the DIME staff. A team participating in DIME will research the field of microgravity, develop a hypothesis, and prepare a proposal for an experiment to be conducted in a NASA microgravity drop tower. A team of NASA scientists and engineers will select the top proposals and then the selected teams will design and build their experiment apparatus. When completed, team representatives will visit NASA Glenn in Cleveland, Ohio to operate their experiment in the 2.2 Second Drop Tower and participate in workshops and center tours. NASA participates in a wide variety of educational activities including competitive events. There are competitive events sponsored by NASA (e.g. NASA Student Involvement Program) and student teams mentored by NASA centers (e.g. For Inspiration and Recognition of Science and Technology Robotics Competition). This participation by NASA in these public forums serves to bring the excitement of aerospace science to students and educators.Researchers from academic institutions, NASA, and industry utilize the 2.2 Second Drop Tower at NASA Glenn Research Center in Cleveland, Ohio for microgravity research. The researcher may be able to complete the suite of experiments in the drop tower but many experiments are precursor experiments for spaceflight experiments. The short turnaround time for an experiment's operations (45 minutes) and ready access to experiment carriers makes the facility amenable for use in a student program. The pilot year for DIME was conducted during the 2000-2001 school year with invitations sent out to Ohio- based schools and organizations. A second pilot year was conducted during the 2001-2002 school year for teams in the six-state region of Illinois, Indiana, Michigan, Minnesota, Ohio, and Wisconsin. The third year for DIME was conducted during the 2002-2003 school year for teams from the fifty United States, the District of Columbia, and Puerto Rico. An annual national DIME program is planned for the foreseeable future. Presented in this paper will be a description of DIME, an overview of the planning and execution of such a program, results from the first three years, and lessons learned from the first national competition.

Study on processing immiscible materials in zero gravity

NASA Technical Reports Server (NTRS)

Reger, J. L.; Mendelson, R. A.

1975-01-01

An experimental investigation was conducted to evaluate mixing immiscible metal combinations under several process conditions. Under one-gravity, these included thermal processing, thermal plus electromagnetic mixing, and thermal plus acoustic mixing. The same process methods were applied during free fall on the MSFC drop tower facility. The design is included of drop tower apparatus to provide the electromagnetic and acoustic mixing equipment, and a thermal model was prepared to design the specimen and cooling procedure. Materials systems studied were Ca-La, Cd-Ga and Al-Bi; evaluation of the processed samples included the morphology and electronic property measurements. The morphology was developed using optical and scanning electron microscopy and microprobe analyses. Electronic property characterization of the superconducting transition temperatures were made using an impedance change-tuned coil method.

Analysis of cryogenic propellant behavior in microgravity and low thrust environments

NASA Technical Reports Server (NTRS)

Fisher, Mark F.; Schmidt, George R.; Martin, James J.

1991-01-01

Predictions of a CFD program calculating a fluid-free surface shape and motion as a function of imposed acceleration are validated against the drop-tower test data collected to support design and performance assessments of the Saturn S-IVB stage liquid-hydrogen tank. The drop-tower facility, experimental package, and experiment procedures are outlined, and the program is described. It is noted that the validation analysis confirms the program's suitability for predicting low-g fluid slosh behavior, and that a similar analysis could examine the effect of incorporating baffles and screens to impede initiation of any unwanted side loads due to slosh. It is concluded that in actual vehicle applications, the engine thrust tailoff profile should be included in computer simulations if the precise interface versus time definition is needed.

Pressure dependence of the electrical properties of GaBi solidified in low gravity

NASA Technical Reports Server (NTRS)

Wu, M. K.; Ashburn, J. R.; Torng, C. J.; Curreri, P. A.; Chu, C. W.

1987-01-01

Immiscible GaBi alloys were solidified during free fall in the NASA Marshall Space Flight Center drop tower, which provides about 4.5 seconds of low gravity. The electrical resistivity and magnetic susceptibility were measured as a function of pressure (up to 18 kbar) and temperature (300 K to 4.2 K) of drop tower (DT) and ground control (GC) samples prepared under identical conditions, except for gravity. At ambient pressure the electrical resistance of the DT sample exhibits a broad maximum at 100 K, while that of GC sample decreases rapidly as temperature decreases. Both DT and GC samples become superconducting at 7.7 K. However, a minor second superconducting phase with a transition temperature at 8.3 K is observed only in the DT samples.

Intracellular Calcium Decreases Upon Hyper Gravity-Treatment of Arabidopsis Thaliana Cell Cultures

NASA Astrophysics Data System (ADS)

Neef, Maren; Denn, Tamara; Ecke, Margret; Hampp, Rüdiger

2016-06-01

Cell cultures of Arabidopsis thaliana ( A. t.) respond to changes in the gravitational field strength with fluctuations of the amount of cytosolic calcium (Ca2+). In parabolic flight experiments, where hyper- and μg phases follow each other, μg clearly increased Ca2+, while hyper-g caused a slight reduction. Since the latter observation had not been reported before, we studied this effect in more detail. Using a special centrifuge for heavy items (ZARM, Bremen, Germany), we determined the hyper-g-dependent intracellular Ca2+ level with transgenic cell lines expressing the Ca2+ sensor, cameleon. This sensor exhibits a shift in fluorescence from 480 to 530 nm in response to Ca2+ binding. The data show a drop in the intracellular Ca2+ concentration with a threshold gravity of around 3 g. This is above hypergravity levels achieved during parabolic flights (1.8 g). The use of mutants with different sub-cellular targets of cameleon expression (nucleus, tonoplast, plasma membrane) gave the same results, i.e. Ca2+ is obviously exported from several intracellular compartments.

Method of forming frozen spheres in a force-free drop tower

NASA Technical Reports Server (NTRS)

Kendall, J. M., Jr. (Inventor)

1982-01-01

Hollow glass spheres are shaped by the effects of surface tension acting on bubbles of glass in its molten state. A downwardly flowing stream of air accelerated at a one-G rate of acceleration is established through a drop bubbles on molten glass are introduced into the stream of air and frozen and as they are accelerated at a one-G rate of acceleration.

Surface settling in partially filled containers upon step reduction in gravity

NASA Technical Reports Server (NTRS)

Weislogel, Marl M.; Ross, Howard D.

1990-01-01

A large literature exists concerning the equilibrium configurations of free liquid/gas surfaces in reduced gravity environments. Such conditions generally yield surfaces of constant curvature meeting the container wall at a particular (contact) angle. The time required to reach and stabilize about this configuration is less studied for the case of sudden changes in gravity level, e.g. from normal- to low-gravity, as can occur in many drop tower experiments. The particular interest here was to determine the total reorientation time for such surfaces in cylinders (mainly), as a function primarily of contact angle and kinematic viscosity, in order to aid in the development of drop tower experiment design. A large parametric range of tests were performed and, based on an accompanying scale analysis, the complete data set was correlated. The results of other investigations are included for comparison.

Modeling the Restraint of Liquid Jets by Surface Tension in Microgravity

NASA Technical Reports Server (NTRS)

Chato, David J.; Jacqmim, David A.

2001-01-01

An axisymmetric phase field model is developed and used to model surface tension forces on liquid jets in microgravity. The previous work in this area is reviewed and a baseline drop tower experiment selected 'for model comparison. A mathematical model is developed which includes a free surface. a symmetric centerline and wall boundaries with given contact angles. The model is solved numerically with a compact fourth order stencil on a equally spaced axisymmetric grid. After grid convergence studies, a grid is selected and all drop tower tests modeled. Agreement was assessed by comparing predicted and measured free surface rise. Trend wise agreement is good but agreement in magnitude is only fair. Suspected sources of disagreement are suspected to be lack of a turbulence model and the existence of slosh baffles in the experiment which were not included in the model.

Gravitational Effects on Flow Instability and Transition in Low Density Jets

NASA Technical Reports Server (NTRS)

Agrawal, Ajay K.; Parthasarathy, Ramkumar

2004-01-01

Experiments were conducted in Earth gravity and microgravity to acquire quantitative data on near field flow structure of helium jets injected into air. Microgravity conditions were simulated in the 2.2-second drop tower at NASA Glenn Research Center. The jet flow was observed by quantitative rainbow schlieren deflectometry, a non-intrusive line of sight measurement technique suited for the microgravity environment. The flow structure was characterized by distributions of helium mole fraction obtained from color schlieren images taken at 60 Hz. Results show that the jet in microgravity was up to 70 percent wider than that in Earth gravity. Experiments reveal that the global flow oscillations observed in Earth gravity are absent in microgravity. The report provides quantitative details of flow evolution as the experiment undergoes change in gravity in the drop tower.

Method and apparatus for generating microshells of refractory materials

NASA Technical Reports Server (NTRS)

Lee, Mark C. (Inventor); Schilling, Christopher (Inventor); Ladner, Jr., George O. (Inventor); Wang, Taylor G. (Inventor)

1987-01-01

A system is described for forming accurately spherical and centered fluid-filled shells, especially of high melting temperature material. Material which is to form the shells is placed in a solid form in a container, and the material is rapidly heated to a molten temperature to avoid recrystallization and the possible generation of unwanted microbubbles in the melt. Immediately after the molten shells are formed, they drop through a drop tower whose upper end is heated along a distance of at least one foot to provide time for dissipation of surface waves on the shells while they cool to a highly viscous, or just above melting temperature so that the bubble within the shell will not rise and become off centered. The rest of the tower is cryogenically cooled to cool the shell to a solid state.

Experimental development of processes to produce homogenized alloys of immiscible metals, phase 3

NASA Technical Reports Server (NTRS)

Reger, J. L.

1976-01-01

An experimental drop tower package was designed and built for use in a drop tower. This effort consisted of a thermal analysis, container/heater fabrication, and assembly of an expulsion device for rapid quenching of heated specimens during low gravity conditions. Six gallium bismuth specimens with compositions in the immiscibility region (50 a/o of each element) were processed in the experimental package: four during low gravity conditions and two under a one gravity environment. One of the one gravity processed specimens did not have telemetry data and was subsequently deleted for analysis since the processing conditions were not known. Metallurgical, Hall effect, resistivity, and superconductivity examinations were performed on the five specimens. Examination of the specimens showed that the gallium was dispersed in the bismuth. The low gravity processed specimens showed a relatively uniform distribution of gallium, with particle sizes of 1 micrometer or less, in contrast to the one gravity control specimen. Comparison of the cooling rates of the dropped specimens versus microstructure indicated that low cooling rates are more desirable.

Sooting Limits Of Microgravity Spherical Diffusion Flames. [conducted in the NASA Glenn 2.2-second drop tower

NASA Technical Reports Server (NTRS)

Sunderland, P. B.; Urban, D. L.; Stocker, D. P.; Chao, B.-H.; Axelbaum, Richard L.; Salzman, Jack (Technical Monitor)

2001-01-01

Limiting conditions for soot-particle inception were studied in microgravity spherical diffusion flames burning ethylene at atmospheric pressure. Nitrogen was supplied in the fuel and/or oxidizer to obtain the broadest range of stoichiometric mixture fraction. Both normal flames (oxygen in ambience) and inverted flames (fuel in ambience) were considered. Microgravity was obtained in the NASA Glenn 2.2-second drop tower. The flames were observed with a color video camera and sooting conditions were defined as conditions for which yellow emission was present throughout the duration of the drop. Sooting limit results were successfully correlated in terms of adiabatic flame temperature and stoichiometric mixture fraction. Soot free conditions were favored by increased stoichiometric mixture fractions. No statistically significant effect of convection direction on sooting limits was observed. The relationship between adiabatic flame temperature and stoichiometric mixture fraction at the sooting limits was found to be in qualitative agreement with a simple theory based on the assumption that soot inception can occur only where temperature and local C/O ratio exceed threshold values (circa 1250 K and 1, respectively).

Before the Drop: Engineers Ready Supersonic Decelerator

NASA Image and Video Library

2014-05-21

A saucer-shaped vehicle part of NASA Low-Density Supersonic Decelerator LDSD project designed to test interplanetary landing devices hangs on a tower in preparation for launch at the Pacific Missile Range Facility in Kauai, Hawaii.

Multiple impacts of dusty projectiles

NASA Astrophysics Data System (ADS)

Kothe, Stefan; Güttler, Carsten; Blum, Jurgen

In the context of early stages of planetesimal formation we performed laboratory and drop tower experiments to study multiple impacts of small dust-aggregate projectiles into solid sintered dust targets. Both collision partners consisted of 1.5 µm monodisperse spherical SiO2 monomers with volume filling factors of 0.15 (projectiles) and 0.35 (targets), respectively. The fragile projectiles were accelerated by a solenoid accelerator with a linear projectile magazine, which enabled us to perform 25 impacts within 4.5 s of microgravity time in the Bremen drop tower. We measured the mass-accretion efficiency for different impact velocities between 3 and 5 m s-1 , using an analytical balance and imaging methods. Furthermore, we observed random collisions among small dust aggregates with sizes around 1 mm and collision velocities of the order of 0.25 m s-1 and used them to improve the dust-aggregate collision model of Güttler et al. (2010). u

Bubble dynamics, two-phase flow, and boiling heat transfer in a microgravity environment

NASA Technical Reports Server (NTRS)

Chung, Jacob N.

1994-01-01

The two-phase bubbly flow and boiling heat transfer in microgravity represents a substantial challenge to scientists and engineers and yet there is an urgent need to seek fundamental understanding in this area for future spacecraft design and space missions. At Washington State University, we have successfully designed, built and tested a 2.1 second drop tower with an innovation airbag deceleration system. Microgravity boiling experiments performed in our 0.6 second Drop Tower produced data flow visualizations that agree with published results and also provide some new understanding concerning flow boiling and microgravity bubble behavior. On the analytical and numerical work, the edge effects of finite divergent electrode plates on the forces experienced by bubbles were investigated. Boiling in a concentric cylinder microgravity and an electric field was numerically predicted. We also completed a feasibility study for microgravity boiling in an acoustic field.

Gravitational Effects on Near Field Flow Structure of Low Density Gas Jets

NASA Technical Reports Server (NTRS)

Griffin, D. W.; Yep, T. W.; Agrawal, A. K.

2005-01-01

Experiments were conducted in Earth gravity and microgravity to acquire quantitative data on near field flow structure of helium jets injected into air. Microgravity conditions were simulated in the 2.2- second drop tower at NASA Glenn Research Center. The jet flow was observed by quantitative rainbow schlieren deflectometry, a non-intrusive line of site measurement technique for the whole field. The flow structure was characterized by distributions of angular deflection and helium mole percentage obtained from color schlieren images taken at 60 Hz. Results show that the jet in microgravity was up to 70 percent wider than that in Earth gravity. The global jet flow oscillations observed in Earth gravity were absent in microgravity, providing direct experimental evidence that the flow instability in the low density jet was buoyancy induced. The paper provides quantitative details of temporal flow evolution as the experiment undergoes change in gravity in the drop tower.

Update on the Purdue University 2-second Drop Tower

NASA Astrophysics Data System (ADS)

Collicott, Steven

A small drop tower of approximately one second drop duration was built in the School of Aero-nautics and Astronautics at Purdue University beginning in 1998 and operated until summer 2007. This inexpensive tower in an old airplane hanger, was built largely by Yongkang Chen, now a Research Professor at Portland State University in Oregon, USA. In about 7 years of operations, the tower generated sufficient science results for Chen's PhD thesis[1] (summarized in three AIAA Journal papers[2-4]), Fitzpatrick's MS thesis[5], two industry projects for since-canceled advanced rodent habitats for ISS, and one project for NASA Marshall. In addition to the science use, Purdue undergraduate students designed, built, and performed simpler fluids experiments for their own career advancement, including a novel investigation of the impact of imperfect repeatability of initial conditions on a zero-g fluids experiment. The tower was also used for outreach to school children. It is most satisfying that Chen's PhD research in this small tower, and subsequent discussions and interactions, helped Weislogel to propose the two Vane Gap tests in his highly successful Capillary Fluids Experiment (CFE) in the International Space Station in 2006 and 2007[6]. Chen as been involved in the remodeling of these two Vane Gap cylinders for subsequent re-launch to ISS for a second round of experiments expected in 2010 and 2011. In August 2007 the School of Aeronautics and Astronautics at Purdue University moved into the new Neil Armstrong Hall of Engineering and construction on a new 2-second drop tower began. A vertical shaft of nearly 23 meters was designed into the building. An approximately 80 m2 general-use fluids lab is at the top level, and a small access room of approximately 9 m2 is at the bottom. However, construction of the new $57M building created only the space for the science facility, not the science facility itself. The science facility is under construction and this paper presents an update on progress for the micro-gravity community. The most noticeable current activity is testing of the air-bag decelerator. The tower is one that will use a free-falling experiment inside of a drag shield to avoid most aerodynamic drag. The airbag is designed from experiences of others yet the small, triangular room in which the tower terminates imposes challenges. The airbag is approximately 1.5m diameter and 1.5m tall. Initial testing led to a desire to increase vent area, and just this week the bag has returned from the shop that was modifying it. On-board computer, battery packs, lighting, and cameras have been acquired. Thanks to Lockheed Martin, one camera is 500 frames per second with 1.3 million 12-bit gray scale pixels per frame. The Spincraft company donated steel hemisphere-cylinders to serve as the nose of the drag shield. Wind tunnel and CFD modeling of the drag shield has been performed by Purdue undergraduate aerospace students. Currently the drag shield structure and experiment package structure are being design and analyzed. The experiment volume is approximately a cylinder 0.45m diameter and 0.6m tall. Tower operation is intended to commence in fall 2010 with inert package drops at full mass and full height. Developing the operations procedures, especially operational safety, are the goals of this work. First science is then expected in the winter. References 1. Y. Chen, "A Study of Capillary Flow in a Vane-wall Gap in Zero Gravity," Ph.D. thesis, School of Aeronautics and Astronautics, Purdue University. August 2003. 2. Y. Chen and S. H. Collicott, "Investigation of the Symmetric Wetting of a Vane-Wall Gap in Propellant Tanks," AIAA Journal, 42, No. 2, pp. 305-314, February 2004. 3. Y. Chen, and S. H. Collicott, "Experimental Study on the Capillary Flow in a Vane-Wall Gap Geometry," AIAA Journal, 43, No. 11, pp. 2395-2403, November, 2005. 4. Y. Chen and S. H. Collicott, "Study of Wetting in an Asymmetrical Vane-Wall Gap in Propellant Tanks," AIAA Journal, 44, 4, pp. 859-867, April 2006. 5. S. L. Fitzpatrick, "A Study of Hydrogen Peroxide Low-Gravity Control for Propellant Management Devices," MS thesis, School of Aeronautics and Astronautics, Purdue Uni-versity. May 2003. 6. M. M. Weislogel, R. Jenson, Y. Chen, S. H. Collicott, J. Klatte, and M. Dreyer. "The capillary flow experiments aboard the International Space Station: Status". Acta Astro-nautica. 65:861-869, 2009

Research of metal solidification in zero-g state. [test apparatus and instrumentation

NASA Technical Reports Server (NTRS)

Aubin, W. M.; Larson, D., Jr.; Geschwind, G. I.

1973-01-01

An experiment test apparatus that allows metal melting and resolidification in the three seconds available during free fall in a drop tower was built and tested in the tower. Droplets (approximately 0.05 cm) of pure nickel and 1090 steel were prepared in this fashion. The apparatus, including instrumentation, is described. As part of the instrumentation, a method for measuring temperature-time histories of the free floating metal droplets was developed. Finally, a metallurgical analysis of the specimens prepared in the apparatus is presented.

Science Support for Space-Based Droplet Combustion: Drop Tower Experiments and Detailed Numerical Modeling

NASA Technical Reports Server (NTRS)

Marchese, Anthony J.; Dryer, Frederick L.

1997-01-01

This program supports the engineering design, data analysis, and data interpretation requirements for the study of initially single component, spherically symmetric, isolated droplet combustion studies. Experimental emphasis is on the study of simple alcohols (methanol, ethanol) and alkanes (n-heptane, n-decane) as fuels with time dependent measurements of drop size, flame-stand-off, liquid-phase composition, and finally, extinction. Experiments have included bench-scale studies at Princeton, studies in the 2.2 and 5.18 drop towers at NASA-LeRC, and both the Fiber Supported Droplet Combustion (FSDC-1, FSDC-2) and the free Droplet Combustion Experiment (DCE) studies aboard the shuttle. Test matrix and data interpretation are performed through spherically-symmetric, time-dependent numerical computations which embody detailed sub-models for physical and chemical processes. The computed burning rate, flame stand-off, and extinction diameter are compared with the respective measurements for each individual experiment. In particular, the data from FSDC-1 and subsequent space-based experiments provide the opportunity to compare all three types of data simultaneously with the computed parameters. Recent numerical efforts are extending the computational tools to consider time dependent, axisymmetric 2-dimensional reactive flow situations.

DIME Students Share Comments About Experiments

NASA Technical Reports Server (NTRS)

2002-01-01

Students discuss fine points of their final design for the drop tower experiment during the second Dropping in a Microgravity Environment (DIME) competition held April 23-25, 2002, at NASA's Glenn Research Center. Competitors included two teams from Sycamore High School, Cincinnati, OH, and one each from Bay High School, Bay Village, OH, and COSI Academy, Columbus, OH. DIME is part of NASA's education and outreach activities. Details are on line at http://microgravity.grc.nasa.gov/DIME_2002.html.

Microgravity

NASA Image and Video Library

2002-08-07

A student assembles a Lego (TM) Challenge device designed to operate in the portable drop tower demonstrator as part of the second Dropping in a Microgravity Environment (DIME) competition held April 23-25, 2002, at NASA's Glenn Research Center. Competitors included two teams from Sycamore High School, Cincinnati, OH, and one each from Bay High School, Bay Village, OH, and COSI Academy, Columbus, OH. DIME is part of NASA's education and outreach activities. Details are on line at http://microgravity.grc.nasa.gov/DIME_2002.html.

Predictions of Helmet Pad Suspension System Performance using Isolated Pad Impact Results

DTIC Science & Technology

2010-09-13

Equation 2 and Equation 3, respectively. 3. METHOD The primary method of data collection for this report is detailed in the 2008 Joint Live Fire ...tests and the helmet system tests (see Figure 3). All testing was performed with a monorail drop tower (see Figure 4) at three conditioning...right) and system test setup (right and center left) Figure 5. MEP monorail drop test setup with a hemispherical impactor (left and center left

Premixed Turbulent Flame Propagation in Microgravity

NASA Technical Reports Server (NTRS)

Menon, Suresh

1999-01-01

A combined numerical-experimental study has been carried out to investigate the structure and propagation characteristics of turbulent premixed flames with and without the influence of buoyancy. Experimentally, the premixed flame characteristics are studied in the wrinkled regime using a Couette flow facility and an isotropic flow facility in order to resolve the scale of flame wrinkling. Both facilities were chosen for their ability to achieve sustained turbulence at low Reynolds number. This implies that conventional diagnostics can be employed to resolve the smallest scales of wrinkling. The Couette facility was also built keeping in mind the constraints imposed by the drop tower requirements. Results showed that the flow in this Couette flow facility achieves full-developed turbulence at low Re and all turbulence statistics are in good agreement with past measurements on large-scale facilities. Premixed flame propagation studies were then carried out both using the isotropic box and the Couette facility. Flame imaging showed that fine scales of wrinkling occurs during flame propagation. Both cases in Ig showed significant buoyancy effect. To demonstrate that micro-g can remove this buoyancy effect, a small drop tower was built and drop experiments were conducted using the isotropic box. Results using the Couette facility confirmed the ability to carry out these unique reacting flow experiments at least in 1g. Drop experiments at NASA GRC were planned but were not completed due to termination of this project.

Flame-Vortex Interactions Imaged in Microgravity - To Assess the Theory Flame Stretch

NASA Technical Reports Server (NTRS)

Driscoll, James F.

2001-01-01

The goals of this research are to: 1) Assess the Theory of Flame Stretch by operating a unique flame-vortex experiment under microgravity conditions in the NASA Glenn 2.2 Second Drop Tower (drops to identify operating conditions have been completed); 2) Obtain high speed shadowgraph images (500-1000 frames/s) using the drop rig (images were obtained at one-g, and the NASA Kodak RO camera is being mounted on the drop rig); 3) Obtain shadowgraph and PIV images at 1-g while varying the effects of buoyancy by controlling the Froude number (completed); 4) Numerically model the inwardly-propagating spherical flame that is observed in the experiment using full chemistry and the RUN 1DL code (completed); 5) Send images of the flame shape to Dr. G. Patniak at NRL who is numerically simulating the entire flame-vortex interaction of the present experiment (data transfer completed); and 6) Assess the feasibility of obtaining PIV velocity field images in the drop rig, which would be useful (but not required) for our assessment of the Theory of Flame Stretch (PIV images were obtained at one-g using same low laser power that is available from fiber optic cable in drop tower). The motivation for the work is to obtain novel measurement needed to develop a physically accurate model of turbulent combustion that can help in the control of engine pollutants. The unique experiment allows, for the first time, the detailed study of a negatively-curved (negatively stretched) flame, which is one of the five fundamental types of premixed flames. While there have been studies of flat flames, positively-curved (outwardly-propagating) cases and positively-strained (counterflow) cases, this is the first detailed study of a negatively-curved (inwardly-propagating) flame. The first set of drops in the 2.2 Second Drop Tower showed that microgravity provides more favorable conditions for achieving inwardly-propagating flames (IPFs) than 1-g. A vortex interacts with a flame and creates a spherical pocket, which burns inwardly. Shadowgraphs at 1000 frames/sec quantify the Markstein number and flame speed. A Low-Laser Power PIV System was developed and is being added to the drop package. Numerical computations were required to explain why the Markstein numbers measured for the inwardly-propagating flames differ from those of outward propagating flames; this is an important research issue in the assessment of the Theory of Flame Stretch. The RUN-1DL code (developed by Prof. B. Rogg) was run for IPF and OPFs with complex methane and propane chemistry. Results confirmed that Ma for the IPFs are larger than for OPFs as was observed experimentally. Physical reasons for these new findings about the Theory of Flame Stretch are being determined from the experiments and the computations. Several journal papers have been published; the drop package is described in the AIAA Journal, while the one-g results appear in three other journal papers.

Wire insulation degradation and flammability in low gravity

NASA Technical Reports Server (NTRS)

Friedman, Robert

1994-01-01

This view-graph presentation covers the following topics: an introduction to spacecraft fire safety, concerns in fire prevention in low gravity, shuttle wire insulation flammability experiment, drop tower risk-based fire safety experiment, and experimental results, conclusions, and proposed studies.

Dropping In a Microgravity Environment (DIME) Contest

NASA Technical Reports Server (NTRS)

2001-01-01

The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. Sandi Thompson of the National Center for Microgravity Research GRC makes a final adjustment to the drop package. This image is from a digital still camera; higher resolution is not available.

Dropping In a Microgravity Environment (DIME) Contest

NASA Technical Reports Server (NTRS)

2001-01-01

The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. Meredith Mendenhall of Sycamore High School, Cincinnati, Ohio, flips on a tape recorder in preparation for a drop. This image is from a digital still camera; higher resolution is not available.

Current Trends on the Applicability of Ground Aerospace Materials Test Data to Space System Environments

NASA Technical Reports Server (NTRS)

Hirsch, David B.

2010-01-01

This slide presentation discusses the application of testing aerospace materials to the environment of space for flammability. Test environments include use of drop towers, and the parabolic flight to simulate the low gravity environment of space.

Combustion Science

NASA Image and Video Library

2002-08-07

Interior of a combustion experiment apparatus used in the 2.2-second drop tower at NASA's Glenn Research Center. This was shown to students participating in the second Dropping in a Microgravity Environment (DIME) competition held April 23-25, 2002, at NASA's Glenn Research Center. Competitors included two teams from Sycamore High School, Cincinnati, OH, and one each from Bay High School, Bay Village, OH, and COSI Academy, Columbus, OH. DIME is part of NASA's education and outreach activities. Details are on line at http://microgravity.grc.nasa.gov/DIME_2002.html.

Microgravity

NASA Image and Video Library

2002-08-07

Two students show the Lego (TM) Challenge device they designed and built to operate in the portable drop tower demonstrator as part of the second Dropping in a Microgravity Environment (DIME) competition held April 23-25, 2002, at NASA's Glenn Research Center. Competitors included two teams from Sycamore High School, Cincinnati, OH, and one each from Bay High School, Bay Village, OH, and COSI Academy, Columbus, OH. DIME is part of NASA's education and outreach activities. Details are on line at http://microgravity.grc.nasa.gov/DIME_2002.html.

Non-contact temperature measurement requirements

NASA Technical Reports Server (NTRS)

Higgins, D. B.; Witherow, W. K.

1989-01-01

The Marshall Space Flight Center is involved with levitation experiments for Spacelab, Space Station, and drop tube/tower operations. These experiments have temperature measurement requirements, that of course must be non-contact in nature. The experiment modules involved are the Acoustic Levitator Furnace (ALF), and the Modular Electromagnetic Levitator (MEL). User requirements of the ALF and drop tube are presented. The center also has temperature measurement needs that are not microgravity experiment oriented, but rather are related to the propulsion system for the STS. This requirement will also be discussed.

Gravity-Dependent Combustion and Fluids Research - From Drop Towers to Aircraft to the ISS

NASA Technical Reports Server (NTRS)

Urban, David L.; Singh, Bhim S.; Kohl, Fred J.

2007-01-01

Driven by the need for knowledge related to the low-gravity environment behavior of fluids in liquid fuels management, thermal control systems and fire safety for spacecraft, NASA embarked on a decades long research program to understand, accommodate and utilize the relevant phenomena. Beginning in the 1950s, and continuing through to today, drop towers and aircraft were used to conduct an ever broadening and increasingly sophisticated suite of experiments designed to elucidate the underlying gravity-dependent physics that drive these processes. But the drop towers and aircraft afford only short time periods of continuous low gravity. Some of the earliest rocket test flights and manned space missions hosted longer duration experiments. The relatively longer duration low-g times available on the space shuttle during the 1980s and 1990s enabled many specialized experiments that provided unique data for a wide range of science and engineering disciplines. Indeed, a number of STS-based Spacelab missions were dedicated solely to basic and applied microgravity research in the biological, life and physical sciences. Between 1980 and 2000, NASA implemented a vigorous Microgravity Science Program wherein combustion science and fluid physics were major components. The current era of space stations from the MIR to the International Space Station have opened up a broad range of opportunities and facilities that are now available to support both applied research for technologies that will help to enable the future exploration missions and for a continuation of the non-exploration basic research that began over fifty years ago. The ISS-based facilities of particular value to the fluid physics and combustion/fire safety communities are the Fluids and Combustion Facility Combustion Integrated Rack and the Fluids Integrated Rack.

Scalar Measurements and Analysis of Helium Jets in Earth Gravity and Microgravity using Rainbow Schlieren Deflectometry

NASA Technical Reports Server (NTRS)

Yep, Tze Wing

2001-01-01

Recent experiments have shown that low-density gas jets injected into a high-density gas undergo an instability mode leading to highly periodic oscillations in the flow field. The transition from laminar to turbulent flow in these jets is abrupt, without a gradual change in scales. Although this type of instability at high Richardson numbers has been attributed to buoyancy, direct physical evidence was not acquired through experiments. In this study, several experiments were conducted in Earth gravity and microgravity to acquire qualitative data on near field flow structure of helium jets injected into air. Microgravity conditions were simulated in the 2.2-second drop tower at NASA Glenn Research Center. The operating parameters of this study included the tube inside diameter, the jet Reynolds number, and the jet Richardson number. Tubes with inside diameters of 19.05 mm and 31.75 mm were used in the experiments conducted in the drop tower. The jet flow was analyzed using quantitative rainbow schlieren deflectometry, a non-intrusive line of sight measurement technique for the whole field. The flow structure was characterized by distributions of angular deflection and the resulting helium mole fraction obtained from color schlieren images taken at 60 Hz. Three sets of experimental data with respect to three schlieren fields of view were acquired for each tube. Results show that the jet in microgravity was up to 70 percent wider than that in Earth gravity. The global jet flow oscillations observed in Earth gravity were absent in microgravity, providing direct experimental evidence that the flow instability in the low-density jet was buoyancy-induced. This study provides quantitative details of temporal flow evolution as the experiments undergo change in gravity in the drop tower.

Combustion Of Interacting Droplet Arrays In Microgravity

NASA Technical Reports Server (NTRS)

Dietrich, D. L.; Struk, P. M.; Ikegami, M.; Xu, G.

2003-01-01

Theory and experiments involving single droplet combustion date back to 1953, with the first microgravity work appearing in 1956. The problem of a spherical droplet burning in an infinite, quiescent microgravity environment is a classical problem in combustion research with the classical solution appearing in nearly every textbook on combustion. The microgravity environment offered by ground-based facilities such as drop towers and space-based facilities is ideal for studying the problem experimentally. A recent review by Choi and Dryer shows significant advances in droplet combustion have been made by studying the problem experimentally in microgravity and comparing the results to one dimensional theoretical and numerical treatments of the problem. Studying small numbers of interacting droplets in a well-controlled geometry represents a logical step in extending single droplet investigations to more practical spray configurations. Studies of droplet interactions date back to Rex and co-workers, and were recently summarized by Annamalai and Ryan. All previous studies determined the change in the burning rate constant, k, or the flame characteristics as a result of interactions. There exists almost no information on how droplet interactions a effect extinction limits, and if the extinction limits change if the array is in the diffusive or the radiative extinction regime. Thus, this study examined experimentally the effect that droplet interactions have on the extinction process by investigating the simplest array configuration, a binary droplet array. The studies were both in normal gravity, reduced pressure ambients and microgravity facilities. The microgravity facilities were the 2.2 and 5.2 second drop towers at the NASA Glenn Research Center and the 10 second drop tower at the Japan Microgravity Center. The experimental apparatus and the data analysis techniques are discussed in detail elsewhere.

The Experiment CPLM (Comportamiento De Puentes Líquidos En Microgravedad) On Board MINISAT 01

NASA Astrophysics Data System (ADS)

Sanz-Andrés, Angel; Rodríguez-De-Francisco, Pablo; Santiago-Prowald, Julián

2001-03-01

The Universidad Politécnica de Madrid participates in the MINISAT 01 program as the experiment CPLM responsible. This experiment aims at the study of the fluid behaviour in reduced gravity conditions. The interest of this study is and has been widely recognised by the scientific community and has potential applications in the pharmaceutical and microelectronic technologies (crystal growth), among others. The scientific team which has developed the CPLM experiment has a wide experience in this field and had participate in the performance of a large number of experiments on the fluid behaviour in reduced gravity conditions in flight (Spacelab missions, TEXUS sounding rockets, KC-135 and Caravelle aeroplanes, drop towers, as well as on earth labs (neutral buoyancy and small scale simulations). The experimental equipment used in CPLMis a version of the payload developed for experimentation on drop towers and on board microsatellites as the UPM-Sat 1, adapted to fly on board MINISAT 01.

Modification Plans For The NASA 5.2 Second Drop Tower

NASA Technical Reports Server (NTRS)

Urban, David

2015-01-01

A design study is currently underway to examine the possibility of converting the NASA Glenn Research Center 5.2 second drop-tower to include testing at partial gravity levels and to increase the test duration to approximately 10 seconds and the number of tests conducted in a day to over 30. This will be achieved by converting to a magnetic-levitation system to drive the test capsule. This conversion will require concessions in certain areas to enable the enhanced capability. In particular the quality of g or vibration attainable in the new design is currently unknown. This capability may trade against payload mass, volume, or test duration. The acceleration quality for partial-g studies and the launch and deceleration levels are also in the process of definition. The status of the redesign study is presented along with discussion of the critical design options. Input from the community is sought to enable optimization of the design for future combustion applications.

An analytical study of reduced-gravity propellant settling

NASA Technical Reports Server (NTRS)

Bradshaw, R. D.; Kramer, J. L.; Masica, W. J.

1974-01-01

Full-scale propellant reorientation flow dynamics for the Centaur D-1T fuel tank were analyzed. A computer code using the simplified marker and cell technique was modified to include the capability for a variable-grid mesh configuration. Use of smaller cells near the boundary, near baffles, and in corners provides improved flow resolution. Two drop tower model cases were simulated to verify program validity: one case without baffles, the other with baffles and geometry identical to Centaur D-1T. Flow phenomena using the new code successfully modeled drop tower data. Baffles are a positive factor in the settling flow. Two full-scale Centaur D-1T cases were simulated using parameters based on the Titan/Centaur proof flight. These flow simulations indicated the time to clear the vent area and an indication of time to orient and collect the propellant. The results further indicated the complexity of the reorientation flow and the long time period required for settling.

Gravitational Effects on Near Field Flow Structure of Low Density Gas Jets

NASA Technical Reports Server (NTRS)

Yep, Tze-Wing; Agrawal, Ajay K.; Griffin, DeVon; Salzman, Jack (Technical Monitor)

2001-01-01

Experiments were conducted in Earth gravity and microgravity to acquire quantitative data on near field flow structure of helium jets injected into air. Microgravity conditions were simulated in the 2.2-second drop tower at NASA Glenn Research Center. The jet flow was observed by quantitative rainbow schlieren deflectometry, a non-intrusive line of site measurement technique for the whole field. The flow structure was characterized by distributions of angular deflection and helium mole percentage obtained from color schlieren images taken at 60 Hz. Results show that the jet flow was significantly influenced by the gravity. The jet in microgravity was up to 70 percent wider than that in Earth gravity. The jet flow oscillations observed in Earth gravity were absent in microgravity, providing direct experimental evidence that the flow instability in the low density jet was buoyancy induced. The paper provides quantitative details of temporal flow evolution as the experiment undergoes a change in gravity in the drop tower.

Effect of a zero g environment on flammability limits as determined using a standard flammability tube apparatus

NASA Technical Reports Server (NTRS)

Strehlow, R. A.; Reuss, D. L.

1980-01-01

Flammability limits in a zero gravity environment were defined. Key aspects of a possible spacelab experiment were investigated analytically, experimentally on the bench, and in drop tower facilities. A conceptual design for a spacelab experiment was developed.

Puddle Jumping

NASA Astrophysics Data System (ADS)

Wollman, Andrew; Snyder, Trevor; Weislogel, Mark

2014-11-01

Rebounding droplets from superhydrophobic surfaces have attracted significant public and scientific attention because they are both enjoyable as well as industrially relevant. Demonstrations of bouncing droplets with volumes between 0.003 and 0.03 ml are common in the literature and limited primarily by gravity. In this presentation we demonstrate large droplet ``rebounds'' made possible by low-gravity testing in a drop tower. The up to 300 ml drops are best described as puddles that launch in a nearly identical manner to rebounding drops 4 orders of magnitude smaller in volume. A variety of jumping liquid and gas puddles are shown including puddles of highly specified and unusual initial geometry. The large length sales of the capillary fluidic surfaces ~ O (10 cm) enable 3D printing of all superhydrophobic surface topologies demonstrated. In addition, we demonstrate such puddle jumping as a passive drop-on-demand technique for large low-gravity drop dynamics investigations; such as collisions, rebounds, heat and mass transfer, and containerless possessing.

Distribution of Cryptococcus neoformans in a natural site.

PubMed Central

Ruiz, A; Fromtling, R A; Bulmer, G S

1981-01-01

Pigeon droppings in a vacant tower were assayed for the number and size of viable cells of Cryptococcus neoformans. The dry, thinly scattered floor debris contained 2.6 x 10(6) viable cells per g--300 times more cells than were cultured from a large, compact pile of pigeon droppings (7.4 x 10(3) cells per g). Aerosols generated from floor debris containing pigeon droppings had an average of 360 viable cells in 31 liters of air; 27 of these cells (7.5%) were 1.1 to 3.3 micrometers in diameter and, therefore, capable of human lung deposition. Environmental factors which may influence the distribution, survival, and proliferation of C. neoformans in nature are discussed. PMID:7012011

Microgravity

NASA Image and Video Library

2001-04-26

The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. Meredith Mendenhall of Sycamore High School, Cincinnati, Ohio, flips on a tape recorder in preparation for a drop. This image is from a digital still camera; higher resolution is not available.

Microgravity

NASA Image and Video Library

2001-04-26

The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. Sandi Thompson of the National Center for Microgravity Research GRC makes a final adjustment to the drop package. This image is from a digital still camera; higher resolution is not available.

Modification of General Research Corporation (GRC) Dynatup 8200 Drop Tower Rebounding Brake System

DTIC Science & Technology

2016-08-01

Having 1.5-inch stroke low-volume actuators, retracted t t Approved for public release; distribution is unlimited. 3 multiple impacts from...rebound period at 1000 fps. Fig. 5 New upgraded 3-inch pneumatic cylinders 3.0-inch stroke high-volume actuators Retracted Position Extended

Impact performance of two bamboo-based laminated composites

Treesearch

Huanrong Liu; Zehui Jiang; Zhengjun Sun; Yan Yan; Zhiyong Cai; Xiubiao Zhang

2017-01-01

The present work aims to determine the impact performance of two bamboo-based laminated composites [bamboo/poplar laminated composite (BPLC) and bamboo/ glass fiber laminated composite (BGFLC)] using lowvelocity impact tests by a drop tower. In addition, fracture characteristics were evaluated using computed tomography (CT). Results showed that BPLC presented better...

DIME Students Show Off their Lego(TM) Challenge Creation

NASA Technical Reports Server (NTRS)

2002-01-01

Two students show the Lego (TM) Challenge device they designed and built to operate in the portable drop tower demonstrator as part of the second Dropping in a Microgravity Environment (DIME) competition held April 23-25, 2002, at NASA's Glenn Research Center. Competitors included two teams from Sycamore High School, Cincinnati, OH, and one each from Bay High School, Bay Village, OH, and COSI Academy, Columbus, OH. DIME is part of NASA's education and outreach activities. Details are on line at http://microgravity.grc.nasa.gov/DIME_2002.html.

Microgravity

NASA Image and Video Library

2002-08-08

In addition to drop tower activities, students assembled a plastic pipe structure underwater in a SCUBA exercise similar to training astronauts receive at NASA Johnson Space Center. This was part of the second Dropping in a Microgravity Environment (DIME) competition held April 23-25, 2002, at NASA's Glenn Research Center. Competitors included two teams from Sycamore High School, Cincinnati, OH, and one each from Bay High School, Bay Village, OH, and COSI Academy, Columbus, OH. DIME is part of NASA's education and outreach activities. Details are on line at http://microgravity.grc.nasa.gov/DIME_2002.html.

Dropping In a Microgravity Environment (DIME) contest

NASA Technical Reports Server (NTRS)

2001-01-01

The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. Here, students from Sycamore High School in Cincinnati, Ohio, help a NASA technician prepare their experiment. This image is from a digital still camera; higher resolution is not available.

Dropping In a Microgravity Environment (DIME) Contest

NASA Technical Reports Server (NTRS)

2001-01-01

The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. Pictured are students from COSI Academy, Columbus, Ohio and their teacher. The other team was from Sycamore High School in Cincinnati, Ohio. This image is from a digital still camera; higher resolution is not available.

Dropping In a Microgravity Environment (DIME) Contest

NASA Technical Reports Server (NTRS)

2001-01-01

The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. Students from Sycamore High School in Cincinnati, Ohio (girls), and the COSI Academy, Columbus, Ohio (boys), participated. This image is from a digital still camera; higher resolution is not available.

Galileo, Gauss, and the Green Monster

ERIC Educational Resources Information Center

Kalman, Dan; Teague, Daniel J.

2013-01-01

Galileo dropped cannonballs from the leaning tower of Pisa to demonstrate something about falling bodies. Gauss was a giant of mathematics and physics who made unparalleled contributions to both fields. More contemporary (and not a person), the Green Monster is the left-field wall at the home of the Boston Red Sox, Fenway Park. Measuring 37 feet…

Wireless Drop Tower for Microgravity Demonstrations. Educational Brief.

ERIC Educational Resources Information Center

National Aeronautics and Space Administration, Washington, DC.

Microgravity-the absence or reduction of some of the effects of gravity-is an important attribute of free-fall. In microgravity (often incorrectly called zero-g), water no longer flows "downhill" and neither do smoke or steam bubbles rise. This changes a number of chemical and physical activities. Experiments in combustion, fluid behavior,…

Dynamics of an Unsteady Diffusion Flame: Effects of Heat Release and Gravity

DTIC Science & Technology

1990-09-27

UNSTEADY DIFFUSION FLAME: EFFECTS OF HEAT RELEASE AND GRAVITY INTRODUCTION Experiments on laminar diffusion flames have shown that gravity affects the flame ... length and width as well as its extinction characteristics (1-4). These studies have been conducted in drop towers and have focused on fuel jets with

The analysis of the process in the cooling tower with the low efficiency

NASA Astrophysics Data System (ADS)

Badriev, A. I.; Sharifullin, V. N.

2017-11-01

We put quite a difficult task maintaining a temperature drop to 11-12 degrees at thermal power plants to ensure the required depth of cooling of vacuum in the condenser, cooling towers. This requirement is achieved with the reducing of the hydraulic load with the low efficiency of the apparatus. The task analysis process in this unit and identify the causes of his poor performance was put in the work. One of the possible reasons may be the heterogeneity of the process in the volume of the apparatus. Therefore, it was decided to investigate experimentally the distribution of the irrigation water and the air flow in the cross section of industrial cooling towers. As a result, we found a significant uneven distribution of flows of water and air in the volume of the apparatus. We have shown theoretically that the uneven distribution of irrigation leads to a significant decrease in the efficiency of evaporation in the cooling tower. The velocity distribution of the air as the tower sections, and inside sections are interesting. The obtained experimental data allowed to establish the internal communication: the effects of the distributions of the density of irrigation in sections of the apparatus for the distribution of changes of the temperature and the air velocity. The obtained results allowed to formulate a methodology for determining process problems and to develop actions on increase of the efficiency of the cooling tower.

DIME Students Participate in SCUBA Lesson Spring 2002

NASA Technical Reports Server (NTRS)

2002-01-01

In addition to drop tower activities, students assembled a plastic pipe structure underwater in a SCUBA exercise similar to training astronauts receive at NASA Johnson Space Center. This was part of the second Dropping in a Microgravity Environment (DIME) competition held April 23-25, 2002, at NASA's Glenn Research Center. Competitors included two teams from Sycamore High School, Cincinnati, OH, and one each from Bay High School, Bay Village, OH, and COSI Academy, Columbus, OH. DIME is part of NASA's education and outreach activities. Details are on line at http://microgravity.grc.nasa.gov/DIME_2002.html.

Microgravity

NASA Image and Video Library

2002-08-07

Members from all four teams were mixed into pairs to work on a Lego (TM) Challenge device to operate in the portable drop tower demonstrator (background). These two team members are about to try out their LEGO (TM) creation. This was part of the second Dropping in a Microgravity Environment (DIME) competition held April 23-25, 2002, at NASA's Glenn Research Center. Competitors included two teams from Sycamore High School, Cincinnati, OH, and one each from Bay High School, Bay Village, OH, and COSI Academy, Columbus, OH. DIME is part of NASA's education and outreach activities. Details are on line at http://microgravity.grc.nasa.gov/DIME_2002.html.

The use of containerless processing in researching reactive materials

NASA Technical Reports Server (NTRS)

Weber, J. K. R.; Krishnan, Shankar; Nordine, Paul C.

1991-01-01

It has recently become possible to perform containerless, high-temperature liquid-phase processing of many nonvolatile materials without resort to orbital microgravity, thereby facilitating the conduct of materials research in conjunction with noncontact diagnostic instruments. The melt-levitation techniques are electromagnetic, aerodynamic, acoustic, aeroacoustic, and electrostatic; nonorbital microgravity conditions are obtainable aboard NASA's KC-135 aircraft on parabolic flight paths, as well as in drop tubes and towers. Applications encompass the purification of metals and the creation of nonequilibrium and metastable structures. Process control and property measurements include optical pyrometry and emissivity, laser polarimetry, and drop calorimetry.

Quantitative Measurement of Oxygen in Microgravity Combustion

NASA Technical Reports Server (NTRS)

Silver, Joel A.

1997-01-01

A low-gravity environment, in space or in ground-based facilities such as drop towers, provides a unique setting for studying combustion mechanisms. Understanding the physical phenomena controlling the ignition and spread of flames in microgravity has importance for space safety as well as for better characterization of dynamical and chemical combustion processes which are normally masked by buoyancy and other gravity-related effects. Due to restrictions associated with performing measurements in reduced gravity, diagnostic methods which have been applied to microgravity combustion studies have generally been limited to capture of flame emissions on film or video, laser Schlieren imaging and (intrusive) temperature measurements using thermocouples. Given the development of detailed theoretical models, more sophisticated diagnostic methods are needed to provide the kind of quantitative data necessary to characterize the properties of microgravity combustion processes as well as provide accurate feedback to improve the predictive capabilities of the models. When the demands of space flight are considered, the need for improved diagnostic systems which are rugged, compact, reliable, and operate at low power becomes apparent. The objective of this research is twofold. First, we want to develop a better understanding of the relative roles of diffusion and reaction of oxygen in microgravity combustion. As the primary oxidizer species, oxygen plays a major role in controlling the observed properties of flames, including flame front speed (in solid or liquid flames), extinguishment characteristics, flame size and flame temperature. The second objective is to develop better diagnostics based on diode laser absorption which can be of real value in both microgravity combustion research and as a sensor on-board Spacelab as either an air quality monitor or as part of a fire detection system. In our prior microgravity work, an eight line-of-sight fiber optic system measured water vapor mole fractions in the NASA Lewis 2.2-sec Drop Tower. In that system, the laser and all electronics resided at the top of the drop tower and was connected via a fiber optic cable to the rig, on which a 'pitch and catch' set of fiber collimating lenses were used to transmit the laser beam across a jet diffusion flame. This system required eight independent detection/demodulation units and had poor spatial resolution. This research builds on this earlier work, resulting in an improved capability for quantitative, nonintrusive measurement of major combustion species. A vertical cavity surface-emitting diode laser (VCSEL) and a continuous spatial scanning method permit the measurement of temporal and spatial profiles of the concentrations and temperatures of molecular oxygen. High detection sensitivity is achieved with wavelength modulation spectroscopy (WMS). One-g experiments are performed using a slot diffusion flame. Microgravity measurements on a solid fuel (cellulose sheet) system are planned for the NASA Lewis 2.2-second Drop Tower Facility.

Development of techniques for processing metal-metal oxide systems

NASA Technical Reports Server (NTRS)

Johnson, P. C.

1976-01-01

Techniques for producing model metal-metal oxide systems for the purpose of evaluating the results of processing such systems in the low-gravity environment afforded by a drop tower facility are described. Because of the lack of success in producing suitable materials samples and techniques for processing in the 3.5 seconds available, the program was discontinued.

Dropping In a Microgravity Environment (DIME) contest

NASA Technical Reports Server (NTRS)

2001-01-01

The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. This is the interior of the Sycamore High School (Cincinnati, Ohio) students' experiment to observe the flame spreading on a 100 percent cotton T-shirt under low-g. This image is from a digital still camera; higher resolution is not available.

Clean Room in the Zero Gravity Research Facility

NASA Image and Video Library

1968-07-21

A technician prepares a test sample in the Zero Gravity Research Facility clean room at the National Aeronautics and Space Administration (NASA) Lewis Research Center. The Zero Gravity Research Facility contained a drop tower which provided five seconds of microgravity during freefall in its 450-foot deep vacuum chamber. The facility has been used for a variety of studies relating to the behavior of fluids and flames in microgravity. During normal operations, a cylindrical 3-foot diameter and 11-foot long vehicle was used to house the experiments, instrumentation, and high speed cameras. The 4.5-foot long and 1.5-foot wide rectangular vehicle, seen in this photograph, was used less frequently. A 3-foot diameter orb was used for the special ten-second drops in which the package was pneumatically shot to the top of the tower then dropped. The facility also contained a control room, shop offices, tool and equipment rooms, and this clean room. The 242.5-foot long and 19.5-foot wide clean room was equipped with specialized cleaning equipment. In the 1960s the room was rated as a class 10,000 clean room, but I was capable of meeting the class 100 requirements. The room included a fume hood, ultrasonic cleaner, and a laminar flow station which operated as a class 100 environment. The environment in the clean room was maintained at 71° F and a relative humidity of 45- percent.

A Fast and Self-Acting Release-Caging-Mechanism for Actively Driven Drop Tower Systems

NASA Astrophysics Data System (ADS)

Gierse, Andreas; Kaczmarczik, Ulrich; Greif, Andreas; Selig, Hanns; von Kampen, Peter; Könemann, Thorben; Lämmerzahl, Claus

2017-10-01

Today's and future scientific research programs ask for high quality microgravity conditions of 10-6 g on ground combined with high repetition rates of 100 flights per day or more. Accordingly, a new type of drop tower, the GraviTower Bremen, (GTB), has been suggested and is currently under development. As a first stage of development, a GTB-Prototype (GTB-Pro) has been designed which uses an active rope drive to accelerate a slider/drag shield and an experiment therein on a vertical parabola. During the free fall phase, the experiment is decoupled from the slider by a self-acting Release-Caging-Mechanism (RCM). Our prototype will provide 2.5 s of microgravity for experiments of up to 500 kg for at least 100 times per day. In this article, the final concept of the engineering of the active rope drive and the RCM are presented in detail. Based on extensive simulations aiming at an optimization of the whole system we developed a hydraulic rope drive system with minimized vibrational amplitude and low number of eigenfrequencies. The RCM achieves a very fast (≤ 0.1 s) self-acting release of the experiment from the slider by making use of the dynamics of the hydraulic rope drive. Furthermore, passive hydraulic stop dampers in the RCM build a passive and self-acting recoupling mechanism. This system is optimized for a fast decoupling to compensate for the time limitation posed by the chosen drive technology. The simulations included a comparison of different drive technologies, physical effects like the Coriolis force, and the dynamics of the RCM system itself.

Big Hydrophobic Capillary Fluidics; Basically Water Ping Pong in Space

NASA Astrophysics Data System (ADS)

Weislogel, Mark; Attari, Babak; Wollman, Andrew; Cardin, Karl; Geile, John; Lindner, Thomas

2016-11-01

Capillary surfaces can be enormous in environments where the effects of gravity are small. In this presentation we review a number of interesting examples from demonstrative experiments performed in drop towers and aboard the International Space Station. The topic then focuses on large length scale hydrophobic phenomena including puddle jumping, spontaneous particle ejections, and large drop rebounds akin to water ping pong in space. Unseen footage of NASA Astronaut Scott Kelly playing water ping pong in space will be shown. Quantitative and qualitative results are offered to assist in the design of experiments for ongoing research. NASA NNX12A047A.

DIME Participants Working on a Legos(TM) Challenge

NASA Technical Reports Server (NTRS)

2002-01-01

Members from all four teams were mixed into pairs to work on a Lego (TM) Challenge device to operate in the portable drop tower demonstrator (background). These two team members are about to try out their LEGO (TM) creation. This was part of the second Dropping in a Microgravity Environment (DIME) competition held April 23-25, 2002, at NASA's Glenn Research Center. Competitors included two teams from Sycamore High School, Cincinnati, OH, and one each from Bay High School, Bay Village, OH, and COSI Academy, Columbus, OH. DIME is part of NASA's education and outreach activities. Details are on line at http://microgravity.grc.nasa.gov/DIME_2002.html.

Summaries of early materials processing in space experiments

NASA Technical Reports Server (NTRS)

Naumann, R. J.; Mason, D.

1979-01-01

Objectives, methods, and results of low-gravity materials processing experiments are summarized, and a bibliography of published results for each experiment is provided. Included are drop tower experiments, the Apollo demonstration experiments, the skylab experiments and demonstration experiments, and the Apollo-Soyuz experiments and demonstrations. The findings of these experiments in the fields of crystal growth, metallurgy, and fluid behavior are summarized.

Sooting and disruption in spherically symmetrical combustion of decane droplets in air

NASA Technical Reports Server (NTRS)

Dryer, F. L.; Williams, F. A.; Haggard, J. B., Jr.; Shaw, B. D.

1987-01-01

The paper presents the results of experiments on the burning of individual 1-2 mm decane droplets in air at room temperature and atmospheric pressure. The NASA Lewis 2.2 s drop tower was used as well as a newly designed droplet-combustion apparatus that promotes nearly spherically symmetrical combustion. Unanticipated disruptions related to sooting behavior were encountered.

Microgravity

NASA Image and Video Library

2000-04-14

Don Gillies, a materials scientist at NASA/Marshall Space Flight Center (MSFC), demonstrates the classroom-size Microgravity Drop Tower Demonstrator. The apparatus provides 1/6 second of microgravity for small experiments. A video camera helps teachers observe what happens inside the package. This demonstration was at the April 2000 conference of the National Council of Teachers of Mathematics (NCTM) in Chicago. Photo credit: NASA/Marshall Space Flight Center (MSFC)

Piezoelectric Response of Ferroelectric Ceramics Under Mechanical Stress

DTIC Science & Technology

2015-09-17

dynamic response, and predict mechanical breakdown of electronic materials, numerous testing techniques such as very high-g machines , drop towers...James C. Hierholzer for building the custom test fixture, Michael D. Craft for his help with static capacitance measurements, Bryan J. Turner, Scott D...ISOLA 370HR Board Specimen Test Set-Up . . . . . . . . . . . . . . . . . . 59 3.3 Printed Circuit Board Electrical Layout

Gas-Bearing Crucible for Shot Tower

NASA Technical Reports Server (NTRS)

Youngberg, C. L.; Miller, C. G.; Stephens, J. B.; Finnerty, A. A.

1983-01-01

Device protects molten drops from contamination and distortion. Gas flowing through levitator tube levitates small balls while they melt. Gas heated by filament extending through center of tube. Gas bearing crucible on tube has concave configuration to hold single relatively large ball or many recesses to hold many small balls. By time spheres reach foam, they are cooled sufficiently by radiation to retain their shape.

Student Design Challenges in Capillary Flow

NASA Technical Reports Server (NTRS)

Stocker, Dennis P.; Wollman, Andrew; Hall, Nancy R.; Weislogel, Mark; DeLombard, Richard

2016-01-01

For some grade 8-12 students, capillary flow has bridged the gap between the classroom and research facility, from normal gravity to microgravity. In the past four years, NASA and the Portland State University (PSU) have jointly challenged students to design test cells, using Computer-Aided Design (CAD), to study capillary action in microgravity as PSU has done on the International Space Station (ISS). Using the student-submitted CAD drawings, the test cells were manufactured by PSU and tested in their 2.1-second drop tower. The microgravity results were made available online for student analysis and reporting. Over 100 such experiments have been conducted, where there has been participation from 15 states plus a German school for the children of U.S. military personnel. In 2016, a related NASA challenge was held in partnership with the ASGSR, again, based on the research conducted by PSU. In this challenge, grade 9-12 students designed and built devices using capillary action to launch droplets as far as possible in NASAs 2.2 Second Drop Tower. Example results will be presented by students at this conference. The challenges engage students in ISS science and technology and can inspire them to pursue technical careers.

Marangoni bubble motion in zero gravity. [Lewis zero gravity drop tower

NASA Technical Reports Server (NTRS)

Thompson, R. L.; Dewitt, K. J.

1979-01-01

It was shown experimentally that the Marangoni phenomenon is a primary mechanism for the movement of a gas bubble in a nonisothermal liquid in a low gravity environment. A mathematical model consisting of the Navier-Stokes and thermal energy equations, together with the appropriate boundary conditions for both media, is presented. Parameter perturbation theory is used to solve this boundary value problem; the expansion parameter is the Marangoni number. The zeroth, first, and second order approximations for the velocity, temperature and pressure distributions in the liquid and in the bubble, and the deformation and terminal velocity of the bubble are determined. Experimental zero gravity data for a nitrogen bubble in ethylene glycol, ethanol, and silicone oil subjected to a linear temperature gradient were obtained using the NASA Lewis zero gravity drop tower. Comparison of the zeroth order analytical results for the bubble terminal velocity showed good agreement with the experimental measurements. The first and second order solutions for the bubble deformation and bubble terminal velocity are valid for liquids having Prandtl numbers on the order of one, but there is a lack of appropriate data to test the theory fully.

Combustion of Interacting Droplet Arrays in a Microgravity Environment

NASA Technical Reports Server (NTRS)

Dietrich, D. L.; Struk, P. M.; Ikegami, M.; Nagaishi, H.; Honma, S.; Ikeda, K.

2001-01-01

Investigations into droplet interactions date back to Rex et al. Annamalai and Ryan and Annamalai published extensive reviews of droplet array and cloud combustion studies. In the majority of the reviewed studies, the authors examined the change in the burning rate constant, k, (relative to that of the single droplet) that results from interactions. More recently, Niioka and co-workers have examined ignition and flame propagation along arrays of interacting droplets with the goal of relating these phenomena in this simplified geometry to the more practical spray configuration. Our work has focussed on droplet interactions under conditions where flame extinction occurs at a finite droplet diameter. In our previous work, we reported that in normal gravity, reduced pressure conditions, droplet interactions improved flame stability and extended flammability limits (by inference). In our recent work, we examine droplet interactions under conditions where the flame extinguishes at a finite droplet diameter in microgravity. The microgravity experiments were in the NASA GRC 2.2 and 5.2 second drop towers, and the JAMIC (Japan Microgravity Center) 10 second drop tower. We also present progress on a numerical model of single droplet combustion that is in the process of being extended to model a binary droplet array.

Payload Planning for the International Space Station

NASA Technical Reports Server (NTRS)

Johnson, Tameka J.

1995-01-01

A review of the evolution of the International Space Station (ISS) was performed for the purpose of understanding the project objectives. It was requested than an analysis of the current Office of Space Access and Technology (OSAT) Partnership Utilization Plan (PUP) traffic model be completed to monitor the process through which the scientific experiments called payloads are manifested for flight to the ISS. A viewing analysis of the ISS was also proposed to identify the capability to observe the United States Laboratory (US LAB) during the assembly sequence. Observations of the Drop-Tower experiment and nondestructive testing procedures were also performed to maximize the intern's technical experience. Contributions were made to the meeting in which the 1996 OSAT or Code X PUP traffic model was generated using the software tool, Filemaker Pro. The current OSAT traffic model satisfies the requirement for manifesting and delivering the proposed payloads to station. The current viewing capability of station provides the ability to view the US LAB during station assembly sequence. The Drop Tower experiment successfully simulates the effect of microgravity and conveniently documents the results for later use. The non-destructive test proved effective in determining stress in various components tested.

Dropping In a Microgravity Environment (DIME) contest

NASA Technical Reports Server (NTRS)

2001-01-01

The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. Here Carol Hodanbosi of the National Center for Microgravity Research and Jose Carrion, a lab mechanic with AKAC, prepare a student experiment package (inside the silver-colored frame) inside the orange-colored drag shield that encloses all experiment hardware. This image is from a digital still camera; higher resolution is not available.

Microgravity Outreach with Math Teachers

NASA Technical Reports Server (NTRS)

2000-01-01

Don Gillies, a materials scientist at NASA/Marshall Space Flight Center (MSFC), demonstrates the classroom-size Microgravity Drop Tower Demonstrator. The apparatus provides 1/6 second of microgravity for small experiments. A video camera helps teachers observe what happens inside the package. This demonstration was at the April 2000 conference of the National Council of Teachers of Mathematics (NCTM) in Chicago. Photo credit: NASA/Marshall Space Flight Center (MSFC)

Microgravity

NASA Image and Video Library

2000-04-14

Jimmy Grisham of the Microgravity Program Plarning Integration Office at NASA/Marshall Space Flight Center, demonstrates the classroom-size Microgravity Drop Tower Demonstrator. The apparatus provides 1/6 second of microgravity for small experiments. A video camera helps teachers observe what happens inside the package. This demonstration was at the April 2000 conference of the National Council of Teachers of Mathematics (NCTM) in Chicago. Photo credit: NASA/Marshall Space Flight Center (MSFC)

Fluid-structure interaction modeling of wind turbines: simulating the full machine

NASA Astrophysics Data System (ADS)

Hsu, Ming-Chen; Bazilevs, Yuri

2012-12-01

In this paper we present our aerodynamics and fluid-structure interaction (FSI) computational techniques that enable dynamic, fully coupled, 3D FSI simulation of wind turbines at full scale, and in the presence of the nacelle and tower (i.e., simulation of the "full machine"). For the interaction of wind and flexible blades we employ a nonmatching interface discretization approach, where the aerodynamics is computed using a low-order finite-element-based ALE-VMS technique, while the rotor blades are modeled as thin composite shells discretized using NURBS-based isogeometric analysis (IGA). We find that coupling FEM and IGA in this manner gives a good combination of efficiency, accuracy, and flexibility of the computational procedures for wind turbine FSI. The interaction between the rotor and tower is handled using a non-overlapping sliding-interface approach, where both moving- and stationary-domain formulations of aerodynamics are employed. At the fluid-structure and sliding interfaces, the kinematic and traction continuity is enforced weakly, which is a key ingredient of the proposed numerical methodology. We present several simulations of a three-blade 5~MW wind turbine, with and without the tower. We find that, in the case of no tower, the presence of the sliding interface has no effect on the prediction of aerodynamic loads on the rotor. From this we conclude that weak enforcement of the kinematics gives just as accurate results as the strong enforcement, and thus enables the simulation of rotor-tower interaction (as well as other applications involving mechanical components in relative motion). We also find that the blade passing the tower produces a 10-12 % drop (per blade) in the aerodynamic torque. We feel this finding may be important when it comes to the fatigue-life analysis and prediction for wind turbine blades.

Area utilization efficiency of a sloping heliostat system for solar concentration.

PubMed

Wei, L Y

1983-02-15

Area utilization efficiency (AUE) is formulated for a sloping heliostat system facing any direction. The effects of slope shading, incidence factor, sun shading, and tower blocking by the mirrors are all taken into account. Our results show that annually averaged AUEs calculated for heliostat systems (1) increase with tower height at low slope angles but less rapidly at high slopes, (2) increase monotonically with slope angle and saturate at large slopes for systems facing due south, (3) reach a maximum at a certain slope for systems facing other directions than due south, and (4) drop sharply at slopes greater than a certain value for systems facing due east or west due to slope shading effect. The results are useful for solar energy collection on nonflat terrains.

Sphere forming method and apparatus

NASA Technical Reports Server (NTRS)

Youngberg, C. L.; Miller, C. G.; Stephens, J. B.; Finnerty, A. A. (Inventor)

1983-01-01

A system is provided for forming small accurately spherical objects. Preformed largely spherical objects are supported at the opening of a conduit on the update of hot gas emitted from the opening, so the object is in a molten state. The conduit is suddenly jerked away at a downward incline, to allow the molten object to drop in free fall, so that surface tension forms a precise sphere. The conduit portion that has the opening, lies in a moderate vacuum chamber, and the falling sphere passes through the chamber and through a briefly opened valve into a tall drop tower that contains a lower pressure, to allow the sphere to cool without deformation caused by falling through air.

Microgravity

NASA Image and Video Library

2001-04-26

The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. Here, students from Sycamore High School in Cincinnati, Ohio, help a NASA technician prepare their experiment. This image is from a digital still camera; higher resolution is not available.

Microgravity

NASA Image and Video Library

2001-04-26

The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. Students from Sycamore High School in Cincinnati, Ohio (girls), and the COSI Academy, Columbus, Ohio (boys), participated. This image is from a digital still camera; higher resolution is not available.

Effects of Buoyancy in Hydrogen Jet Diffusion Flames

NASA Technical Reports Server (NTRS)

Agrawal, A. K.; Al-Ammar, K.; Gollahalli, S. R.; Griffin, D. W.

1999-01-01

This project was carried out to understand the effects of heat release and buoyancy on the flame structure of diffusion flames. Experiments were conducted at atmospheric pressure in both normal gravity and microgravity conditions in the NASA LeRC 2.2 s drop tower. Experiments were also conducted in a variable pressure combustion facility in normal gravity to scale buoyancy and thus, to supplement the drop tower experiments. Pure H2 or H2 mixed with He was used as the jet fluid to avoid the complexities associated with soot formation. Fuel jet burning in quiescent air was visualized and quantified by the Rainbow Schlieren Deflectometry (RSD) to obtain scalar profiles (temperature, oxygen concentration) within the flame. Burner tube diameter (d) was varied from 0.3 to 1.19 mm producing jet exit Reynolds numbers ranging from 40 to 1900, and generating flames encompassing laminar and transitional (laminar to turbulent) flow structure. Some experiments were also complemented with the CFD analysis. In a previous paper, we have presented details of the RSD technique, comparison of computed and measured scalar distributions, and effects of buoyancy on laminar and transitional H2 gas-jet diffusion flames. Results obtained from the RSD technique, variable pressure combustion chamber, and theoretical models have been published. Subsequently, we have developed a new drop rig with improved optical and image acquisition. In this set up, the schlieren images are acquired in real time and stored digitally in RAM of an onboard computer. This paper deals with laminar diffusion flames of pure H2 in normal and microgravity.

Status of Electrostatic Accelerometer Development for Gravity Recovery and Climate Experiment Follow-On Mission (GRACE FO)

NASA Astrophysics Data System (ADS)

Perrot, Eddy; Boulanger, Damien; Christophe, Bruno; Foulon, Bernard; Liorzou, Françoise; Lebat, Vincent; Huynh, Phuong-Anh

2015-04-01

The GRACE FO mission, led by the JPL (Jet Propulsion Laboratory), is an Earth-orbiting gravity mission, continuation of the GRACE mission, which will produce an accurate model of the Earth's gravity field variation providing global climatic data during five years at least. The mission involves two satellites in a loosely controlled tandem formation, with a micro-wave link measuring the inter-satellites distance variation. Earth's mass distribution non-uniformities cause variations of the inter-satellite distance. This variation is measured to recover gravity, after subtracting the non-gravitational contributors, as the residual drag. ONERA (the French Aerospace Lab) is developing, manufacturing and testing electrostatic accelerometers measuring this residual drag applied on the satellites. The accelerometer is composed of two main parts: the Sensor Unit (including the Sensor Unit Mechanics - SUM - and the Front-End Electronic Unit - FEEU) and the Interface Control Unit - ICU. In the Accelerometer Core, located in the Sensor Unit Mechanics, the proof mass is levitated and maintained at the center of an electrode cage by electrostatic forces. Thus, any drag acceleration applied on the satellite involves a variation on the servo-controlled electrostatic suspension of the mass. The voltage on the electrodes providing this electrostatic force is the measurement output of the accelerometer. The impact of the accelerometer defaults (geometry, electronic and parasitic forces) leads to bias, misalignment and scale factor error, non-linearity and noise. Some of these accelerometer defaults are characterized by tests with micro-gravity pendulum bench on ground and with drops in ZARM catapult. The Critical Design Review was achieved successfully on September 2014. The Engineering Model (EM) was integrated and tested successfully, with ground levitation, drops, Electromagnetic Compatibility and thermal vacuum. The integration of the first Flight Model has begun on December 2014 and will be achieved on January 2015. The results of the Engineering Model tests and the status of the Flight Models will be presented.

Tests Results of the Electrostatic Accelerometer Flight Models for Gravity Recovery and Climate Experiment Follow-On Mission (GRACE FO)

NASA Astrophysics Data System (ADS)

Perrot, E.; Boulanger, D.; Christophe, B.; Foulon, B.; Lebat, V.; Huynh, P. A.; Liorzou, F.

2015-12-01

The GRACE FO mission, led by the JPL (Jet Propulsion Laboratory), is an Earth-orbiting gravity mission, continuation of the GRACE mission, which will produce an accurate model of the Earth's gravity field variation providing global climatic data during five years at least. The mission involves two satellites in a loosely controlled tandem formation, with a micro-wave link measuring the inter-satellites distance variation. Earth's mass distribution non-uniformities cause variations of the inter-satellite distance. This variation is measured to recover gravity, after subtracting the non-gravitational contributors, as the residual drag. ONERA (the French Aerospace Lab) is developing, manufacturing and testing electrostatic accelerometers measuring this residual drag applied on the satellites. The accelerometer is composed of two main parts: the Sensor Unit (including the Sensor Unit Mechanics - SUM - and the Front-End Electronic Unit - FEEU) and the Interface Control Unit - ICU. In the Accelerometer Core, located in the Sensor Unit Mechanics, the proof mass is levitated and maintained at the center of an electrode cage by electrostatic forces. Thus, any drag acceleration applied on the satellite involves a variation on the servo-controlled electrostatic suspension of the mass. The voltage on the electrodes providing this electrostatic force is the output measurement of the accelerometer. The impact of the accelerometer defaults (geometry, electronic and parasitic forces) leads to bias, misalignment and scale factor error, non-linearity and noise. Some of these accelerometer defaults are characterized by tests with micro-gravity pendulum bench on ground and with drops in ZARM catapult. The Critical Design Review was achieved successfully on September 2014. The Engineering Model (EM) was integrated and tested successfully, with ground levitation, drops, Electromagnetic Compatibility and thermal vacuum. The integration of the two Flight Models was done on July 2015. The tests will be achieved from July to November 2015. The results of the Engineering Model and Flight Models tests will be presented.

Microgravity Outreach with Math Teachers

NASA Technical Reports Server (NTRS)

2000-01-01

Jimmy Grisham of the Microgravity Program Plarning Integration Office at NASA/Marshall Space Flight Center (MSFC), demonstrates the classroom-size Microgravity Drop Tower Demonstrator. This apparatus provides 1/6 second of microgravity for small experiments. A video camera helps teachers observe what happens inside the package. This demonstration was at the April 2000 conference of the National Council of Teachers of Mathematics (NCTM) in Chicago. Photo credit: NASA/Marshall Space Flight Center (MSFC)

Microgravity Outreach with Math Teachers

NASA Technical Reports Server (NTRS)

2000-01-01

Jimmy Grisham of the Microgravity Program Plarning Integration Office at NASA/Marshall Space Flight Center, demonstrates the classroom-size Microgravity Drop Tower Demonstrator. The apparatus provides 1/6 second of microgravity for small experiments. A video camera helps teachers observe what happens inside the package. This demonstration was at the April 2000 conference of the National Council of Teachers of Mathematics (NCTM) in Chicago. Photo credit: NASA/Marshall Space Flight Center (MSFC)

Microgravity

NASA Image and Video Library

2001-04-25

The arnual conference for the Educator Resource Center Network (ERCN) Coordinators was held at Glenn Research Center at Lewis Field in Cleveland, Ohio. The conference included participants from NASA's Educator Resource Centers located throughout the country. The Microgravity Science Division at Glenn sponsored a Microgravity Day for all the conference participants. Dr. Wil Roberson and Marge Lehky prepare a demonstration with the mini-drop tower. This image is from a digital still camera; higher resolution is not available.

Test Package Plummets in the Zero Gravity Research Facility

NASA Image and Video Library

1966-09-21

National Aeronautics and Space Administration (NASA) Lewis Research Center. Lewis researchers had been studying the behavior of liquid in microgravity for several years using ballistic rocket flights, aircraft flying series of parabolas, and in the 2.2-Second Drop Tower. It was easier to control experiments and repeat tests based on almost instantaneous test results in the Zero Gravity Research Facility than missiles or aircraft. It also more than doubled the microgravity time of the original drop tower. The experiments were enclosed in a large experiment package that was suspended inside the chamber. A vacuum was introduced to the chamber before the package was released. The test equipment allowed researchers to film and take measurements of the experiment as it was falling. The 2500‐pound package was slowed by special Styrofoam‐like pellets in a decelerator cart. An experiment, traveling 176 feet per second, was stopped in about 15 feet of deceleration material. The facility’s designers struggled to determine the correct type of deceleration pellets to use. For several years Lewis engineers tested various samples from manufacturers. The final selection was not made until the facility’s completion in May 1966, just before the facility made its public debut at the 1966 Inspection of the Center.

Characterization and detection of acceleration-induced cavitation in soft materials using a drop-tower-based integrated system

NASA Astrophysics Data System (ADS)

Kang, Wonmo; Chen, YungChia; Bagchi, Amit; O'Shaughnessy, Thomas J.

2017-12-01

The material response of biologically relevant soft materials, e.g., extracellular matrix or cell cytoplasm, at high rate loading conditions is becoming increasingly important for emerging medical implications including the potential of cavitation-induced brain injury or cavitation created by medical devices, whether intentional or not. However, accurately probing soft samples remains challenging due to their delicate nature, which often excludes the use of conventional techniques requiring direct contact with a sample-loading frame. We present a drop-tower-based method, integrated with a unique sample holder and a series of effective springs and dampers, for testing soft samples with an emphasis on high-rate loading conditions. Our theoretical studies on the transient dynamics of the system show that well-controlled impacts between a movable mass and sample holder can be used as a means to rapidly load soft samples. For demonstrating the integrated system, we experimentally quantify the critical acceleration that corresponds to the onset of cavitation nucleation for pure water and 7.5% gelatin samples. This study reveals that 7.5% gelatin has a significantly higher, approximately double, critical acceleration as compared to pure water. Finally, we have also demonstrated a non-optical method of detecting cavitation in soft materials by correlating cavitation collapse with structural resonance of the sample container.

Microgravity Propellant Tank Geyser Analysis and Prediction

NASA Technical Reports Server (NTRS)

Thornton, Randall J.; Hochstein, John I.; Turner, James E. (Technical Monitor)

2001-01-01

An established correlation for geyser height prediction of an axial jet inflow into a microgravity propellant tank was analyzed and an effort to develop an improved correlation was made. The original correlation, developed using data from ethanol flow in small-scale drop tower tests, uses the jet-Weber number and the jet-Bond number to predict geyser height. A new correlation was developed from the same set of experimental data using the jet-Weber number and both the jet-Bond number and tank-Bond number to describe the geyser formation. The resulting correlation produced nearly a 40% reduction in geyser height predictive error compared to the original correlation with experimental data. Two additional tanks were computationally modeled in addition to the small-scale tank used in the drop tower testing. One of these tanks was a 50% enlarged small-scale tank and the other a full-scale 2 m radius tank. Simulations were also run for liquid oxygen and liquid hydrogen. Results indicated that the new correlation outperformed the original correlation in geyser height prediction under most circumstances. The new correlation has also shown a superior ability to recognize the difference between flow patterns II (geyser formation only) and III (pooling at opposite end of tank from the bulk fluid region).

Rectangular Drop Vehicle in the Zero Gravity Research Facility

NASA Image and Video Library

1969-03-21

A rectangular drop test vehicle perched above 450-foot shaft at the Zero Gravity Research Facility at NASA Lewis Research Center. The drop tower was designed to provide five seconds of microgravity during a normal drop, but had a pneumatic gun that could quickly propel the vehicle to the top of the shaft prior to its drop, thus providing ten seconds of microgravity. The shaft contained a steel-lined vacuum chamber 20 feet in diameter and 469 feet deep. The package was stopped at the bottom of the pit by a 15-foot deep deceleration cart filled with polystyrene pellets. During normal operations, a cylindrical 3-foot diameter and 11-foot long vehicle was used to house the experiments, instrumentation, and high speed cameras. The 4.5-foot long and 1.5-foot wide rectangular vehicle, seen in this photograph, was used less frequently. A 3-foot diameter orb was used for the ten second drops. After the test vehicle was prepared it was suspended above the shaft from the top of the chamber. A lid was used to seal the top of the chamber. The vacuum system reduced the pressure levels inside the chamber. The bolt holding the vehicle was then sheared and the vehicle plummeted into the deceleration cart.

The Measurement of the Surface Energy of Solids by Sessile Drop Accelerometry

NASA Astrophysics Data System (ADS)

Calvimontes, Alfredo

2018-05-01

A new physical method, the sessile drop accelerometry (SDACC) for the study and measurement of the interfacial energies of solid-liquid-gas systems, is tested and discussed in this study. The laboratory instrument and technique—a combination of a drop shape analyzer with high-speed camera and a laboratory drop tower- and the evaluation algorithms, were designed to calculate the interfacial energies as a function of the geometrical changes of a sessile droplet shape due to the effect of "switching off" gravity during the experiment. The method bases on Thermodynamics of Interfaces and differs from the conventional approach of the two hundred-years-old Young's equation in that it assumes a thermodynamic equilibrium between interfaces, rather than a balance of tensions on a point of the solid-liquid-gas contour line. A comparison of the mathematical model that supports the method with the widely accepted Young`s equation is discussed in detail in this study. The method opens new possibilities to develop surface characterization procedures by submitting the solid-liquid-system to artificial generated and uniform force fields.

Apparatus for production of ultrapure amorphous metals utilizing acoustic cooling

NASA Technical Reports Server (NTRS)

Lee, M. C. (Inventor)

1985-01-01

Amorphous metals are produced by forming a molten unit of metal and deploying the unit into a bidirectional acoustical levitating field or by dropping the unit through a spheroidizing zone, a slow quenching zone, and a fast quenching zone in which the sphere is rapidly cooled by a bidirectional jet stream created in the standing acoustic wave field produced between a half cylindrical acoustic driver and a focal reflector or a curved driver and a reflector. The cooling rate can be further augmented first by a cryogenic liquid collar and secondly by a cryogenic liquid jacket surrounding a drop tower. The molten unit is quenched to an amorphous solid which can survive impact in a unit collector or is retrieved by a vacuum chuck.

Microgravity

NASA Image and Video Library

2001-04-26

The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. Pictured are students from COSI Academy, Columbus, Ohio and their teacher. The other team was from Sycamore High School in Cincinnati, Ohio. This image is from a digital still camera; higher resolution is not available.

Microgravity

NASA Image and Video Library

2001-04-26

The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. This is the interior of the Sycamore High School (Cincinnati, Ohio) students' experiment to observe the flame spreading on a 100 percent cotton T-shirt under low-g. This image is from a digital still camera; higher resolution is not available.

Drop Tower Characterization of Army Research Lab (ARL)-Fabricated Thin-Film Lead Zirconate Titanate (PZT) Transducers

DTIC Science & Technology

2012-04-01

TRADE NAME, TRADEMARK, MANUFACTURER , OR OTHERWISE, DOES NOT CONSTITUTE OR IMPLY ITS ENDORSEMENT, RECOMMENDATION, OR FAVORING BY THE U.S. GOVERNMENT...TRADE NAMES USE OF TRADE NAMES OR MANUFACTURERS IN THIS REPORT DOES NOT CONSTITUTE AN OFFICIAL ENDORSEMENT OR APPROVAL OF THE USE OF...on Gel-Pak Ready for Noodle Wire Attachment ..................... 10 13. Waveshaper (on Right) Beside a 0.5-Inch Steel Ball

Buoyancy Effects on Flow Transition in Low-Density Inertial Gas Jets

NASA Technical Reports Server (NTRS)

Pasumarthi, Kasyap S.; Agrawal, Ajay K.

2005-01-01

Effects of buoyancy on transition from laminar to turbulent flow are presented for momentum-dominated helium jet injected into ambient air. The buoyancy was varied in a 2.2-sec drop tower facility without affecting the remaining operating parameters. The jet flow in Earth gravity and microgravity was visualized using the rainbow schlieren deflectometry apparatus. Results show significant changes in the flow structure and transition behavior in the absence of buoyancy.

Acoustic Excitation of Liquid Fuel Droplets and Coaxial Jets

DTIC Science & Technology

2009-01-01

would also like to acknowledge the support of the NASA Microgravity Combustion program which made possible the completion of this research and Maj...fuels exposed to different acoustic excitation conditions in a laboratory environment and during free-fall (microgravity) conditions in a NASA drop tower...then sent to two amplifiers, one for each piezo-siren. The amplifiers were a Krohn-Hite (model 7500) and a Trek (model PZD2000A), which amplified the

Grating droplets with a mesh

NASA Astrophysics Data System (ADS)

Soto, Dan; Le Helloco, Antoine; Clanet, Cristophe; Quere, David; Varanasi, Kripa

2016-11-01

A drop thrown against a mesh can pass through its holes if impacting with enough inertia. As a result, although part of the droplet may remain on one side of the sieve, the rest will end up grated through the other side. This inexpensive method to break up millimetric droplets into micrometric ones may be of particular interest in a wide variety of applications: enhancing evaporation of droplets launched from the top of an evaporative cooling tower or preventing drift of pesticides sprayed above crops by increasing their initial size and atomizing them at the very last moment with a mesh. In order to understand how much liquid will be grated we propose in this presentation to start first by studying a simpler situation: a drop impacting a plate pierced with a single off centered hole. The study of the role of natural parameters such as the radius drop and speed or the hole position, size and thickness allows us to discuss then the more general situation of a plate pierced with multiple holes: the mesh.

Magnetic levitation in two-dimensional geometry with translational invariance

NASA Astrophysics Data System (ADS)

Lorin, C.; Mailfert, A.

2008-11-01

The development of activities in space and of the corresponding technologies requires research on the behavior of both matter and biological organisms under weightless conditions. Various methods have been invented in order to simulate weightlessness, for example, drop towers, sounding rockets, or parabolic flights. Magnetic field ground-based devices have also been developed. This paper introduces an optimization method of the magnetic field so as to obtain magnetic levitation in a two-dimensional cylindrical geometry.

Quantification of the Design Relationship Between Ground Vehicle Weight and Occupant Safety Under Blast Loading

DTIC Science & Technology

2011-04-01

particular, we examine the opportunity to tune the seating system design parameters with a prescribed vehicle mass and blast pulse to minimize the...behavior of the physical vertical drop tower tests used to study aircraft seat ejection and ground vehicle blast events. This model was created and...driver’s seat , though it is expected that passengers should experience a comparable range of acceleration pulses given that the blast positioning is uniform

Absolute and Convective Instability of a Liquid Jet in Microgravity

NASA Technical Reports Server (NTRS)

Lin, Sung P.; Vihinen, I.; Honohan, A.; Hudman, Michael D.

1996-01-01

The transition from convective to absolute instability is observed in the 2.2 second drop tower of the NASA Lewis Research Center. In convective instability the disturbance grows spatially as it is convected downstream. In absolute instability the disturbance propagates both downstream and upstream, and manifests itself as an expanding sphere. The transition Reynolds numbers are determined for two different Weber numbers by use of Glycerin and a Silicone oil. Preliminary comparisons with theory are made.

Tuned mass damping system for a pendulum in gravity and microgravity fields

NASA Astrophysics Data System (ADS)

Atour, Farah

2016-07-01

An electrodynamic tether is a simple idea, but one with an amazing number of uses. Electrodynamic tether is a long conductor wire that is attached to the satellite, which can act as a generator or motor, from its motion through the earth's magnetic field. And it has the potential to make space travel significantly cheaper. The lack of electrodynamic tether's widespread in common applications can be attributed to the variable Lorentz forces occuring on the tethers, which will cause them to oscillate and may go out of control, de-orbit the satellite and fall to Earth. A tuned mass damper system, for short refered as tilger, is suggested as damper of oscillations of tethers. A system composed of a tuned mass damper and a simple pendulum simulating the tether was therefore constructed. 350 sets of experimental trials were done on the system, while it was installed inside a drop tower capsule resting on the ground, in order to pick four optimum setup experiments that will undergo a series of microgravity experiments at the Bremen Drop Tower in Bremen, Germany. The GJU Bachelor Research students found that the oscillations of the simple pendulum will not be affected by the tilger during the free fall experiment, except if a feedback mechanism is installed between the simple pendulum and the tilger. In this case, the tilger will dampen the simple pendulum oscillations during free fall.

Richtmyer-Meshkov instability experiments of miscible and immiscible incompressible fluids

NASA Astrophysics Data System (ADS)

Krivets, Vitaliy; Holt, Brason; Mokler, Matthew; Jacobs, Jeffrey

2017-11-01

Experiments were conducted in a 3 m tall vertical drop tower setup. A flat interface separating two liquids of differing density is formed in the Plexiglas tank with the heavier fluid in the bottom and the lighter one on top. Two liquids pairs were utilized, one - miscible (isopropyl alcohol and a calcium nitrate water mixture) and the other immiscible (silicone oil with the same heavy liquid), both with Atwood near 0.2. The tank is mounted on a rail mounted sled at 2 m initial height where an initial perturbation is generated using vertical periodic motion with 10 Hz frequency and 1 mm displacement, thus producing 3D interfacial waves. An impulsive acceleration, with approximately 100g magnitude, is imparted to the sled by a rail mounted weight released and allowed to fall, impacting the sled from above. Both weight and sled then travel freely down the rails where they are smoothly decelerated at the bottom of drop tower by magnetic brakes. PLIF is used to visualize mixing process by seeding fluorescein in the bottom fluid and illuminating using laser diode from above forming thin vertical sheet. The resulting fluorescent image sequences are captured using a digital camera mounted to the sled operating at a 100 Hz framing rate. Comparisons of the measured growth of the mixing zone for both immiscible and miscible liquid combinations with theoretical models are presented.

Model of ASTM Flammability Test in Microgravity: Iron Rods

NASA Technical Reports Server (NTRS)

Steinberg, Theodore A; Stoltzfus, Joel M.; Fries, Joseph (Technical Monitor)

2000-01-01

There is extensive qualitative results from burning metallic materials in a NASA/ASTM flammability test system in normal gravity. However, this data was shown to be inconclusive for applications involving oxygen-enriched atmospheres under microgravity conditions by conducting tests using the 2.2-second Lewis Research Center (LeRC) Drop Tower. Data from neither type of test has been reduced to fundamental kinetic and dynamic systems parameters. This paper reports the initial model analysis for burning iron rods under microgravity conditions using data obtained at the LERC tower and modeling the burning system after ignition. Under the conditions of the test the burning mass regresses up the rod to be detached upon deceleration at the end of the drop. The model describes the burning system as a semi-batch, well-mixed reactor with product accumulation only. This model is consistent with the 2.0-second duration of the test. Transient temperature and pressure measurements are made on the chamber volume. The rod solid-liquid interface melting rate is obtained from film records. The model consists of a set of 17 non-linear, first-order differential equations which are solved using MATLAB. This analysis confirms that a first-order rate, in oxygen concentration, is consistent for the iron-oxygen kinetic reaction. An apparent activation energy of 246.8 kJ/mol is consistent for this model.

Radiative Enhancement Effects on Flame Spread (REEFS) Project Studied "Green House" Effects on Fire Spread

NASA Technical Reports Server (NTRS)

Gokoglu, Suleyman A.; Ronney, Paul

2003-01-01

The Radiative Enhancement Effects on Flame Spread (REEFS) project, slated for flight aboard the International Space Station, reached a major milestone by holding its Science Concept Review this year. REEFS is led by principal investigator Paul Ronney from the University of Southern California in conjunction with a project team from the NASA Glenn Research Center. The study is focusing on flame spread over flat solid fuel beds to improve our understanding of more complex fires, such as those found in manned spacecraft and terrestrial buildings. The investigation has direct implications for fire safety, both for space and Earth applications, and extends previous work with emphasis on the atmospheres and flow environments likely to be present in fires that might occur in microgravity. These atmospheres will contain radiatively active gases such as carbon dioxide (CO2) from combustion products, and likely gaseous fuels such as carbon monoxide (CO) from incomplete combustion of solid fuel, as well as flows induced by ventilation currents. During tests in the 2.2-Second Drop Tower and KC-135 aircraft at Glenn, the principal investigator introduced the use of foam fuels for flame spread experiments over thermally thick fuels to obtain large spread rates in comparison to those of dense fuels such as PMMA. This enables meaningful results to be obtained even in the 2.2 s available in drop tower experiments.

Critical point wetting drop tower experiment

NASA Technical Reports Server (NTRS)

Kaukler, William F.

1990-01-01

The 100 m Drop Tower at NASA-Marshall was used to provide the step change in acceleration from 1.0 to 0.0005 g. An inter-fluid meniscus oscillates vertically within a cylindrical container when suddenly released from earth's gravity and taken into a microgravity environment. Oscillations damp out from energy dissipative mechanisms such as viscosity and interfacial friction. Damping of the oscillations by the later mechanism is affected by the nature of the interfacial junction between the fluid-fluid interface and the container wall. In earlier stages of the project, the meniscus shape which developed during microgravity conditions was applied to evaluations of wetting phenomena near the critical temperature. Variations in equilibrium contact angle against the container wall were expected to occur under critical wetting conditions. However, it became apparent that the meaningful phenomenon was the damping of interfacial oscillations. This latter concept makes up the bulk of this report. Perfluoromethyl cyclohexane and isopropanol in glass were the materials used for the experiment. The wetting condition of the fluids against the wall changes at the critical wetting transition temperature. This change in wetting causes a change in the damping characteristics of the interfacial excursions during oscillation and no measurable change in contact angle. The effect of contact line friction measured above and below the wetting transition temperature was to increase the period of vertical oscillation for the vapor-liquid interface when below the wetting transition temperature.

Centrifuge in Free Fall: Combustion at Partial Gravity

NASA Technical Reports Server (NTRS)

Ferkul, Paul

2017-01-01

A centrifuge apparatus is developed to study the effect of variable acceleration levels in a drop tower environment. It consists of a large rotating chamber, within which the experiment is conducted. NASA Glenn Research Center 5.18-second Zero-Gravity Facility drop tests were successfully conducted at rotation rates up to 1 RPS with no measurable effect on the overall Zero-Gravity drop bus. Arbitrary simulated gravity levels from zero to 1-g (at a radius of rotation 30 cm) were produced. A simple combustion experiment was used to exercise the capabilities of the centrifuge. A total of 23 drops burning a simulated candle with heptane and ethanol fuel were performed. The effect of gravity level (rotation rate) and Coriolis force on the flames was observed. Flames became longer, narrower, and brighter as gravity increased. The Coriolis force tended to tilt the flames to one side, as expected, especially as the rotation rate was increased. The Zero-Gravity Centrifuge can be a useful tool for other researchers interested in the effects of arbitrary partial gravity on experiments, especially as NASA embarks on future missions which may be conducted in non-Earth gravity.

SS/RCS surface tension propellant acquisition/expulsion tankage technology

NASA Technical Reports Server (NTRS)

1975-01-01

The analysis, design, fabrication, and testing of a propellant tank that satisfies the requirements of the space shuttle is presented. This mission presents very stringent and sometimes conflicting requirements. A compartmented-tank device was developed and various ground and drop tower test techniques were employed to verify the design using both subscale and full-scale hardware. Performance was established with scale models and further substantiation was obtained with the full-scale tankage. Fabrication, acceptance, fill and drain, inspection, and other ground handling procedures were developed.

NASA Test Conductor Monitoring DIME competition

NASA Technical Reports Server (NTRS)

2002-01-01

A NASA test conductor at the top of the 2.2-second Drop Tower monitors a student lecture at a lower level. This was part of the Microgravity Environment (DIME) competition held April 23-25, 2002, at NASA's Glenn Research Center. Competitors included two teams from Sycamore High School, Cincinnati, OH, and one each from Bay High School, Bay Village, OH, and COSI Academy, Columbus, OH. DIME is part of NASA's education and outreach activities. Details are on line at http://microgravity.grc.nasa.gov/DIME_2002.html.

U.S. Army Dugway Proving Ground, UT and the West Desert Test Center

DTIC Science & Technology

2001-04-30

Optic Network •32 Channels of Video •7 Communications Consoles with 20 Radio Nets and Phone Patch •Over 40 Communication Drops & Cell Phones •Centralized... Phone Tower Sites Cell Phone Activation May ‘01 Logistical Support Full Serv ice Com mun ity l Ground Transportation and Maintenance – Vehicle Support...Voice, Data & Video Communications in Mission Control Center •Data Speed: 100 MB/sec •Ethernet Connections •Commercial Power to most Sites Cell

Microgravity

NASA Image and Video Library

2002-08-07

A NASA test conductor at the top of the 2.2-second Drop Tower monitors a student lecture at a lower level. This was part of the Microgravity Environment (DIME) competition held April 23-25, 2002, at NASA's Glenn Research Center. Competitors included two teams from Sycamore High School, Cincinnati, OH, and one each from Bay High School, Bay Village, OH, and COSI Academy, Columbus, OH. DIME is part of NASA's education and outreach activities. Details are on line at http://microgravity.grc.nasa.gov/DIME_2002.html.

Microgravity

NASA Image and Video Library

2001-04-26

The first NASA Dropping In a Microgravity Environment (DIME) student competition pilot project came to a conclusion at the Glenn Research Center in April 2001. The competition involved high-school student teams who developed the concept for a microgravity experiment and prepared an experiment proposal. The two student teams - COSI Academy, sponsored by the Columbus Center of Science and Industry, and another team from Cincinnati, Ohio's Sycamore High School, designed a microgravity experiment, fabricated the experimental apparatus, and visited NASA Glenn to operate their experiment in the 2.2 Second Drop Tower. Here Carol Hodanbosi of the National Center for Microgravity Research and Jose Carrion, a lab mechanic with AKAC, prepare a student experiment package (inside the silver-colored frame) inside the orange-colored drag shield that encloses all experiment hardware. This image is from a digital still camera; higher resolution is not available.

Status of Electrostatic Accelerometer Development for Gravity Recovery and Climate Experiment Follow-on Mission (GRACE FO)

NASA Astrophysics Data System (ADS)

Lebat, V.; Boulanger, D.; Christophe, B.; Foulon, B.; Liorzou, F.; Perrot, E.; Huynh, P. A.

2014-12-01

The GRACE FO mission, led by the JPL (Jet Propulsion Laboratory), is an Earth-orbiting gravity mission, continuation of the GRACE mission, which will produce an accurate model of the Earth's gravity field variation providing global climatic data during five years at least. The mission involves two satellites in a loosely controlled tandem formation, with a micro-wave link measuring the inter-satellites distance variation. Earth's mass distribution non-uniformities cause variations of the inter-satellite distance. This variation is measured to recover gravity, after subtracting the non-gravitational contributors, as the residual drag. ONERA (the French Aerospace Lab) is developing, manufacturing and testing electrostatic accelerometers measuring this residual drag applied on the satellites. The accelerometer is composed of two main parts: the Sensor Unit (including the Sensor Unit Mechanics - SUM - and the Front-End Electronic Unit - FEEU) and the Interface Control Unit - ICU. In the Accelerometer Core, located in the Sensor Unit Mechanics, the proof mass is levitated and maintained at the center of an electrode cage by electrostatic forces. Thus, any drag acceleration applied on the satellite involves a variation on the servo-controlled electrostatic suspension of the mass. The voltage on the electrodes providing this electrostatic force is the measurement output of the accelerometer. The impact of the accelerometer defaults (geometry, electronic and parasitic forces) leads to bias, misalignment and scale factor error, non-linearity and noise. Some of these accelerometer defaults are characterized by tests with micro-gravity pendulum bench on ground and with drops in ZARM catapult. The Preliminary Design Review was achieved successfully on November 2013. The Engineering Model (EM) was integrated successfully and is under test, with ground levitation, drops, Electromagnetic Compatibility and thermal vacuum. The complete EM tests will be achieved on October 2014. The Critical Design Review is scheduled at the end of September 2014, and the integration of the first Flight Model will begin on October 2014. The results of the Engineering Model tests and the status of the Flight Models will be presented.

Mean curvature model for a quasi-static advancing meniscus: a drop tower test

NASA Astrophysics Data System (ADS)

Chen, Yongkang; Tavan, Noel; Weislogel, Mark

A critical geometric wetting condition resulting in a significant shift of a capillary fluid from one region of a container to another was recently demonstrated during experiments performed aboard the International Space Station (the Capillary Flow Experiments, Vane Gap test units, bulk shift phenomena). Such phenomena are of interest for advanced methods of control for large quantities of liquids aboard spacecraft. The dynamics of the flows are well understood, but analytical models remain qualitative without the correct capillary pressure driving force for the shifting bulk fluid—where one large interface (meniscus) advances while another recedes. To determine this pressure an investigation of the mean curvature of the advancing meniscus is presented which is inspired by earlier studies of receding bulk menisci in non-circular cylindrical containers. The approach is permissible only in the quasi-static limit. It will be shown that the mean curvature of the advancing bulk meniscus is related to that of the receding bulk meniscus, both of which are highly sensitive to container geometry and wetting conditions. The two meniscus curvatures are identical for any control parameter at the critical value identified by the Concus-Finn analysis. However, they differ when the control parameter is below its critical value. Experiments along these lines are well suited for drop towers and comparisons with the analytical predictions implementing the mean curvature model are presented. The validation opens a pathway to the analysis of such flows in containers of great geometric complexity.

Research on ignition and flame spread of solid materials in Japan

NASA Technical Reports Server (NTRS)

Ito, Kenichi; Fujita, Osamu

1995-01-01

Fire safety is one of the main concerns for crewed missions such as the space station. Materials used in spacecraft may burn even if metalic. There are severe restrictions on the materials used in spacecraft from the view of fire safety. However, such restrictions or safety standards are usually determined based on experimental results under normal gravity, despite large differences between the phenomena under normal and microgravity. To evaluate the appropriateness of materials for use in space, large amount of microgravity fire-safety combustion data is urgently needed. Solid material combustion under microgravity, such as ignition and flame spread, is a relatively new research field in Japan. As the other reports in this workshop describe, most of microgravity combustion research in Japan is droplet combustion as well as some research on gas phase combustion. Since JAMIC, the Japan Microgravity Center, (which offers 10 seconds microgravity time) opened in 1992, microgravity combustion research is robust, and many drop tests relating to solid combustion (paper combustion, cotton string combustion, metal combustion with Aluminium or Magnesium) have been performed. These tests proved that the 10 seconds of microgravity time at JAMIC is useful for solid combustion research. Some experiments were performed before JAMIC opened. For example, latticed paper was burned under microgravity by using a 50 m drop tower to simulate porous material combustion under microgravity. A 50 m tower provides only 2 seconds microgravity time however, and it was not long enough to investigate the solid combustion phenomena.

Factors affecting the recovery of Legionella pneumophila serogroup 1 from cooling tower water systems.

PubMed

Lu, H F; Tsou, M F; Huang, S Y; Tsai, W C; Chung, J G; Cheng, K S

2001-09-01

A total of 20 water samples collected from the cooling towers at 20 different sites were analyzed under various conditions for the presence of Legionella pneumophila serogroup 1. A comparative assessment was performed to evaluate methods of sample collection (spray drops, beneath water at 20- to 40-cm depth, and water outlet), concentration (filtration and centrifugation), acid buffer treatment (no treatment, treatment for 3, 5, and 15 min), and CO2 incubation or candle jar incubation. The reduction in viable colonies and false negative rate were compared for the different factors. No quantitative differences in isolation of L. pneumophila serogroup 1 was found among samples collected from water at a depth of 20 to 40 cm, from water outlet, and from spray drops. Treatment in an acid buffer for 15 min significantly reduced the recovery rate, with a reduction in bacterial counts of about 40%, compared with a 3-min (12%) or a 5-min (25%) treatment. Acid buffer treatment for 3 or 5 min reduced the overgrowth of commensal flora. This treatment improved the selectivity but not the sensitivity for L. pneumophila serogroup 1. Colonies on plates incubated at 37 degrees C in a candle jar with a humidified atmosphere grew better than those incubated at 35 degrees C with 5% CO2. These results demonstrate that methods of sample collection, concentration, and incubation, but not collection site, can affect the isolation rate for L. pneumophila serogroup 1.

Two-stage solar power tower cavity-receiver design and thermal performance analysis

NASA Astrophysics Data System (ADS)

Pang, Liping; Wang, Ting; Li, Ruihua; Yang, Yongping

2017-06-01

New type of two-stage solar power tower cavity-receiver is designed and a calculating procedure of radiation, convection and flow under the Gaussian heat flux is established so as to determine the piping layout and geometries in the receiver I and II and the heat flux distribution in different positions is obtained. Then the main thermal performance on water/steam temperature, steam quality, wall temperature along the typical tubes and pressure drop are specified according to the heat transfer and flow characteristics of two-phase flow. Meanwhile, a series of systematic design process is promoted and analysis on thermal performance of the two receivers is conducted. Results show that this type of two-stage cavity-receivers can minimize the size and reduce the mean temperature of receiver I while raise the average heat flux, thus increase the thermal efficiency of the two receivers; besides, the multiple serpentine tubes from header can make a more uniform distribution of the outlet parameters, preventing wall overheated.

Analysis and test for space shuttle propellant dynamics

NASA Technical Reports Server (NTRS)

Berry, R. L.; Demchak, L. J.; Tegart, J. R.

1983-01-01

This report presents the results of a study to develop an analytical model capable of predicting the dynamic interaction forces on the Shuttle External Tank, due to large amplitude propellant slosh during RTLS separation. The report details low-g drop tower and KC-135 test programs that were conducted to investigate propellant reorientation during RTLS. In addition, the development of a nonlinear finite element slosh model (LAMPS2, two dimensional, and one LAMPS3, three dimensional) is presented. Correlation between the model and test data is presented as a verification of the modeling approach.

A Dust Aggregation and Concentration System (DACS) for the Microgravity Space Environment

NASA Technical Reports Server (NTRS)

Giovane, F. J.; Blum, J.

1999-01-01

The Dust Aggregation and Concentration System, DACS, Project is an international effort intended to complete the preliminary definition of a system for suspending and concentrating dust particles in a microgravity environment for extended periods of time. The DACS design concept is based on extensive ground, drop tower, and parabolic flight tests. During the present proposed work, the DACS design will be completed, and a Science Requirements Document generated. At the end of the proposed 2 year project, DACS will be positioned to enter the advanced definition phase.

Transducer Workshop (17th) Held in San Diego, California on June 22-24, 1993

DTIC Science & Technology

1993-06-01

weight in a drop tower, such as the primer tester shown in figure 1. The calibration procedure must be repeated for each lot of copper inserts, and small...force vs. time curve (i.e impulse = area unxer the curve). The FPyF can be used in the primer tester (shown in figure 1) as well as in a weapon...microphones. Plstonphone Output 124 dB, 250 Hz DEAD WEIGHT TESTIER USED AS A PRESSURE RELEASE CALIBRATOR The dead weight tester is designed and most

Quantitative Species Measurements in Microgravity Combustion Flames using Near-Infrared Diode Lasers

NASA Technical Reports Server (NTRS)

Silver, Joel A.

1999-01-01

Understanding the physical phenomena controlling the ignition and spread of flames in microgravity has importance for space safety as well as for characterizing dynamical and chemical combustion processes which are normally masked by buoyancy and other gravity-related effects. Unfortunately, combustion is highly complicated by fluid mechanical and chemical kinetic processes, requiring the use of numerical modeling to compare with carefully designed experiments. More sophisticated diagnostic methods are needed to provide the kind of quantitative data necessary to characterize the properties of microgravity combustion as well as provide accurate feedback to improve the predictive capabilities of the models. Diode lasers are a natural choice for use under the severe conditions of low gravity experiments. Reliable, simple solid state operation at low power satisfies the operational restrictions imposed by drop towers, aircraft and space-based studies. Modulation wavelength absorption spectroscopy (WMS) provides a means to make highly sensitive and quantitative measurements of local gas concentration and, in certain cases, temperature. With near-infrared diode lasers, detection of virtually all major combustion species with extremely rapid response time is possible in an inexpensive package. Advancements in near-infrared diode laser fabrication technology and concurrent development of optical fibers for these lasers led to their use in drop towers. Since near-infrared absorption line strengths for overtone and combination vibrational transitions are weaker than the mid-infrared fundamental bands, WMS techniques are applied to increase detection sensitivity and allow measurement of the major combustion gases. In the first microgravity species measurement, Silver et al. mounted a fiber-coupled laser at the top of the NASA 2.2-sec drop tower and piped the light through a single-mode fiber to the drop rig. A fiber splitter divided the light into eight channels that directed the laser beam across a methane or propane diffusion jet flame. The light beams were recaptured by a set of gradient index lenses, coupled back into separate fiber optic lines, and transmitted back to detectors and electronics in the instrument package. In these experiments a 6-mm od fiber cable (containing the nine optical fibers) fell with the drop rig. Using separate detection and demodulation channels, spatial and temporal (up to 20 Hz) maps of water vapor and methane concentrations were obtained at differing heights in the flames. While this apparatus was useful from a demonstration standpoint, several drawbacks needed attention before useful scientific measurements could be obtained. First, eight lines of sight are somewhat insufficient for detailing the spatial profiles of the gas. Second, multiple detection channels operating in parallel are both expensive and present a challenge for accurate calibration. As a result, a newer scanning system was developed in our first contract under this program. The primary characteristic of this system is that it contains a single detection channel and achieves "continuous" spatial resolution by scanning the laser beam across the flame region, then directing this beam onto a single detector. Thus spatial measurements are converted to a temporal series of data. The true spatial resolution is limited only by the beam diameter and width of the sweep. In these experiments the beam is focused to about 1-mm diameter and scans across a region up to 4-cm wide.

Free Fall Plasma-Arc Reactor for Synthesis of Carbon Nanotubes in Microgravity

NASA Technical Reports Server (NTRS)

Alford, J. M.; Mason, G. R.; Feinkema, D. A.

2006-01-01

High temperatures inside the plasma of a carbon arc generate strong buoyancy driven convection which has an effect on the growth and morphology of the single-walled carbon nanotubes (SWNTs). To study the effect of buoyancy on the arc process, a miniature carbon arc apparatus was designed and developed to synthesize SWNTs in a microgravity environment substantially free from buoyant convective flows. An arc reactor was operated in the 2.2- and 5.18-second drop towers at the NASA Glenn Research Center. The apparatus employed a 4 mm diameter anode and was powered by a portable battery pack capable of providing in excess of 300 amps at 30 volts to the arc for the duration of a 5-second drop. However, the principal result is that no dramatic difference in sample yield or composition was noted between normal gravity, 2.2-and 5-second long microgravity runs.

An Experimental Study of Turbulent Nonpremixed Jet Flames in Crossflow Under Low-Gravity Conditions

NASA Astrophysics Data System (ADS)

Boxx, Isaac G.; Idicheria, Cherian A.; Clemens, Noel T.

2002-11-01

We will present results of a study of turbulent nonpremixed jet flames in crossflow under normal and low gravity conditions. This enables us to experimentally separate the competing influences of initial jet-to-crossflow momentum ratio and buoyancy effects on the flame structure. The low gravity conditions (10-30 milli-g) are achieved by dropping a self-contained jet flame rig in the University of Texas 1.25-second drop tower facility. This rig uses a small blow-through wind tunnel to create the crossflow. The jet flames issue from an orifice that is flush with the wall. High-speed CCD imaging of jet flame luminosity is the primary diagnostic. We present results for hydrocarbon jet flames with initial jet-to-crossflow momentum ratios of 10-20. Results such as flame trajectory, flame length, large scale structure and flame tip dynamics will be presented.

Suppression of Low Strain Rate Nonpremixed Flames by an Agent

NASA Technical Reports Server (NTRS)

Olson, Sandra L. (Technical Monitor); Hamins, A.; Bundy, M.; Oh, C. B.; Park, J.; Puri, I. K.

2004-01-01

The extinction and structure of non-premixed methane/air flames were investigated in normal gravity and microgravity through the comparison of experiments and calculations using a counterflow configuration. From a fire safety perspective, low strain rate conditions are important for several reasons. In normal gravity, many fires start from small ignition sources where the convective flow and strain rates are weak. Fires in microgravity conditions, such as a manned spacecraft, may also occur in near quiescent conditions where strain rates are very low. When designing a fire suppression system, worst-case conditions should be considered. Most diffusion flames become more robust as the strain rate is decreased. The goal of this project is to investigate the extinction limits of non-premixed flames using various agents and to compare reduced gravity and normal gravity conditions. Experiments at the NASA Glenn Research Center's 2.2-second drop tower were conducted to attain extinction and temperature measurements in low-strain non-premixed flames. Extinction measurements using nitrogen added to the fuel stream were performed for global strain rates from 7/s to 50/s. The results confirmed the "turning point" behavior observed previously by Maruta et al. in a 10 s drop tower. The maximum nitrogen volume fraction in the fuel stream needed to assure extinction for all strain rates was measured to be 0.855+/-0.016, associated with the turning point determined to occur at a strain rate of 15/s. The critical nitrogen volume fraction in the fuel stream needed for extinction of 0-g flames was measured to be higher than that of 1-g flames.

Large-Scale Flow Structure in Turbulent Nonpremixed Flames under Normal- And Low-Gravity Conditions

NASA Technical Reports Server (NTRS)

Clemens, N. T.; Idicheria, C. A.; Boxx, I. G.

2001-01-01

It is well known that buoyancy has a major influence on the flow structure of turbulent nonpremixed jet flames. Buoyancy acts by inducing baroclinic torques, which generate large-scale vortical structures that can significantly modify the flow field. Furthermore, some suggest that buoyancy can substantially influence the large-scale structure of even nominally momentum-dominated flames, since the low velocity flow outside of the flame will be more susceptible to buoyancy effects. Even subtle buoyancy effects may be important because changes in the large-scale structure affects the local entrainment and fluctuating strain rate, and hence the structure of the flame. Previous studies that have compared the structure of normal- and micro-gravity nonpremixed jet flames note that flames in microgravity are longer and wider than in normal-gravity. This trend was observed for jet flames ranging from laminar to turbulent regimes. Furthermore, imaging of the flames has shown possible evidence of helical instabilities and disturbances starting from the base of the flame in microgravity. In contrast, these characteristics were not observed in normal-gravity. The objective of the present study is to further advance our knowledge of the effects of weak levels of buoyancy on the structure of transitional and turbulent nonpremixed jet flames. In later studies we will utilize the drop tower facilities at NASA Glenn Research Center (GRC), but the preliminary work described in this paper was conducted using the 1.25-second drop tower located at the University of Texas at Austin. A more detailed description of these experiments can be found in Idicheria et al.

Protein spheres prepared by drop jet freeze drying.

PubMed

Eggerstedt, Sören N; Dietzel, Mathias; Sommerfeld, Martin; Süverkrüp, Richard; Lamprecht, Alf

2012-11-15

In spray freeze drying (SFD) solutions are frozen by spraying into a very cold environment and subsequently dried by sublimation. In contrast to conventional freeze drying, spray freeze drying has the possibility to produce flowable lyophilizates which offers a variety of new pharmaceutical applications. Here, a drop jet nozzle is proposed as liquid dispenser that is able to produce droplets with a very narrow size distribution compared to standard methods. The drop jet nozzle is mounted in a spray tower designed to prevent direct contact of the product with the freezing medium. Various formulations have been tested containing lysozyme as model protein and stabilizers such as bovine serum albumin, polyvinylpyrrolidone or dextran in various concentrations and mannitol. Excellent free flowing and nearly monodispersed, porous particles are produced where particle properties can be controlled by formulation and process conditions. The particle diameter varied between 231 ± 3 μm and 310 ± 10 μm depending on the formulation composition. The lysozyme activity was >94 ± 5% for all formulations exhibiting a full preservation of enzyme activity. This new method is very promising for the production of nearly monodisperse particulate lyophilizates in various therapeutic applications. Copyright © 2012 Elsevier B.V. All rights reserved.

Fluid oscillation in the Drop Tower

NASA Technical Reports Server (NTRS)

Kaukler, William F.

1988-01-01

An interfluid meniscus oscillates within a cylindrical container when suddenly released from earth's gravity and taken into a microgravity environment. Oscillations damp out from energy dissipative mechanisms such as viscosity and interfacial friction. Damping out of the oscillations by the latter mechanism is affected by the nature of the interfacial junction between the fluid-fluid interface and the container wall. Perfluoromethylcyclohexane and isopropanol in glass were the materials used for the experiment. The wetting condition of the fluids against the wall changes at the critical wetting transition temperature. This change in wetting causes a change in the damping characteristics.

Materials separation by dielectrophoresis

NASA Technical Reports Server (NTRS)

Sagar, A. D.; Rose, R. M.

1988-01-01

The feasibility of vacuum dielectrophoresis as a method for particulate materials separation in a microgravity environment was investigated. Particle separations were performed in a specially constructed miniature drop-tower with a residence time of about 0.3 sec. Particle motion in such a system is independent of size and based only on density and dielectric constant, for a given electric field. The observed separations and deflections exceeded the theoretical predictions, probably due to multiparticle effects. In any case, this approach should work well in microgravity for many classes of materials, with relatively simple apparatus and low weight and power requirements.

A summary of existing and planned experiment hardware for low-gravity fluids research

NASA Technical Reports Server (NTRS)

Hill, Myron E.; O'Malley, Terence F.

1991-01-01

NASA's ground-based and space-based low-gravity facilities are summarized, and an overview of selected experiments that have been developed for use in these facilities is presented. A variety of ground-based facilities (drop towers and aircraft) used to conduct low-gravity experiments for in-space experimentation are described. Capabilities that are available to the researcher and future on-orbit fluids facilities are addressed. The payload bay facilities range from the completely self-contained, relatively small get-away-special canisters to the Materials Science Laboratory and to the larger Spacelab facilities that require crew interaction.

Gas liquid flow at microgravity conditions - Flow patterns and their transitions

NASA Technical Reports Server (NTRS)

Dukler, A. E.; Fabre, J. A.; Mcquillen, J. B.; Vernon, R.

1987-01-01

The prediction of flow patterns during gas-liquid flow in conduits is central to the modern approach for modeling two phase flow and heat transfer. The mechanisms of transition are reasonably well understood for flow in pipes on earth where it has been shown that body forces largely control the behavior observed. This work explores the patterns which exist under conditions of microgravity when these body forces are suppressed. Data are presented which were obtained for air-water flow in tubes during drop tower experiments and Learjet trajectories. Preliminary models to explain the observed flow pattern map are evolved.

Performance of a capillary propellant management device with hydrazine

NASA Technical Reports Server (NTRS)

Tegart, J. R.

1979-01-01

The propellant management device that was successfully used in the Viking Orbiter spacecraft was selected for the main propulsion system of the Teleoperator Retrieval System (TRS). Due to differences in the missions and different propellants, the operation of this sheet metal vane device required reverification for the TRS application. An analytical investigation was performed considering the adverse acceleration environment and the high contract angle of the hydrazine propellant. Drop tower tests demonstrated that the device would provide propellant acquisition while the TRS was docked with Skylab, but its operation would have to be supplemented through propellant settling when free-flying.

Smoke detection in low-G fires

NASA Technical Reports Server (NTRS)

Urban, David L.; Griffin, Devon W.; Gard, Melissa Y.; Hoy, Michael

1995-01-01

Fires in spacecraft are considered a credible risk. To respond to this risk, NASA flew fire detectors on Skylab and the Space Shuttle (STS) and included them in the design for International Space Station Alpha (ISSA). In previous missions (Mercury, Gemini and Apollo), the crew quarters were so cramped that it was not considered credible that the astronauts could fail to observe a fire. The Skylab nodule included approximately 20 UV fire detectors. The space shuttle has 9 ionization detectors in the mid deck and flight deck and Spacelab has six additional ionization detectors. The planned detectors for ISSA are laser-diode, forward-scattering, smoke or particulate detectors. Current plans for the ISSA call for two detectors in the open area of the module and detectors in racks that have both cooling air flow and electrical power. Due to the complete absence of data concerning the nature of particulate and radiant emission from low-g fires, all three of these detector systems were designed based upon 1-g test data. As planned mission durations and complexity increase and the volume of spacecraft increases, the need for and importance of effective, crew independent, fire detection grows significantly. This requires more knowledge concerning low-gravity fires and how they might be detected. To date, no combustion-generated particulate samples have been collected for well-developed microgravity flames. All of the extant data come from drop tower tests and therefore only correspond to the early stages of a fire. The fuel sources were restricted to laminar gas-jet diffusion flames and rapidly overheated wire insulation. These gas-jet drop tower tests indicate, through thermophoretic sampling, that soot primaries and aggregates (groups of primary particles) in micro-g may be significantly larger than those in normal-g (ng). This raises new scientific questions about soot processes as well as practical issues for particulate detection/alarm threshold levels used in on-orbit smoke detectors. Furthermore, it is widely speculated but unverified that the aggregates will grow to very large scales in a microgravity fire of longer duration than available on the ground. Preliminary tests in the 2.2 second drop tower suggest that particulate generated by overheated wire insulation will also be larger in microgravity than in normal gravity. TEM grids downstream of the fire region in the WIF experiment as well as visual observation of long string-like aggregates, further confirm this suggestion. The combined impact of these limited results and theoretical predictions is that direct knowledge of low-g combustion particulate as opposed to extrapolation from 1-g data is needed for a more confident design of smoke detectors for spacecraft.

Verify MesoNAM Performance

NASA Technical Reports Server (NTRS)

Bauman, William H., III

2010-01-01

The AMU conducted an objective analysis of the MesoNAM forecasts compared to observed values from sensors at specified KSC/CCAFS wind towers by calculating the following statistics to verify the performance of the model: 1) Bias (mean difference), 2) Standard deviation of Bias, 3) Root Mean Square Error (RMSE), and 4) Hypothesis test for Bias = O. The 45 WS LWOs use the MesoNAM to support launch weather operations. However, the actual performance of the model at KSC and CCAFS had not been measured objectively. The analysis compared the MesoNAM forecast winds, temperature and dew point to the observed values from the sensors on wind towers. The data were stratified by tower sensor, month and onshore/offshore wind direction based on the orientation of the coastline to each tower's location. The model's performance statistics were then calculated for each wind tower based on sensor height and model initialization time. The period of record for the data used in this task was based on the operational start of the current MesoNAM in mid-August 2006 and so the task began with the first full month of data, September 2006, through May 2010. The analysis of model performance indicated: a) The accuracy decreased as the forecast valid time from the model initialization increased, b) There was a diurnal signal in T with a cool bias during the late night and a warm bias during the afternoon, c) There was a diurnal signal in Td with a low bias during the afternoon and a high bias during the late night, and d) The model parameters at each vertical level most closely matched the observed parameters at heights closest to those vertical levels. The AMU developed a GUI that consists of a multi-level drop-down menu written in JavaScript embedded within the HTML code. This tool allows the LWO to easily and efficiently navigate among the charts and spreadsheet files containing the model performance statistics. The objective statistics give the LWOs knowledge of the model's strengths and weaknesses and the GUI allows quick access to the data which will result in improved forecasts for operations.

Investigation of buoyancy effects on turbulent nonpremixed jet flames by using normal and low-gravity conditions

NASA Astrophysics Data System (ADS)

Idicheria, Cherian Alex

An experimental study was performed with the aim of investigating the structure of transitional and turbulent nonpremixed jet flames under different gravity conditions. In particular, the focus was to determine the effect of buoyancy on the mean and fluctuating characteristics of the jet flames. Experiments were conducted under three gravity levels, viz. 1 g, 20 mg and 100 mug. The milligravity and microgravity conditions were achieved by dropping a jet-flame rig in the UT-Austin 1.25-second and the NASA-Glenn Research Center 2.2-second drop towers, respectively. The principal diagnostics employed were time-resolved, cinematographic imaging of the visible soot luminosity and planar laser Mie scattering (PLMS). For the cinematographic flame luminosity imaging experiments, the flames studied were piloted nonpremixed propane, ethylene and methane jet flames at source Reynolds numbers ranging from 2000 to 10500. From the soot luminosity images, mean and root-mean square (RMS) images were computed, and volume rendering of the image sequences was used to investigate the large-scale structure evolution and flame tip dynamics. The relative importance of buoyancy was quantified with the parameter, xL , as defined by Becker and Yamazaki [1978]. The results show, in contrast to previous microgravity studies, that the high Reynolds number flames have the same flame length irrespective of the gravity level. The RMS fluctuations and volume renderings indicate that the large-scale structure and flame tip dynamics are essentially identical to those of purely momentum driven flames provided xL is approximately less than 2. The volume-renderings show that the luminous structure celerities (normalized by jet exit velocity) are approximately constant for xL < 6, but are substantially larger for xL > 8. The celerity values for xL > 8 are seen to follow a x3/2L scaling, which can be predicted with a simplified momentum equation analysis for the buoyancy-dominated regime. The underlying turbulent structure and mean mixture fraction characteristics were investigated in nonreacting and reacting jets with a PLMS diagnostic system developed for the UT-Austin 1.25-second drop tower. (Abstract shortened by UMI.)

PREFACE: International Symposium on Physical Sciences in Space

NASA Astrophysics Data System (ADS)

Meyer, Andreas; Egry, Ivan

2011-12-01

ISPS is the major international scientific forum for researchers in physics utilizing the space environment, in particular microgravity. It is intended to inspire and encourage cross-cutting discussions between different scientific communities working in the same environment. Contributions discussing results of experiments carried out on drop towers, parabolic aircraft flights, sounding rockets, unmanned recoverable capsules and, last but not least, the International Space Station ISS, are the backbone of this conference series, complemented by preparatory ground-based work, both experimentally and theoretically. The first International Symposium on Physical Sciences in Space (ISPS) sponsored by the International Microgravity Strategic Planning Group (IMSPG) took place in 2000 in Sorrento, Italy. IMSPG seeks to coordinate the planning of space for research in physical sciences by space agencies worldwide. AEB (Brazil), ASI (Italy), CNES (France), CSA (Canada), DLR (Germany), ESA (Europe), JAXA (Japan), NASA (USA), NSAU (Ukraine) and RSA (Russia) are members, and CNSA (China) and ISRO (India) are also invited to join IMSPG meetings. ISPS-4 was the fourth symposium in that series, following ISPS-2 organized by CSA in 2004 in Toronto, Canada, and ISPS-3 organized in 2007 by JAXA in Nara, Japan. ISPS-4 was jointly organized by ESA and DLR on behalf of the IMSPG and was held in Bonn from 11-15 July 2011. 230 participants from 17 different countries attended ISPS-4. Recent microgravity experiments were presented, analysed, and set in context to results from Earth bound experiments in 16 plenary and 68 topical talks. Lively discussions continued during two dedicated poster sessions and at the exhibition booths of space industry and research centers with new flight hardware on display. The oral presentations at ISPS4 were selected exclusively on the basis of scientific merit, as evidenced through the submitted abstracts. The selection was performed by the International Scientific Program Committee. It is our pleasure to thank the members of this committee for their excellent support in setting up a high-quality, well-balanced program. We also thank our sponsors, the German Aerospace Center and the European Space Agency, the Bundesministerium für Wirtschaft und Technologie (German Federal Ministry of Economics and Technology), the ZARM Center of Applied Space Technology and Microgravity as well as our industrial sponsors EADS-Astrium and Kayser-Threde, for their generous contributions. Our special thanks go to the authors and reviewers of the papers in these proceedings. Together we were able to realize up-to-date, peer reviewed conference proceedings, containing new and original data. Thanks to their efforts and that of the IOP Publishing staff, we succeeded in publishing the proceedings within six months of the conference. We are confident that this collection of papers will provide a useful reference for all workers in the field. Andreas Meyer and Ivan Egry Chairmen ISPS-4 Institute of Materials Physics in Space German Aerospace Center, Cologne Conference photograph Opening ceremony Professor Dr Andreas Meyer, Chairman ISPS 4, Professor Dr Johann-Dietrich Wörner, CEO DLR, and Dr Martin Zell, Head of ESA ISS Utilisation (left to right), at the opening ceremony of ISPS-4.

Laser diagnostics for microgravity droplet studies

NASA Technical Reports Server (NTRS)

Winter, Michael

1993-01-01

Rapid advances have recently been made in numerical simulation of droplet combustion under microgravity conditions, while experimental capabilities remain relatively primitive. Calculations can now provide detailed information on mass and energy transport, complex gas-phase chemistry, multi-component molecular diffusion, surface evaporation and heterogeneous reaction, which provides a clearer picture of both quasi-steady as well as dynamic behavior of droplet combustion. Experiments concerning these phenomena typically result in pictures of the burning droplets, and the data therefrom describe droplet surface regression along with flame and soot shell position. With much more precise, detailed, experimental diagnostics, significant gains could be made on the dynamics and flame structural changes which occur during droplet combustion. Since microgravity experiments become increasingly more expensive as they progress from drop towers and flights to spaceborne experiments, there is a great need to maximize the information content from these experiments. Sophisticated measurements using laser diagnostics on individual droplets and combustion phenomena are now possible. These include measuring flow patterns and temperature fields within droplets, vaporization rates and vaporization enhancement, radical species profiling in flames and gas-phase flow-tagging velocimetry. Although these measurements are sophisticated, they have undergone maturation to the degree where with some development, they are applicable to studies of microgravity droplet combustion. This program beginning in September of 1992, will include a series of measurements in the NASA Learjet, KC-135 and Drop Tower facilities for investigating the range of applicability of these diagnostics while generating and providing fundamental data to ongoing NASA research programs in this area. This program is being conducted in collaboration with other microgravity investigators and is aimed toward supplementing their experimental efforts.

Radiative Heat Loss Measurements During Microgravity Droplet Combustion in a Slow Convective Flow

NASA Technical Reports Server (NTRS)

Hicks, Michael C.; Kaib, Nathan; Easton, John; Nayagam, Vedha; Williams, Forman A.

2003-01-01

Radiative heat loss from burning droplets in a slow convective flow under microgravity conditions is measured using a broad-band (0.6 to 40 microns) radiometer. In addition, backlit images of the droplet as well as color images of the flame were obtained using CCD cameras to estimate the burning rates and the flame dimensions, respectively. Tests were carried out in air at atmospheric pressure using n-heptane and methanol fuels with imposed forced flow velocities varied from 0 to 10 centimeters per second and initial droplet diameters varied from 1 to 3 millimeters. Slow convective flows were generated using three different experimental configurations in three different facilities in preparation for the proposed International Space Station droplet experiments. In the 2.2 Second Drop-Tower Facility a droplet supported on the leading edge of a quartz fiber is placed within a flow tunnel supplied by compressed air. In the Zero-Gravity Facility (five-second drop tower) a tethered droplet is translated in a quiescent ambient atmosphere to establish a uniform flow field around the droplet. In the KC 135 aircraft an electric fan was used to draw a uniform flow past a tethered droplet. Experimental results show that the burn rate increases and the overall flame size decreases with increases in forced-flow velocities over the range of flow velocities and droplet sizes tested. The total radiative heat loss rate, Q(sub r), decreases as the imposed flow velocity increases with the spherically symmetric combustion having the highest values. These observations are in contrast to the trends observed for gas-jet flames in microgravity, but consistent with the observations during flame spread over solid fuels where the burning rate is coupled to the forced flow as here.

Studies of the Wetting of Gaps in Weightlessness

NASA Astrophysics Data System (ADS)

Collicott, Steven H.; Chen, Yongkang

2010-10-01

The geometry of a thin sheet metal vane terminating near a wall in a surface tension propellant management device (PMD) is common in devices designed by various people. A research program into the capillary fluid physics of the common vane-wall gap began in 1998 with the arrival of the second author at the School of Aeronautics and Astronautics at Purdue University. Drop tower experiments, Surface Evolver computations, and analysis were combined to explore the details of the fluid behavior in the vane-wall gap geometry. Results of four vane-wall gap experiment topics: critical wetting, advance rates, sensitivity to vane orientation, and effect of imperfect initial conditions, are discussed here. This work led to a desire by Weislogel to incorporate this type of geometry into his "Capillary Fluids Experiment" (CFE) that operated flawlessly on the International Space Station in 2006 and 2007. It is found that the wetting of vane-wall gaps is predicted correctly through use of the critical wetting analysis of Concus and Finn. Furthermore, the dynamics of the wetting flows are found to have scaling of flow rates versus time similar to those known for capillary advances in solid corners. In some cases, a seemingly misaligned vane is found to have more rapid capillary advance than for the same vane and gap but with the vane normal to the tank wall. An initial drop tower study of sensitivity to imperfect initial conditions shows that a critical wetting flow is largely immune to small tilts in the initial test orientation but that larger errors can be seen in cases that lack critical wetting and in the measurements of the time history of the meniscus minimum point.

ICME for Crashworthiness of TWIP Steels: From Ab Initio to the Crash Performance

NASA Astrophysics Data System (ADS)

Güvenç, O.; Roters, F.; Hickel, T.; Bambach, M.

2015-01-01

During the last decade, integrated computational materials engineering (ICME) emerged as a field which aims to promote synergetic usage of formerly isolated simulation models, data and knowledge in materials science and engineering, in order to solve complex engineering problems. In our work, we applied the ICME approach to a crash box, a common automobile component crucial to passenger safety. A newly developed high manganese steel was selected as the material of the component and its crashworthiness was assessed by simulated and real drop tower tests. The crashworthiness of twinning-induced plasticity (TWIP) steel is intrinsically related to the strain hardening behavior caused by the combination of dislocation glide and deformation twinning. The relative contributions of those to the overall hardening behavior depend on the stacking fault energy (SFE) of the selected material. Both the deformation twinning mechanism and the stacking fault energy are individually well-researched topics, but especially for high-manganese steels, the determination of the stacking-fault energy and the occurrence of deformation twinning as a function of the SFE are crucial to understand the strain hardening behavior. We applied ab initio methods to calculate the stacking fault energy of the selected steel composition as an input to a recently developed strain hardening model which models deformation twinning based on the SFE-dependent dislocation mechanisms. This physically based material model is then applied to simulate a drop tower test in order to calculate the energy absorption capacity of the designed component. The results are in good agreement with experiments. The model chain links the crash performance to the SFE and hence to the chemical composition, which paves the way for computational materials design for crashworthiness.

Combustion of Interacting Droplet Arrays in a Microgravity Environment

NASA Technical Reports Server (NTRS)

Dietrich, D. L.; Struk, P. M.; Kitano, K.; Ikegami, M.

1999-01-01

Investigations into droplet interactions date back to Rex et al. Recently, Annamalai and Ryan and Annamalai published extensive reviews of droplet array and cloud combustion studies. The authors studied the change in the burning rate constant, k, (relative to that of the single droplet) that results from interactions. Under certain conditions, there exists a separation distance where the droplet lifetime reaches a minimum, or average burning rate constant is a maximum . Additionally, since inter-droplet separation distance, L, increases relative to the droplet size, D, as the burning proceeds, the burning rate is not constant throughout the burn, but changes continuously with time. Only Law and co-workers and Mikami et al. studied interactions under conditions where buoyant forces were negligible. Comparing their results with existing theory, Law and co-workers found that theory over predicted the persistency and intensity of droplet interactions. The droplet interactions also depended on the initial array configuration as well as the instantaneous array configuration. They also concluded that droplet heating was retarded due to interactions and that the burning process did not follow the "D-squared" law. Mikami et al. studied the combustion of a two-droplet array of heptane burning in air at one atm pressure in microgravity. They showed that the instantaneous burning rate constant increases throughout the droplet lifetime, even for a single droplet. Also, the burn time of the array reached a minimum at a critical inter-droplet spacing. In this article, we examine droplet interactions in normal and microgravity environments. The microgravity experiments were in the NASA GRC 2.2 and 5.2 second drop towers, and the JAMIC (Japan Microgravity Center) 10 second drop tower. Special emphasis is directed to combustion under conditions that yield finite extinction diameters, and to determine how droplet interactions affect the extinction process.

Study on Orbital Liquid Transport and Interface Behavior in Vane Tank

NASA Astrophysics Data System (ADS)

Kang, Qi; Rui, Wei

2016-07-01

Liquid propellant tank is used to supply gas free liquid for spacecraft as an important part of propulsion system. The liquid behavior dominated by surface tension in microgravity is obviously different with that on the ground, which put forward a new challenge to the liquid transport and relocation. The experiments which are investigated at drop tower in National Microgravity Lab have concentrated on liquid relocation following thruster firing. Considered that the liquid located at the bottom in the direction of the acceleration vector, a sphere scale vane tank is used to study the liquid-gas interface behaviors with different acceleration vector and different filling independently and we obtain a series of stable equilibrium interface and relocation time. We find that there is an obvious sedimentation in the direction of acceleration vector when fill rate greater than 2% fill. Suggestions have been put forward that outer vanes transferring liquid to the outlet should be fixed and small holes should be dogged at the vane close to the center post to improve the liquid flow between different vanes when B0 is greater than 2.5. The research about liquid transport alone ribbon vanes is simulated though software Flow3D. The simulation process is verified by comparing the liquid lip and vapor-liquid interface obtained from drop tower experiment and simulation result when fill rate is 15%. Then the influence of fill rate, numbers of vanes and the gap between vane and wall is studied through the same simulate process. Vanes' configurations are also changed to study the effect on the lip and liquid volume below some section. Some suggestions are put forward for the design of vanes.

Evaluating Material Flammability in Microgravity and Martian Gravity Compared to the NASA Standard Normal Gravity Test

NASA Technical Reports Server (NTRS)

Oslon, Sandra. L.; Ferkul, Paul

2012-01-01

Drop tower tests are conducted at Martian gravity to determine the flammability of three materials compared to previous tests in other normal gravity and reduced gravity environments. The comparison is made with consideration of a modified NASA standard test protocol. Material flammability limits in the different gravity and flow environments are tabulated to determine the factor of safety associated with normal gravity flammability screening. Previous testing at microgravity and Lunar gravity indicated that some materials burned to lower oxygen concentrations in low gravity than in normal gravity, although the low g extinction limit criteria are not the same as 1g due to time constraints in drop testing. Similarly, the data presented in this paper for Martian gravity suggest that there is a gravity level below Earth s at which materials burn more readily than on Earth. If proven for more materials, this may indicate the need to include a factor of safety on 1g flammability limits.

Behavior of fluids in a weightless environment

NASA Technical Reports Server (NTRS)

Fester, D. A.; Eberhardt, R. N.; Tegart, J. R.

1977-01-01

Fluid behavior in a low-g environment is controlled primarily by surface tension forces. Certain fluid and system characteristics determine the magnitude of these forces for both a free liquid surface and liquid in contact with a solid. These characteristics, including surface tension, wettability or contact angle, system geometry, and the relationships governing their interaction, are discussed. Various aspects of fluid behavior in a low-g environment are then presented. This includes the formation of static interface shapes, oscillation and rotation of drops, coalescence, the formation of foams, tendency for cavitation, and diffusion in liquids which were observed during the Skylab fluid mechanics science demonstrations. Liquid reorientation and capillary pumping to establish equilibrium configurations for various system geometries, observed during various free-fall (drop-tower) low-g tests, are also presented. Several passive low-g fluid storage and transfer systems are discussed. These systems use surface tension forces to control the liquid/vapor interface and provide gas-free liquid transfer and liquid-free vapor venting.

Experimental Investigation of Rotating Menisci

NASA Astrophysics Data System (ADS)

Reichel, Yvonne; Dreyer, Michael E.

2014-07-01

In upper stages of spacecrafts, Propellant Management Devices (PMD's) can be used to position liquid propellant over the outlet in the absence of gravity. Centrifugal forces due to spin of the upper stage can drive the liquid away from the desired location resulting in malfunction of the stage. In this study, a simplified model consisting of two parallel, segmented and unsegmented disks and a central tube assembled at the center of the upper disk is analyzed experimentally during rotation in microgravity. For each drop tower experiment, the angular speed caused by a centrifugal stage in the drop capsule is kept constant. Steady-states for the menisci between the disks are observed for moderate rotation. For larger angular speeds, a stable shape of the free surfaces fail to sustain and the liquid is driven away. Additionally, tests were performed without rotation to quantify two effects: the removal of a metallic cylinder around the model to establish the liquid column and the determination of the the settling time from terrestrial to microgravity conditions.

Research on metal solidification in zero-g state

NASA Technical Reports Server (NTRS)

Papazian, J. M.; Larson, D. J., Jr.

1975-01-01

The containerless solidification of several pure metals and metallic alloys was studied in a low gravity environment. The tests were performed in the MSFC 4.2 s drop tower using a rapid wire melting apparatus designed and built for this purpose. Pure iron and nickel, and alloys of iron-nickel, iron-carbon, nickel-aluminum and tungsten-rhenium were all melted and solidified at a gravity level of approximately 100.000/-4 g. Interpretation of the results has led to an appreciation of the factors controlling the successful execution of this drop test experiment and to a delineation of the limits of applicability of the apparatus. Preliminary metallurgical evaluations are presented of the overall shapes, lattice parameters, surface microstructure,, cross-sectional microstructures, solidification and transformation sequences, evaporative segregation, and localized solute redistribution observed in the low-gravity specimens. The effects of low gravity on metallic solidification are discussed with particular emphasis on observations of spontaneous undercooling and evaporative segregation in uncontained melts.

A Comparison of Quasi-Static Indentation and Drop-Weight Impact Testing on Carbon-Epoxy Laminates

NASA Technical Reports Server (NTRS)

Prabhakaran, R.

2001-01-01

The project had two objectives: 1) The primary objective was to characterize damage tolerance of composite materials. To accomplish this, polymer matrix composites were to be subjected to static indentation as well as low-velocity impacts and the results analyzed. 2) A second objective was to investigate the effects of laser shock peening on the damage tolerance of aerospace materials, such as aluminum alloys, in terms of crack nucleation and crack propagation. The impact testing was proposed to be performed using a Dynatup drop tower. The specimens were to be placed over a square opening in a steel platen and impacted with a hemispherical tup. The damage was to be characterized in the laminate specimens. The damage tolerance of aerospace alloys was to be studied by conducting fatigue tests on aluminum alloy specimens with prior shock peening treatment. The crack length was to be monitored by a microscope and the crack propagation rate, da/dN, determined.

Using the Tower of Hanoi puzzle to infuse your mathematics classroom with computer science concepts

NASA Astrophysics Data System (ADS)

Marzocchi, Alison S.

2016-07-01

This article suggests that logic puzzles, such as the well-known Tower of Hanoi puzzle, can be used to introduce computer science concepts to mathematics students of all ages. Mathematics teachers introduce their students to computer science concepts that are enacted spontaneously and subconsciously throughout the solution to the Tower of Hanoi puzzle. These concepts include, but are not limited to, conditionals, iteration, and recursion. Lessons, such as the one proposed in this article, are easily implementable in mathematics classrooms and extracurricular programmes as they are good candidates for 'drop in' lessons that do not need to fit into any particular place in the typical curriculum sequence. As an example for readers, the author describes how she used the puzzle in her own Number Sense and Logic course during the federally funded Upward Bound Math/Science summer programme for college-intending low-income high school students. The article explains each computer science term with real-life and mathematical examples, applies each term to the Tower of Hanoi puzzle solution, and describes how students connected the terms to their own solutions of the puzzle. It is timely and important to expose mathematics students to computer science concepts. Given the rate at which technology is currently advancing, and our increased dependence on technology in our daily lives, it has become more important than ever for children to be exposed to computer science. Yet, despite the importance of exposing today's children to computer science, many children are not given adequate opportunity to learn computer science in schools. In the United States, for example, most students finish high school without ever taking a computing course. Mathematics lessons, such as the one described in this article, can help to make computer science more accessible to students who may have otherwise had little opportunity to be introduced to these increasingly important concepts.

Low Stretch Solid-Fuel Flame Transient Response to a Step Change in Gravity

NASA Technical Reports Server (NTRS)

Armstrong, J. B.; Olson, S. L.; T'ien, J. S.

2003-01-01

The effect of a step change in gravity level on the stability of low stretch diffusion flames over a solid fuel is studied both numerically and experimentally. Drop tower experiments have been conducted in NASA Glenn Research Center's 5.2 Zero Gravity Facility. In the experiments burning PMMA cylinders, a dynamic transition is observed when the steadily burning 1g flame is dropped and becomes a 0g flame. To understand the physics behind this dynamic transition, a transient stagnation point model has been developed which includes gas-phase radiation and solid phase coupling to describe this dynamic process. In this paper, the experimental results are compared with the model predictions. Both model and experiment show that the interior of the solid phase does not have time to change significantly in the few seconds of drop time, so the experimental results are pseudo-steady in the gas-phase, but the solid is inherently unsteady over long time scales. The model is also used to examine the importance of fractional heat losses on extinction, which clearly demonstrates that as the feedback from the flame decreases, the importance of the ongoing heat losses becomes greater, and extinction is observed when these losses represent 80% or more of the flame feedback.

Response of DP 600 products to dynamic impact loads

NASA Astrophysics Data System (ADS)

Clark, Deidra Darcell

The objective of this study was to compare the microstructural response of various DP 600 products subjected to low velocity, dynamic impact tests, typically encountered in a car crash. Since the response of steel is sensitive to its microstructure as controlled by the alloying elements, phase content, and processing; various DP 600 products may respond differently to crashes. The microstructure before and after dynamic impact deformation at 5 and 10 mph was characterized with regards to grain size, morphology, and phase content among vendors A, B, and C to evaluate efficiency in absorbing energy mechanisms during a crash simulated by dynamic impact testing in a drop tower.

Water Recovery with the Heat Melt Compactor in a Microgravity Environment

NASA Technical Reports Server (NTRS)

Golliher, Eric L.; Goo, Jonathan; Fisher, John

2015-01-01

The Heat Melt Compactor is a proposed utility that will compact astronaut trash, extract the water for eventual re-use, and form dry square tiles that can be used as additional ionizing radiation shields for future human deep space missions. The Heat Melt Compactor has been under development by a consortium of NASA centers. The downstream portion of the device is planned to recover a small amount of water while in a microgravity environment. Drop tower low gravity testing was performed to assess the effect of small particles on a capillary-based water/air separation device proposed for the water recovery portion of the Heat Melt Compactor.

Flame Structure and Scalar Properties in Microgravity Laminar Fires

NASA Technical Reports Server (NTRS)

Feikema, D. A.; Lim, J.; Sivathanu, Y.

2006-01-01

Recent results from microgravity combustion experiments conducted in the Zero Gravity Facility (ZGF) 5.18 second drop tower are reported. Emission mid-infrared spectroscopy measurements have been completed to quantitatively determine the flame temperature, water and carbon dioxide vapor concentrations, radiative emissive power, and soot concentrations in a microgravity laminar ethylene/air flame. The ethylene/air laminar flame conditions are similar to previously reported experiments including the Flight Project, Laminar Soot Processes (LSP). Soot concentrations and gas temperatures are in reasonable agreement with similar results available in the literature. However, soot concentrations and flame structure dramatically change in long duration microgravity laminar diffusion flames as demonstrated in this paper.

Modification of pure oxygen absorption equipment for concurrent stripping of carbon dioxide

USGS Publications Warehouse

Watten, B.J.; Sibrell, P.L.; Montgomery, G.A.; Tsukuda, S.M.

2004-01-01

The high solubility of carbon dioxide precludes significant desorption within commercial oxygen absorption equipment. This operating characteristic of the equipment limits its application in recirculating water culture systems despite its ability to significantly increase allowable fish loading rates (kg/(L min)). Carbon dioxide (DC) is typically removed by air stripping. This process requires a significant energy input for forced air movement, air heating in cold climates and water pumping. We developed a modification for a spray tower that provides for carbon dioxide desorption as well as oxygen absorption. Elimination of the air-stripping step reduces pumping costs while allowing dissolved nitrogen to drop below saturation concentrations. This latter response provides for an improvement in oxygen absorption efficiency within the spray tower. DC desorption is achieved by directing head-space gases from the spray tower (O2, N2, CO2) through a sealed packed tower scrubber receiving a 2 N NaOH solution. Carbon dioxide is selectively removed from the gas stream, by chemical reaction, forming the product Na 2CO3. Scrubber off-gas, lean with regard to carbon dioxide but still rich with oxygen, is redirected through the spray tower for further stripping of DC and absorption of oxygen. Make-up NaOH is metered into the scrubbing solution sump on an as needed basis as directed by a feedback control loop programmed to maintain a scrubbing solution pH of 11.4-11.8. The spent NaOH solution is collected, then regenerated for reuse, in a batch process that requires relatively inexpensive hydrated lime (Ca(OH)2). A by-product of the regeneration step is an alkaline filter cake, which may have use in bio-solids stabilization. Given the enhanced gas transfer rates possible with chemical reaction, the required NaOH solution flow rate through the scrubber represents a fraction of the spray tower water flow rate. Further, isolation of the water being treated from the atmosphere (1), allows for an improvement in oxygen absorption efficiency by maintaining DN well below local saturation concentrations (2), minimizes building energy requirements related to heating and ventilation and (3), reduces the potential for pathogen transmittance. We report on the performance of a test scrubber evaluated over a range of NaOH solution temperatures, pH, packing irrigation rates, and gas stream compositions. We also describe our experience with the process in a pilot scale recirculating water (trout) production system.

A Method for Assessing Material Flammability for Micro-Gravity Environments

NASA Technical Reports Server (NTRS)

Steinhaus, T.; Olenick, S. M.; Sifuentes, A.; Long, R. T.; Torero, J. L.

1999-01-01

On a spacecraft, one of the greatest fears during a mission is the outbreak of a fire. Since spacecraft are enclosed spaces and depend highly on technical electronics, a small fire could cause a large amount of damage. NASA uses upward flame spread as a "worst case scenario" evaluation for materials and the Heat and Visible Smoke Release Rates Test to assess the damage potential of a fire. Details of these tests and the protocols followed are provided by the "Flammability, Odor, Offgassing, and Compatibility Requirements and Test Procedures for Materials in Environments that Support Combustion" document. As pointed by Ohlemiller and Villa, the upward flame spread test does not address the effect of external radiation on ignition and spread. External radiation, as that coming from an overheated electrical component, is a plausible fire scenario in a space facility and could result in a reversal of the flammability rankings derived from the upward flame spread test. The "Upward Flame Propagation Test" has been the subject of strong criticism in the last few years. In many cases, theoretical exercises and experimental results have demonstrated the possibility of a reversal in the material flammability rankings from normal to micro-gravity. Furthermore, the need to incorporate information on the effects of external radiation and opposed flame spread when ranking materials based on their potential to burn in micro-gravity has been emphasized. Experiments conducted in a 2.2 second drop tower with an ethane burner in an air cross flow have emphasized that burning at the trailing edge is deterred in micro-gravity due to the decreased oxygen transport. For very low air flow velocities (U<0.005 m/s) the flame envelopes the burner and a slight increase in velocity results in extinction of the trailing edge (U>0.01 m/s). Only for U>0.l m/s extinction is observed at the leading edge (blow-off). Three dimensional numerical calculations performed for thin cellulose centrally ignited with an axisymmetric source have shown that under the presence of a forced flow slower than 0.035 m/s flames spreads only opposing the flow. Extinction is observed at the trailing edge with no concurrent propagation. Experiments conducted by the same authors at the JAMIC 10 second drop tower verified these calculations. Reducing the oxygen supply to the flame also results in a decrease of the Damk6hler number which might lead to extinction. Greyson et al. and Ferkul conducted experiments in micro-gravity (5 second drop tower) with thin paper and observed that at very low flow velocities concurrent flame spread will stop propagating and the flame will reduce in size and extinguish. They noted that quenching differs significantly from blow-off in that the upstream leading edge will remain anchored to the burn out edge.

Impact behavior of a high viscosity magnetorheological fluid-based energy absorber with a radial flow mode

NASA Astrophysics Data System (ADS)

Fu, Benyuan; Liao, Changrong; Li, Zhuqiang; Xie, Lei; Zhang, Peng; Jian, Xiaochun

2017-02-01

High viscosity linear polysiloxane magnetorheological fluid (HVLP MRF) was demonstrated with excellent suspension stability. Such material is suitable for application in the magnetorheological energy absorbers (MREAs) under axial impact loading conditions. On this basis, a new energy absorber incorporating a radial valve with high magnetic field utilization and a corrugated tube is proposed. In energy absorption applications where the MREA is rarely if ever used, our MREA takes the ultra-stable HVLP MRF as controlled medium in order for a long-term stability. For MREA performing at very high shear rates where the minor losses are important contributing factors to damping, a nonlinear analytical model, based on the Herschel-Bulkley flow model (HB model), is developed taking into account the effects of minor losses (called HBM model). The HB model parameters are determined by rheological experiments with a commercial shear rheometer. Then, continuity equation and governing differential equation of the HVLP MRF in radial flow are established. Based on the HB model, the expressions of radial velocity distribution are deduced. The influences of minor losses on pressure drop are analyzed with mean fluid velocities. Further, mechanical behavior of the corrugated tube is investigated via drop test. In order to verify the theoretical methodology, a MREA is fabricated and tested using a high-speed drop tower facility with a 600 kg mass at different drop heights and in various magnetic fields. The experiment results show that the HBM model is capable of well predicting the impact behavior of the proposed MREA.

Measurement of Two-Phase Flow Characteristics Under Microgravity Conditions

NASA Technical Reports Server (NTRS)

Keshock, E. G.; Lin, C. S.; Edwards, L. G.; Knapp, J.; Harrison, M. E.; Xhang, X.

1999-01-01

This paper describes the technical approach and initial results of a test program for studying two-phase annular flow under the simulated microgravity conditions of KC-135 aircraft flights. A helical coil flow channel orientation was utilized in order to circumvent the restrictions normally associated with drop tower or aircraft flight tests with respect to two-phase flow, namely spatial restrictions preventing channel lengths of sufficient size to accurately measure pressure drops. Additionally, the helical coil geometry is of interest in itself, considering that operating in a microgravity environment vastly simplifies the two-phase flows occurring in coiled flow channels under 1-g conditions for virtually any orientation. Pressure drop measurements were made across four stainless steel coil test sections, having a range of inside tube diameters (0.95 to 1.9 cm), coil diameters (25 - 50 cm), and length-to-diameter ratios (380 - 720). High-speed video photographic flow observations were made in the transparent straight sections immediately preceding and following the coil test sections. A transparent coil of tygon tubing of 1.9 cm inside diameter was also used to obtain flow visualization information within the coil itself. Initial test data has been obtained from one set of KC-135 flight tests, along with benchmark ground tests. Preliminary results appear to indicate that accurate pressure drop data is obtainable using a helical coil geometry that may be related to straight channel flow behavior. Also, video photographic results appear to indicate that the observed slug-annular flow regime transitions agree quite reasonably with the Dukler microgravity map.

Schlieren Measurements of Buoyancy Effects on Flow Transition in Low-Density Gas Jets

NASA Technical Reports Server (NTRS)

Pasumarthi, Kasyap S.; Agrawal, Ajay K.

2005-01-01

The transition from laminar to turbulent flow in helium jets discharged into air was studied using Rainbow Schlieren Deflectometry technique. In particular, the effects of buoyancy on jet oscillations and flow transition length were considered. Experiments to simulate microgravity were conducted in the 2.2s drop tower at NASA Glenn Research Center. The jet Reynolds numbers varied from 800 to1200 and the jet Richardson numbers ranged between 0.01 and 0.004. Schlieren images revealed substantial variations in the flow structure during the drop. Fast Fourier Transform (FFT) analysis of the data obtained in Earth gravity experiments revealed the existence of a discrete oscillating frequency in the transition region, which matched the frequency in the upstream laminar regime. In microgravity, the transition occurred farther downstream indicating laminarization of the jet in the absence of buoyancy. The amplitude of jet oscillations was reduced by up to an order of magnitude in microgravity. Results suggest that jet oscillations were buoyancy induced and that the brief microgravity period may not be sufficient for the oscillations to completely subside.

Benefits of ESA Gravity-Related Hands-on Programmes for University Students' Careers

NASA Astrophysics Data System (ADS)

Callens, Natacha; Ha, Lily; Galeone, Piero

2016-10-01

The Education Office of the European Space Agency (ESA) offers university students, from ESA Member and Cooperating States, the opportunity to perform investigations in physical sciences, life sciences, and technology, under different gravity conditions through three educational programmes. The "Fly Your Thesis!" (FYT) programme makes use of parabolic flights and the "Drop Your Thesis!" (DYT) programme utilizes a drop tower as microgravity carriers, while the "Spin Your Thesis!" (SYT) programme uses a large centrifuge to create hypergravity. To date, more than hundred university students had the chance to participate in the design, development, and performance of one or more experiments during dedicated campaigns. In the following paper, we examine demographics of past participants of the ESA Education Office gravity-related opportunities over the past seven years and evaluate the benefits of these educational programmes for the participants' studies and careers. Student teams that participated in one of the programmes between 2009 and 2013 were contacted to fill in a questionnaire. The feedback from the students demonstrate significant benefits extending far beyond the primary educational objectives of these programmes.

An experimental and analytical investigation of thermoacoustic convection heat transfer in gravity and zero-gravity environments

NASA Technical Reports Server (NTRS)

Parang, Masood

1986-01-01

An experimental and analytical study of Thermoacoustic Convection heat transfer in gravity and zero-gravity environments is presented. The experimental apparatus consisted of a cylinder containing air as a fluid. The side wall of the cylinder was insulated while the bottom wall was allowed to remain at the ambient temperature. The enclosed air was rapidly heated by the top surface which consisted of a thin stainless steel foil connected to a battery pack as the power source. Thermocouples were used to measure the transient temperature of the air on the axis of the cylinder. The ouput of the thermocouples was displayed on digital thermometers and the temperature displays were recorded on film using a high-speed movie camera. Temperature measurements were obtained in the zero-gravity environment by dropping the apparatus in the 2-Seconds Zero-Gravity Drop Tower Facilities of NASA Lewis Research Center. In addition, experiments were also performed in the gravity environment and the results are compared in detail with those obtained under zero-gravity conditions.

Radiation-Driven Flame Spread Over Thermally-Thick Fuels in Quiescent Microgravity Environments

NASA Technical Reports Server (NTRS)

Honda, Linton K.; Son, Youngjin; Ronney, Paul D.; Olson, Sandra (Technical Monitor); Gokoglu, Suleyman (Technical Monitor)

2001-01-01

Microgravity experiments on flame spread over thermally thick fuels were conducted using foam fuels to obtain low density and thermal conductivity, and thus large spread rate (Sf) compared to dense fuels such as PMMA. This scheme enabled meaningful results to lie obtained even in 2.2 second drop tower experiments. It was found that, in contrast conventional understanding; steady spread can occur over thick fuels in quiescent microgravity environments, especially when a radiatively active diluent gas such as CO2 is employed. This is proposed to be due to radiative transfer from the flame to the fuel surface. Additionally, the transition from thermally thick to thermally thin behavior with decreasing bed thickness is demonstrated.

Microgravity

NASA Image and Video Library

2004-04-15

STEP will carry concentric test masses to Earth orbit to test a fundamental assumption underlying Einstein's theory of general relativity: that gravitational mass is equivalent to inertial mass. STEP is a 21st-century version of the test that Galileo is said to have performed by dropping a carnon ball and a musket ball simultaneously from the top of the Leaning Tower of Pisa to compare their accelerations. During the STEP experiment, four pairs of test masses will be falling around the Earth, and their accelerations will be measured by superconducting quantum interference devices (SQUIDS). The extended time sensitivity of the instruments will allow the measurements to be a million times more accurate than those made in modern ground-based tests.

Evaluation of simple deployment mechanism of multiple rovers by microgravity experiments using a drop tower

NASA Astrophysics Data System (ADS)

Yoshimitsu, Tetsuo; Yano, Hajime; Kubota, Takashi; Adachi, Tadashi; Ishigami, Genya

2012-07-01

Introduction, Japan has announced the official development of ``Hayabusa-2'', the second sample return mission to a Near-Earth asteroid. When the development is made smoothly, Hayabusa-2 will be launched in 2014. The predecessor spacecraft ``Hayabusa'' made a great success when it returned to the Earth in June 2010 with a capsule containing some particles obtained from S-type asteroid ``Itokawa.'' Rover system, The authors installed a tiny hopping rover called ``MINERVA'' into Hayabusa spacecraft. MINERVA weights only 591[g] but has an autonomous exploration capability on the microgravity environment on the small solar system bodies. MINERVA was successfully deployed from the mother spacecraft on 12 Nov 2005 at the vicinity of the target asteroid. But unfortunately it became a solar orbiting satellite since the relative position and the speed of the mother spacecraft around the target asteroid were worst. Nevertheless it worked well, demonstrating an autnomous capability and had survived until the comunication link was lost. The authors plan to install some rovers also into Hayabusa-2. The total concept is the same but this time multiple rovers are considered. Deployment mechanism, Two rovers are installed in one container and are developed at the same time. The maximum allowed weight for the container including two rovers is 2.5[kg] and we have to seek for a simple and a light-weighted deployment system. We developed a new deployment system drastically sophisticated from the one used for MINERVA in Hayabusa mission. Both the cover and the rovers are pushed by the springs after the tightly winded wire has been cut by the deployment trigger form the spacecraft. The new deployment system enables the following things. The cover and the rovers are deployed in different directions in one action. The uncertainty of the deployment speed is decreased. Microgravity experiment, Thanks to the courtesy of DLR (German Aerospace Center) based on the international cooperation between Germany and Japan on the development of Hayabusa-2 spacecraft, we had an opprotunity to evaluate the performance of the above mentioned deployment system by using the drop tower in Bremen. We made six drops in January 2012 to look at the speed and the direction of the cover and the rovers using various parameters, which were all performed successfully. This paper reports the result of the microgravity experiments.

Capabilities and constraints of NASA's ground-based reduced gravity facilities

NASA Technical Reports Server (NTRS)

Lekan, Jack; Neumann, Eric S.; Sotos, Raymond G.

1993-01-01

The ground-based reduced gravity facilities of NASA have been utilized to support numerous investigations addressing various processes and phenomina in several disciplines for the past 30 years. These facilities, which include drop towers, drop tubes, aircraft, and sounding rockets are able to provide a low gravity environment (gravitational levels that range from 10(exp -2)g to 10(exp -6)g) by creating a free fall or semi-free fall condition where the force of gravity on an experiment is offset by its linear acceleration during the 'fall' (drop or parabola). The low gravity condition obtained on the ground is the same as that of an orbiting spacecraft which is in a state of perpetual free fall. The gravitational levels and associated duration times associated with the full spectrum of reduced gravity facilities including spaced-based facilities are summarized. Even though ground-based facilities offer a relatively short experiment time, this available test time has been found to be sufficient to advance the scientific understanding of many phenomena and to provide meaningful hardware tests during the flight experiment development process. Also, since experiments can be quickly repeated in these facilities, multistep phenomena that have longer characteristic times associated with them can sometimes be examined in a step-by-step process. There is a large body of literature which has reported the study results achieved through using reduced-gravity data obtained from the facilities.

Technology to Facilitate the Use of Impaired Waters in Cooling Towers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Colborn, Robert

The project goal was to develop an effective silica removal technology and couple that with existing electro-dialysis reversal (EDR) technology to achieve a cost effective treatment for impaired waters to allow for their use in the cooling towers of coal fired power plants. A quantitative target of the program was a 50% reduction in the fresh water withdrawal at a levelized cost of water of $3.90/Kgal. Over the course of the program, a new molybdenum-modified alumina was developed that significantly outperforms existing alumina materials in silica removal both kinetically and thermodynamically. The Langmuir capacity is 0.11g silica/g adsorbent. Moreover, amore » low cost recycle/regeneration process was discovered to allow for multiple recycles with minimal loss in activity. On the lab scale, five runs were carried out with no drop in performance between the second and fifth run in ability to absorb the silica from water. The Mo-modified alumina was successfully prepared on a multiple kilogram scale and a bench scale model column was used to remove 100 ppm of silica from 400 liters of simulated impaired water. Significant water savings would result from such a process and the regeneration process could be further optimized to reduce water requirements. Current barriers to implementation are the base cost of the adsorbent material and the fine powder form that would lead to back pressure on a large column. If mesoporous materials become more commonly used in other areas and the price drops from volume and process improvements, then our material would also lower in price because the amount of molybdenum needed is low and no additional processing is required. There may well be engineering solutions to the fine powder issue; in a simple concept experiment, we were able to pelletize our material with Boehmite, but lost performance due to a dramatic decrease in surface area.« less

Critical Velocities in Open Capillary Flow

NASA Technical Reports Server (NTRS)

Dreyer, Michael; Langbein, Dieter; Rath, Hans J.

1996-01-01

This paper describes the proposed research program on open capillary flow and the preliminary work performed theoretically and in drop tower experiments. The work focuses on the fundamental physical understanding of the flow through capillary bound geometries, where the circumference of the cross section of the flow path contains free surfaces. Examples for such a flow configuration are capillary vanes in surface tension tanks, flow along edges and corners and flow through liquid bridges. The geometries may be classified by their cross section areas, wetted circumferences and the radii of curvature of the free surfaces. In the streaming float zone the flow path is bound by a free surface only. The ribbon vane is a model for vane types used in surface tension tanks, where a structure in proximity to the tank wall forms a capillary gap. A groove is used in heat pipes for the transportation of the condensed working fluid to the heat source and a wedge may occur in a spaceborne experiment where fluid has to be transported by the means of surface tension. The research objectives are the determination of the maximum volume flux, the observation of the free surfaces and the liquid flow inside the flow path as well as the evaluation of the limiting capillary wave speed. The restriction of the maximum volume flux is due to convective forces (flow velocity exceeding the capillary wave speed) and/or viscous forces, i.e. the viscous head loss along the flow path must be compensated by the capillary pressure due to the curved free surface. Exceeding the maximum volume flux leads to the choking of the flow path, thus the free surface collapses and.gas ingestion occurs at the outlet. The means are ground-based experimental work with plateau tanks and in a drop tower, a sounding rocket flight, and theoretical analysis with integral balances as well as full three dimensional CFD solutions for flow with free surfaces.

Theoretical Basis for Estimated Test Times and Conditions for Drop Tower and Space-Based Droplet Burning Experiments With Methanol and N-Heptane

NASA Technical Reports Server (NTRS)

Marchese, Anthony J.; Dryer, Fredrick L.; Choi, Mun Y.

1994-01-01

In order to develop an extensive envelope of test conditions for NASA's space-based Droplet Combustion Experiment (DCE) as well those droplet experiments which can be performed using a drop tower, the transient vaporization and combustion of methanol and n-heptane droplets were simulated using a recently developed fully time-dependent, spherically symmetric droplet combustion model. The transient vaporization of methanol and n-heptane was modeled to characterize the instantaneous gas phase composition surrounding the droplet prior to the introduction of an ignition source. The results for methanol/air showed that the entire gas phase surrounding a 2 mm methanol droplet deployed in zero-g .quickly falls outside the lean flammability limit. The gas phase surrounding an identically-sized n-heptane droplet, on the other hand, remains flammable. The combustion of methanol was then modeled considering a detailed gas phase chemical kinetic mechanism (168 steps, 26 species) and the effect of the dissolution of flame-generated water into the liquid droplet. These results were used to determine the critical ignition diameter required to achieve quasi-steady droplet combustion in a given oxidizing environment. For droplet diameters greater than the critical ignition diameter, the model predicted a finite diameter at which the flame would extinguish. These extinction diameters were found to vary significantly with initial droplet diameter. This phenomenon appears to be unique to the transient heat transfer, mass transfer and chemical kinetics of the system and thus has not been reported elsewhere to date. The extinction diameter was also shown to vary significantly with the liquid phase Lewis number since the amount of water present in the droplet at extinction is largely governed by the rate at which water is transported into the droplet via mass diffusion. Finally, the numerical results for n-heptane combustion were obtained using both 2 step and 96 step semi-emperical chemical kinetic mechanisms. Neither mechanism exhibited the variation of extinction diameter with initial diameter.

Electrostatic Accelerometer for the Gravity Recovery and Climate Experiment Follow-On Mission (GRACE FO)

NASA Astrophysics Data System (ADS)

Perrot, Eddy; Boulanger, Damien; Christophe, Bruno; Foulon, Bernard; Liorzou, Françoise; Lebat, Vincent

2014-05-01

The GRACE FO mission, led by the JPL (Jet Propulsion Laboratory), is an Earth-orbiting gravity mission, continuation of the GRACE mission, that will produce an accurate model of the Earth's gravity field variation providing global climatic data during five year at least. The mission involves two satellites in a loosely controlled tandem formation, with a micro-wave link, and optionally a laser link, measuring the inter-satellites distance variation. Non-uniformities in the distribution of the Earth's mass cause the distance between the two satellites to vary. This variation is measured to recover gravity, after subtracting the non-gravitational contributors, as the residual drag. ONERA (the French Aerospace Lab) is developing, manufacturing and testing electrostatic accelerometers measuring this residual drag applied on the satellites. The accelerometer is composed of two main parts: the Sensor Unit (including the Sensor Unit Mechanics - SUM - and the Front-End Electronic Unit - FEEU) and the Interface Control Unit. In the Accelerometer Core, located in the Sensor Unit Mechanics, the proof mass is levitated and maintained in a center of an electrode cage by electrostatic forces. Thus, any drag acceleration applied on the satellite involves a variation on the servo-controlled electrostatic suspension of the mass. The voltage on the electrodes providing this electrostatic force is the measurement output of the accelerometer. The Preliminary Design Review was achieved successfully on November 2013. The FEEU Engineering Model is under test. Preliminary results on electronic unit will be compared with the expected performance. The integration of the SUM Engineering Model and the first ground levitation of the proof-mass will be presented. The impact of the accelerometer defaults (geometry, electronic and parasitic forces) leads to bias, misalignment and scale factor error, non-linearity and noise. Some of these accelerometer defaults are characterized by tests with micro-gravity pendulum bench and with drops in ZARM catapult. The post-processing needed to achieve the performance, in particular with regards to the temperature stability, will be explained.

Features of the Drag-Free-Simulator demonstrated for the Microscope-mission

NASA Astrophysics Data System (ADS)

List, Meike; Bremer, Stefanie; Dittus, Hansjoerg; Selig, Hanns

The ZARM Drag-Free-Simulator is being developed as a tool for comprehensive mission modeling. Environmental disturbances like solar radiation pressure, atmospheric drag, interactions between the satellite and the Earth's magnetic field can be taken into account via several models. Besides the gravitational field of the Earth, the influence of Sun, Moon and the planets including Pluto can be considered for aimed simulations, too. Methods of modeling and implementation will be presented. At the moment, effort is made to adapt this simulation tool for the french mission MICRO- SCOPE which is designed for testing the equivalence principle up to an accuracy of η=10-15 . Additionally, detailed modeling of on-board capacitive sensors is necessary for a better understanding of the real system. The actual status of mission modeling will be reported.

How Einstein Created Relativity out of Physics and Astronomy

NASA Astrophysics Data System (ADS)

Topper, David R.

In the 1590s, while teaching at the University of Pisa, Galileo Galilei tried to solve a puzzle. It involved an apparent contradiction between what he was convinced was true about the world, but which our experience of the world implied was not true. The consensus among almost everyone, scientists and others, was that the Earth was not only the center of the universe, and that it remain fixed and unmovable in this place, but that our experience of everything going around us - Sun, Moon, stars, all things up in the sky - was proof that it could not be otherwise. It is impossible for the Earth to move, for if it did, we would experience that motion in various ways. At the very least, clouds and birds could not catch-up with a moving Earth. Or, a weight dropped from a tower would not fall vertically to the bottom, but would fall "behind" the tower. Of course, these things do not happen: therefore, not only is there nothing in our experience of the world that contradicts a stationary Earth, but everything we see and experience actually supports an immovable Earth. So why was Galileo puzzled? Because he was one of the few thinkers at this time who was increasing convinced, obstinately, that the Earth does move.

Variable velocity in solar external receivers

NASA Astrophysics Data System (ADS)

Rodríguez-Sánchez, M. R.; Sánchez-González, A.; Acosta-Iborra, A.; Santana, D.

2017-06-01

One of the major problems in solar external receivers is tube overheating, which accelerates the risk of receiver failure. It can be solved implementing receivers with high number of panels. However, it exponentially increases the pressure drop in the receiver and the parasitic power consumption of the Solar Power Tower (SPT), reducing the global efficiency of the SPT. A new concept of solar external receiver, named variable velocity receiver, is able to adapt their configuration to the different flux density distributions. A set of valves allows splitting in several independent panels those panels in which the wall temperature is over the limit. It increases the velocity of the heat transfer fluid (HTF) and its cooling capacity. This receiver does not only reduce the wall temperature of the tubes, but also simplifies the control of the heliostat field and allows to employ more efficient aiming strategies. In this study, it has been shown that variable velocity receiver presents high advantages with respect to traditional receiver. Nevertheless, more than two divisions per panels are not recommendable, due to the increment of the pressure drop over 70 bars. In the design point (12 h of the Spring Equinox), the use of a variable number of panels between 18 and 36 (two divisions per panel), in a SPT similar to Gemasolar, improves the power capacity of the SPT in 5.7%, with a pressure drop increment of 10 bars. Off-design, when the flux distribution is high and not symmetric (e.g. 10-11 h), the power generated by the variable velocity receiver is 18% higher than the generated by the traditional receiver, at these hours the pressure drop increases almost 20 bars.

The Satellite Test of the Equivalence Principle (STEP)

NASA Technical Reports Server (NTRS)

2004-01-01

STEP will carry concentric test masses to Earth orbit to test a fundamental assumption underlying Einstein's theory of general relativity: that gravitational mass is equivalent to inertial mass. STEP is a 21st-century version of the test that Galileo is said to have performed by dropping a carnon ball and a musket ball simultaneously from the top of the Leaning Tower of Pisa to compare their accelerations. During the STEP experiment, four pairs of test masses will be falling around the Earth, and their accelerations will be measured by superconducting quantum interference devices (SQUIDS). The extended time sensitivity of the instruments will allow the measurements to be a million times more accurate than those made in modern ground-based tests.

Prediction of the effect of temperature on impact damage in carbon/epoxy laminates

NASA Astrophysics Data System (ADS)

Gómez del Río, T.; Zaera, R.; Navarro, C.

2003-09-01

The effect of temperature on impact damage in Carbon Fiber Reinforced Plastic (CFRP) tape laminates produced by low velocity impact was studied by numerical simulations made to model drop weight tower impact tests on carbon/epoxy laminate composites. The damage model was implemented into a user subroutine of the finite element code ABAQUS. The model takes into account the thermal stresses resulting form the different thermal expansion coefficients in each ply of the laminate. The tests and simulations show how temperature affects the propagation of each damage mode. Matrix cracking and delamination are greatly affected by low temperature, white matrix crushing and fibre failure appear only in a small region at all the impact energies and test temperatures.

Novel active driven drop tower facility for microgravity experiments investigating production technologies on the example of substrate-free additive manufacturing

NASA Astrophysics Data System (ADS)

Lotz, Christoph; Wessarges, Yvonne; Hermsdorf, Jörg; Ertmer, Wolfgang; Overmeyer, Ludger

2018-04-01

Through the striving of humanity into space, new production processes and technologies for the use under microgravity will be essential in the future. Production of objects in space demands for new processes, like additive manufacturing. This paper presents the concept and the realization for a new machine to investigate microgravity production processes on earth. The machine is based on linear long stator drives and a vacuum chamber carrying up to 1000 kg. For the first time high repetition rate and associated low experimental costs can provide basic research. The paper also introduces the substrate-free additive manufacturing as a future research topic and one of our primary application.

Determination of the natural convection coefficient in low-gravity

NASA Technical Reports Server (NTRS)

Goldmeer, J.; Motevalli, V.; Haghdoust, M.; Jumper, G.

1992-01-01

Fire safety is an important issue in the current space program; ignition in low-g needs to be studied. The reduction in the gravitational acceleration causes changes in the ignition process. This paper examines the effect of gravity on natural convection, which is one of the important parameters in the ignition process. The NASA-Lewis 2.2 Second Drop Tower provided the low-gravity environment for the experiments. A series of experiments was conducted to measure the temperature of a small copper plate which was heated by a high intensity lamp. These experiments verified that in low-gravity the plate temperature increased faster than in the corresponding 1-g cases, and that the natural convection coefficient rapidly decreased in the low-gravity environment.

A summary of existing and planned experiment hardware for low-gravity fluids research

NASA Technical Reports Server (NTRS)

Hill, Myron E.; Omalley, Terence F.

1991-01-01

An overview is presented of (1) existing ground-based, low gravity research facilities, with examples of hardware capabilities, and (2) existing and planned space-based research facilities, with examples of current and past flight hardware. Low-gravity, ground-based facilities, such as drop towers and aircraft, provide the experimenter with quick turnaround time, easy access to equipment, gravity levels ranging from 10(exp -2) to 10(exp -6) G, and low-gravity durations ranging from 2 to 30 sec. Currently, the only operational space-based facility is the Space Shuttle. The Shuttle's payload bay and middeck facilities are described. Existing and planned low-gravity fluids research facilities are also described with examples of experiments and hardware capabilities.

Quantitative Studies on the Propagation and Extinction of Near-Limit Premixed Flames Under Normal and Microgravity

NASA Technical Reports Server (NTRS)

Dong, Y.; Spedding, G. R.; Egolfopoulos, F. N.; Miller, F. J.

2003-01-01

The main objective of this research is to introduce accurate fluid mechanics measurements diagnostics in the 2.2-s drop tower for the determination of the detailed flow-field at the states of extinction. These results are important as they can then be compared with confidence with detailed numerical simulations so that important insight is provided into near-limit phenomena that are controlled by not well-understood kinetics and thermal radiation processes. Past qualitative studies did enhance our general understanding on the subject. However, quantitative studies are essential for the validation of existing models that subsequently be used to describe near-limit phenomena that can initiate catastrophic events in micro- and/or reduced gravity environments.

Saturn Apollo Program

NASA Image and Video Library

1970-01-22

This Saturn V S-II (second) stage is being lifted into position for a test at the Vehicle Assembly Building at the Kennedy Space Center. When the Saturn V booster stage (S-IC) burned out and dropped away, power for the Saturn was provided by the 82-foot-long and 33-foot-diameter S-II stage. Developed by the Space Division of North American Aviation under the direction of the Marshall Space Flight Center, the stage utilized five J-2 engines, each producing 200,000 pounds of thrust. The engines used liquid oxygen and liquid hydrogen as propellants. The towering 363-foot Saturn V was a multi-stage, multi-engine launch vehicle standing taller than the Statue of Liberty. Altogether, the Saturn V engines produced as much power as 85 Hoover Dams.

Parametric Investigation of Liquid Jets in Low Gravity

NASA Technical Reports Server (NTRS)

Chato, David J.

2005-01-01

An axisymmetric phase field model is developed and used to model surface tension forces on liquid jets in microgravity. The previous work in this area is reviewed and a baseline drop tower experiment selected for model comparison. This paper uses the model to parametrically investigate the influence of key parameters on the geysers formed by jets in microgravity. Investigation of the contact angle showed the expected trend of increasing contact angle increasing geyser height. Investigation of the tank radius showed some interesting effects and demonstrated the zone of free surface deformation is quite large. Variation of the surface tension with a laminar jet showed clearly the evolution of free surface shape with Weber number. It predicted a breakthrough Weber number of 1.

Preliminary Results of a Microgravity Investigation to Measure Net Charge on Granular Materials

NASA Technical Reports Server (NTRS)

Green, Robert D.; Myers, Jerry G.; Hansen, Bonnie L.

2003-01-01

Accurate characterization of the electrostatic charge on granular materials has typically been limited to materials with diameters on the order of 10 microns and below due to high settling velocities of larger particles. High settling velocities limit both the time and the acceptable uncertainty with which a measurement can be made. A prototype device has been developed at NASA Glenn Research Center (GRC) to measure coulombic charge on individual particles of granular materials that are 50 to 500 microns in diameter. This device, a novel extension of Millikan's classic oil drop experiment, utilizes the NASA GRC 2.2 second drop tower to extend the range of electrostatic charge measurements to accommodate moderate size granular materials. A dielectric material with a nominal grain diameter between 1.06 and 250 microns was tribocharged using a dry gas jet, suspended in a 5x10x10 cm enclosure during a 2.2 second period of microgravity and exposed to a known electric field. The response was recorded on video and post processed to allow tracking of individual particles. By determining the particle trajectory and velocity, estimates of the coulombic charge were made. Over 30 drops were performed using this technique and the analysis showed that first order approximations of coulombic charge could successfully be obtained, with the mean charge of 3.4E-14 coulombs measured for F-75 Ottawa quartz sand. Additionally, the measured charge showed a near-Gaussian distribution, with a standard deviation of 2.14E -14 coulombs.

Capillary Flow in an Interior Corner

NASA Technical Reports Server (NTRS)

Weislogel, Mark Milton

1996-01-01

The design of fluids management processes in the low-gravity environment of space requires an accurate model and description of capillarity-controlled flow in containers of irregular geometry. Here we consider the capillary rise of a fluid along an interior corner of a container following a rapid reduction in gravity. The analytical portion of the work presents an asymptotic formulation in the limit of a slender fluid column, slight surface curvature along the corner, small inertia, and low gravity. New similarity solutions are found and a list of closed form expressions is provided for flow rate and column length. In particular, it is found that the flow is proportional to t(exp 1/2) for a constant height boundary condition, t(exp 2/5) for a spreading drop, and t(exp 3/5) for constant flow. In the experimental portion of the work, measurements from a 2.2s drop tower are reported. An extensive data set, collected over a previously unexplored range of flow parameters, includes estimates of repeatability and accuracy, the role of inertia and column slenderness, and the effects of corner angle, container geometry, and fluid properties. Comprehensive comparisons are made which illustrate the applicability of the analytic results to low-g fluid systems design.

NASA Microgravity Science Competition for High-school-aged Student Teams

NASA Technical Reports Server (NTRS)

DeLombard, Richard; Stocker, Dennis; Hodanbosi, Carol; Baumann, Eric

2002-01-01

NASA participates in a wide variety of educational activities including competitive events. There are competitive events sponsored by NASA and student teams which are mentored by NASA centers. This participation by NASA in public forums serves to bring the excitement of aerospace science to students and educators. A new competition for highschool-aged student teams involving projects in microgravity has completed two pilot years and will have national eligibility for teams during the 2002-2003 school year. A team participating in the Dropping In a Microgravity Environment will research the field of microgravity, develop a hypothesis, and prepare a proposal for an experiment to be conducted in a microgravity drop tower facility. A team of NASA scientists and engineers will select the top proposals and those teams will then design and build their experiment apparatus. When the experiment apparatus are completed, team representatives will visit NASA Glenn in Cleveland, Ohio for operation of their facility and participate in workshops and center tours. Presented in this paper will be a description of DIME, an overview of the planning and execution of such a program, results from the first two pilot years, and a status of the first national competition.

Wind turbine tower for storing hydrogen and energy

DOEpatents

Fingersh, Lee Jay [Westminster, CO

2008-12-30

A wind turbine tower assembly for storing compressed gas such as hydrogen. The tower assembly includes a wind turbine having a rotor, a generator driven by the rotor, and a nacelle housing the generator. The tower assembly includes a foundation and a tubular tower with one end mounted to the foundation and another end attached to the nacelle. The tower includes an in-tower storage configured for storing a pressurized gas and defined at least in part by inner surfaces of the tower wall. In one embodiment, the tower wall is steel and has a circular cross section. The in-tower storage may be defined by first and second end caps welded to the inner surface of the tower wall or by an end cap near the top of the tower and by a sealing element attached to the tower wall adjacent the foundation, with the sealing element abutting the foundation.

Application of Pulsed Electrical Fields for Advanced Cooling and Water Recovery in Coal-Fired Power Plant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Young Cho; Alexander Fridman

2009-04-02

The overall objective of the present work was to develop technologies to reduce freshwater consumption in a cooling tower of coal-based power plant so that one could significantly reduce the need of make-up water. The specific goal was to develop a scale prevention technology based an integrated system of physical water treatment (PWT) and a novel filtration method so that one could reduce the need for the water blowdown, which accounts approximately 30% of water loss in a cooling tower. The present study investigated if a pulsed spark discharge in water could be used to remove deposits from the filtermore » membrane. The test setup included a circulating water loop and a pulsed power system. The present experiments used artificially hardened water with hardness of 1,000 mg/L of CaCO{sub 3} made from a mixture of calcium chloride (CaCl{sub 2}) and sodium carbonate (Na{sub 2}CO{sub 3}) in order to produce calcium carbonate deposits on the filter membrane. Spark discharge in water was found to produce strong shockwaves in water, and the efficiency of the spark discharge in cleaning filter surface was evaluated by measuring the pressure drop across the filter over time. Results showed that the pressure drop could be reduced to the value corresponding to the initial clean state and after that the filter could be maintained at the initial state almost indefinitely, confirming the validity of the present concept of pulsed spark discharge in water to clean dirty filter. The present study also investigated the effect of a plasma-assisted self-cleaning filter on the performance of physical water treatment (PWT) solenoid coil for the mitigation of mineral fouling in a concentric counterflow heat exchanger. The self-cleaning filter utilized shockwaves produced by pulse-spark discharges in water to continuously remove scale deposits from the surface of the filter, thus keeping the pressure drop across the filter at a relatively low value. Artificial hard water was used in the present fouling experiments for three different cases: no treatment, PWT coil only, and PWT coil plus self-cleaning filter. Fouling resistances decreased by 59-72% for the combined case of PWT coil plus filter compared with the values for no-treatment cases. SEM photographs showed much smaller particle sizes for the combined case of PWT coil plus filter as larger particles were continuously removed from circulating water by the filter. The x-ray diffraction data showed calcite crystal structures for all three cases.« less

Miniature Arcs for Synthesis of Carbon Nanotubes in Microgravity

NASA Technical Reports Server (NTRS)

Alford, J. M.; Mason, G. R.; Feikema, D. A.

2006-01-01

Although many methods are available for producing single-walled carbon nanotubes (SWNTs), the conventional carbon arc process remains the most popular due to its simplicity and large production rate. In the carbon arc, SWNTs are catalytically synthesized by rapidly evaporating a graphite anode impregnated with NiN metal catalyst from which the nanotubes grow in an inert atmosphere. However, high temperatures inside the carbon arc generate strong buoyancy driven convection, and it is hypothesized that the non-uniform environment created by this flow has a large effect on the growth and morphology of the SWNTs. To study the effect of buoyancy on the arc process, a miniature carbon arc apparatus was developed to synthesize SWNTs in a microgravity environment substantially free from these strong convective flows. The reactor was operated for either 2.2 or 5 seconds during free-fall in the drop towers at the NASA Glenn Research Center. Two apparatus designs differing mainly in their production rate and power capacity were investigated. The first consisted of a miniaturized carbon arc employing a 1 mm diameter graphite anode and powered by a 0.54 F capacitor bank charged to 65 V. The second, larger apparatus employed a 4 mm diameter anode and was powered by a portable battery pack capable of providing in excess of 300 amps at 30 volts to the arc for the duration of a 5 second drop. Initial results indicated that transient heating is a very large effect in the short-duration drop tower carbon arcs, and thermal equilibrium of the arc plasma, buffer gas, and apparatus was not attained during the short microgravity periods. In addition, removal of the buoyant convection by the microgravity now allowed clear observation of large jets of evaporated carbon vapor streaming from the anode and mixing with the inert buffer gas. The initial mixing of these jets with the cold buffer gas combined with the thermal transient made it difficult to establish a uniform high temperature environment around the arc in the 2.1 to 5 second microgravity time interval, and even with a very high-powered arc, the arc region was cooler than in continuously operated arcs. Despite these difficulties, the miniature arc produced SWNTs in microgravity. However, given the large thermal transient to overcome, no dramatic difference in sample yield or composition was noted between normal gravity and q2-,andL%econd long microgravity runs.

The influence and analysis of natural crosswind on cooling characteristics of the high level water collecting natural draft wet cooling tower

NASA Astrophysics Data System (ADS)

Ma, Libin; Ren, Jianxing

2018-01-01

Large capacity and super large capacity thermal power is becoming the main force of energy and power industry in our country. The performance of cooling tower is related to the water temperature of circulating water, which has an important influence on the efficiency of power plant. The natural draft counter flow wet cooling tower is the most widely used cooling tower type at present, and the high cooling tower is a new cooling tower based on the natural ventilation counter flow wet cooling tower. In this paper, for high cooling tower, the application background of high cooling tower is briefly explained, and then the structure principle of conventional cooling tower and high cooling tower are introduced, and the difference between them is simply compared. Then, the influence of crosswind on cooling performance of high cooling tower under different wind speeds is introduced in detail. Through analysis and research, wind speed, wind cooling had little impact on the performance of high cooling tower; wind velocity, wind will destroy the tower inside and outside air flow, reducing the cooling performance of high cooling tower; Wind speed, high cooling performance of cooling tower has increased, but still lower than the wind speed.

Experiment plans to study preignition processes of a pool fire in low gravity. M.S. Thesis - 1988 Final Report

NASA Technical Reports Server (NTRS)

Schiller, David N.

1989-01-01

Science requirements are specified to guide experimental studies of transient heat transfer and fluid flow in an enclosure containing a two-layer gas-and-liquid system heated unevenly from above. Specifications are provided for experiments in three separate settings: (1) a normal gravity laboratory, (2) the NASA-LeRC Drop towers, and (3) a space-based laboratory (e.g., Shuttle, Space Station). A rationale is developed for both minimum and desired requirement levels. The principal objective of the experimental effort is to validate a computational model of the enclosed liquid fuel pool during the preignition phase and to determine via measurement the role of gravity on the behavior of the system. Preliminary results of single-phase normal gravity experiments and simulations are also presented.

Premixed Flames Under Microgravity and Normal Gravity Conditions

NASA Astrophysics Data System (ADS)

Krikunova, Anastasia I.; Son, Eduard E.

2018-03-01

Premixed conical CH4-air flames were studied experimentally and numerically under normal straight, reversed gravity conditions and microgravity. Low-gravity experiments were performed in Drop tower. Classical Bunsen-type burner was used to find out features of gravity influence on the combustion processes. Mixture equivalence ratio was varied from 0.8 to 1.3. Wide range of flow velocity allows to study both laminar and weakly turbulized flames. High-speed flame chemoluminescence video-recording was used as diagnostic. The investigations were performed at atmospheric pressure. As results normalized flame height, laminar flame speed were measured, also features of flame instabilities were shown. Low- and high-frequency flame-instabilities (oscillations) have a various nature as velocity fluctuations, preferential diffusion instability, hydrodynamic and Rayleigh-Taylor ones etc., that was explored and demonstrated.

Characterization and Demonstrations of Laser-Induced Incandescence in both Normal and Low-Gravity

NASA Technical Reports Server (NTRS)

VanderWal, Randall L.

1997-01-01

Knowledge of soot volume fraction is important to a wide range of combustion studies in microgravity. Laser-induced incandescence (LII) offers high sensitivity, high temporal and spatial resolution in addition to geometric versatility for real-time determination of soot volume fraction. Implementation of LII into the 2.2 see drop tower at The NASA-Lewis Research Center along with system characterization is described. Absolute soot volume fraction measurements are presented for laminar and turbulent gas-jet flames in microgravity to illustrate the capabilities of LII in microgravity. Comparison between LII radial intensity profiles with soot volume fraction profiles determined through a full-field light extinction technique are also reported validating the accuracy of LII for soot volume fraction measurements in a microgravity environment.

Test and Analysis Correlation of High Speed Impacts of Ice Cylinders

NASA Technical Reports Server (NTRS)

Fasanella, Edwin L.; Boitnott, Richard L.; Kellas, Sotiris

2006-01-01

During the space shuttle return-to-flight preparations following the Columbia accident, finite element models were needed that could predict the threshold of critical damage to the orbiter s wing leading edge from ice debris impacts. Hence, an experimental program was initiated to provide crushing data from impacted ice for use in dynamic finite element material models. A high-speed drop tower was configured to capture force time-histories of ice cylinders for impacts up to approximately 100 ft/s. At low velocity, the force-time history depended heavily on the internal crystalline structure of the ice. However, for velocities of 100 ft/s and above, the ice fractured on impact, behaved more like a fluid, and the subsequent force-time history curves were much less dependent on the internal crystalline structure.

Dynamic Crush Characterization of Ice

NASA Technical Reports Server (NTRS)

Fasanella, Edwin L.; Boitnott, Richard L.; Kellas, Sotiris

2006-01-01

During the space shuttle return-to-flight preparations following the Columbia accident, finite element models were needed that could predict the threshold of critical damage to the orbiter's wing leading edge from ice debris impacts. Hence, an experimental program was initiated to provide crushing data from impacted ice for use in dynamic finite element material models. A high-speed drop tower was configured to capture force time histories of ice cylinders for impacts up to approximately 100 ft/s. At low velocity, the force-time history depended heavily on the internal crystalline structure of the ice. However, for velocities of 100 ft/s and above, the ice fractured on impact, behaved more like a fluid, and the subsequent force-time history curves were much less dependent on the internal crystalline structure.

Transitional Gas Jet Diffusion Flames in Microgravity

NASA Technical Reports Server (NTRS)

Agrawal, Ajay K.; Alammar, Khalid; Gollahalli, S. R.; Griffin, DeVon (Technical Monitor)

2000-01-01

Drop tower experiments were performed to identify buoyancy effects in transitional hydrogen gas jet diffusion flames. Quantitative rainbow schlieren deflectometry was utilized to optically visualize the flame and to measure oxygen concentration in the laminar portion of the flame. Test conditions consisted of atmospheric pressure flames burning in quiescent air. Fuel from a 0.3mm inside diameter tube injector was issued at jet exit Reynolds numbers (Re) of 1300 to 1700. Helium mole percentage in the fuel was varied from 0 to 40%. Significant effects of buoyancy were observed in near field of the flame even-though the fuel jets were momentum-dominated. Results show an increase of breakpoint length in microgravity. Data suggest that transitional flames in earth-gravity at Re<1300 might become laminar in microgravity.

Capillary Flows Along Open Channel Conduits: The Open-Star Section

NASA Technical Reports Server (NTRS)

Weislogel, Mark; Geile, John; Chen, Yongkang; Nguyen, Thanh Tung; Callahan, Michael

2014-01-01

Capillary rise in tubes, channels, and grooves has received significant attention in the literature for over 100 years. In yet another incremental extension of such work, a transient capillary rise problem is solved for spontaneous flow along an interconnected array of open channels forming what is referred to as an 'open-star' section. This geometry possesses several attractive characteristics including passive phase separations and high diffusive gas transport. Despite the complex geometry, novel and convenient approximations for capillary pressure and viscous resistance enable closed form predictions of the flow. As part of the solution, a combined scaling approach is applied that identifies unsteady-inertial-capillary, convective-inertial-capillary, and visco-capillary transient regimes in a single parameter. Drop tower experiments are performed employing 3-D printed conduits to corroborate all findings.

Liquid jet impingement normal to a disk in zero gravity. Ph.D. Thesis Toledo Univ.

NASA Technical Reports Server (NTRS)

Labus, T. L.

1977-01-01

The free surface shapes of circular liquid jets impinging normal to sharp-edged disks in zero gravity are determined. Zero gravity drop tower experiments yielded three distinct flow patterns that were classified in terms of the relative effects of surface tension and inertial forces. An order of magnitude analysis was conducted that indicated regions where viscous forces were not significant in the computation of free surface shapes. The free surface analysis was simplified by transforming the governing potential flow equations and boundary conditions into the inverse plane, where the stream function and velocity potential became the coordinates. The resulting nonlinear equations were solved by standard finite difference methods, and comparisons were made with the experimental data for the inertia dominated regime.

High-Speed Rainbow Schlieren Visualization of an Oscillating Helium Jet Undergoing Gravitational Change

NASA Technical Reports Server (NTRS)

Leptuch, Peter A.; Agrawal, Ajay K.

2005-01-01

Rainbow schlieren deflectometry combined with high-speed digital imaging was used to study buoyancy effects on flow structure of a helium jet discharged vertically into air. The experimental data were taken using the 2.2-sec drop tower facility at the NASA John H. Glenn Research Center in Cleveland, Ohio. The test conditions pertained to jet Reynolds number of 490 and jet Richardson number of 0.11, for which buoyancy is often considered unimportant. Experimental results show global oscillations at a frequency of 27 Hz in Earth gravity. In microgravity, the jet oscillations vanished and the jet width increased. Results provide a direct physical evidence of the importance of buoyancy on the flow structure of low-density gas jets at a Richardson number considered too small to account for gravity.

The Second Stage of a Saturn V Ready For Test

NASA Technical Reports Server (NTRS)

1970-01-01

This Saturn V S-II (second) stage is being lifted into position for a test at the Vehicle Assembly Building at the Kennedy Space Center. When the Saturn V booster stage (S-IC) burned out and dropped away, power for the Saturn was provided by the 82-foot-long and 33-foot-diameter S-II stage. Developed by the Space Division of North American Aviation under the direction of the Marshall Space Flight Center, the stage utilized five J-2 engines, each producing 200,000 pounds of thrust. The engines used liquid oxygen and liquid hydrogen as propellants. The towering 363-foot Saturn V was a multi-stage, multi-engine launch vehicle standing taller than the Statue of Liberty. Altogether, the Saturn V engines produced as much power as 85 Hoover Dams.

Isothermal gas-liquid flow at reduced gravity

NASA Technical Reports Server (NTRS)

Dukler, A. E.

1990-01-01

Research on adiabatic gas-liquid flows under reduced gravity condition is presented together with experimental data obtained using a NASA-Lewis RC 100-ft drop tower and in a LeRC Learjet. It is found that flow patterns and characteristics remain unchanged after the first 1.5 s into microgravity conditions and that the calculated time for a continuity wave to traverse the test section is less than 1.2 s. It is also found that the dispersed bubbles move at the same velocity as that of the front of the slug and that the transition between bubbly and slug flow is insensitive to diameter. Both the bubbly and the slug flows are suggested to represent a continuum of the same physical process. The characteristics of annular, slug, and bubbly flows are compared.

Bose-Einstein condensation in microgravity.

PubMed

van Zoest, T; Gaaloul, N; Singh, Y; Ahlers, H; Herr, W; Seidel, S T; Ertmer, W; Rasel, E; Eckart, M; Kajari, E; Arnold, S; Nandi, G; Schleich, W P; Walser, R; Vogel, A; Sengstock, K; Bongs, K; Lewoczko-Adamczyk, W; Schiemangk, M; Schuldt, T; Peters, A; Könemann, T; Müntinga, H; Lämmerzahl, C; Dittus, H; Steinmetz, T; Hänsch, T W; Reichel, J

2010-06-18

Albert Einstein's insight that it is impossible to distinguish a local experiment in a "freely falling elevator" from one in free space led to the development of the theory of general relativity. The wave nature of matter manifests itself in a striking way in Bose-Einstein condensates, where millions of atoms lose their identity and can be described by a single macroscopic wave function. We combine these two topics and report the preparation and observation of a Bose-Einstein condensate during free fall in a 146-meter-tall evacuated drop tower. During the expansion over 1 second, the atoms form a giant coherent matter wave that is delocalized on a millimeter scale, which represents a promising source for matter-wave interferometry to test the universality of free fall with quantum matter.

Partial gravity reaction experiment sysytem on graund using multi-Copter

NASA Astrophysics Data System (ADS)

Hasegawa, Katsuya; Maeda, Naoko

2016-07-01

In order to enable further space exploration into the space, Moon, Mars, and other planets, it is essential to understand the physiological response to low gravity environments. However, We made low gravity environment for studies using the satellite parabolic flight and drop tower. It is very expensive experiment that low gravity physiological response. Because, it requires rockets and airplanes and dedicated Tower, low gravity conditions test have not been conducted sufficiently due to the extraordinary high cost for conducting experiments. The study present is to develop the radio-controlled multicopter system that is used for the controlled falling flight vehicle (not free fall). During the controlled falling, the payload is exposed to a certain level of low gravity. 1) G profile: low gravity from 0 g to 1 g that will last approximately 5seconds, 50 kg. 2) Supply limited imaging techniques, high-speed or normal video and X ray images. 3) Wireless transmission of up to 64 channels of analog and digital signals. This vehicle is designed for experimentation on various model organisms, from cells to animals and plants. The multicopter flight system enables conducting experiments in low gravity conditions with less than 1% of the budget for spaceflight or parabolic flights. Experiment is possible to perform repeated many times in one day. We can expect reproducible results from many repeated trials at the lowest cost.

DETAIL VIEW OF AERIAL TRAM SUPPORT TOWER SIX WITH TOWERS ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

DETAIL VIEW OF AERIAL TRAM SUPPORT TOWER SIX WITH TOWERS SEVEN,EIGHT, NINE, TEN, AND BREAK OVER TOWER IN DISTANCE, LOOKING NORTH. TOWER SIX IS THE LAST BEFORE A DEEP CHASM, AS IS SEEN BY THE DISTANCE BETWEEN TOWERS SIX AND SEVEN. SEE CA-291-48 (CT) FOR IDENTICAL COLOR TRANSPARENCY. - Keane Wonder Mine, Park Route 4 (Daylight Pass Cutoff), Death Valley Junction, Inyo County, CA

DETAIL VIEW OF AERIAL TRAM SUPPORT TOWER SIX WITH TOWERS ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

DETAIL VIEW OF AERIAL TRAM SUPPORT TOWER SIX WITH TOWERS SEVEN, EIGHT, NINE, TEN, AND BREAK OVER TOWER IN DISTANCE, LOOKING NORTH. TOWER SIX IS THE LAST BEFORE A DEEP CHASM, AS IS SEEN BY THE DISTANCE BETWEEN TOWERS SIX AND SEVEN. SEE CA-291-21 FOR IDENTICAL B&W NEGATIVE. - Keane Wonder Mine, Park Route 4 (Daylight Pass Cutoff), Death Valley Junction, Inyo County, CA

Effects of trees on momentum exchange within and above a real urban environment

NASA Astrophysics Data System (ADS)

Salesky, S.; Giometto, M. G.; Christen, A.; Egli, P. E.; Schmid, M. F.; Tooke, T. R.; Coops, N. C.; Parlange, M. B.

2017-12-01

Large-eddy simulations (LES) are used to gain insight into the effects of trees on momentum transfer rates characterizing the atmosphere within and above a real urban canopy. Several areas are considered that are part of a neighbourhood in the city of Vancouver, BC, Canada where a small fraction of trees are taller than buildings. In this area, eight years of continuous wind and turbulence measurements are available from a 30 m meteorological tower. Buildings and vegetation geometries are obtained from airborne light detection and ranging (LiDAR) data. In the LES algorithm, buildings are accounted through an immersed boundary method, whereas vegetation is parameterized via a location-specific leaf area density. LES are performed varying wind direction and leaf area densities. Surface roughness lengths (z0) from both LES and tower measurements are sensitive to the 0 ≤ LAI/λ < 3 parameter, where LAI is the leaf area index and λ is the frontal area fraction of buildings characterizing a given canopy. For instance, tower measurements predict a 19% seasonal increase in z0, slightly lower than the 27% increase featured by LES for the most representative canopy (leaves-off LAI/λ = 0.74, leaves-on LAI/λ = 2.24). Removing vegetation from such a canopy would cause a dramatic drop of approximately 50% in z0 when compared to the reference summer value. The momentum displacement height (d) from LES also consistently increases as LAI/λ increases, due to the disproportionate amount of drag that the (few) relatively taller trees exert on the flow. Within the urban canopy, the effects of trees are twofold: on one hand, they act as a direct momentum sink for the mean flow; on the other, they reduce downward turbulent transport of high-momentum fluid, significantly reducing the wind intensity at the heights where people live and buildings consume energy.

The Physics of Protoplanetesimal Dust Agglomerates. V. Multiple Impacts of Dusty Agglomerates at Velocities Above the Fragmentation Threshold

NASA Astrophysics Data System (ADS)

Kothe, Stefan; Güttler, Carsten; Blum, Jürgen

2010-12-01

In recent years, a number of new experiments have advanced our knowledge on the early growth phases of protoplanetary dust aggregates. Some of these experiments have shown that collisions between porous and compacted agglomerates at velocities above the fragmentation threshold velocity can lead to growth of the compact body, when the porous collision partner fragments upon impact and transfers mass to the compact agglomerate. To obtain a deeper understanding of this potentially important growth process, we performed laboratory and drop tower experiments to study multiple impacts of small, highly porous dust-aggregate projectiles onto sintered dust targets. The projectile and target consisted of 1.5 μm monodisperse, spherical SiO2 monomers with volume filling factors of 0.15 ± 0.01 and 0.45 ± 0.05, respectively. The fragile projectiles were accelerated by a solenoid magnet and combined with a projectile magazine with which 25 impacts onto the same spot on the target could be performed in vacuum. We measured the mass-accretion efficiency and the volume filling factor for different impact velocities between 1.5 and 6.0 m s^{-1}. The experiments at the lowest impact speeds were performed in the Bremen drop tower under microgravity conditions to allow partial mass transfer also for the lowest adhesion case. Within this velocity range, we found a linear increase of the accretion efficiency with increasing velocity. In the laboratory experiments, the accretion efficiency increases from 0.12 to 0.21 in units of the projectile mass. The recorded images of the impacts showed that the mass transfer from the projectile to the target leads to the growth of a conical structure on the target after less than 100 impacts. From the images, we also measured the volume filling factors of the grown structures, which ranged from 0.15 (uncompacted) to 0.40 (significantly compacted) with increasing impact speed. The velocity dependency of the mass-transfer efficiency and the packing density of the resulting aggregates augment our knowledge of the aggregate growth in protoplanetary disks and should be taken into account for future models of protoplanetary dust growth.

Solar tower enhanced natural draft dry cooling tower

NASA Astrophysics Data System (ADS)

Yang, Huiqiang; Xu, Yan; Acosta-Iborra, Alberto; Santana, Domingo

2017-06-01

Concentrating Solar Power (CSP) plants are located in desert areas where the Direct Normal Irradiance (DNI) value is very high. Since water resource is scarcely available, mechanical draft cooing technology is commonly used, with power consumption of mechanical fans being approximately 2% of the total power generated. Today, there is only one solar power plant (Khi Solar One in South Africa) uses a condenser installed in a Natural Draft Cooling (NDC) tower that avoids the windage loss of water occurring in wet cooling towers. Although, Khi Solar One is a cavity receiver power tower, the receivers can be hung onto the NDC tower. This paper looks at a novel integration of a NDC tower into an external molten salt receiver of a solar power plant, which is one of a largest commercial molten salt tower in China, with 100MWe power capacity. In this configuration study, the NDC tower surrounds the concrete tower of the receiver concentrically. In this way, the receiver concrete tower is the central support of the NDC tower, which consists of cable networks that are fixed to the concrete tower and suspended at a certain height over the floor. The cable networks support the shell of the NDC tower. To perform a preliminary analysis of the behavior of this novel configuration, two cases of numerical simulation in three dimensional (3D) models have been solved using the commercial Computational Fluid Dynamics (CFD) code, ANSYS Fluent 6.3. The results show that the integration of the NDC tower into an external central receiver tower is feasible. Additionally, the total heat transfer rate is not reduced but slightly increases when the molten salt receiver is in operation because of the additional natural draft induced by the high temperature of the receiver.

Summary of tower designs for large horizontal axis wind turbines

NASA Technical Reports Server (NTRS)

Frederick, G. R.; Savino, J. M.

1986-01-01

Towers for large horizontal axis wind turbines, machines with a rotor axis height above 30 meters and rated at more than 500 kW, have varied in configuration, materials of construction, type of construction, height, and stiffness. For example, the U.S. large HAWTs have utilized steel truss type towers and free-standing steel cylindrical towers. In Europe, the trend has been to use only free-standing and guyed cylindrical towers, but both steel and reinforced concrete have been used as materials of construction. These variations in materials of construction and type of construction reflect different engineering approaches to the design of cost effective towers for large HAWTs. Tower designs are the NASA/DOE Mod-5B presently being fabricated. Design goals and requirements that influence tower configuration, height and materials are discussed. In particular, experiences with United States large wind turbine towers are elucidated. Finally, current trends in tower designs for large HAWTs are highlighted.

13. INTERIOR VIEW OF TOWER OFFICE SHOWING CONTROL TOWER DESK, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

13. INTERIOR VIEW OF TOWER OFFICE SHOWING CONTROL TOWER DESK, FACING NORTHWEST. - U.S. Naval Base, Pearl Harbor, Signal Tower, Corner of Seventh Street & Avenue D east of Drydock No. 1, Pearl City, Honolulu County, HI

Evaluation of dynamic response for monopole and hybrid wind mill tower

NASA Astrophysics Data System (ADS)

Shah, Hemal J.; Desai, Atul K.

2017-07-01

The wind mill towers are constructed using monopoles or lattice type tower. As the height of tower increases it gives more power but it becomes uneconomical, so in the present research work innovative wind mill tower such as combination of monopole and lattice tower is analyzed using FEM software. When the tall structures are constructed on soft soil it becomes dynamically sensitive so 3 types of soil such as hard, medium and soft soil is also modeled and the innovative tower is studied for different operating frequencies of wind turbine. From study it is concluded that the innovative tower will reduce resonance condition considering soil structure interaction.

Condensation on Slippery Asymmetric Bumps

NASA Astrophysics Data System (ADS)

Park, Kyoo-Chul; Kim, Philseok; Aizenberg, Joanna

Controlling dropwise condensation by designing surfaces that enable droplets to grow rapidly and be shed as quickly as possible is fundamental to water harvesting systems, thermal power generation, distillation towers, etc. However, cutting-edge approaches based on micro/nanoscale textures suffer from intrinsic trade-offs that make it difficult to optimize both growth and transport at once. Here we present a conceptually different design approach based on principles derived from Namib desert beetles, cacti, and pitcher plants that synergistically couples both aspects of condensation and outperforms other synthetic surfaces. Inspired by an unconventional interpretation of the role of the beetle's bump geometry in promoting condensation, we show how to maximize vapor diffusion flux at the apex of convex millimetric bumps by optimizing curvature and shape. Integrating this apex geometry with a widening slope analogous to cactus spines couples rapid drop growth with fast directional transport, by creating a free energy profile that drives the drop down the slope. This coupling is further enhanced by a slippery, pitcher plant-inspired coating that facilitates feedback between coalescence-driven growth and capillary-driven motion. We further observe an unprecedented six-fold higher exponent in growth rate and much faster shedding time compared to other surfaces. We envision that our fundamental understanding and rational design strategy can be applied to a wide range of phase change applications.

Condensation on Slippery Asymmetric Bumps

NASA Astrophysics Data System (ADS)

Park, Kyoo-Chul; Kim, Philseok; Aizenberg, Joanna

2016-11-01

Controlling dropwise condensation by designing surfaces that enable droplets to grow rapidly and be shed as quickly as possible is fundamental to water harvesting systems, thermal power generation, distillation towers, etc. However, cutting-edge approaches based on micro/nanoscale textures suffer from intrinsic trade-offs that make it difficult to optimize both growth and transport at once. Here we present a conceptually different design approach based on principles derived from Namib desert beetles, cacti, and pitcher plants that synergistically couples both aspects of condensation and outperforms other synthetic surfaces. Inspired by an unconventional interpretation of the role of the beetle's bump geometry in promoting condensation, we show how to maximize vapor diffusion flux at the apex of convex millimetric bumps by optimizing curvature and shape. Integrating this apex geometry with a widening slope analogous to cactus spines couples rapid drop growth with fast directional transport, by creating a free energy profile that drives the drop down the slope. This coupling is further enhanced by a slippery, pitcher plant-inspired coating that facilitates feedback between coalescence-driven growth and capillary-driven motion. We further observe an unprecedented six-fold higher exponent in growth rate and much faster shedding time compared to other surfaces. We envision that our fundamental understanding and rational design strategy can be applied to a wide range of phase change applications.

Spontaneous Droplet Jump with Electro-Bouncing

NASA Astrophysics Data System (ADS)

Schmidt, Erin; Weislogel, Mark

2016-11-01

We investigate the dynamics of water droplet jumps from superhydrophobic surfaces in the presence of an electric field during a step reduction in gravity level. In the brief free-fall environment of a drop tower, when a strong non-homogeneous electric field (with a measured strength between 0 . 39 and 2 . 36 kV/cm) is imposed, body forces acting on the jumped droplets are primarily supplied by polarization stress and Coulombic attraction instead of gravity. The droplet charge, measured to be on the order of 2 . 3 . (10-11) C, originates by electro-osmosis of charged species at the (PTFE coated) hydrophobic surface interface. This electric body force leads to a droplet bouncing behavior similar to well-known phenomena in 1-g, though occurring for larger drops 0.1 mL for a given range of impact Weber numbers, We < 20 . In 1-g, for We > 0 . 4 , impact recoil behavior on a super-hydrophobic surface is normally dominated by damping from contact line hysteresis and by air-layer interactions. However, in the strong electric field, the droplet bounce dynamics additionally include electrohydrodynamic effects on wettability and Cassie-Wenzel transition. This is qualitatively discussed in terms of coefficients of restitution and trends in contact time. This work was supported primarily by NASA Cooperative Agreement NNX12A047A.

Water Impact of Syntactic Foams

PubMed Central

Shams, Adel; Zhao, Sam; Porfiri, Maurizio

2017-01-01

Syntactic foams are particulate composite materials that are extensively integrated in naval and aerospace structures as core materials for sandwich panels. While several studies have demonstrated the potential of syntactic foams as energy absorbing materials in impact tests, our understanding of their response to water impact remains elusive. In this work, we attempt a first characterization of the behavior of a vinyl ester/glass syntactic subject to slamming. High-speed imaging is leveraged to elucidate the physics of water impact of syntactic foam wedges in a free-fall drop tower. From the images, we simultaneously measure the deformation of the wedge and the hydrodynamic loading, thereby clarifying the central role of fluid–structure interaction during water impact. We study two different impact heights and microballoon density to assess the role of impact energy and syntactic foam composition on the slamming response. Our results demonstrate that both these factors have a critical role on the slamming response of syntactic foams. Reducing the density of microballoons might help to reduce the severity of the hydrodynamic loading experienced by the wedge, but this comes at the expense of a larger deformation. Such a larger deformation could ultimately lead to failure for large drop heights. These experimental results offer compelling evidence for the role of hydroelastic coupling in the slamming response of syntactic foams. PMID:28772581

Research on Condition Assessment Method of Transmission Tower Under the Action of Strong Wind

NASA Astrophysics Data System (ADS)

Huang, Ren-mou; An, Li-qiang; Zhang, Rong-lun; Wu, Jiong; Liang, Ya-feng

2018-03-01

Transmission towers are often subjected to the external damage of severe weather like strong wind and so on, which may cause the collapse due to the yield and fracture of the tower material. Aiming this issue, an assessment method was proposed in this paper to assess the operation condition of transmission towers under strong wind. With a reasonable assess index system established firstly, then the internal force of the tower material was solved and its stability was determined through the mechanical analysis of the transmission tower finite element model. Meanwhile, the condition risk level of the tower was finally determined by considering the difference among the influences of other factors like corrosion and loose of members, slope on the transmission tower through the analytic hierarchy process. The assessment method was applied to assess the wind-induced collapse of towers in 110kV Bao Yi II line in Wenchang City, Hainan Province, of which the result proves the method can assess the condition of transmission tower under strong wind and of guiding significance for improving the windproof capability of transmission towers.

Tower Temperature and Humidity Sensors (TWR) Handbook

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cook, DR

2010-02-01

Three tall towers are installed at the Atmospheric Radiation Measurement (ARM) Climate Research Facility: a 60-meter triangular tower at the Southern Great Plains (SGP) Central Facility (CF), a 21-meter walkup scaffolding tower at the SGP Okmulgee forest site (E21), and a 40-meter triangular tower at the North Slope of Alaska (NSA) Barrow site. The towers are used for meteorological, radiological, and other measurements.

SWECS tower dynamics analysis methods and results

NASA Technical Reports Server (NTRS)

Wright, A. D.; Sexton, J. H.; Butterfield, C. P.; Thresher, R. M.

1981-01-01

Several different tower dynamics analysis methods and computer codes were used to determine the natural frequencies and mode shapes of both guyed and freestanding wind turbine towers. These analysis methods are described and the results for two types of towers, a guyed tower and a freestanding tower, are shown. The advantages and disadvantages in the use of and the accuracy of each method are also described.

5. View of south tower, facing northnortheast from south bank ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. View of south tower, facing north-northeast from south bank of the Columbia River. Center tower and north tower in background, lower right. - Pasco-Kennewick Transmission Line, Columbia River Crossing Towers, Columbia Drive & Gum Street, Kennewick, Benton County, WA

The Effects of Compressive Preloads on the Compression-After-Impact Strength of Carbon/Epoxy

NASA Technical Reports Server (NTRS)

Nettles, Alan T.

1994-01-01

A fixture to apply compressive loads to composite specimens during an impact event was used to assess the effect of prestresses on the compression-after-impact (CAI) strength of 16 ply quasi-isotropic carbon/epoxy test coupons. Advanced design of experiments techniques were used to evaluate a range of prestresses and impact energies on two material systems, T300/934 and IM7/8551-7. An instrumented drop tower supplied impact energies between 1 and 9 Joules for the T300/934 material and between 4 and 16 Joules for the IM7/8551-7 material. The prestress values varied between a low of 5.7 Wa and a high of 287 NDa. Results showed some change in CAI strength that could be attributed to the prestresses on the specimens.

Capabilities and constraints of combustion diagnostics in microgravity

NASA Technical Reports Server (NTRS)

Greenberg, Paul S.

1993-01-01

A significant scientific return from both existing and proposed microgravity combustion science experiments is substantially dependent on the availability of diagnostic systems for the collection of the required scientific data. To date, the available diagnostic instrumentation has consisted primarily of conventional photographic media and intrusive temperature and velocity probes, such as thermocouples and hot wire anemometers. This situation has arisen primarily due to the unique and severe operational constraints inherent in reduced gravity experimentation. Each of the various reduced gravity facilities is accompanied by its own peculiar envelope of capabilities and constraints. Drop towers, for example, pose strict limitations on available working volume and power, as well as autonomy of operation. In contrast, hardware developed for space flight applications can be somewhat less constrained in regards to the aforementioned quantities, but is additionally concerned with numerous issues involving safety and reliability.

Contributions of microgravity test results to the design of spacecraft fire-safety systems

NASA Technical Reports Server (NTRS)

Friedman, Robert; Urban, David L.

1993-01-01

Experiments conducted in spacecraft and drop towers show that thin-sheet materials have reduced flammability ranges and flame-spread rates under quiescent low-gravity environments (microgravity) compared to normal gravity. Furthermore, low-gravity flames may be suppressed more easily by atmospheric dilution or decreasing atmospheric total pressure than their normal-gravity counterparts. The addition of a ventilating air flow to the low-gravity flame zone, however, can greatly enhance the flammability range and flame spread. These results, along with observations of flame and smoke characteristics useful for microgravity fire-detection 'signatures', promise to be of considerable value to spacecraft fire-safety designs. The paper summarizes the fire detection and suppression techniques proposed for the Space Station Freedom and discusses both the application of low-gravity combustion knowledge to improve fire protection and the critical needs for further research.

Electrical Aspects of Flames in Microgravity Combustion

NASA Technical Reports Server (NTRS)

Dunn-Rankin, D.; Strayer, B.; Weinberg, F.; Carleton, F.

1999-01-01

A principal characteristic of combustion in microgravity is the absence of buoyancy driven flows. In some cases, such as for spherically symmetrical droplet burning, the absence of buoyancy is desirable for matching analytical treatments with experiments. In other cases, however, it can be more valuable to arbitrarily control the flame's convective environment independent of the environmental gravitational condition. To accomplish this, we propose the use of ion generated winds driven by electric fields to control local convection of flames. Such control can produce reduced buoyancy (effectively zero buoyancy) conditions in the laboratory in 1-g facilitating a wide range of laser diagnostics that can probe the system without special packaging required for drop tower or flight tests. In addition, the electric field generated ionic winds allow varying gravitational convection equivalents even if the test occurs in reduced gravity environments.

Comparison of the biological NH3 removal characteristics among four inorganic packing materials.

PubMed

Hirai, M; Kamamoto, M; Yani, M; Shoda, M

2001-01-01

Four inorganic packing materials were evaluated in terms of their availability as a packing material of a packed tower deodorization apparatus (biofilter) from the viewpoints of biological NH3 removal characteristics and some physical properties. Porous ceramics (A), calcinated cristobalite (B), calcinated and formed obsidian (C), granulated and calculated soil (D) were used. The superiority of these packing materials determined based on the values of non-biological removal per unit weight or unit volume of packing material, complete removal capacity of NH3 per unit weight of packing material per day or unit volume of packing material per day and pressure drop of the packed bed was in the order of A approximately = C > B > or = D. Packing materials A and C with high porosity, maximum water content, and suitable mean pore diameter showed excellent removal capacity.

Comparison of the biological H2S removal characteristics among four inorganic packing materials.

PubMed

Hirai, M; Kamamoto, M; Yani, M; Shoda, M

2001-01-01

Four inorganic packing materials were evaluated in terms of their availability as packing materials of a packed tower deodorization apparatus (biofilter) from the viewpoints of biological H2S removal characteristics and some physical properties. Among porous ceramics (A), calcinated cristobalite (B), calcinated and formed obsidian (C), granulated and calcinated soil (D), the superiority of these packing materials determined based on the values of non-biological removal per unit weight or unit volume of packing material, complete removal capacity of H2S per unit weight of packing material per day or unit volume of packing material per day and pressure drop of the packed bed was in the order of A approximately equal to C > D approximately equal to B, which is correlated with the maximum water content, porosity, and mean pore diameter.

Steady Capillary Driven Flow

NASA Technical Reports Server (NTRS)

Weislogel, Mark M.

1996-01-01

A steady capillary driven flow is developed for a liquid index in a circular tube which is partially coated with a surface modifier to produce a discontinuous wetting condition from one side of the tube to the other. The bulk flow is novel in that it is truly steady, and controlled solely by the physics associated with dynamic wetting. The influence of gravity on the flow is minimized through the use of small diameter tubes approximately O(1 mm) tested horizontally in a laboratory and larger tubes approximately O(10 mm) tested in the low gravity environment of a drop tower. Average steady velocities are predicted and compared against a large experimental data set which includes the effects of tube dimensions and fluid properties. The sensitivity of the velocity to surface cleanliness is dramatic and the advantages of experimentation in a microgravity environment are discussed.

Effects of Core-Shell Rubber (CSR) Nanoparticles on the Fracture Toughness of an Epoxy Resin at Cryogenic Temperatures

NASA Technical Reports Server (NTRS)

Wang, J.; Cannon, S. A.; Schneider, J. A.

2008-01-01

This study investigates the effects of core-shell rubber (CSR) nanoparticles on the fracture toughness of an epoxy resin at liquid nitrogen (LN2) temperatures. Varying amounts of Kane Ace (Registered TradeMark) MX130 toughening agent were added to a commercially available EPON 862/W epoxy resin. Resulting fracture toughness was evaluated by the use of Charpy impact tests conducted on an instrumented drop tower. The size and distribution of the CSR nanoparticles were characterized using Transmission Electric Microscopy (TEM) and Small Angle X-ray Scattering (SAXS). Up to nominal 4.6% addition of the CSR nanoparticles, resulted in a nearly 5 times increase in the measured breaking energy. However, further increases in the amount of CSR nanoparticles had no appreciable affect on the breaking energy.

Thermal Characteristics and Structure of Fully-Modulated, Turbulent Diffusion Flames in Microgravity

NASA Technical Reports Server (NTRS)

Hermanson, J. C.; Johari, H.; Stocker, D. P.; Hegde, U. G.

2003-01-01

Turbulent jet diffusion flames are studied in microgravity and normal gravity under fully-modulated conditions for a range of injection times and a 50% duty cycle. Diluted ethylene was injected through a 2-mm nozzle at a Reynolds number of 5,000 into an open duct, with a slow oxidizer co-flow. Microgravity tests are conducted in NASA's 2.2 Second Drop Tower. Flames with short injection times and high duty cycle exhibit a marked increase in the ensemble-averaged flame length due to the removal of buoyancy. The cycle-averaged centerline temperature profile reveals higher temperatures in the microgravity flames, especially at the flame tip where the difference is about 200 K. In addition, the cycle-averaged measurements of flame radiation were about 30% to 60% greater in microgravity than in normal gravity.

Microgravity combustion science: Progress, plans, and opportunities

NASA Technical Reports Server (NTRS)

1992-01-01

An earlier overview is updated which introduced the promise of microgravity combustion research and provided a brief survey of results and then current research participants, the available set of reduced gravity facilities, and plans for experimental capabilities in the space station era. Since that time, several research studies have been completed in drop towers and aircraft, and the first space based combustion experiments since Skylab have been conducted on the Shuttle. The microgravity environment enables a new range of experiments to be performed since buoyancy induced flows are nearly eliminated, normally obscured forces and flows may be isolated, gravitational settling or sedimentation is nearly eliminated, and larger time or length scales in experiments are feasible. In addition to new examinations of classical problems, (e.g., droplet burning), current areas of interest include soot formation and weak turbulence, as influenced by gravity.

Accessing space: A catalogue of process, equipment and resources for commercial users

NASA Technical Reports Server (NTRS)

1988-01-01

This catalogue, produced by NASA's Office of Commercial Programs, provides a broad source of information for the commercial developer interested in the areas of microgravity research and remote sensing. Methods for accessing space for research are reviewed including the shuttle, expendable launch vehicles, suborbital sounding rockets, experimental aircraft, and drop towers and other ground-based facilities. Procedures for using these vehicles and facilities are described along with funding options to pay for their use. Experiment apparatus and carriers for microgravity research are also described. A separate directory of resources and services is also included which contains a listing of transportation products and services, a listing of businesses and industries which provide space-related services and products, and a listing of the NASA and CCDS (Center for the Commercial Development of Space) points of contact.

Heat Transfer to a Thin Solid Combustible in Flame Spreading at Microgravity

NASA Technical Reports Server (NTRS)

Bhattacharjee, S.; Altenkirch, R. A.; Olson, S. L.; Sotos, R. G.

1991-01-01

The heat transfer rate to a thin solid combustible from an attached diffusion flame, spreading across the surface of the combustible in a quiescent, microgravity environment, was determined from measurements made in the drop tower facility at NASA-Lewis Research Center. With first-order Arrhenius pyrolysis kinetics, the solid-phase mass and energy equations along with the measured spread rate and surface temperature profiles were used to calculate the net heat flux to the surface. Results of the measurements are compared to the numerical solution of the complete set of coupled differential equations that describes the temperature, species, and velocity fields in the gas and solid phases. The theory and experiment agree on the major qualitative features of the heat transfer. Some fundamental differences are attributed to the neglect of radiation in the theoretical model.

Lunar surface vehicle model competition

NASA Technical Reports Server (NTRS)

1990-01-01

During Fall and Winter quarters, Georgia Tech's School of Mechanical Engineering students designed machines and devices related to Lunar Base construction tasks. These include joint projects with Textile Engineering students. Topics studied included lunar environment simulator via drop tower technology, lunar rated fasteners, lunar habitat shelter, design of a lunar surface trenching machine, lunar support system, lunar worksite illumination (daytime), lunar regolith bagging system, sunlight diffusing tent for lunar worksite, service apparatus for lunar launch vehicles, lunar communication/power cables and teleoperated deployment machine, lunar regolith bag collection and emplacement device, soil stabilization mat for lunar launch/landing site, lunar rated fastening systems for robotic implementation, lunar surface cable/conduit and automated deployment system, lunar regolith bagging system, and lunar rated fasteners and fastening systems. A special topics team of five Spring quarter students designed and constructed a remotely controlled crane implement for the SKITTER model.

Wet cooling towers: rule-of-thumb design and simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leeper, Stephen A.

1981-07-01

A survey of wet cooling tower literature was performed to develop a simplified method of cooling tower design and simulation for use in power plant cycle optimization. The theory of heat exchange in wet cooling towers is briefly summarized. The Merkel equation (the fundamental equation of heat transfer in wet cooling towers) is presented and discussed. The cooling tower fill constant (Ka) is defined and values derived. A rule-of-thumb method for the optimized design of cooling towers is presented. The rule-of-thumb design method provides information useful in power plant cycle optimization, including tower dimensions, water consumption rate, exit air temperature,more » power requirements and construction cost. In addition, a method for simulation of cooling tower performance at various operating conditions is presented. This information is also useful in power plant cycle evaluation. Using the information presented, it will be possible to incorporate wet cooling tower design and simulation into a procedure to evaluate and optimize power plant cycles.« less

5. VIEW EAST, height finder radar towers, radar tower (unknown ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. VIEW EAST, height finder radar towers, radar tower (unknown function), prime search radar tower, operations building, and central heating plant - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

17. VIEW OF THE TOP OF THE TOWER SHOWING BASE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

17. VIEW OF THE TOP OF THE TOWER SHOWING BASE OF TOWER MAST AND WOOD DECKING ON SIGNAL TOWER ROOF. - U.S. Naval Base, Pearl Harbor, Signal Tower, Corner of Seventh Street & Avenue D east of Drydock No. 1, Pearl City, Honolulu County, HI

You're a What?: Tower Technician

ERIC Educational Resources Information Center

Vilorio, Dennis

2012-01-01

In this article, the author talks about the role and functions of a tower technician. A tower technician climbs up the face of telecommunications towers to remove, install, test, maintain, and repair a variety of equipment--from antennas to light bulbs. Tower technicians also build shelters and radiofrequency shields for electronic equipment, lay…

Vibration analysis of three guyed tower designs for intermediate size wind turbines

NASA Technical Reports Server (NTRS)

Christie, R. J.

1982-01-01

Three guyed tower designs were analyzed for intermediate size wind turbines. The four lowest natural frequencies of vibration of the three towers concepts were estimated. A parametric study was performed on each tower to determine the effect of varying such tower properties as the inertia and stiffness of the tower and guys, the inertia values of the nacelle and rotor, and the rotational speed of the rotor. Only the two lowest frequencies were in a range where they could be excited by the rotor blade passing frequencies. There two frequencies could be tuned by varying the guy stiffness, the guy attachment point on the tower, the tower and mass stiffness, and the nacelle/rotor/power train masses.

Lifting system and apparatus for constructing wind turbine towers

DOEpatents

Livingston, Tracy; Schrader, Terry; Goldhardt, James; Lott, James

2011-02-01

The disclosed invention is utilized for mounting a wind turbine and blade assembly on the upper end of a wind turbine tower. The invention generally includes a frame or truss that is pivotally secured to the top bay assembly of the tower. A transverse beam is connected to the frame or truss and extends fore of the tower when the frame or truss is in a first position and generally above the tower when in a second position. When in the first position, a wind turbine or blade assembly can be hoisted to the top of the tower. The wind turbine or blade assembly is then moved into position for mounting to the tower as the frame or truss is pivoted to a second position. When the turbine and blade assembly are secured to the tower, the frame or truss is disconnected from the tower and lowered to the ground.

2004 Savannah River Cooling Tower Collection (U)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garrett, Alfred; Parker, Matthew J.; Villa-Aleman, E.

2005-05-01

The Savannah River National Laboratory (SRNL) collected ground truth in and around the Savannah River Site (SRS) F-Area cooling tower during the spring and summer of 2004. The ground truth data consisted of air temperatures and humidity inside and around the cooling tower, wind speed and direction, cooling water temperatures entering; inside adn leaving the cooling tower, cooling tower fan exhaust velocities and thermal images taken from helicopters. The F-Area cooling tower had six cells, some of which were operated with fans off during long periods of the collection. The operating status (fan on or off) for each of themore » six cells was derived from operations logbooks and added to the collection database. SRNL collected the F-Area cooling tower data to produce a database suitable for validation of a cooling tower model used by one of SRNL's customer agencies. SRNL considers the data to be accurate enough for use in a model validation effort. Also, the thermal images of the cooling tower decks and throats combined with the temperature measurements inside the tower provide valuable information about the appearance of cooling towers as a function of fan operating status and time of day.« less

The effect of a tall tower on flow and dispersion through a model urban neighborhood: part 2. Pollutant dispersion.

PubMed

Brixey, Laurie A; Heist, David K; Richmond-Bryant, Jennifer; Bowker, George E; Perry, Steven G; Wiener, Russell W

2009-12-01

This article is the second in a two-paper series presenting results from wind tunnel and computational fluid dynamics (CFD) simulations of flow and dispersion in an idealized model urban neighborhood. Pollutant dispersion results are presented and discussed for a model neighborhood that was characterized by regular city blocks of three-story row houses with a single 12-story tower located at the downwind edge of one of these blocks. The tower had three significant effects on pollutant dispersion in the surrounding street canyons: drawing the plume laterally towards the tower, greatly enhancing the vertical dispersion of the plume in the wake of the tower, and significantly decreasing the residence time of pollutants in the wake of the tower. In the wind tunnel, tracer gas released in the avenue lee of the tower, but several blocks away laterally, was pulled towards the tower and lifted in the wake of the tower. The same lateral movement of the pollutant was seen in the next avenue, which was approximately 2.5 tower heights downwind of the tower. The tower also served to ventilate the street canyon directly in its wake more rapidly than the surrounding areas. This was evidenced by CFD simulations of concentration decay where the residence time of pollutants lee of the 12-story tower was found to be less than half the residence time behind a neighboring three-story building. This same phenomenon of rapid vertical dispersion lee of a tower among an array of smaller buildings was also demonstrated in a separate set of wind tunnel experiments using an array of cubical blocks. A similar decrease in the residence time was observed when the height of one block was increased.

Tower Shielding Reactor II design and operation report: Vol. 2. Safety Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holland, L. B.; Kolb, J. O.

1970-01-01

Information on the Tower Shielding Reactor II is contained in the TSR-II Design and Operation Report and in the Tower Shielding Facility Manual. The TSR-II Design and Operating Report consists of three volumes. Volume 1 is Descriptions of the Tower Shielding Reactor II and Facility; Volume 2 is Safety analysis of the Tower Shielding Reactor II; and Volume 3 is the Assembly and Testing of the Tower Shielding Reactor II Control Mechanism Housing.

COOLING TOWER PUMP HOUSE, TRA606. THREE OF SIX SECTIONS OF ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

COOLING TOWER PUMP HOUSE, TRA-606. THREE OF SIX SECTIONS OF COOLING TOWER ARE VISIBLE ABOVE RAILING. PUMP HOUSE IN FOREGROUND IS ON SOUTH SIDE OF COOLING TOWER. NOTE THREE PIPES TAKING WATER FROM PUMP HOUSE TO HOT DECK OF COOLING TOWER. EMERGENCY WATER SUPPLY TOWER IS ALSO IN VIEW. INL NEGATIVE NO. 6197. Unknown Photographer, 6/27/1952 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

[Genotypic variability and persistence of Legionella pulsed-field gel electrophoresis patterns in 16 cooling towers in Shanghai, China].

PubMed

Chen, Ming-liang; Wang, Gang-yi; Chen, Min; Zhou, Hai-jian; Shao, Zhu-jun; Zhang, Xi; Wu, Fan

2010-07-01

To investigate the genotypic characteristics and persistence of Legionella pulsed-field gel electrophoresis (PFGE) patterns in 16 air-conditioner cooling towers in six different public sites of Shanghai. From May to October, continuous sampling was operated once per month in 2007. Legionella strains isolated from the 16 cooling towers were confirmed by serological and latex agglutination. PFGE was applied for the fingerprinting of the isolates, while the cluster results of PFGE were analyzed by BioNumerics software. 131 strains of Legionella were isolated, including L. pneumophila, L. bozemanae, L. micdadei and L. anisa. 52 distinguishable PFGE patterns were differentiated among the 16 cooling towers, with 37 patterns were owned by just one cooling tower, which was not shared with other cooling towers, while 15 patterns were shared by more than 2 cooling towers. All the cooling towers had ≥ 2 PFGE patterns, while in 13 cooling towers the same PFGE patterns were recovered during the six months. From June to October of 2007, 18 strains of Legionella belonging to the PFGE pattern of LPAs.SH0078 were isolated continuously from 6 cooling towers. This study demonstrated great genotypic diversity and complexity of Legionella in cooling towers. Persistence of the PFGE patterns was observed in 81.25% of the cooling towers. The PFGE pattern of LPAs. SH0078 was distributed widely, suggesting it might be the dominate strain in Shanghai.

78 FR 11146 - Utility Scale Wind Towers From the People's Republic of China: Antidumping Duty Order

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-15

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-981] Utility Scale Wind Towers...''), the Department is issuing an antidumping duty order on utility scale wind towers (``wind towers... investigation of wind towers from the PRC.\\1\\ On February 8, 2013, the ITC notified the Department of its...

The shape of the Eiffel Tower

NASA Astrophysics Data System (ADS)

Gallant, Joseph

2002-02-01

The distinctive shape of the Eiffel Tower is based on simple physics and is designed so that the maximum torque created by the wind is balanced by the torque due to the Tower's weight. We use this idea to generate an equation for the shape of the Tower. The solution depends only on the width of the base and the maximum wind pressure. We parametrize the wind pressure and reproduce the shape of the Tower. We also discuss some of the Tower's interesting history and characteristics.

THE TOWER HOUSE, LOOKING WEST. The tower house provided a ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

THE TOWER HOUSE, LOOKING WEST. The tower house provided a water tank on the second floor that gravity fed water to the Kineth house and farm buildings. The one-story addition to the west of the tower provided workshop space. The hog shed is seen on the left of the image and the concrete foundation of the upright silo is in the foreground on the right. - Kineth Farm, Tower House, 19162 State Route 20, Coupeville, Island County, WA

Development of Meteorological Towers Using Advanced Composite Materials

NASA Astrophysics Data System (ADS)

Alshurafa, Sami A.

The research program involved both numerical and experimental work. The numerical analysis was conducted to simulate the static and dynamic behaviour of the 81 m meteorological FRP guyed tower under wind and ice loading. The FRP tower consisted of 16 segments each made of 3 cells connected together to form an equilateral triangle having equal sides of 450 mm. The segments were interconnected using internal sleeves. Various non-linear finite element models were developed to study a number of design parameters for the 81 m FRP tower such as, different laminates containing a variety of stacking sequences of laminate orientations with various thicknesses, different cable diameters, and appropriate guy cable spacing levels. The effect of pre-stressing the guy cables up to 10 % of their breaking strength was investigated. The effect of fibre volume fraction on the design of the FRP tower was also examined. Furthermore, an 8.6 m FRP tower segment was designed using the finite element analysis and subject to the same loading conditions experienced by the bottom section of the 81 m FRP tower. A modal analysis was carried out for both the 8.6 m FRP tower segment with and without a mass on the top as well as for the 81 m FRP guyed tower to evaluate the vibration performance of these towers. The experimental work involved extensive material testing to define the material properties for use in the analysis of the 81 m FRP tower. It also involved the design and fabrication of a special collapsible mandrel for fabricating the FRP cells for the 8.6 m tower segment. The 8.6 m tower was tested horizontally under static lateral loading to 80 % of its estimated failure load using a "whiffle tree" arrangement, in order to simulate a uniformly distributed wind loading. Later, the same FRP tower was erected in a vertical position and was tested with and without a mass on top under dynamic loading to obtain the natural frequencies. Lastly, a comparative study was conducted between two 81 m FRP towers having different fibre volume fractions and a steel tower having a circular cross section.

69. INTERIOR VIEW OF THE ABSORPTION TOWER BUILDING, ABSORPTION TOWER ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

69. INTERIOR VIEW OF THE ABSORPTION TOWER BUILDING, ABSORPTION TOWER UNDER CONSTRUCTION. (DATE UNKNOWN). - United States Nitrate Plant No. 2, Reservation Road, Muscle Shoals, Muscle Shoals, Colbert County, AL

Method and system for simulating heat and mass transfer in cooling towers

DOEpatents

Bharathan, Desikan; Hassani, A. Vahab

1997-01-01

The present invention is a system and method for simulating the performance of a cooling tower. More precisely, the simulator of the present invention predicts values related to the heat and mass transfer from a liquid (e.g., water) to a gas (e.g., air) when provided with input data related to a cooling tower design. In particular, the simulator accepts input data regarding: (a) cooling tower site environmental characteristics; (b) cooling tower operational characteristics; and (c) geometric characteristics of the packing used to increase the surface area within the cooling tower upon which the heat and mass transfer interactions occur. In providing such performance predictions, the simulator performs computations related to the physics of heat and mass transfer within the packing. Thus, instead of relying solely on trial and error wherein various packing geometries are tested during construction of the cooling tower, the packing geometries for a proposed cooling tower can be simulated for use in selecting a desired packing geometry for the cooling tower.

Design and Fabrication of a Hele-Shaw Apparatus for Observing Instabilities of Diffusion Flames

NASA Technical Reports Server (NTRS)

Wichman, I. S.; Oravecz-Simpkins, L.; Olson, S.

2001-01-01

Examinations of flame fronts spreading over solid fuels in an opposed flow of oxidizer have shown that the flame front fragments into smaller (cellular) flames. These 'flamelets' will oscillate, recombine, or extinguish, indicating that they are in the near extinction limit regime (i.e., to one side of the quenching branch of the flammability map). Onset of unstable cellular flamelet formation for flame spread over thin fuels occurs when a heat-sink substrate is placed a small distance from the underside of the fuel. This heat-sink substrate (or backing) displaces the quenching branch of the flammability map in a direction that causes the instabilities to occur at higher air velocities. Similar near-limit behavior has been observed in other works using different fuels, thus suggesting that these dynamic mechanisms are fuel-independent and therefore fundamental attributes of flames in this near-limit flame spread regime. The objective of this project is to determine the contributions of the hydrodynamic and thermodiffusive mechanisms to the observed formation of flame instabilities. From this, a model of diffusion flame instabilities shall be generated. Previously, experiments were conducted in NASA drop towers, thereby limiting observation time to O(1-5 sec). The NASA tests exhibited flamelet survival for the entire drop time, suggesting that flamelets (i.e., small cellular flames) might exist, if permitted, for longer time periods. By necessity, experiments were limited to thermally thin cellulose fuels (approximately 0.001 in thick): instabilities could form by virtue of faster spread rates over thin fuels. Unstable behavior was unlikely in the short drop time for thicker fuels. In the International Space Station (ISS), microgravity time is unlimited, so both thin and thick fuels can be tested.

1. Light tower/keeper's house and abandoned light tower, view northwest, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. Light tower/keeper's house and abandoned light tower, view northwest, south southeast and east northeast sides - Matinicus Rock Light Station, Matinicus Island, on Matinicus Rock, Matinicus, Knox County, ME

2. Abandoned light tower and keeper's house/light tower, view southeast, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. Abandoned light tower and keeper's house/light tower, view southeast, north northwest and west southwest sides - Matinicus Rock Light Station, Matinicus Island, on Matinicus Rock, Matinicus, Knox County, ME

Wind turbine generator application places unique demands on tower design and materials

NASA Technical Reports Server (NTRS)

Kita, J. P.

1978-01-01

The most relevant contractual tower design requirements and goal for the Mod-1 tower are related to steel truss tower construction, cost-effective state-of-the-art design, a design life of 30 years, and maximum wind conditions of 120 mph at 30 feet elevation. The Mod-1 tower design approach was an iterative process. Static design loads were calculated and member sizes and overall geometry chosen with the use of finite element computer techniques. Initial tower dynamic characteristics were then combined with the dynamic properties of the other wind turbine components, and a series of complex dynamic computer programs were run to establish a dynamic load set and then a second tower design.

Some techniques for reducing the tower shadow of the DOE/NASA mod-0 wind turbine tower. [wind tunnel tests to measure effects of tower structure on wind velocity

NASA Technical Reports Server (NTRS)

Burley, R. R.; Savino, J. M.; Wagner, L. H.; Diedrich, J. H.

1979-01-01

Wind speed profile measurements to measure the effect of a wind turbine tower on the wind velocity are presented. Measurements were made in the wake of scale models of the tower and in the wake of certain full scale components to determine the magnitude of the speed reduction (tower shadow). Shadow abatement techniques tested on the towers included the removal of diagonals, replacement of diagonals and horizontals with round cross section members, installation of elliptical shapes on horizontal members, installation of airfoils on vertical members, and application of surface roughness to vertical members.

Evaluation of Tower Shadowing on Anemometer Measurements at Los Alamos National Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruggeman, David Alan

2016-06-14

The objective of this study is to evaluate the effect of tower shadowing from the meteorology towers at LANL during 2014. This study is in response to the Department of Energy Meteorological Coordinating Council visit in 2015 that recommended an evaluation of any biases in the wind data introduced by the tower and boom alignment at all meteorology towers.

Optimal Inflatable Space Towers with 3 - 100 km Height

NASA Technical Reports Server (NTRS)

Bolonkin, Alexander

2003-01-01

Theory and computations are provided for building inflatable space towers up to one hundred kilometers in height. These towers can be used for tourism, scientific observation of space, observation of the Earth's surface, weather and upper atmosphere, and for radio, television, and communication transmissions. These towers can also be used to launch space ships and Earth satellites. These projects are not expensive and do not require rockets. They require thin strong films composed from artificial fibers and fabricated by current industry. The towers can be built using present technology. The towers can be used (for tourism, communication, etc.) during the construction process and provide self-financing for further construction. The tower design does not require work at high altitudes; all construction can be done at the Earth's surface. The transport system for a tower consists of a small engine (used only for friction compensation) located at the Earth's surface. The tower is separated into sections and has special protection mechanisms in case of damage. Problems involving security, control, repair, and stability of the proposed towers are addressed in other publications. The author is prepared to discuss these and other problems with serious organizations desiring to research and develop these projects.

Tower Based Load Measurements for Individual Pitch Control and Tower Damping of Wind Turbines

NASA Astrophysics Data System (ADS)

Kumar, A. A.; Hugues-Salas, O.; Savini, B.; Keogh, W.

2016-09-01

The cost of IPC has hindered adoption outside of Europe despite significant loading advantages for large wind turbines. In this work we presented a method for applying individual pitch control (including for higher-harmonics) using tower-top strain gauge feedback instead of blade-root strain gauge feedback. Tower-top strain gauges offer hardware savings of approximately 50% in addition to the possibility of easier access for maintenance and installation and requiring a less specialised skill-set than that required for applying strain gauges to composite blade roots. A further advantage is the possibility of using the same tower-top sensor array for tower damping control. This method is made possible by including a second order IPC loop in addition to the tower damping loop to reduce the typically dominating 3P content in tower-top load measurements. High-fidelity Bladed simulations show that the resulting turbine spectral characteristics from tower-top feedback IPC and from the combination of tower-top IPC and damping loops largely match those of blade-root feedback IPC and nacelle- velocity feedback damping. Lifetime weighted fatigue analysis shows that the methods allows load reductions within 2.5% of traditional methods.

Recent Results From the NOAA/ESRL GMD Tall Tower Network

NASA Astrophysics Data System (ADS)

Andrews, A. E.; Tans, P. P.; Peters, W.; Hirsch, A.; Sweeney, C.; Petron, G.; Kofler, J.; Zhao, C.; Masarie, K.; Wofsy, S. C.; Matross, D. M.; Mahadevan, P.; Longo, M.; Gerbig, C.; Lin, J. C.

2006-12-01

We will present a summary of new results from NOAA Earth System Research Laboratory`s Tall Tower greenhouse gas monitoring network. The tower network is operated by the Global Monitoring Division, which also maintains the global Cooperative Air Sampling network and a network of aircraft profiling sites over North America. Tall tower CO2 mixing ratio measurements are sensitive to upwind fluxes over scales of hundreds of kilometers, and the primary objective of the tower network is to obtain regionally representative carbon flux estimates for the North American continent. Mixing ratios of CO2 and CO are measured semi-continuously at the towers, and the KWKT-TV tower site near Moody, TX has recently also been equipped with sensors to measure radon and O3. Daily flask samples are collected at the KWKT tower and analyzed for CO2, CO, CH4, SF6, N2O, H2, stable isotopes of CO2 and CH4, COS, and a variety of halocarbon and hydrocarbon species. Daily flask sampling will be implemented at all tower sites within the next few years. We have used the Stochastic Time Inverted Lagrangian Transport (STILT) model to investigate upwind influences on the tower observations. CO measurements provide an indicator of polluted air masses, and we will present a summary of the frequency and origin of pollution events observed at the towers. We will present an analysis of the primary factors contributing to observed CO2 variability along with average seasonal and diurnal cycles of CO2 at the tower sites. Tower measurements are being used to evaluate atmospheric transport models in the context of the Transcom Continuous experiment and are an important constraint for CO2 data assimilation systems that produce regional to global carbon flux estimates with up to weekly resolution.

DETAIL OF VALVE TOWER SHOWING SLUICE GATE ON EAST SIDE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

DETAIL OF VALVE TOWER SHOWING SLUICE GATE ON EAST SIDE OF TOWER. VIEW FACING WEST - Schofield Barracks Military Reservation, Ku Tree Reservoir, Valve Tower, Kalakoa Stream, East Range, Wahiawa, Honolulu County, HI

Genotypic variability and persistence of Legionella pneumophila PFGE patterns in 34 cooling towers from two different areas.

PubMed

Sanchez, Inma; Garcia-Nuñez, Marian; Ragull, Sonia; Sopena, Nieves; Pedro-Botet, Maria Luisa; Estere, Maria; Rey-Joly, Celestino; Sabria, Miquel; Esteve, Maria

2008-02-01

Genotypic variability and clonal persistence are important concepts in molecular epidemiology as they facilitate the search for the source of sporadic cases or outbreaks of legionellosis. We studied the genotypic variability and persistence of Legionella pulsed-field gel electrophoresis (PFGE) patterns over time (period > 6 months) in 34 positive cooling towers from two different areas. In area A, radius of 70 km, 52 indistinguishable PFGE patterns were differentiated among the 27 cooling towers. In 13 cooling towers we observed >or= 2 PFGE patterns. Each cooling tower had its own indistinguishable Legionella PFGE pattern which was not shared with any other cooling tower. In area B, radius of 1 km, 10 indistinguishable PFGE patterns were obtained from the seven cooling towers. In four, we observed >or= 2 PFGE patterns. Three of these 10 indistinguishable PFGE patterns were shared by more than one cooling tower. In 27 of 34 cooling towers the same PFGE pattern was recovered after 6 months to up to 5 years of follow-up. The large genotypic diversity of Legionella observed in the cooling towers aids in the investigation of community outbreaks of Legionnaires' disease. However, shared patterns in small areas may confound the epidemiological investigation. The persistence of some PFGE patterns in cooling towers makes the recovery of the Legionella isolate causing the outbreak possible over time.

Effect of solar radiation on the performance of cross flow wet cooling tower in hot climate of Iran

NASA Astrophysics Data System (ADS)

Banooni, Salem; Chitsazan, Ali

2016-11-01

In some cities such as Ahvaz-Iran, the solar radiation is very high and the annual-mean-daily of the global solar radiation is about 17.33 MJ m2 d-1. Solar radiation as an external heat source seems to affect the thermal performance of the cooling towers. Usually, in modeling cooling tower, the effects of solar radiation are ignored. To investigate the effect of sunshade on the performance and modeling of the cooling tower, the experiments were conducted in two different states, cooling towers with and without sunshade. In this study, the Merkel's approach and finite difference technique are used to predict the thermal behavior of cross flow wet cooling tower without sunshade and the results are compared with the data obtained from the cooling towers with and without sunshade. Results showed that the sunshade is very efficient and it reduced the outlet water temperature, the approach and the water exergy of the cooling tower up to 1.2 °C, 15 and 1.1 %, respectively and increased the range and the efficiency of the cooling tower up to 29 and 37 %, respectively. Also, the sunshade decreased the error between the experimental data of the cooling tower with sunshade and the modeling results of the cooling tower without sunshade 1.85 % in average.

3. VIEW NORTHWEST, height finder radar towers, and radar tower ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. VIEW NORTHWEST, height finder radar towers, and radar tower (unknown function) - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

Effects of trees on mean wind, turbulence and momentum exchange within and above a real urban environment

NASA Astrophysics Data System (ADS)

Giometto, M. G.; Christen, A.; Egli, P. E.; Schmid, M. F.; Tooke, R. T.; Coops, N. C.; Parlange, M. B.

2017-08-01

Large-eddy simulations (LES) are used to gain insight into the effects of trees on turbulence, aerodynamic parameters, and momentum transfer rates characterizing the atmosphere within and above a real urban canopy. Several areas are considered that are part of a neighborhood in the city of Vancouver, BC, Canada where a small fraction of trees are taller than buildings. In this area, eight years of continuous wind and turbulence measurements are available from a 30 m meteorological tower. Data from airborne light detection and ranging (LiDAR) are used to represent both buildings and vegetation at the LES resolution. In the LES algorithm, buildings are accounted through an immersed boundary method, whereas vegetation is parameterized via a location-specific leaf area density. LES are performed including and excluding vegetation from the considered urban areas, varying wind direction and leaf area density. Surface roughness lengths (z0) from both LES and tower measurements are sensitive to the 0 ≤ LAI /λfb < 3 parameter, where LAI is the leaf area index and λfb is the frontal area fraction of buildings characterizing a given canopy. For instance, tower measurements predict a 19% seasonal increase in z0, slightly lower than the 27% increase featured by LES for the most representative canopy (leaves-off LAI / λfSUP>b = 0.74 , leaves-on LAI /λfb = 2.24). Removing vegetation from such a canopy would cause a dramatic drop of approximately 50% in z0 when compared to the reference summer value. The momentum displacement height (d) from LES also consistently increases as LAI / λfb increases, due in large part to the disproportionate amount of drag that the (few) relatively taller trees exert on the flow. LES and measurements both predict an increase in the ratio of turbulent to mean kinetic energy (TKE/MKE) at the tower sampling height going from winter to summer, and LES also show how including vegetation results in a more (positive) negatively skewed (horizontal) vertical velocity distribution - reflecting a more intermittent velocity field which favors sweep motions when compared to ejections. Within the urban canopy, the effects of trees are twofold: on one hand, they act as a direct momentum sink for the mean flow; on the other, they reduce downward turbulent transport of high-momentum fluid, significantly reducing the wind intensity at the heights where people live and buildings consume energy.

A comment on towers for windmills. [structural and economic criteria

NASA Technical Reports Server (NTRS)

Budgen, H. P.

1973-01-01

Design considerations for windmill tower structures include the effects of normal wind forces on the rotor and on the tower. Circular tabular or masonry towers present a relatively simple aerodynamic solution. Economic factors establish the tubular tower as superior for small and medium sized windmills. Concrete and standard concrete block designs are cheaper than refabricated steel structures that have to be freighted.

Cooperative Research Projects in the Microgravity Combustion Science Programs Sponsored by NASA and NEDO

NASA Technical Reports Server (NTRS)

Ross, Howard (Compiler)

2000-01-01

This document contains the results of a collection of selected cooperative research projects between principal investigators in the microgravity combustion science programs, sponsored by NASA and NEDO. Cooperation involved the use of drop towers in Japan and the United States, and the sharing of subsequent research data and findings. The topical areas include: (1) Interacting droplet arrays, (2) high pressure binary fuel sprays, (3) sooting droplet combustion, (4) flammability limits and dynamics of spherical, premixed gaseous flames and, (5) ignition and transition of flame spread across thin solid fuel samples. All of the investigators view this collaboration as a success. Novel flame behaviors were found and later published in archival journals. In some cases the experiments provided verification of the design and behavior in subsequent experiments performed on the Space Shuttle. In other cases, the experiments provided guidance to experiments that are expected to be performed on the International Space Station.

Mass Transport Phenomena Between Bubbles and Dissolved Gases in Liquids Under Reduced Gravity Conditions

NASA Technical Reports Server (NTRS)

Dewitt, K. J.; Brockwell, J. L.

1985-01-01

The long term objective of the experiment is to observe the dissolution of isolated, immobile gas bubbles of specified size and composition in a solvent liquid of known concentration in the reduced gravity environment of earth orbit. Preliminary bubble dissolution experiment conducted both in the NASA Lewis 2.2 sec drop tower and in normal gravity using SO2 - Toluene system were not completely successful in their objective. The method of gas injection and lack of bubble interface stabiliy experienced due to the extreme solubility of SO in Toluene has the effects of changing the problem from that of bubble dissolution to one of bubble formation stability and subsequent dissolution in a liquid of unknown initial solute concentration. Current work involves further experimentation in order to refine the bubble injection system and to investigate the concept of having a bubble with a critical radius in a state of unstable equilibrium.

Report of the committee on a commercially developed space facility

NASA Technical Reports Server (NTRS)

Shea, Joseph F.; Stever, H. Guyford; Cutter, W. Bowman, III; Demisch, Wolfgang H.; Fink, Daniel J.; Flax, Alexander H.; Gatos, Harry C.; Glicksman, Martin E.; Lanzerotti, Louis J.; Logsdon, John M., III

1989-01-01

Major facilities that could support significant microgravity research and applications activity are discussed. The ground-based facilities include drop towers, aircraft flying parabolic trajectories, and sounding rockets. Facilities that are intrinsically tied to the Space Shuttle range from Get-Away-Special canisters to Spacelab long modules. There are also orbital facilities which include recoverable capsules launched on expendable launch vehicles, free-flying spacecraft, and space stations. Some of these existing, planned, and proposed facilities are non-U.S. in origin, but potentially available to U.S. investigators. In addition, some are governmentally developed and operated whereas others are planned to be privately developed and/or operated. Tables are provided to show the facility, developer, duration, estimated gravity level, crew interaction, flight frequency, year available, power to payload, payload volume, and maximum payload mass. The potential of direct and indirect benefits of manufacturing in space are presented.

Atom Interferometry for Detection of Gravitational Waves: Progress and Prospects

NASA Astrophysics Data System (ADS)

Hogan, Jason

2015-04-01

Gravitational wave astronomy promises to provide a new window into the universe, collecting information about astrophysical systems and cosmology that is difficult or impossible to acquire by other methods. Detector designs based on atom interferometry offer a number of advantages over traditional approaches, including access to conventionally inaccessible frequency ranges and substantially reduced antenna baselines. Atomic physics techniques also make it possible to build a gravitational wave detector with a single linear baseline, potentially offering advantages in cost and design flexibility. In support of these proposals, recent progress in long baseline atom interferometry has enabled observation of matter wave interference with atomic wavepacket separations exceeding 10 cm and interferometer durations of more than 2 seconds. These results are obtained in a 10-meter drop tower incorporating large momentum transfer atom optics. This approach can provide ground-based proof-of-concept demonstrations of many of the technical requirements of both terrestrial and satellite gravitational wave detectors.

Space processing experimental apparatus - A survey

NASA Technical Reports Server (NTRS)

Siebel, M. P.

1977-01-01

The processing of materials in a low-g environment was started approximately 10 years ago. This article surveys the apparatus developed during that period. A low-g environment occurs naturally in a free-flying spacecraft (e.g., in manned flights such as Apollo, Skylab, and ASTP); low-g conditions also occur in other free-falling bodies such as sounding rockets and drop tower capsules. Apparatus has been developed for all these craft. Most of the apparatus described serves to melt and resolidify materials in low g; the material may be contained or, by virtue of the environment, freely floating. Other apparatus for separation of intimately mixed components or species is also described. A general conclusion is drawn that the apparatus addresses only a few of the possibilities available, is still at the experimental stage, and is of laboratory scale. It is predicted that processes showing promise will be scaled up to derive economic advantages in the Shuttle era of space flight.

Dynamic Mechanical Properties and Fracture Surface Morphologies of Core-Shell Rubber (CSR) Toughened Epoxy at Liquid Nitrogen (Ln2) Temperatures

NASA Technical Reports Server (NTRS)

Wang, J.; Magee, D.; Schneider, J. A.

2009-01-01

The dynamic mechanical properties and fracture surface morphologies were evaluated for a commercial epoxy resin toughened with two types of core-shell rubber (CSR) toughening agents (Kane Ace(Registered TradeMark) MX130 and MX960). The impact resistance (R) was evaluated by the resulting breaking energy measured in Charpy impact tests conducted on an instrumented drop tower. The resulting fracture surface morphologies were examined using Scanning Electron Microscopy (SEM). Fractographic observations of the CSR toughened epoxy tested at ambient temperature, showed a fracture as characterized by slender dendrite textures with large voids. The increasing number of dendrites and decreasing size of scale-like texture with more CSR particles corresponded with increased R. As the temperature decreased to Liquid Nitrogen (LN 2), the fracture surfaces showed a fracture characterized by a rough, torn texture containing many river markings and deep furrows.

FLEX: A Decisive Step Forward in NASA's Combustion Research Program

NASA Technical Reports Server (NTRS)

Hickman, John M.; Dietrich, Daniel L.; Hicks, Michael C.; Nayagam, Vedha; Stocker, Dennis

2012-01-01

Stemming from the need to prevent, detect and suppress on-board spacecraft fires, the NASA microgravity combustion research program has grown to include fundamental research. From early experiment, we have known that flames behave differently in microgravity, and this environment would provide an ideal laboratory for refining many of the long held principals of combustion science. A microgravity environment can provide direct observation of phenomena that cannot be observed on Earth. Through the years, from precursor work performed in drop towers leading to experiments on the International Space Station (ISS), discoveries have been made about the nature of combustion in low gravity environments. These discoveries have uncovered new phenomena and shed a light on many of the fundamental phenomena that drive combustion processes. This paper discusses the NASA microgravity combustion research program taking place in the ISS Combustion Integrated Rack, its various current and planned experiments, and the early results from the Flame Extinguishment (FLEX) Experiment.

Research and competition: Best partners

NASA Technical Reports Server (NTRS)

Shaw, J. M.

1986-01-01

NASA's Microgravity Science and Applications Program is directed toward research in the science and technology of processing materials under conditions of low gravity. The objective is to make a detailed examination of the constraints imposed by gravitational forces on Earth. The program is expected to lead ultimately to the development of new materials and processes in Earth-based commercial applications, adding to this nation's technological base. An important resource that U.S. researchers have readily available to them is the new Microgravity Materials Science Laboratory (MMSL) at NASA Lewis Research Center in Cleveland. A typical scenario for a microgravity materials experiment at Lewis would begin by establishing 1-g baseline data in the MMSL and then proceeding, if it is indicated, to a drop tower or to simulated microgravity conditions in a research aircraft to qualify the project for space flight. A major component of Lewis microgravity materials research work involves the study of metal and alloy solidification fundamentals.

Observations of F- and P-Mode Oscillations of High Degree (500 Is Less Than L Is Less Than 2500) in Quiet and Active Sun

NASA Technical Reports Server (NTRS)

Tarbell, T. D.; Peri, M.; Frank, Z.; Shine, R.; Title, A. M.

1988-01-01

Spectra (l - v diagrams) from high resolution observations taken at the Vacuum Tower Telescope (NSO/Sunspot) are presented. The raw data are CCD images taken through the SOUP narrowband filter in Fe I 5576 A. Four filtergrams spaced through the spectral line are combined to form velocity movies. Spectra for 80 min of data with 0.5 to 1.5 arcsec resolution are presented for the entire field-of-view and for quiet and magnetic (plage) subregions. Ridges f and p1 to p5 are evident in velocity spectra, extending to l = 2500 (f), l = 1800 (p1), and l = 1200 (p2). Much less power is seen in the magnetic region than in the quiet Sun. Three-dimensional Fourier filtering shows that oscillation velocity amplitude drops sharply at the boundary of the active region for each family of modes considered.

Low Velocity Impact Behavior of Glass Filled Fiber-Reinforced Thermoplastic Engine Components

PubMed Central

Mouti, Zakaria; Westwood, Keith; Kayvantash, Kambiz; Njuguna, James

2010-01-01

This paper concerns automotive parts located underneath the engine and in particular the engine oil pan. Classically made of stamped steel or cast aluminum, new developments have allowed the manufacture oil pans with polyamide 66 reinforced by 35% weight of short glass fiber. However, polyamides have some limitations and the most significant is their response to localized impact loading. The nature of the impact considered here is of a typical stone collected from the road and projected into the oil pan.  Low velocity impact investigations were carried out using a gas gun and drop weight tower.  The study shows that the design of the oil pan has a significant contribution in the shock absorption. In addition to the material properties, the geometry and the ribbing both cleverly combined, increase the impact resistance of the component significantly. Areas of oil pan design improvement have been identified and conclusions drawn.

How to Demonstrate Microgravity in your Classroom

NASA Technical Reports Server (NTRS)

DeLombard, Richard; Hall, Nancy Rabel

2013-01-01

Learn why zero gravity is a misnomer and learn how to demonstrate microgravity to students and the general public. In this session, a short theory segment will explain and reinforce these concepts so that you may explain to others. Session participants will also see simple equipment that demonstrates microgravity during the session and can just as well be done in the classroom or museum exhibit hall. The hands-on demonstration devices range from a leaky water bottle to an electronic drop tower with an on-board camera. The session will also include demonstration techniques for Physics, Forces & Motion, and orbits. This material is useful for middle school forces and motions instruction, high school physics instruction, public demonstrations at conferences & school open houses, travelling museum exhibits, fixed museum exhibits, and independent student projects or experiments. These activities also connect the terrestrial demonstration with planetary & moon motion, comet trajectory, and more.

Formation of Carbon Nanotubes in a Microgravity Environment

NASA Technical Reports Server (NTRS)

Alford, J. M.; Mason, G. R.; Feikema, D. A.

2001-01-01

Even though nanotube science has become one of the worlds most rapidly advancing areas of research, very little is known about the processes involved in nanotube synthesis. To study the formation of carbon nanotubes in an environment unhindered by the buoyancy induced flows generated by the high temperatures necessary to vaporize carbon and grow nanotubes, we have designed a miniature carbon arc apparatus that can produce carbon nanotubes under microgravity conditions. During the first phase of this project, we designed, built, and successfully tested the mini carbon arc in both 1g and 2.2 sec drop tower microgravity conditions. We have demonstrated that microgravity can eliminate the strong convective flows from the carbon arc and we have successfully produced single-walled carbon nanotubes in microgravity. We believe that microgravity processing will allow us to better understand the nanotube formation process and eventually allow us to grow nanotubes that are superior to ground-based production.

Contributions of Microgravity Test Results to the Design of Spacecraft Fire Safety Systems

NASA Technical Reports Server (NTRS)

Friedman, Robert; Urban, David L.

1993-01-01

Experiments conducted in spacecraft and drop towers show that thin-sheet materials have reduced flammability ranges and flame-spread rates under quiescent low-gravity environments (microgravity) as compared to normal gravity. Furthermore, low-gravity flames may be suppressed more easily by atmospheric dilution or decreasing atmospheric total pressure than their normal-gravity counterparts. The addition of a ventilating air flow to the low-gravity flame zone, however, can greatly enhance the flammability range and flame spread. These results, along with observations of flame and smoke characteristics useful for microgravity fire-detection 'signatures', promise to be of considerable value to spacecraft fire-safety designs. The paper summarizes the fire detection and suppression techniques proposed for the Space Station Freedom and discusses both the application of low-gravity combustion knowledge to improve fire protection and the critical needs for further research.

Model equations for the Eiffel Tower profile: historical perspective and new results

NASA Astrophysics Data System (ADS)

Weidman, Patrick; Pinelis, Iosif

2004-07-01

Model equations for the shape of the Eiffel Tower are investigated. One model purported to be based on Eiffel's writing does not give a tower with the correct curvature. A second popular model not connected with Eiffel's writings provides a fair approximation to the tower's skyline profile of 29 contiguous panels. Reported here is a third model derived from Eiffel's concern about wind loads on the tower, as documented in his communication to the French Civil Engineering Society on 30 March 1885. The result is a nonlinear, integro-differential equation which is solved to yield an exponential tower profile. It is further verified that, as Eiffel wrote, "in reality the curve exterior of the tower reproduces, at a determined scale, the same curve of the moments produced by the wind". An analysis of the actual tower profile shows that it is composed of two piecewise continuous exponentials with different growth rates. This is explained by specific safety factors for wind loading that Eiffel & Company incorporated in the design of the free-standing tower. To cite this article: P. Weidman, I. Pinelis, C. R. Mecanique 332 (2004).

Fire ants perpetually rebuild sinking towers.

PubMed

Phonekeo, Sulisay; Mlot, Nathan; Monaenkova, Daria; Hu, David L; Tovey, Craig

2017-07-01

In the aftermath of a flood, fire ants, Solenopsis invicta , cluster into temporary encampments. The encampments can contain hundreds of thousands of ants and reach over 30 ants high. How do ants build such tall structures without being crushed? In this combined experimental and theoretical study, we investigate the shape and rate of construction of ant towers around a central support. The towers are bell shaped, consistent with towers of constant strength such as the Eiffel tower, where each element bears an equal load. However, unlike the Eiffel tower, the ant tower is built through a process of trial and error, whereby failed portions avalanche until the final shape emerges. High-speed and novel X-ray videography reveal that the tower constantly sinks and is rebuilt, reminiscent of large multicellular systems such as human skin. We combine the behavioural rules that produce rafts on water with measurements of adhesion and attachment strength to model the rate of growth of the tower. The model correctly predicts that the growth rate decreases as the support diameter increases. This work may inspire the design of synthetic swarms capable of building in vertical layers.

Fire ants perpetually rebuild sinking towers

NASA Astrophysics Data System (ADS)

Phonekeo, Sulisay; Mlot, Nathan; Monaenkova, Daria; Hu, David L.; Tovey, Craig

2017-07-01

In the aftermath of a flood, fire ants, Solenopsis invicta, cluster into temporary encampments. The encampments can contain hundreds of thousands of ants and reach over 30 ants high. How do ants build such tall structures without being crushed? In this combined experimental and theoretical study, we investigate the shape and rate of construction of ant towers around a central support. The towers are bell shaped, consistent with towers of constant strength such as the Eiffel tower, where each element bears an equal load. However, unlike the Eiffel tower, the ant tower is built through a process of trial and error, whereby failed portions avalanche until the final shape emerges. High-speed and novel X-ray videography reveal that the tower constantly sinks and is rebuilt, reminiscent of large multicellular systems such as human skin. We combine the behavioural rules that produce rafts on water with measurements of adhesion and attachment strength to model the rate of growth of the tower. The model correctly predicts that the growth rate decreases as the support diameter increases. This work may inspire the design of synthetic swarms capable of building in vertical layers.

Fire ants perpetually rebuild sinking towers

PubMed Central

Phonekeo, Sulisay; Mlot, Nathan; Monaenkova, Daria; Tovey, Craig

2017-01-01

In the aftermath of a flood, fire ants, Solenopsis invicta, cluster into temporary encampments. The encampments can contain hundreds of thousands of ants and reach over 30 ants high. How do ants build such tall structures without being crushed? In this combined experimental and theoretical study, we investigate the shape and rate of construction of ant towers around a central support. The towers are bell shaped, consistent with towers of constant strength such as the Eiffel tower, where each element bears an equal load. However, unlike the Eiffel tower, the ant tower is built through a process of trial and error, whereby failed portions avalanche until the final shape emerges. High-speed and novel X-ray videography reveal that the tower constantly sinks and is rebuilt, reminiscent of large multicellular systems such as human skin. We combine the behavioural rules that produce rafts on water with measurements of adhesion and attachment strength to model the rate of growth of the tower. The model correctly predicts that the growth rate decreases as the support diameter increases. This work may inspire the design of synthetic swarms capable of building in vertical layers. PMID:28791170

2. Southern Light Tower and Northern Light Tower, view north, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. Southern Light Tower and Northern Light Tower, view north, south sides - Kennebec River Light Station, South side of Doubling Point Road, off State Highway 127, 1.8 miles south of U.S. Route 1, Arrowsic, Sagadahoc County, ME

Surface and Tower Meteorological Instrumentation at NSA Handbook - January 2006

DOE Office of Scientific and Technical Information (OSTI.GOV)

MT Ritsche

2006-01-30

The Surface and Tower Meteorological Instrumentation at Atqasuk (METTWR2H) uses mainly conventional in situ sensors to measure wind speed, wind direction, air temperature, dew point and humidity mounted on a 10-m tower. It also obtains barometric pressure, visibility, and precipitation data from sensors at or near the base of the tower. In addition, a Chilled Mirror Hygrometer is located at 1 m for comparison purposes. Temperature and relative humidity probes are mounted at 2 m and 5 m on the tower. For more information, see the Surface and Tower Meteorological Instrumentation at Atqasuk Handbook.

Load-Direction-Derived Support Structures for Wind Turbines: A Lattice Tower Concept and Preparations for Future Certifications: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jonkman, Jason; Damiani, Rick R; Struve, Achim

The call for more cost-effective and environmentally friendly tower concepts is motivated by tower costs [1] and tower CO2-emission contributions [2], which are high relative to the whole wind turbine system. The proposed rotatable tower concept with yaw bearing at the bottom instead of the top of the tower will provide beneficial economic and environmental impacts to the turbine system. This wind alignment capability indicates a load-direction-derived tower design. By combining this approach with a lattice concept, large material and cost savings for the tower can be achieved. This paper presents a way to analyze and verify the proposed designmore » through aero-servo-elastic simulations, which make future certifications of rotatable tower concepts viable. For this reason, the state-of-the-art, open-source lattice-tower finite-element-method (FEM) module SubDyn [10], developed by the National Renewable Energy Laboratory, has been modified to account for arbitrary member cross-sections. Required changes in the beam element stiffness and mass matrix formulation took place according to an energy method [13]. All validated adaptions will be usable within the aero-servo-elastic simulation framework FAST and are also beneficial for other nonrotatable lattice structures.« less

Mapping carbon flux uncertainty and selecting optimal locations for future flux towers in the Great Plains

USGS Publications Warehouse

Gu, Yingxin; Howard, Daniel M.; Wylie, Bruce K.; Zhang, Li

2012-01-01

Flux tower networks (e. g., AmeriFlux, Agriflux) provide continuous observations of ecosystem exchanges of carbon (e. g., net ecosystem exchange), water vapor (e. g., evapotranspiration), and energy between terrestrial ecosystems and the atmosphere. The long-term time series of flux tower data are essential for studying and understanding terrestrial carbon cycles, ecosystem services, and climate changes. Currently, there are 13 flux towers located within the Great Plains (GP). The towers are sparsely distributed and do not adequately represent the varieties of vegetation cover types, climate conditions, and geophysical and biophysical conditions in the GP. This study assessed how well the available flux towers represent the environmental conditions or "ecological envelopes" across the GP and identified optimal locations for future flux towers in the GP. Regression-based remote sensing and weather-driven net ecosystem production (NEP) models derived from different extrapolation ranges (10 and 50%) were used to identify areas where ecological conditions were poorly represented by the flux tower sites and years previously used for mapping grassland fluxes. The optimal lands suitable for future flux towers within the GP were mapped. Results from this study provide information to optimize the usefulness of future flux towers in the GP and serve as a proxy for the uncertainty of the NEP map.

Role of bacterial adhesion in the microbial ecology of biofilms in cooling tower systems.

PubMed

Liu, Yang; Zhang, Wei; Sileika, Tadas; Warta, Richard; Cianciotto, Nicholas P; Packman, Aaron

2009-01-01

The fate of the three heterotrophic biofilm forming bacteria, Pseudomonas aeruginosa, Klebsiella pneumoniae and Flavobacterium sp. in pilot scale cooling towers was evaluated both by observing the persistence of each species in the recirculating water and the formation of biofilms on steel coupons placed in each cooling tower water reservoir. Two different cooling tower experiments were performed: a short-term study (6 days) to observe the initial bacterial colonization of the cooling tower, and a long-term study (3 months) to observe the ecological dynamics with repeated introduction of the test strains. An additional set of batch experiments (6 days) was carried out to evaluate the adhesion of each strain to steel surfaces under similar conditions to those found in the cooling tower experiments. Substantial differences were observed in the microbial communities that developed in the batch systems and cooling towers. P. aeruginosa showed a low degree of adherence to steel surfaces both in batch and in the cooling towers, but grew much faster than K. pneumoniae and Flavobacterium in mixed-species biofilms and ultimately became the dominant organism in the closed batch systems. However, the low degree of adherence caused P. aeruginosa to be rapidly washed out of the open cooling tower systems, and Flavobacterium became the dominant microorganism in the cooling towers in both the short-term and long-term experiments. These results indicate that adhesion, retention and growth on solid surfaces play important roles in the bacterial community that develops in cooling tower systems.

Role of bacterial adhesion in the microbial ecology of biofilms in cooling tower systems

PubMed Central

Liu, Yang; Zhang, Wei; Sileika, Tadas; Warta, Richard; Cianciotto, Nicholas P.; Packman, Aaron

2009-01-01

The fate of the three heterotrophic biofilm forming bacteria, Pseudomonas aeruginosa, Klebsiella pneumoniae and Flavobacterium sp. in pilot scale cooling towers was evaluated both by observing the persistence of each species in the recirculating water and the formation of biofilms on steel coupons placed in each cooling tower water reservoir. Two different cooling tower experiments were performed: a short-term study (6 days) to observe the initial bacterial colonization of the cooling tower, and a long-term study (3 months) to observe the ecological dynamics with repeated introduction of the test strains. An additional set of batch experiments (6 days) was carried out to evaluate the adhesion of each strain to steel surfaces under similar conditions to those found in the cooling tower experiments. Substantial differences were observed in the microbial communities that developed in the batch systems and cooling towers. P. aeruginosa showed a low degree of adherence to steel surfaces both in batch and in the cooling towers, but grew much faster than K. pneumoniae and Flavobacterium in mixed-species biofilms and ultimately became the dominant organism in the closed batch systems. However, the low degree of adherence caused P. aeruginosa to be rapidly washed out of the open cooling tower systems, and Flavobacterium became the dominant microorganism in the cooling towers in both the short-term and long-term experiments. These results indicate that adhesion, retention and growth on solid surfaces play important roles in the bacterial community that develops in cooling tower systems. PMID:19177226

8. VIEW OF THE EAST BASE CONNECTION OF ANTENNA TOWER ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. VIEW OF THE EAST BASE CONNECTION OF ANTENNA TOWER S-111 FACING NORTHEAST. BUILDING 1 AND ANTENNA TOWER S-110 IN THE BACKGROUND. - U.S. Naval Base, Pearl Harbor, Lualualei Radio Transmitter, Edison & Tower Drives, Pearl City, Honolulu County, HI

8. GENERAL VIEW OF TOWER 32, LEFT, AND TOWER 31, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. GENERAL VIEW OF TOWER 32, LEFT, AND TOWER 31, RIGHT. VIEW LOOKING NORTH SHOWING AERIAL WIRE DESIGN WITH VERTICAL 'TOP HAT' WIRES IN CENTER. - Chollas Heights Naval Radio Transmitting Facility, 6410 Zero Road, San Diego, San Diego County, CA

Microwave Tower Deflection Monitor

NASA Astrophysics Data System (ADS)

Truax, Bruce E.

1980-10-01

This paper describes an instrument which is capable of monitoring both the twist and lateral motion of a microwave tower. The Microwave Tower Deflection Monitor (MTDM) gives designers the capability of evaluating towers, both for troubleshooting purposes and comparison with design theory. The MTDM has been designed to operate on a broad range of tower structures in a variety of weather conditions. The instrument measures tower motion by monitoring the position of two retroreflectors mounted on the top of the tower. The two retroreflectors are located by scanning a laser beam in a raster pattern in the vicinity of the reflector. When a retroreflector is struck its position is read by a microprocessor and stored on a magnetic tape. Position resolution of better than .5 cm at 200 ft. has been observed in actual tests.

KSC-99pp1239

NASA Image and Video Library

1999-10-14

KENNEDY SPACE CENTER, FLA. — Two 34-year-old towers on Launch Complex 41, Cape Canaveral Air Station, fall to the ground amid the black smoke from explosives set to topple them. Weighing two million pounds, the umbilical tower (left) was approximately 200 feet high. The taller 300-foot Mobile Service Tower (right) weighs five million pounds. About 200 pounds of linear-shaped charges were used to topple the towers so that the materials can be recycled. Adjacent to the towers are lightning protection structures, which will remain on the site. The towers are being demolished to make room for Lockheed Martin's 14-acre Vehicle Integration Facility (VIF), under construction. The implosion and removal of the tower debris is expected to be completed in two months. The VIF will be used for Lockheed Martin's Atlas V Launch System.

KSC-99pp1238

NASA Image and Video Library

1999-10-14

KENNEDY SPACE CENTER, FLA. — Two 34-year-old towers on Launch Complex 41, Cape Canaveral Air Station, lie on the ground amid the black smoke from explosives set to topple them. Weighing two million pounds, the umbilical tower (left) was approximately 200 feet high. The taller 300-foot Mobile Service Tower (right) weighs five million pounds. About 200 pounds of linear-shaped charges were used to topple the towers so that the materials can be recycled. Adjacent to the towers are lightning protection structures, which will remain on the site. The towers are being demolished to make room for Lockheed Martin's 14-acre Vehicle Integration Facility (VIF), under construction. The implosion and removal of the tower debris is expected to be completed in two months. The VIF will be used for Lockheed Martin's Atlas V Launch System.

PBF Cooling Tower and it Auxiliary Building (PER624) to left ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

PBF Cooling Tower and it Auxiliary Building (PER-624) to left of tower. Camera facing west and the east louvered face of the tower. Details include secondary coolant water riser piping and flow control valves (butterfly valves) to distribute water evenly to all sections of tower. Photographer: Holmes. Date: May, 20, 1970. INEEL negative no. 70-2322 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

2. VIEW SOUTHWEST, prime search radar tower, height finder radar ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. VIEW SOUTHWEST, prime search radar tower, height finder radar towards, height finder radar towers, and radar tower (unknown function) - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

4. VIEW NORTHEAST, radar tower (unknown function), prime search radar ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. VIEW NORTHEAST, radar tower (unknown function), prime search radar tower, emergency power building, and height finder radar tower - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

3. View from former light tower to Cape Elizabeth Light ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. View from former light tower to Cape Elizabeth Light Tower, view northeast, southwest side of Cape Elizabeth Tower - Cape Elizabeth Light Station, Near Two Lights State Park at end of Two Lights Road, off State Highway 77, Cape Elizabeth, Cumberland County, ME

The optimal operation of cooling tower systems with variable-frequency control

NASA Astrophysics Data System (ADS)

Cao, Yong; Huang, Liqing; Cui, Zhiguo; Liu, Jing

2018-02-01

This study investigates the energy performance of chiller and cooling tower systems integrated with variable-frequency control for cooling tower fans and condenser water pumps. With regard to an example chiller system serving an office building, Chiller and cooling towers models were developed to assess how different variable-frequency control methods of cooling towers fans and condenser water pumps influence the trade-off between the chiller power, pump power and fan power under various operating conditions. The matching relationship between the cooling tower fans frequency and condenser water pumps frequency at optimal energy consumption of the system is introduced to achieve optimum system performance.

Coupling Stable Water Isotopes in Vapor and Precipitation to Raindrop Size Distributions at a Mid-latitude Tall-tower Site to Evaluate the Role of Rain Evaporation in Boundary Layer Moisture Recycling

NASA Astrophysics Data System (ADS)

Kaushik, A.; Noone, D.

2016-12-01

The continental boundary layer moisture balance plays an important role in regulating water and energy exchange between the surface and the atmosphere, yet the mechanisms associated with moistening and drying are both poorly observed and modeled. Stable water isotope ratio measurements can provide insights into air mass origins, convection dynamics and mechanisms dominating atmosphere-land surface water fluxes. Profiles can be exploited to improve estimates of boundary layer moistening associated with evaporation of falling precipitation and contributions from surface evapotranspiration. We present two years of in situ tower-based measurements of isotope ratios of water vapor and precipitation (δD and δ18O) and raindrop size distributions from the Boulder Atmospheric Observatory (BAO) tall-tower site in Erie, Colorado. Isotope vapor measurements were made at 1 Hz with a full cycle from the surface to 300 meters recorded every 80 minutes. At the surface and 300m, water samples were collected during precipitation events and raindrop sizes were measured continuously using Parsivel instruments. We use this unique suite of measurements and, in particular, exploit the differences between the surface and 300m observations to constrain the surface layer hydrological mass balance during and after rain events, and evaluate parameterization choices for rain evaporation and moisture recycling in current isotope-enabled climate models. Aggregate raindrop size measurements showed shifts from populations of smaller raindrops at 300m to larger raindrops at the surface, contrary to what is expected for rain evaporation. Convective storms resulted in more uniform signatures between the surface and 300m, as well as longer isotope equilibration and adjustment time scales, whereas low Dexcess signatures (<9 to negative) during stratiform drizzle events were indicative of a greater degree of rain evaporation. Our observational results suggest that water vapor-rain equilibration is rarely achieved, and modification of the kinetic fractionation factor is necessary to better capture drop-size related isotope changes. This has implications not only for refining current global climate models, but also for interpreting proxy records connected to rainfall signatures that aid in understanding past hydrology.

Main photoautotrophic components of biofilms in natural draft cooling towers.

PubMed

Hauer, Tomáš; Čapek, Petr; Böhmová, Petra

2016-05-01

While photoautotrophic organisms are an important component of biofilms that live in certain regions of natural draft cooling towers, little is known about these communities. We therefore examined 18 towers at nine sites to identify the general patterns of community assembly in three distinct tower parts, and we examined how community structures differ depending on geography. We also compared the newly acquired data with previously published data. The bottom sections of draft cooling towers are mainly settled by large filamentous algae, primarily Cladophora glomerata. The central portions of towers host a small amount of planktic algae biomass originating in the cooling water. The upper fourths of towers are colonized by biofilms primarily dominated by cyanobacteria, e.g., members of the genera Gloeocapsa and Scytonema. A total of 41 taxa of phototrophic microorganisms were identified. Species composition of the upper fourth of all towers was significantly affected by cardinal position. There was different species composition at positions facing north compared to positions facing south. West- and east-facing positions were transitory and highly similar to each other in terms of species composition. Biofilms contribute to the degradation of paint coatings inside towers.

The Quality Control Algorithms Used in the Process of Creating the NASA Kennedy Space Center Lightning Protection System Towers Meteorological Database

NASA Technical Reports Server (NTRS)

Orcutt, John M.; Brenton, James C.

2016-01-01

The methodology and the results of the quality control (QC) process of the meteorological data from the Lightning Protection System (LPS) towers located at Kennedy Space Center (KSC) launch complex 39B (LC-39B) are documented in this paper. Meteorological data are used to design a launch vehicle, determine operational constraints, and to apply defined constraints on day-of-launch (DOL). In order to properly accomplish these tasks, a representative climatological database of meteorological records is needed because the database needs to represent the climate the vehicle will encounter. Numerous meteorological measurement towers exist at KSC; however, the engineering tasks need measurements at specific heights, some of which can only be provided by a few towers. Other than the LPS towers, Tower 313 is the only tower that provides observations up to 150 m. This tower is located approximately 3.5 km from LC-39B. In addition, data need to be QC'ed to remove erroneous reports that could pollute the results of an engineering analysis, mislead the development of operational constraints, or provide a false image of the atmosphere at the tower's location.

BEOS-A new approach to promote and organize industrial ISS utilization

NASA Astrophysics Data System (ADS)

Luttmann, Helmut; Buchholz, Henning; Bratke, Burkhard; Hueser, Detlev; Dittus, Hansjörg

2000-01-01

In order to develop and to market innovative services and products for the operation of the ISS and its utilization, three players have teamed up together and established an entity called BEOS (Bremen Engineering Operations Science). The team is made up of DaimlerChrysler Aerospace, OHB-System and ZARM, the Center of Applied Space Technology and Microgravity at the University of Bremen. It is the aim of BEOS to represent a competent industrial interface to potential ISS users from the space and non-space industries. In this effort BEOS is supporting and supplementing the activities of the space agencies, especially in the field of industrial and/or commercial ISS utilization. With this approach BEOS is creating new business opportunities not only for its team members but also for its customers from industry. Besides the fostering of industrial research in space, nontechnical fields of space utilization like entertainment, advertisement, education and space travel represent further key sectors for the marketing efforts of BEOS. .

MICROSCOPE mission: drag-free and attitude control system expertise activities toward the scientific team

NASA Astrophysics Data System (ADS)

Delavault, Stéphanie; Prieur, Pascal; Liénart, Thomas; Robert, Alain; Guidotti, Pierre-Yves

2018-04-01

Microscope is a CNES-ESA-ONERA-CNRS-OCA-DLR-ZARM mission dedicated to the test of the Equivalence Principle with an improved accuracy of 10-15. The 300 kg drag-free microsatellite was launched on April 25th 2016 into a 710 km dawndusk sun-synchronous orbit for a 2-year mission. To comply with stringent requirements, the drag-free and attitude control system (DFACS) involves the scientific accelerometer as main sensor and a set of 8 cold gas proportional thrusters. Once in mission mode, within the CNES drag-free expertise center (CECT) the DFACS team provides several services to the system and to the scientific mission center: cold gas monitoring and management, `Attitude' ancillary data, DFACS expertise ancillary data. For this purpose, expertise tools have been implemented in the CECT, using the flexibility and efficiency of Matlab™ utilities. This paper presents the role of the CECT within the mission and details the expertise activities of the DFACS team illustrated with some typical in flight results.

Numerical simulations in the development of propellant management devices

NASA Astrophysics Data System (ADS)

Gaulke, Diana; Winkelmann, Yvonne; Dreyer, Michael

Propellant management devices (PMDs) are used for positioning the propellant at the propel-lant port. It is important to provide propellant without gas bubbles. Gas bubbles can inflict cavitation and may lead to system failures in the worst case. Therefore, the reliable operation of such devices must be guaranteed. Testing these complex systems is a very intricate process. Furthermore, in most cases only tests with downscaled geometries are possible. Numerical sim-ulations are used here as an aid to optimize the tests and to predict certain results. Based on these simulations, parameters can be determined in advance and parts of the equipment can be adjusted in order to minimize the number of experiments. In return, the simulations are validated regarding the test results. Furthermore, if the accuracy of the numerical prediction is verified, then numerical simulations can be used for validating the scaling of the experiments. This presentation demonstrates some selected numerical simulations for the development of PMDs at ZARM.

An Estimate of Avian Mortality at Communication Towers in the United States and Canada

PubMed Central

Longcore, Travis; Rich, Catherine; Mineau, Pierre; MacDonald, Beau; Bert, Daniel G.; Sullivan, Lauren M.; Mutrie, Erin; Gauthreaux, Sidney A.; Avery, Michael L.; Crawford, Robert L.; Manville, Albert M.; Travis, Emilie R.; Drake, David

2012-01-01

Avian mortality at communication towers in the continental United States and Canada is an issue of pressing conservation concern. Previous estimates of this mortality have been based on limited data and have not included Canada. We compiled a database of communication towers in the continental United States and Canada and estimated avian mortality by tower with a regression relating avian mortality to tower height. This equation was derived from 38 tower studies for which mortality data were available and corrected for sampling effort, search efficiency, and scavenging where appropriate. Although most studies document mortality at guyed towers with steady-burning lights, we accounted for lower mortality at towers without guy wires or steady-burning lights by adjusting estimates based on published studies. The resulting estimate of mortality at towers is 6.8 million birds per year in the United States and Canada. Bootstrapped subsampling indicated that the regression was robust to the choice of studies included and a comparison of multiple regression models showed that incorporating sampling, scavenging, and search efficiency adjustments improved model fit. Estimating total avian mortality is only a first step in developing an assessment of the biological significance of mortality at communication towers for individual species or groups of species. Nevertheless, our estimate can be used to evaluate this source of mortality, develop subsequent per-species mortality estimates, and motivate policy action. PMID:22558082

Analysis of wind-resistant and stability for cable tower in cable-stayed bridge with four towers

NASA Astrophysics Data System (ADS)

Meng, Yangjun; Li, Can

2017-06-01

Wind speed time history simulation methods have been introduced first, especially the harmonic synthesis method introduced in detail. Second, taking Chishi bridge for example, choosing the particular sections, and combined with the design wind speed, three-component coefficient simulate analysis between -4°and 4°has been carry out with the Fluent software. The results show that drag coefficient reaches maximum when the attack Angle is 1°. According to measured wind speed samples,time history curves of wind speed at bridge deck and tower roof have been obtained,and wind-resistant time history analysis for No.5 tower has been carry out. Their results show that the dynamic coefficients are different with different calculation standard, especially transverse bending moment, pulsating crosswind load does not show a dynamic amplification effect.Under pulsating wind loads at bridge deck or tower roof, the maximum displacement at the top of the tower and the maximum stress at the bottom of the tower are within the allowable range. The transverse stiffness of tower is greater than that of the longitudinal stiffness, therefore wind-resistant analysis should give priority to the longitudinal direction. Dynamic coefficients are different with different standard, the maximum dynamic coefficient should be used for the pseudo-static analysis.Finally, the static stability of tower is analyzed with different load combinations, and the galloping stabilities of cable tower is proved.

An estimate of avian mortality at communication towers in the United States and Canada.

PubMed

Longcore, Travis; Rich, Catherine; Mineau, Pierre; MacDonald, Beau; Bert, Daniel G; Sullivan, Lauren M; Mutrie, Erin; Gauthreaux, Sidney A; Avery, Michael L; Crawford, Robert L; Manville, Albert M; Travis, Emilie R; Drake, David

2012-01-01

Avian mortality at communication towers in the continental United States and Canada is an issue of pressing conservation concern. Previous estimates of this mortality have been based on limited data and have not included Canada. We compiled a database of communication towers in the continental United States and Canada and estimated avian mortality by tower with a regression relating avian mortality to tower height. This equation was derived from 38 tower studies for which mortality data were available and corrected for sampling effort, search efficiency, and scavenging where appropriate. Although most studies document mortality at guyed towers with steady-burning lights, we accounted for lower mortality at towers without guy wires or steady-burning lights by adjusting estimates based on published studies. The resulting estimate of mortality at towers is 6.8 million birds per year in the United States and Canada. Bootstrapped subsampling indicated that the regression was robust to the choice of studies included and a comparison of multiple regression models showed that incorporating sampling, scavenging, and search efficiency adjustments improved model fit. Estimating total avian mortality is only a first step in developing an assessment of the biological significance of mortality at communication towers for individual species or groups of species. Nevertheless, our estimate can be used to evaluate this source of mortality, develop subsequent per-species mortality estimates, and motivate policy action.

Analysis of Ideal Towers for Tall Wind Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dykes, Katherine L; Damiani, Rick R; Roberts, Joseph O

Innovation in wind turbine tower design is of significant interest for future development of wind power plants. First, wind turbine towers account for a large portion of overall capital expenditures for wind power projects. Second, for low wind-resource regions of the world, the use of low-cost tall-tower technology has the potential to open new markets for development. This study investigates the relative potential of various tower configurations in terms of mass and cost. For different market applications and hub heights, idealized tall towers are designed and compared. The results show that innovation in wind turbine controls makes reaching higher hubmore » heights with current technology economically viable. At the same time, new technologies hold promise for reducing tower costs as these technologies mature and hub heights reach twice the current average.« less

Analysis of Ideal Towers for Tall Wind Applications: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dykes, Katherine L; Damiani, Rick R; Roberts, Joseph O

Innovation in wind turbine tower design is of significant interest for future development of wind power plants. First, wind turbine towers account for a large portion of overall capital expenditures for wind power projects. Second, for low wind-resource regions of the world, the use of low-cost tall-tower technology has the potential to open new markets for development. This study investigates the relative potential of various tower configurations in terms of mass and cost. For different market applications and hub heights, idealized tall towers are designed and compared. The results show that innovation in wind turbine controls makes reaching higher hubmore » heights with current technology economically viable. At the same time, new technologies hold promise for reducing tower costs as these technologies mature and hub heights reach twice the current average.« less

KSC-99pp1240

NASA Image and Video Library

1999-10-14

KENNEDY SPACE CENTER, FLA. — Two 34-year-old towers on Launch Complex 41, Cape Canaveral Air Station, fall to the ground amid the black smoke from explosives set to topple them. Weighing two million pounds, the umbilical tower (left) was approximately 200 feet high. The taller 300-foot Mobile Service Tower (right), still falling, weighs five million pounds. About 200 pounds of linear-shaped charges were used to topple the towers so that the materials can be recycled. Adjacent to the towers are lightning protection structures, which will remain on the site. The towers are being demolished to make room for Lockheed Martin's 14-acre Vehicle Integration Facility (VIF), under construction. The implosion and removal of the tower debris is expected to be completed in two months. The VIF will be used for Lockheed Martin's Atlas V Launch System.

Turbulent Premixed Flame Propagation in Microgravity

NASA Technical Reports Server (NTRS)

Menon, S.; Disseau, M.; Chakravarthy, V. K.; Jagoda, J.

1997-01-01

A facility in which turbulent Couette flow could be generated in a microgravity environment was designed and built. To fit into the NASA Lewis drop tower the device had to be very compact. This means that edge effects and flow re-circulation were expected to affect the flow. The flow was thoroughly investigated using LDV and was found to be largely two dimensional away from the edges with constant turbulence intensities in the core. Slight flow asymmetries are introduced by the non symmetric re-circulation of the fluid outside the test region. Belt flutter problems were remedied by adding a pair of guide plates to the belt. In general, the flow field was found to be quite similar to previously investigated Couette flows. However, turbulence levels and associated shear stresses were higher. This is probably due to the confined re-circulation zone reintroducing turbulence into the test section. An estimate of the length scales in the flow showed that the measurements were able to resolve nearly all the length scales of interest. Using a new LES method for subgrid combustion it has been demonstrated that the new procedure is computational feasible even on workstation type environment. It is found that this model is capable of capturing the propagation of the premixed names by resolving the flame in the LES grid within 2-3 grid points. In contrast, conventional LES results in numerical smearing of the flame and completely inaccurate estimate of the turbulent propagation speed. Preliminary study suggests that there is observable effect of buoyancy in the 1g environment suggesting the need for microgravity experiments of the upcoming experimental combustion studies. With the cold flow properties characterized, an identical hot flow facility is under construction. It is assumed that the turbulence properties ahead of the flame in this new device will closely match the results obtained here. This is required since the hot facility will not enable LDV measurements. The reacting flow facility is also being constructed with planned drop tower experiments in mind. Therefore, issues related to safety and structural integrity are being take into account. Further development of the numerical model will also be carried out to include finite-rate kinetics for representative premixed cases. More detail analysis of the flame structure and propagation nature will be investigated. Simulations will also be compared to the flame properties observed in the experiments.

Wintering Sandhill Crane exposure to wind energy development in the central and southern Great Plains, USA

USGS Publications Warehouse

Pearse, Aaron T.; Brandt, David; Krapu, Gary

2016-01-01

Numerous wind energy projects have been constructed in the central and southern Great Plains, USA, the main wintering area for midcontinental Sandhill Cranes (Grus canadensis). In an initial assessment of the potential risks of wind towers to cranes, we estimated spatial overlap, investigated potential avoidance behavior, and determined the habitat associations of cranes. We used data from cranes marked with platform transmitting terminals (PTTs) with and without global positioning system (GPS) capabilities. We estimated the wintering distributions of PTT-marked cranes prior to the construction of wind towers, which we compared with current tower locations. Based on this analysis, we found 7% spatial overlap between the distributions of cranes and towers. When we looked at individually marked cranes, we found that 52% would have occurred within 10 km of a tower at some point during winter. Using data from cranes marked after tower construction, we found a potential indication of avoidance behavior, whereby GPS-marked cranes generally used areas slightly more distant from existing wind towers than would be expected by chance. Results from a habitat selection model suggested that distances between crane locations and towers may have been driven more by habitat selection than by avoidance, as most wind towers were constructed in locations not often selected by wintering cranes. Our findings of modest regional overlap and that few towers have been placed in preferred crane habitat suggest that the current distribution of wind towers may be of low risk to the continued persistence of wintering midcontinental Sandhill Cranes in the central and southern Great Plains.

Occurrence of infected amoebae in cooling towers compared with natural aquatic environments: implications for emerging pathogens.

PubMed

Berk, S G; Gunderson, J H; Newsome, A L; Farone, A L; Hayes, B J; Redding, K S; Uddin, N; Williams, E L; Johnson, R A; Farsian, M; Reid, A; Skimmyhorn, J; Farone, M B

2006-12-01

Many species of bacteria pathogenic to humans, such as Legionella, are thought to have evolved in association with amoebal hosts. Several novel unculturable bacteria related to Legionella have also been found in amoebae, a few of which have been thought to be causes of nosocomial infections in humans. Because amoebae can be found in cooling towers, we wanted to know whether cooling tower environments might enhance the association between amoebae and bacterial pathogens of amoebae in order to identify potential "hot spots" for emerging human pathogens. To compare occurrence of infected amoebae in natural environments with those in cooling towers, 40 natural aquatic environments and 40 cooling tower samples were examined. Logistic regression analysis determined variables that were significant predictors of the occurrence of infected amoebae, which were found in 22 of 40 cooling tower samples but in only 3 of the 40 natural samples. An odds ratio showed that it is over 16 times more likely to encounter infected amoebae in cooling towers than in natural environments. Environmental data from cooling towers and natural habitats combined revealed dissolved organic carbon (DOC) and pH were predictors of the occurrence of the pathogens, however, when cooling tower data alone were analyzed, no variables accounted for the occurrence. Several bacteria have novel rRNA sequences, and most strains were not culturable outside of amoebae. Such pathogens of amoebae may spread to the environment via aerosols from cooling towers. Studies of emerging infectious diseases should strongly consider cooling towers as a source of amoeba-associated pathogens.

78 FR 11152 - Utility Scale Wind Towers from the People's Republic of China: Countervailing Duty Order

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-15

... DEPARTMENT OF COMMERCE International Trade Administration [C-570-982] Utility Scale Wind Towers...''), the Department is issuing a countervailing duty order on utility scale wind towers (``wind towers..., 2012, the Department published the final determination in the countervailing duty investigation of wind...

10. VIEW OF ANTENNA TOWER S111 FROM THE NORTHEAST SIDE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

10. VIEW OF ANTENNA TOWER S-111 FROM THE NORTHEAST SIDE LOOKING UP. A PARABLOIC ANTENNA MOUNTED ON THE TOWER IS LOCATED IN THE LOWER LEFT OF PHOTO. - U.S. Naval Base, Pearl Harbor, Lualualei Radio Transmitter, Edison & Tower Drives, Pearl City, Honolulu County, HI

14 CFR 170.13 - Airport Traffic Control Tower (ATCT) establishment criteria.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Airport Traffic Control Tower (ATCT... AIR TRAFFIC CONTROL SERVICES AND NAVIGATIONAL FACILITIES Airport Traffic Control Towers § 170.13 Airport Traffic Control Tower (ATCT) establishment criteria. (a) The following criteria along with general...

Microgravity Spray Cooling Research for High Powered Laser Applications

NASA Technical Reports Server (NTRS)

Zivich, Chad P.

2004-01-01

An extremely powerful laser is being developed at Goddard Space Flight Center for use on a satellite. This laser has several potential applications. One application is to use it for upper atmosphere weather research. In this case, the laser would reflect off aerosols in the upper atmosphere and bounce back to the satellite, where the aerosol velocities could be calculated and thus the upper atmosphere weather patterns could be monitored. A second application would be for the US. Air Force, which wants to use the laser strategically as a weapon for satellite defense. The Air Force fears that in the coming years as more and more nations gain limited space capabilities that American satellites may become targets, and the laser could protect the satellites. Regardless of the ultimate application, however, a critical step along the way to putting the laser in space is finding a way to efficiently cool it. While operating the laser becomes very hot and must be cooled to prevent overheating. On earth, this is accomplished by simply running cool tap water over the laser to keep it cool. But on a satellite, this is too inefficient. This would require too much water mass to be practical. Instead, we are investigating spray cooling as a means to cool the laser in microgravity. Spray cooling requires much less volume of fluid, and thus could be suitable for use on a satellite. We have inherited a 2.2 second Drop Tower rig to conduct our research with. In our experiments, water is pressurized with a compressed air tank and sprayed through a nozzle onto our test plate. We can vary the pressure applied to the water and the temperature of the plate before an experiment trial. The whole process takes place in simulated microgravity in the 2.2 second Drop Tower, and a high speed video camera records the spray as it hits the plate. We have made much progress in the past few weeks on these experiments. The rig originally did not have the capability to heat the test plate, but I did some heat transfer calculations and picked out a heater to order for the rig. I learned QBasic programming language to change the operating code for our drops, allowing us to rapidly cycle the spray nozzle open and closed to study the effects. We have derived an equation for flow rate vs. pressure for our experiment. We have recorded several videos of drops at different pressures, some with heated test plate and some without, and have noticed substantial differences in the liquid behavior. I have also changed the computer program to write a file with temperature vs. time profiles for the test plate, and once the necessary thermocouple comes in (it was ordered last week), we will have temperature profiles to accompany the videos. Once we have these temperature profiles to go with the videos, we will be able to see how the temperature is affected by the spray at different pressures, and how the spray changes its behavior once as the plate changes from hot to cool. With quantitative temperature data, we can then mathematically model the heat transfer from the plate to the cooling spray. Finally, we can look at the differences between trials in microgravity and those in normal earth gravity.

Comparative Soot Diagnostics: Preliminary Results

NASA Technical Reports Server (NTRS)

Urban, David L.; Griffin, DeVon W.; Gard, Melissa Y.

1997-01-01

The motivation for the Comparative Soot Diagnostics (CSD) experiment lies in the broad practical importance of understanding combustion generated particulate. Depending upon the circumstances, particulate matter can affect the durability and performance of combustion equipment, can be a pollutant, can be used to detect fires and, in the form of soot, can be the dominant source of radiant energy from flames. The nonbuoyant structure of most flames of practical interest makes understanding of soot processes in low gravity flames important to our ability to predict fire behavior on earth. These studies also have direct applications to fire safety in human-crew spacecraft, since smoke is the indicator used for automated detection in current spacecraft. In the earliest missions (Mercury, Gemini and Apollo), the crew quarters were so cramped that it was considered reasonable that the astronauts would rapidly detect any fire. The Skylab module, however, included approximately 20 UV-sensing fire detectors. The Space Shuttle has 9 particle-ionization smoke detectors in the mid-deck and flight deck and Spacelab has six additional particle-ionization smoke detectors. The designated detectors for the ISS are laser-diode, forward-scattering, smoke or particulate detectors. Current plans for the ISS call for two detectors in the open area of the module, and detectors in racks that have both cooling air flow and electrical power. Due to the complete absence of data concerning the nature of particulate and radiant emission from incipient and fully developed low-g fires, all three of these detector systems were designed based upon l-g test data and experience. As planned mission durations and complexity increase and the volume of spacecraft increases, the need for and importance of effective, crew-independent, fire detection grows significantly. To provide this level of protection, more knowledge is needed concerning low-gravity fire phenomena and, in particular, how they might be detected and suppressed. Prior to CSD, no combustion-generated particulate samples had been collected near the flame zone for well-developed microgravity flames. All of the extant data either came from drop tower tests and therefore only corresponded to the early stages of a fire or were collected far from the flame zone. The fuel sources in the drop tower tests were restricted to laminar gas-jet diffusion flames and very rapidly overheated wire insulation. The gas-jet tests indicated, through thermophoretic sampling, (2) that soot primaries and aggregates (groups of primary particles) in low-gravity may be significantly larger than those in normal gravity (1-g). This raises new scientific questions about soot processes as well as practical issues for particulate size sensitivity and detection alarm threshold levels used in on-orbit smoke detectors. Preliminary tests in the 2.2 second drop tower suggest that particulate generated by overheated wire insulation may be larger in low-g than in 1-g. Transmission Electron Microscope (TEM) grids downstream of the fire region in the Wire Insulation Flammability experiment as well as visual observation of long string-like aggregates, further confirm this suggestion. The combined impact of these limited results and theoretical predictions is that, as opposed to extrapolation from l-g data, direct knowledge of low-g combustion particulate is needed for more confident design of smoke detectors for spacecraft. This paper describes the operation and preliminary results of the CSD, a project conceived and developed at NASA Lewis Research Center. The CSD flight experiment was conducted in the Middeck Glovebox Facility (MGBX) on USMP-3. The project is support by NASA Headquarters Microgravity Science and Applications Division and Code Q. The results presented here are from the microgravity portion of the experiment, including the temporal response of the detectors and average sizes of the primary and aggregate particles captured on the thermophoretic probes.

Carbon Nanotube Tower-Based Supercapacitor

NASA Technical Reports Server (NTRS)

Meyyappan, Meyya (Inventor)

2012-01-01

A supercapacitor system, including (i) first and second, spaced apart planar collectors, (ii) first and second arrays of multi-wall carbon nanotube (MWCNT) towers or single wall carbon nanotube (SWCNT) towers, serving as electrodes, that extend between the first and second collectors where the nanotube towers are grown directly on the collector surfaces without deposition of a catalyst and without deposition of a binder material on the collector surfaces, and (iii) a porous separator module having a transverse area that is substantially the same as the transverse area of at least one electrode, where (iv) at least one nanotube tower is functionalized to permit or encourage the tower to behave as a hydrophilic structure, with increased surface wettability.

KSC-99pp1220

NASA Image and Video Library

1999-10-14

KENNEDY SPACE CENTER, FLA. -- Live TV trucks (far right) from local channels merge at the site of the fallen Mobile Service Tower (MST) and umbilical tower nearby after their demolition. The towers were demolished to make room for Lockheed Martin's 14-acre Vehicle Integration Facility (VIF), under construction. Weighing two million pounds, the umbilical tower was approximately 200 feet high. The taller 300-foot MST weighed five million pounds. About 200 pounds of linear-shaped charges were used to bring down the towers so that the materials can be recycled. The implosion and removal of the tower debris is expected to be completed in two months. The VIF will be used for Lockheed Martin's Atlas V Launch System.

KSC-99pp1219

NASA Image and Video Library

1999-10-14

KENNEDY SPACE CENTER, FLA. -- Live TV trucks from local channels merge at the site of the fallen Mobile Service Tower (MST) and umbilical tower nearby after their demolition. The towers were demolished to make room for Lockheed Martin's 14-acre Vehicle Integration Facility (VIF), under construction. Weighing two million pounds, the umbilical tower was approximately 200 feet high. The taller 300-foot MST weighed five million pounds. About 200 pounds of linear-shaped charges were used to bring down the towers so that the materials can be recycled. The implosion and removal of the tower debris is expected to be completed in two months. The VIF will be used for Lockheed Martin's Atlas V Launch System.

The influence of liquid-gas velocity ratio on the noise of the cooling tower

NASA Astrophysics Data System (ADS)

Yang, Bin; Liu, Xuanzuo; Chen, Chi; Zhao, Zhouli; Song, Jinchun

2018-05-01

The noise from the cooling tower has a great influence on psychological performance of human beings. The cooling tower noise mainly consists of fan noise, falling water noise and mechanical noise. This thesis used DES turbulence model with FH-W model to simulate the flow and sound pressure field in cooling tower based on CFD software FLUENT and analyzed the influence of different kinds noise, which affected by diverse factors, on the cooling tower noise. It can be concluded that the addition of cooling water can reduce the turbulence and vortex noise of the rotor fluid field in the cooling tower at some extent, but increase the impact noise of the liquid-gas two phase. In general, the cooling tower noise decreases with the velocity ratio of liquid to gas increasing, and reaches the lowest when the velocity ratio of liquid to gas is close to l.

Dynamic Responses and Vibration Control of the Transmission Tower-Line System: A State-of-the-Art Review

PubMed Central

Chen, Bo; Guo, Wei-hua; Li, Peng-yun; Xie, Wen-ping

2014-01-01

This paper presented an overview on the dynamic analysis and control of the transmission tower-line system in the past forty years. The challenges and future developing trends in the dynamic analysis and mitigation of the transmission tower-line system under dynamic excitations are also put forward. It also reviews the analytical models and approaches of the transmission tower, transmission lines, and transmission tower-line systems, respectively, which contain the theoretical model, finite element (FE) model and the equivalent model; shows the advances in wind responses of the transmission tower-line system, which contains the dynamic effects under common wind loading, tornado, downburst, and typhoon; and discusses the dynamic responses under earthquake and ice loads, respectively. The vibration control of the transmission tower-line system is also reviewed, which includes the magnetorheological dampers, friction dampers, tuned mass dampers, and pounding tuned mass dampers. PMID:25105161

Visibility analysis of fire lookout towers in the Boyabat State Forest Enterprise in Turkey.

PubMed

Kucuk, Omer; Topaloglu, Ozer; Altunel, Arif Oguz; Cetin, Mehmet

2017-07-01

For a successful fire suppression, it is essential to detect and intervene forest fires as early as possible. Fire lookout towers are crucial assets in detecting forest fires, in addition to other technological advancements. In this study, we performed a visibility analysis on a network of fire lookout towers currently operating in a relatively fire-prone region in Turkey's Western Black Sea region. Some of these towers had not been functioning properly; it was proposed that these be taken out of the grid and replaced with new ones. The percentage of visible areas under the current network of fire lookout towers was 73%; it could rise to 81% with the addition of newly proposed towers. This study was the first research to conduct a visibility analysis of current and newly proposed fire lookout towers in the Western Black Sea region and focus on its forest fire problem.

On the Path to SunShot: Advancing Concentrating Solar Power Technology Performance and Dispatchability.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mehos, Mark; Turchi, Craig; Jorgensen, Jennie

2016-03-01

Since the SunShot Vision Study (DOE 2012) was published, global deployment of concentrating solar power (CSP) has increased threefold to nearly 4,500 MW, with a similar threefold increase in operational capacity to 1,650 MW within the United States. Growth in U.S. CSP capacity has primarily been driven by policy support at the state and federal levels. State-driven renewable portfolio standards (RPSs), combined with a 30% federal investment tax credit (ITC) and federal loan guarantees, provided the opportunity for CSP developers to kick-start construction of CSP plants throughout the Southwest. Figure ES-1 demonstrates that deployment and private- and public-sector research andmore » development have led to dramatic cost reductions that have placed CSP well on the path to reaching the U.S. Department of Energy’s SunShot Initiative goal of 6 cents/kWh by 2020. In comparing the estimated capital costs from the SunShot Vision Study and the current analysis, we find that parabolic trough solar-field costs have fallen more rapidly than predicted, although the drop in solar-field costs was offset by the additional costs of moving from a wet-cooled power block in 2010 to a more expensive dry-cooled power block in 2015. The predicted 2015 decline in tower costs was in line with expectations, primarily driven by reduced heliostat costs. Figure ES-1 shows the reduction in levelized cost of electricity (LCOE) for both parabolic trough and tower systems, in addition to the projected 2020 SunShot target.« less

77 FR 9700 - Utility Scale Wind Towers From China and Vietnam

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-17

...)] Utility Scale Wind Towers From China and Vietnam Determinations On the basis of the record \\1\\ developed... threatened with material injury by reason of imports from China of utility scale wind towers, provided for in... with material injury by reason of imports from Vietnam of utility scale wind towers, provided for in...

78 FR 10210 - Utility Scale Wind Towers From China and Vietnam

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-13

...)] Utility Scale Wind Towers From China and Vietnam Determinations On the basis of the record \\1\\ developed... with material injury by reason of imports of utility scale wind towers from China and Vietnam, provided... of imports of utility scale wind towers from China and Vietnam. Commissioner Dean A. Pinkert...

Convection towers

DOEpatents

Prueitt, Melvin L.

1996-01-01

Convection towers which are capable of cleaning the pollution from large quantities of air, of generating electricity, and of producing fresh water utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity, and condensers produce fresh water.

Convection towers

DOEpatents

Prueitt, Melvin L.

1995-01-01

Convection towers which are capable of cleaning the pollution from large quantities of air, of generating electricity, and of producing fresh water utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity, and condensers produce fresh water.

Convection towers

DOEpatents

Prueitt, M.L.

1996-01-16

Convection towers which are capable of cleaning the pollution from large quantities of air, of generating electricity, and of producing fresh water utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity, and condensers produce fresh water. 6 figs.

14 CFR 139.329 - Pedestrians and ground vehicles.

Code of Federal Regulations, 2010 CFR

2010-01-01

... by an employee, tenant, or contractor; (c) When an air traffic control tower is in operation, ensure... between the tower and the pedestrian, vehicle, or escort; (d) When an air traffic control tower is not in operation, or there is no air traffic control tower, provide adequate procedures to control pedestrians and...

15. GENERAL EASTERN VIEW OF LINDE 1000 TONS PER DAY ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

15. GENERAL EASTERN VIEW OF LINDE 1000 TONS PER DAY HIGH PURITY OXYGEN MAKING PLANT SHOWING TWIN OXYGEN FRACTIONATING TOWER (ON RIGHT), VERMICULITE STORAGE TOWERS (ON LEFT FOREGROUND), AND AN ARGON FRACTIONATING TOWER (BEHIND VERMICULITE STORAGE TOWER). - U.S. Steel Duquesne Works, Fuel & Utilities Plant, Along Monongahela River, Duquesne, Allegheny County, PA

Airborne LIDAR point cloud tower inclination judgment

NASA Astrophysics Data System (ADS)

liang, Chen; zhengjun, Liu; jianguo, Qian

2016-11-01

Inclined transmission line towers for the safe operation of the line caused a great threat, how to effectively, quickly and accurately perform inclined judgment tower of power supply company safety and security of supply has played a key role. In recent years, with the development of unmanned aerial vehicles, unmanned aerial vehicles equipped with a laser scanner, GPS, inertial navigation is one of the high-precision 3D Remote Sensing System in the electricity sector more and more. By airborne radar scan point cloud to visually show the whole picture of the three-dimensional spatial information of the power line corridors, such as the line facilities and equipment, terrain and trees. Currently, LIDAR point cloud research in the field has not yet formed an algorithm to determine tower inclination, the paper through the existing power line corridor on the tower base extraction, through their own tower shape characteristic analysis, a vertical stratification the method of combining convex hull algorithm for point cloud tower scarce two cases using two different methods for the tower was Inclined to judge, and the results with high reliability.

The Effect Analysis of Strain Rate on Power Transmission Tower-Line System under Seismic Excitation

PubMed Central

Wang, Wenming

2014-01-01

The effect analysis of strain rate on power transmission tower-line system under seismic excitation is studied in this paper. A three-dimensional finite element model of a transmission tower-line system is created based on a real project. Using theoretical analysis and numerical simulation, incremental dynamic analysis of the power transmission tower-line system is conducted to investigate the effect of strain rate on the nonlinear responses of the transmission tower and line. The results show that the effect of strain rate on the transmission tower generally decreases the maximum top displacements, but it would increase the maximum base shear forces, and thus it is necessary to consider the effect of strain rate on the seismic analysis of the transmission tower. The effect of strain rate could be ignored for the seismic analysis of the conductors and ground lines, but the responses of the ground lines considering strain rate effect are larger than those of the conductors. The results could provide a reference for the seismic design of the transmission tower-line system. PMID:25105157

Collapse and pull - down analysis of high voltage electricity transmission towers subjected to cyclonic wind

NASA Astrophysics Data System (ADS)

Ahmed, Ammar; Arthur, Craig; Edwards, Mark

2010-06-01

Bulk electricity transmission lines are linear assets that can be very exposed to wind effects, particularly where they traverse steep topography or open coastal terrain in cyclonic regions. Interconnected nature of the lattice type towers and conductors also, present complex vulnerabilities. These relate to the direction of wind attack to the conductors and the cascading failure mechanisms in which the failure of a single tower has cascading effects on neighbouring towers. Such behaviour is exacerbated by the finely tuned nature of tower design which serves to minimize cost and reserve strength at design wind speeds. There is a clear need to better quantify the interdependent vulnerabilities of these critical infrastructure assets in the context of the severe wind hazard. This paper presents a novel methodology developed for the Critical Infrastructure Protection Modelling and Analysis (CIPMA) capability for assessing local wind speeds and the likelihood of tower failure for a range of transmission tower and conductor types. CIPMA is a program managed by the Federal Attorney-General's Department and Geoscience Australia is leading the technical development. The methodology then involves the development of heuristically derived vulnerability models that are consistent with Australian industry experience and full-scale static tower testing results, considering isolated tower loss along with three interdependent failure mechanisms to give overall likelihoods of failure.

Energy conservation strategies, the ignored cooling towers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burger, R.

1997-06-01

Because of their apparent lack of sophistication, cooling towers are usually considered orphans of the facilities operation. Historically, cooling towers have been neglected in refrigeration air conditioning systems, electric power generating stations, manufacturing plants, and chemical process plants. Operators are aware of the importance of their sophisticated equipment but, they take the apparently simple cooling towers and cold water returning for granted, Since the box looks sturdy and the fans are rotating, the operators think all is well and ignore the quality of water coming off the tower. A cooling tower is purchased for Design Conditions of performance which aremore » specified. Design Conditions relate to the volume of circulating water (GPM), hot water temperature (HWT), cold water temperature (CWT) discharge, and wet bulb temperature (WBT). The WBT consisting of ambient temperature and relative humidity. After the tower is on line and the CWT becomes inadequate, many engineers look to solutions other than the obvious. All cooling towers are purchased to function at 100% of capability in accordance with Design Condition. In the real world of on-stream utilization, the level of operation is lower. It can be deficient as much as 30% due to a variety of reasons which are not necessarily due to the failure of the performance of the tower.« less

Convective Cloud Towers and Precipitation Initiation, Frequency and Intensity

NASA Astrophysics Data System (ADS)

Vant-hull, B.; Mahani, S. E.; Autones, F.; Rabin, R.; Mecikalski, J. R.; Khanbilvardi, R.

2012-12-01

: Geosynchronous satellite retrieval of precipitation is desirable because it would provide continuous observation throughout most of the globe in regions where radar data is not available. In the current work the distribution of precipitation rates is examined as a function of cloud tower area and cloud top temperature. A thunderstorm tracking algorithm developed at Meteo-France is used to track cumulus towers that are matched up with radar data at 5 minute 1 km resolution. It is found that roughly half of the precipitation occurs in the cloud mass that surrounds the towers, and when a tower is first detected the precipitation is already in progress 50% of the time. The average density of precipitation per area is greater as the towers become smaller and colder, yet the averaged shape of the precipitation intensity distribution is remarkably constant in all convective situations with cloud tops warmer than 220 K. This suggests that on average all convective precipitation events look the same, unaffected by the higher frequency of occurrence per area inside the convective towers. Only once the cloud tops are colder than 220 K does the precipitation intensity distribution become weighted towards higher instantaneous intensities. Radar precipitation shown in shades of green to blue, lightning in orange; black diamonds are coldest points in each tower. Ratio of number of pixels of given precipitation inside versus outside the convective towers, for various average cloud top temperatures. A flat plot indicates the distribution of rainfall inside and outside the towers has the same shape.

Identification of tower-wake distortions using sonic anemometer and lidar measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCaffrey, Katherine; Quelet, Paul T.; Choukulkar, Aditya

The eXperimental Planetary boundary layer Instrumentation Assessment (XPIA) field campaign took place in March through May 2015 at the Boulder Atmospheric Observatory, utilizing its 300 m meteorological tower, instrumented with two sonic anemometers mounted on opposite sides of the tower at six heights. This allowed for at least one sonic anemometer at each level to be upstream of the tower at all times and for identification of the times when a sonic anemometer is in the wake of the tower frame. Other instrumentation, including profiling and scanning lidars aided in the identification of the tower wake. Here we compare pairsmore » of sonic anemometers at the same heights to identify the range of directions that are affected by the tower for each of the opposing booms. The mean velocity and turbulent kinetic energy are used to quantify the wake impact on these first- and second-order wind measurements, showing up to a 50% reduction in wind speed and an order of magnitude increase in turbulent kinetic energy. Comparisons of wind speeds from profiling and scanning lidars confirmed the extent of the tower wake, with the same reduction in wind speed observed in the tower wake, and a speed-up effect around the wake boundaries. Wind direction differences between pairs of sonic anemometers and between sonic anemometers and lidars can also be significant, as the flow is deflected by the tower structure. Comparisons of lengths of averaging intervals showed a decrease in wind speed deficit with longer averages, but the flow deflection remains constant over longer averages. Furthermore, asymmetry exists in the tower effects due to the geometry and placement of the booms on the triangular tower. An analysis of the percentage of observations in the wake that must be removed from 2 min mean wind speed and 20 min turbulent values showed that removing even small portions of the time interval due to wakes impacts these two quantities. Furthermorew, a vast majority of intervals have no observations in the tower wake, so removing the full 2 or 20 min intervals does not diminish the XPIA dataset.« less

Identification of tower-wake distortions using sonic anemometer and lidar measurements

DOE PAGES

McCaffrey, Katherine; Quelet, Paul T.; Choukulkar, Aditya; ...

2017-02-02

The eXperimental Planetary boundary layer Instrumentation Assessment (XPIA) field campaign took place in March through May 2015 at the Boulder Atmospheric Observatory, utilizing its 300 m meteorological tower, instrumented with two sonic anemometers mounted on opposite sides of the tower at six heights. This allowed for at least one sonic anemometer at each level to be upstream of the tower at all times and for identification of the times when a sonic anemometer is in the wake of the tower frame. Other instrumentation, including profiling and scanning lidars aided in the identification of the tower wake. Here we compare pairsmore » of sonic anemometers at the same heights to identify the range of directions that are affected by the tower for each of the opposing booms. The mean velocity and turbulent kinetic energy are used to quantify the wake impact on these first- and second-order wind measurements, showing up to a 50% reduction in wind speed and an order of magnitude increase in turbulent kinetic energy. Comparisons of wind speeds from profiling and scanning lidars confirmed the extent of the tower wake, with the same reduction in wind speed observed in the tower wake, and a speed-up effect around the wake boundaries. Wind direction differences between pairs of sonic anemometers and between sonic anemometers and lidars can also be significant, as the flow is deflected by the tower structure. Comparisons of lengths of averaging intervals showed a decrease in wind speed deficit with longer averages, but the flow deflection remains constant over longer averages. Furthermore, asymmetry exists in the tower effects due to the geometry and placement of the booms on the triangular tower. An analysis of the percentage of observations in the wake that must be removed from 2 min mean wind speed and 20 min turbulent values showed that removing even small portions of the time interval due to wakes impacts these two quantities. Furthermorew, a vast majority of intervals have no observations in the tower wake, so removing the full 2 or 20 min intervals does not diminish the XPIA dataset.« less

Seismic response of a full-scale wind turbine tower using experimental and numerical modal analysis

NASA Astrophysics Data System (ADS)

Kandil, Kamel Sayed Ahmad; Saudi, Ghada N.; Eltaly, Boshra Aboul-Anen; El-khier, Mostafa Mahmoud Abo

2016-12-01

Wind turbine technology has developed tremendously over the past years. In Egypt, the Zafarana wind farm is currently generating at a capacity of 517 MW, making it one of the largest onshore wind farms in the world. It is located in an active seismic zone along the west side of the Gulf of Suez. Accordingly, seismic risk assessment is demanded for studying the structural integrity of wind towers under expected seismic hazard events. In the context of ongoing joint Egypt-US research project "Seismic Risk Assessment of Wind Turbine Towers in Zafarana wind Farm Egypt" (Project ID: 4588), this paper describes the dynamic performance investigation of an existing Nordex N43 wind turbine tower. Both experimental and numerical work are illustrated explaining the methodology adopted to investigate the dynamic behavior of the tower under seismic load. Field dynamic testing of the full-scale tower was performed using ambient vibration techniques (AVT). Both frequency domain and time domain methods were utilized to identify the actual dynamic properties of the tower as built in the site. Mainly, the natural frequencies, their corresponding mode shapes and damping ratios of the tower were successfully identified using AVT. A vibration-based finite element model (FEM) was constructed using ANSYS V.12 software. The numerical and experimental results of modal analysis were both compared for matching purpose. Using different simulation considerations, the initial FEM was updated to finally match the experimental results with good agreement. Using the final updated FEM, the response of the tower under the AQABA earthquake excitation was investigated. Time history analysis was conducted to define the seismic response of the tower in terms of the structural stresses and displacements. This work is considered as one of the pioneer structural studies of the wind turbine towers in Egypt. Identification of the actual dynamic properties of the existing tower was successfully performed based on AVT. Using advanced techniques in both the field testing and the numerical investigations produced reliable FEM specific for the tested tower, which can be further used in more advanced structural investigations for improving the design of such special structures.

How many flux towers are enough? How tall is a tower tall enough? How elaborate a scaling is scaling enough?

NASA Astrophysics Data System (ADS)

Xu, K.; Sühring, M.; Metzger, S.; Desai, A. R.

2017-12-01

Most eddy covariance (EC) flux towers suffer from footprint bias. This footprint not only varies rapidly in time, but is smaller than the resolution of most earth system models, leading to a systemic scale mismatch in model-data comparison. Previous studies have suggested this problem can be mitigated (1) with multiple towers, (2) by building a taller tower with a large flux footprint, and (3) by applying advanced scaling methods. Here we ask: (1) How many flux towers are needed to sufficiently sample the flux mean and variation across an Earth system model domain? (2) How tall is tall enough for a single tower to represent the Earth system model domain? (3) Can we reduce the requirements derived from the first two questions with advanced scaling methods? We test these questions with output from large eddy simulations (LES) and application of the environmental response function (ERF) upscaling method. PALM LES (Maronga et al. 2015) was set up over a domain of 12 km x 16 km x 1.8 km at 7 m spatial resolution and produced 5 hours of output at a time step of 0.3 s. The surface Bowen ratio alternated between 0.2 and 1 among a series of 3 km wide stripe-like surface patches, with horizontal wind perpendicular to the surface heterogeneity. A total of 384 virtual towers were arranged on a regular grid across the LES domain, recording EC observations at 18 vertical levels. We use increasing height of a virtual flux tower and increasing numbers of virtual flux towers in the domain to compute energy fluxes. Initial results show a large (>25) number of towers is needed sufficiently sample the mean domain energy flux. When the ERF upscaling method was applied to the virtual towers in the LES environment, we were able to map fluxes over the domain to within 20% precision with a significantly smaller number of towers. This was achieved by relating sub-hourly turbulent fluxes to meteorological forcings and surface properties. These results demonstrate how advanced scaling techniques can decrease the number of towers, and thus experimental expense, required for domain-scaling over heterogeneous surface.

Dimensions of Air Traffic Control Tower Information Needs: From Information Requests to Display Design

ERIC Educational Resources Information Center

Durso, Francis T.; Johnson, Brian R.; Crutchfield, Jerry M.

2010-01-01

In an effort to determine the information needs of tower air traffic controllers, instructors from the Federal Aviation Administration's Academy in Oklahoma City were asked to control traffic in a high-fidelity tower cab simulator. Information requests were made apparent by eliminating access to standard tower information sources. Instead,…

Convection towers

DOEpatents

Prueitt, Melvin L.

1994-01-01

Convection towers which are capable of cleaning the pollution from large quantities of air and of generating electricity utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity. Other embodiments may also provide fresh water, and operate in an updraft mode.

Convection towers

DOEpatents

Prueitt, M.L.

1994-02-08

Convection towers which are capable of cleaning the pollution from large quantities of air and of generating electricity utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity. Other embodiments may also provide fresh water, and operate in an updraft mode. 5 figures.

Ivory Basements and Ivory Towers

ERIC Educational Resources Information Center

Fitzgerald, Tanya

2012-01-01

The metaphors of the ivory tower and ivory basement are used in this chapter to reflect how many women understand and experience the academy. The ivory tower signifies a place that is protected, a place of privilege and authority and a place removed from the outside world (and consequently the rigours of the market place). The ivory tower, by…

Cell-Phone Tower Power System Prototype Testing for Verizon Wireless |

Science.gov Websites

Verizon Wireless Cell-Phone Tower Power System Prototype Testing for Verizon Wireless For Verizon Wireless Advanced Manufacturing Research | NREL Cell-Phone Tower Power System Prototype Testing for , NREL tested a new cell-phone tower power system prototype based on DC interconnection and photovoltaics

VIEW OF BUILDING 215A, THE WATER TOWER, LOOKING WEST, SOUTHWEST. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW OF BUILDING 215A, THE WATER TOWER, LOOKING WEST, SOUTHWEST. CONSTRUCTION ON BUILDING 215A BEGAN IN 1952. THE WATER TOWER IS 155 FEET TALL AND IS THE TALLEST STRUCTURE AT THE ROCKY FLATS PLANT - Rocky Flats Plant, Water Tower, Northwest quadrant of Plant near west terminus of Central Avenue, Golden, Jefferson County, CO

77 FR 3440 - Utility Scale Wind Towers From the People's Republic of China and the Socialist Republic of...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-24

... Exhibit II-12. Petitioner determined labor costs using the labor consumption rates of the Wind Tower... natural gas costs using the natural gas consumption rates derived from the Wind Tower Producer's.... Petitioner determined labor costs using the labor consumption rates of the Wind Tower Producer. See Volume IV...

Approximate method for calculating free vibrations of a large-wind-turbine tower structure

NASA Technical Reports Server (NTRS)

Das, S. C.; Linscott, B. S.

1977-01-01

A set of ordinary differential equations were derived for a simplified structural dynamic lumped-mass model of a typical large-wind-turbine tower structure. Dunkerley's equation was used to arrive at a solution for the fundamental natural frequencies of the tower in bending and torsion. The ERDA-NASA 100-kW wind turbine tower structure was modeled, and the fundamental frequencies were determined by the simplified method described. The approximate fundamental natural frequencies for the tower agree within 18 percent with test data and predictions analyzed.

Feasibility Study on High Concentrating Photovoltaic Power Towers

NASA Astrophysics Data System (ADS)

Frohberger, Dirk; Jaus, Joachim; Wiesenfarth, Maike; Schramek, Philipp; Bett, Andreas W.

2010-10-01

This paper presents an analysis on the concept of high concentrating PV power towers. A feasibility study is conducted in order to evaluate the future potential of this technology. Objective of the analysis is to provide an improved basis for establishing research and development priorities for the PV power tower concept. Performance assessments and cost calculations for a 1 MW prototype PV tower power are derived. Based on the assumption of a highly homogeneously illuminated receiver, levelized costs of electricity of 0.29 €/kWh have been calculated for a prototype PV tower power.

System and method for aligning heliostats of a solar power tower

DOEpatents

Convery, Mark R.

2013-01-01

Disclosed is a solar power tower heliostat alignment system and method that includes a solar power tower with a focal area, a plurality of heliostats that each reflect sunlight towards the focal area of the solar power tower, an off-focal area location substantially close to the focal area of the solar power tower, a communication link between the off-focal area location and a misaligned heliostat, and a processor that interprets the communication between the off-focal area location and the misaligned heliostat to identify the misaligned heliostat from the plurality of heliostats and that determines a correction for the identified misaligned heliostat to realign the misaligned heliostat to reflect sunlight towards the focal area of the solar power tower.

Control of Carbon Nanotube Density and Tower Height in an Array

NASA Technical Reports Server (NTRS)

Delzeit, Lance D. (Inventor); Schipper, John F. (Inventor)

2010-01-01

A method for controlling density or tower height of carbon nanotube (CNT) arrays grown in spaced apart first and second regions on a substrate. CNTs having a first density range (or first tower height range) are grown in the first region using a first source temperature range for growth. Subsequently or simultaneously, CNTs having a second density range (or second tower height range), having an average density (or average tower height) in the second region different from the average density (or average tower height) for the first region, are grown in the second region, using supplemental localized hearing for the second region. Application for thermal dissipation and/or dissipation of electrical charge or voltage in an electronic device are discussed.

Atom chip gravimeter

NASA Astrophysics Data System (ADS)

Schubert, Christian; Abend, Sven; Gebbe, Martina; Gersemann, Matthias; Ahlers, Holger; Müntinga, Hauke; Matthias, Jonas; Sahelgozin, Maral; Herr, Waldemar; Lämmerzahl, Claus; Ertmer, Wolfgang; Rasel, Ernst

2016-04-01

Atom interferometry has developed into a tool for measuring rotations [1], accelerations [2], and testing fundamental physics [3]. Gravimeters based on laser cooled atoms demonstrated residual uncertainties of few microgal [2,4] and were simplified for field applications [5]. Atomic gravimeters rely on the interference of matter waves which are coherently manipulated by laser light fields. The latter can be interpreted as rulers to which the position of the atoms is compared. At three points in time separated by a free evolution, the light fields are pulsed onto the atoms. First, a coherent superposition of two momentum states is produced, then the momentum is inverted, and finally the two trajectories are recombined. Depending on the acceleration the atoms experienced, the number of atoms detected in the output ports will change. Consequently, the acceleration can be determined from the output signal. The laser cooled atoms with microkelvin temperatures used in state-of-the-art gravimeters impose limits on the accuracy [4]. Therefore, ultra-cold atoms generated by Bose-Einstein condensation and delta-kick collimation [6,7] are expected to be the key for further improvements. These sources suffered from a low flux implying an incompatible noise floor, but a competitive performance was demonstrated recently with atom chips [8]. In the compact and robust setup constructed for operation in the drop tower [6] we demonstrated all steps necessary for an atom chip gravimeter with Bose-Einstein condensates in a ground based operation. We will discuss the principle of operation, the current performance, and the perspectives to supersede the state of the art. The authors thank the QUANTUS cooperation for contributions to the drop tower project in the earlier stages. This work is supported by the German Space Agency (DLR) with funds provided by the Federal Ministry for Economic Affairs and Energy (BMWi) due to an enactment of the German Bundestag under grant numbers DLR 50WM1552-1557 (QUANTUS-IV-Fallturm) and by the Deutsche Forschungsgemeinschaft in the framework of the SFB 1128 geo-Q. [1] P. Berg et al., Composite-Light-Pulse Technique for High-Precision Atom Interferometry, Phys. Rev. Lett., 114, 063002, 2015. [2] A. Peters et al., Measurement of gravitational acceleration by dropping atoms, Nature 400, 849, 1999. [3] D. Schlippert et al., Quantum Test of the Universality of Free Fall, Phys. Rev. Lett., 112, 203002, 2014. [4] A. Louchet-Chauvet et al., The influence of transverse motion within an atomic gravimeter, New J. Phys. 13, 065026, 2011. [5] Q. Bodart et al., A cold atom pyramidal gravimeter with a single laser beam, Appl. Phys. Lett. 96, 134101, 2010. [6] H. Müntinga et al., Interferometry with Bose-Einstein Condensates in Microgravity, Phys. Rev. Lett., 110, 093602, 2013. [7] T. Kovachy et al., Matter Wave Lensing to Picokelvin Temperatures, Phys. Rev. Lett. 114, 143004, 2015. [8] J. Rudolph et al., A high-flux BEC source for mobile atom interferometers, New J. Phys. 17, 065001, 2015.

The Damaging Effects of Earthquake Excitation on Concrete Cooling Towers

NASA Astrophysics Data System (ADS)

Abedi-Nik, Farhad; Sabouri-Ghomi, Saeid

2008-07-01

Reinforced concrete cooling towers of hyperbolic shell configuration find widespread application in utilities engaged in the production of electric power. In design of critical civil infrastructure of this type, it is imperative to consider all the possible loading conditions that the cooling tower may experience, an important loading condition in many countries is that of the earthquake excitation, whose influence on the integrity and stability of cooling towers is profound. Previous researches have shown that the columns supporting a cooling tower are sensitive to earthquake forces, as they are heavily loaded elements that do not possess high ductility, and understanding the behavior of columns under earthquake excitation is vital in structural design because they provide the load path for the self weight of the tower shell. This paper presents the results of a finite element investigation of a representative "dry" cooling tower, using realistic horizontal and vertical acceleration data obtained from the recent and widely-reported Tabas, Naghan and Bam earthquakes in Iran. The results of both linear and nonlinear analyses are reported in the paper, the locations of plastic hinges within the supporting columns are identified and the ramifications of the plastic hinges on the stability of the cooling tower are assessed. It is concluded that for the (typical) cooling tower configuration analyzed, the columns that are instrumental in providing a load path are influenced greatly by earthquake loading, and for the earthquake data used in this study the representative cooling tower would be rendered unstable and would collapse under the earthquake forces considered.

The Damaging Effects of Earthquake Excitation on Concrete Cooling Towers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abedi-Nik, Farhad; Sabouri-Ghomi, Saeid

2008-07-08

Reinforced concrete cooling towers of hyperbolic shell configuration find widespread application in utilities engaged in the production of electric power. In design of critical civil infrastructure of this type, it is imperative to consider all the possible loading conditions that the cooling tower may experience, an important loading condition in many countries is that of the earthquake excitation, whose influence on the integrity and stability of cooling towers is profound. Previous researches have shown that the columns supporting a cooling tower are sensitive to earthquake forces, as they are heavily loaded elements that do not possess high ductility, and understandingmore » the behavior of columns under earthquake excitation is vital in structural design because they provide the load path for the self weight of the tower shell. This paper presents the results of a finite element investigation of a representative 'dry' cooling tower, using realistic horizontal and vertical acceleration data obtained from the recent and widely-reported Tabas, Naghan and Bam earthquakes in Iran. The results of both linear and nonlinear analyses are reported in the paper, the locations of plastic hinges within the supporting columns are identified and the ramifications of the plastic hinges on the stability of the cooling tower are assessed. It is concluded that for the (typical) cooling tower configuration analyzed, the columns that are instrumental in providing a load path are influenced greatly by earthquake loading, and for the earthquake data used in this study the representative cooling tower would be rendered unstable and would collapse under the earthquake forces considered.« less

Simulation of Pressure-swing Distillation for Separation of Ethyl Acetate-Ethanol-Water

NASA Astrophysics Data System (ADS)

Yang, Jing; Zhou, Menglin; Wang, Yujie; Zhang, Xi; Wu, Gang

2017-12-01

In the light of the azeotrope of ethyl acetate-ethanol-water, a process of pressure-swing distillation is proposed. The separation process is simulated by Aspen Plus, and the effects of theoretical stage number, reflux ratio and feed stage about the pressure-swing distillation are optimized. Some better process parameters are as follows: for ethyl acetate refining tower, the pressure is 500.0 kPa, theoretical stage number is 16, reflux ratio is 0.6, feed stage is 5; for crude ethanol tower, the pressure is 101.3 kPa, theoretical stage number is 15, reflux ratio is 0.3, feed stage is 4; for ethanol tower, the pressure is 101.3 kPa, theoretical stage number is 25, reflux ratio is 1.2, feed stage is 10. The mass fraction of ethyl acetate in the bottom of the ethyl acetate refining tower reaches 0.9990, the mass fraction of ethanol in the top of the ethanol tower tower reaches 0.9017, the mass fraction of water in the bottom of the ethanol tower tower reaches 0.9622, and there is also no ethyl acetate in the bottom of the ethanol tower. With laboratory tests, experimental results are in good agreement with the simulation results, which indicates that the separation of ethyl acetate ethanol water can be realized by the pressure-swing distillation separation process. Moreover, it has certain practical significance to industrial practice.

2. Signal Tower, looking east. Delaware, Lackawanna & Western ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. Signal Tower, looking east. - Delaware, Lackawanna & Western Railroad, Scranton Yards, Mattes Street Signal Tower, 80 feet Southwest of Railroad Alley & Cedar Avenue, Scranton, Lackawanna County, PA

Performance Evaluation of a Mechanical Draft Cross Flow Cooling Towers Employed in a Subtropical Region

NASA Astrophysics Data System (ADS)

Muthukumar, Palanisamy; Naik, Bukke Kiran; Goswami, Amarendra

2018-02-01

Mechanical draft cross flow cooling towers are generally used in a large-scale water cooled condenser based air-conditioning plants for removing heat from warm water which comes out from the condensing unit. During this process considerable amount of water in the form of drift (droplets) and evaporation is carried away along with the circulated air. In this paper, the performance evaluation of a standard cross flow induced draft cooling tower in terms of water loss, range, approach and cooling tower efficiency are presented. Extensive experimental studies have been carried out in three cooling towers employed in a water cooled condenser based 1200 TR A/C plant over a period of time. Daily variation of average water loss and cooling tower performance parameters have been reported for some selected days. The reported average water loss from three cooling towers is 4080 l/h and the estimated average water loss per TR per h is about 3.1 l at an average relative humidity (RH) of 83%. The water loss during peak hours (2 pm) is about 3.4 l/h-TR corresponding to 88% of RH and the corresponding efficiency of cooling towers varied between 25% and 45%.

Finite Element Analysis of the Maximum Stress at the Joints of the Transmission Tower

NASA Astrophysics Data System (ADS)

Itam, Zarina; Beddu, Salmia; Liyana Mohd Kamal, Nur; Bamashmos, Khaled H.

2016-03-01

Transmission towers are tall structures, usually a steel lattice tower, used to support an overhead power line. Usually, transmission towers are analyzed as frame-truss systems and the members are assumed to be pin-connected without explicitly considering the effects of joints on the tower behavior. In this research, an engineering example of joint will be analyzed with the consideration of the joint detailing to investigate how it will affect the tower analysis. A static analysis using STAAD Pro was conducted to indicate the joint with the maximum stress. This joint will then be explicitly analyzed in ANSYS using the Finite Element Method. Three approaches were used in the software which are the simple plate model, bonded contact with no bolts, and beam element bolts. Results from the joint analysis show that stress values increased with joint details consideration. This proves that joints and connections play an important role in the distribution of stress within the transmission tower.

Investigation of flow characteristics of a single and two-adjacent natural draft dry cooling towers under cross wind condition

NASA Astrophysics Data System (ADS)

Mekanik, Abolghasem; Soleimani, Mohsen

2007-11-01

Wind effect on natural draught cooling towers has a very complex physics. The fluid flow and temperature distribution around and in a single and two adjacent (tandem and side by side) dry-cooling towers under cross wind are studied numerically in the present work. Cross-wind can significantly reduce cooling efficiency of natural-draft dry-cooling towers, and the adjacent towers can affect the cooling efficiency of both. In this paper we will present a complex computational model involving more than 750,000 finite volume cells under precisely defined boundary condition. Since the flow is turbulent, the standard k-ɛ turbulence model is used. The numerical results are used to estimate the heat transfer between radiators of the tower and air surrounding it. The numerical simulation explained the main reason for decline of the thermo-dynamical performance of dry-cooling tower under cross wind. In this paper, the incompressible fluid flow is simulated, and the flow is assumed steady and three-dimensional.

'Towers in the Tempest' Computer Animation Submission

NASA Technical Reports Server (NTRS)

Shirah, Greg

2008-01-01

The following describes a computer animation that has been submitted to the ACM/SIGGRAPH 2008 computer graphics conference: 'Towers in the Tempest' clearly communicates recent scientific research into how hurricanes intensify. This intensification can be caused by a phenomenon called a 'hot tower.' For the first time, research meteorologists have run complex atmospheric simulations at a very fine temporal resolution of 3 minutes. Combining this simulation data with satellite observations enables detailed study of 'hot towers.' The science of 'hot towers' is described using: satellite observation data, conceptual illustrations, and a volumetric atmospheric simulation data. The movie starts by showing a 'hot tower' observed by NASA's Tropical Rainfall Measuring Mission (TRMM) spacecraft's three dimensional precipitation radar data of Hurricane Bonnie. Next, the dynamics of a hurricane and the formation of 'hot towers' are briefly explained using conceptual illustrations. Finally, volumetric cloud, wind, and vorticity data from a supercomputer simulation of Hurricane Bonnie are shown using volume techniques such as ray marching.

Minimizing corrosion in coal liquid distillation

DOEpatents

Baumert, Kenneth L.; Sagues, Alberto A.; Davis, Burtron H.

1985-01-01

In an atmospheric distillation tower of a coal liquefaction process, tower materials corrosion is reduced or eliminated by introduction of boiling point differentiated streams to boiling point differentiated tower regions.

3. West elevation of Signal Tower. Delaware, Lackawanna & ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. West elevation of Signal Tower. - Delaware, Lackawanna & Western Railroad, Scranton Yards, Mattes Street Signal Tower, 80 feet Southwest of Railroad Alley & Cedar Avenue, Scranton, Lackawanna County, PA

Enumeration of Legionella pneumophila in cooling tower water systems.

PubMed

Türetgen, Irfan; Sungur, Esra Ilhan; Cotuk, Aysin

2005-01-01

Legionella pneumophila, the causative agent of Legionnaires' disease, is known to colonise and frequently grow in cooling tower waters. Disease is acquired by inhaling aerosol contaminated by legionellae. Determination of the count of Legionella pneumophila in cooling tower waters may, therefore, be useful for risk assessment. In our survey, 103 water samples from 50 cooling towers were examined over a five-year period to indicate the seasonal distribution and the ecology of L. pneumophila, as regards temperature and pH. L. pneumophila serogroup 1 was found in 44% of the isolated strains, which is primarily responsible for the majority of Legionnaires' disease. The large majority of examined towers had levels of L. pneumophila in the high-risk category. These cooling towers have been linked to many outbreaks of Legionnaires' disease.

Movement planning reflects skill level and age changes in toddlers

PubMed Central

Chen, Yu-ping; Keen, Rachel; Rosander, Kerstin; von Hofsten, Claes

2010-01-01

Kinematic measures of children’s reaching were found to reflect stable differences in skill level for planning for future actions. Thirty-five toddlers (18–21 months) were engaged in building block towers (precise task) and in placing blocks into an open container (imprecise task). Sixteen children were re-tested on the same tasks a year later. Longer deceleration as the hand approached the block for pickup was found in the tower task compared to the imprecise task, indicating planning for the second movement. More skillful toddlers who could build high towers had a longer deceleration phase when placing blocks on the tower than toddlers who built low towers. Kinematic differences between the groups remained a year later when all children could build high towers. PMID:21077868

VALVE TOWER FROM HIGH GROUND NEAR APPROACH BRIDGE. VIEW FACING ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VALVE TOWER FROM HIGH GROUND NEAR APPROACH BRIDGE. VIEW FACING NORTHEAST - Schofield Barracks Military Reservation, Ku Tree Reservoir, Valve Tower, Kalakoa Stream, East Range, Wahiawa, Honolulu County, HI

PBF Cooling Tower. Hot deck of Cooling Tower with fan ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

PBF Cooling Tower. Hot deck of Cooling Tower with fan motors in place. Fan's propeller blades (not in view) rotate within lower portion of vents. Inlet pipe is a left of view. Contractor's construction buildings in view to right. Photographer: Larry Page. Date: June 30, 1969. INEEL negative no. 69-3781 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

Some extemporaneous comments on our experiences with towers for wind generators

NASA Technical Reports Server (NTRS)

Hutter, U.

1973-01-01

A wind generator tower must be designed to withstand fatigue forces and gust winds loads. Optimum tower height depends on the energy cost to the customer because an increase in height results in an increase in the cost of the plant. It is suggested that costs are minimum for the shortest tower possible and that the rotor should be as large as possible.

Evaluating the effectiveness of wildlife detection and observation technologies at a solar power tower facility

USGS Publications Warehouse

Diehl, Robert H.; Valdez, Ernest W.; Preston, Todd M.; Wellik, Mike J.; Cryan, Paul

2016-01-01

Solar power towers produce electrical energy from sunlight at an industrial scale. Little is known about the effects of this technology on flying animals and few methods exist for automatically detecting or observing wildlife at solar towers and other tall anthropogenic structures. Smoking objects are sometimes observed co-occurring with reflected, concentrated light (“solar flux”) in the airspace around solar towers, but the identity and origins of such objects can be difficult to determine. In this observational pilot study at the world’s largest solar tower facility, we assessed the efficacy of using radar, surveillance video, and insect trapping to detect and observe animals flying near the towers. During site visits in May and September 2014, we monitored the airspace surrounding towers and observed insects, birds, and bats under a variety of environmental and operational conditions. We detected and broadly differentiated animals or objects moving through the airspace generally using radar and near solar towers using several video imaging methods. Video revealed what appeared to be mostly small insects burning in the solar flux. Also, we occasionally detected birds flying in the solar flux but could not accurately identify birds to species or the types of insects and small objects composing the vast majority of smoking targets. Insect trapping on the ground was somewhat effective at sampling smaller insects around the tower, and presence and abundance of insects in the traps generally trended with radar and video observations. Traps did not tend to sample the larger insects we sometimes observed flying in the solar flux or found dead on the ground beneath the towers. Some of the methods we tested (e.g., video surveillance) could be further assessed and potentially used to automatically detect and observe flying animals in the vicinity of solar towers to advance understanding about their effects on wildlife.

Evaluating the Effectiveness of Wildlife Detection and Observation Technologies at a Solar Power Tower Facility.

PubMed

Diehl, Robert H; Valdez, Ernest W; Preston, Todd M; Wellik, Michael J; Cryan, Paul M

2016-01-01

Solar power towers produce electrical energy from sunlight at an industrial scale. Little is known about the effects of this technology on flying animals and few methods exist for automatically detecting or observing wildlife at solar towers and other tall anthropogenic structures. Smoking objects are sometimes observed co-occurring with reflected, concentrated light ("solar flux") in the airspace around solar towers, but the identity and origins of such objects can be difficult to determine. In this observational pilot study at the world's largest solar tower facility, we assessed the efficacy of using radar, surveillance video, and insect trapping to detect and observe animals flying near the towers. During site visits in May and September 2014, we monitored the airspace surrounding towers and observed insects, birds, and bats under a variety of environmental and operational conditions. We detected and broadly differentiated animals or objects moving through the airspace generally using radar and near solar towers using several video imaging methods. Video revealed what appeared to be mostly small insects burning in the solar flux. Also, we occasionally detected birds flying in the solar flux but could not accurately identify birds to species or the types of insects and small objects composing the vast majority of smoking targets. Insect trapping on the ground was somewhat effective at sampling smaller insects around the tower, and presence and abundance of insects in the traps generally trended with radar and video observations. Traps did not tend to sample the larger insects we sometimes observed flying in the solar flux or found dead on the ground beneath the towers. Some of the methods we tested (e.g., video surveillance) could be further assessed and potentially used to automatically detect and observe flying animals in the vicinity of solar towers to advance understanding about their effects on wildlife.

Evaluating the Effectiveness of Wildlife Detection and Observation Technologies at a Solar Power Tower Facility

PubMed Central

Diehl, Robert H.; Valdez, Ernest W.; Preston, Todd M.; Wellik, Michael J.; Cryan, Paul M.

2016-01-01

Solar power towers produce electrical energy from sunlight at an industrial scale. Little is known about the effects of this technology on flying animals and few methods exist for automatically detecting or observing wildlife at solar towers and other tall anthropogenic structures. Smoking objects are sometimes observed co-occurring with reflected, concentrated light (“solar flux”) in the airspace around solar towers, but the identity and origins of such objects can be difficult to determine. In this observational pilot study at the world’s largest solar tower facility, we assessed the efficacy of using radar, surveillance video, and insect trapping to detect and observe animals flying near the towers. During site visits in May and September 2014, we monitored the airspace surrounding towers and observed insects, birds, and bats under a variety of environmental and operational conditions. We detected and broadly differentiated animals or objects moving through the airspace generally using radar and near solar towers using several video imaging methods. Video revealed what appeared to be mostly small insects burning in the solar flux. Also, we occasionally detected birds flying in the solar flux but could not accurately identify birds to species or the types of insects and small objects composing the vast majority of smoking targets. Insect trapping on the ground was somewhat effective at sampling smaller insects around the tower, and presence and abundance of insects in the traps generally trended with radar and video observations. Traps did not tend to sample the larger insects we sometimes observed flying in the solar flux or found dead on the ground beneath the towers. Some of the methods we tested (e.g., video surveillance) could be further assessed and potentially used to automatically detect and observe flying animals in the vicinity of solar towers to advance understanding about their effects on wildlife. PMID:27462989

OVERVIEW OF VALVE TOWER FROM NORTHERN SIDE OF BASIN. VIEW ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

OVERVIEW OF VALVE TOWER FROM NORTHERN SIDE OF BASIN. VIEW FACING SOUTHWEST - Schofield Barracks Military Reservation, Ku Tree Reservoir, Valve Tower, Kalakoa Stream, East Range, Wahiawa, Honolulu County, HI

Geology of Devils Tower National Monument, Wyoming

USGS Publications Warehouse

Robinson, Charles Sherwood

1956-01-01

Devils Tower is a steep-sided mass of igneous rock that rises above the surrounding hills and the valley of the Belle Fourche River in Crook County, Wyo. It is composed of a crystalline rock, classified as phonolite porphyry, that when fresh is gray but which weathers to green or brown. Vertical joints divide the rock mass into polygonal columns that extend from just above the base to the top of the Tower. The hills in the vicinity and at the base of the Tower are composed of red, yellow, green, or gray sedimentary rocks that consist of sandstone, shale, or gypsum. These rocks, in aggregate about 400 feet thick, include, from oldest to youngest, the upper part of the Spearfish formation, of Triassic age, the Gypsum Spring formation, of Middle Jurassic age, and the Sundance formation, of Late Jurassic age. The Sundance formation consists of the Stockade Beaver shale member, the Hulett sandstone member, the Lak member, and the Redwater shale member. The formations have been only slightly deformed by faulting and folding. Within 2,000 to 3.000 feet of the Tower, the strata for the most part dip at 3 deg - 5 deg towards the Tower. Beyond this distance, they dip at 2 deg - 5 deg from the Tower. The Tower is believed to have been formed by the intrusion of magma into the sedimentary rocks, and the shape of the igneous mass formed by the cooled magma is believed to have been essentially the same as the Tower today. Devils Tower owes its impressiveness to its resistance to erosion as compared with the surrounding sedimentary rocks, and to the contrast of the somber color of the igneous column to the brightly colored bands of sedimentary rocks.

28. WEST CONFEDERATE AVENUE, OBSERVATION TOWER, VIEW FROM THE TOP ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

28. WEST CONFEDERATE AVENUE, OBSERVATION TOWER, VIEW FROM THE TOP OF TOWER TO SOUTH. NOTE FOREST AND AGRICULTURAL LANDSCAPES. VIEW S. - Gettysburg National Military Park Tour Roads, Gettysburg, Adams County, PA

6. View of south tower, facing south from Clover Island, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. View of south tower, facing south from Clover Island, across boat moorage channel. - Pasco-Kennewick Transmission Line, Columbia River Crossing Towers, Columbia Drive & Gum Street, Kennewick, Benton County, WA

1. Perspective of Mattes Street Signal Tower looking southwest. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. Perspective of Mattes Street Signal Tower looking southwest. - Delaware, Lackawanna & Western Railroad, Scranton Yards, Mattes Street Signal Tower, 80 feet Southwest of Railroad Alley & Cedar Avenue, Scranton, Lackawanna County, PA

7. Detail of first floor doorway to Signal Tower. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. Detail of first floor doorway to Signal Tower. - Delaware, Lackawanna & Western Railroad, Scranton Yards, Mattes Street Signal Tower, 80 feet Southwest of Railroad Alley & Cedar Avenue, Scranton, Lackawanna County, PA

Evaporation Tower With Prill Nozzles

NASA Technical Reports Server (NTRS)

Du Fresne, E. R.

1984-01-01

Tower more efficient than conventional evaporation equipment. Liquids such as milk and fruit juice concentrated by passing them through tiny nozzle to form droplets, then allowing droplets to fall through evacuated tower with cooled walls.

2. Detail of tower foundation with lightning transfer wire, southeast ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. Detail of tower foundation with lightning transfer wire, southeast corner - Cold Mountain Fire Lookout Station, Lookout Tower, Krassel District, Frank Church River of No Return Wilderness, Dixie, Idaho County, ID

Flux Sampling Errors for Aircraft and Towers

NASA Technical Reports Server (NTRS)

Mahrt, Larry

1998-01-01

Various errors and influences leading to differences between tower- and aircraft-measured fluxes are surveyed. This survey is motivated by reports in the literature that aircraft fluxes are sometimes smaller than tower-measured fluxes. Both tower and aircraft flux errors are larger with surface heterogeneity due to several independent effects. Surface heterogeneity may cause tower flux errors to increase with decreasing wind speed. Techniques to assess flux sampling error are reviewed. Such error estimates suffer various degrees of inapplicability in real geophysical time series due to nonstationarity of tower time series (or inhomogeneity of aircraft data). A new measure for nonstationarity is developed that eliminates assumptions on the form of the nonstationarity inherent in previous methods. When this nonstationarity measure becomes large, the surface energy imbalance increases sharply. Finally, strategies for obtaining adequate flux sampling using repeated aircraft passes and grid patterns are outlined.

Legionnaires' Disease Outbreak at a Long-Term Care Facility Caused by a Cooling Tower Using an Automated Disinfection System--Ohio, 2013.

PubMed

Quinn, Celia; Demirjian, Alicia; Watkins, Louise Francois; Tomczyk, Sara; Lucas, Claressa; Brown, Ellen; Kozak-Muiznieks, Natalia; Benitez, Alvaro; Garrison, Laurel E; Kunz, Jasen; Brewer, Scott; Eitniear, Samantha; DiOrio, Mary

2015-12-01

On July 9, 2013, an outbreak of Legionnaires' disease (LD) was identified at Long-Term Care Facility A in central Ohio. This article describes the investigation of the outbreak and identification of the outbreak source, a cooling tower using an automated biocide delivery system. In total, 39 outbreak LD cases were identified; among these, six patients died. Water samples from a cooling tower were positive for Legionella pneumophila serogroup 1, reactive to monoclonal antibody 2, with matching sequence type to a patient isolate. An electronic control system turned off cooling tower pumps during low-demand periods, preventing delivery of disinfectant by a timed-release system, and leading to amplification of Legionella in the cooling tower. Guidelines for tower maintenance should address optimal disinfection when using automated systems.

A Meso-Climatology Study of the High-Resolution Tower Network Over the Florida Spaceport

NASA Technical Reports Server (NTRS)

Case, Jonathan L.; Bauman, William H., III

2004-01-01

Forecasters at the US Air Force 45th Weather Squadron (45 WS) use wind and temperature data from the tower network over the Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS) to evaluate Launch Commit Criteria and to issue and verify temperature and wind advisories, watches, and warnings for ground operations. The Spaceflight Meteorology Group at the Johnson Space Center in Houston, TX also uses these data when issuing forecasts for shuttle landings at the KSC Shuttle Landing Facility. Systematic biases in these parameters at any of the towers could adversely affect an analysis, forecast, or verification for all of these operations. In addition, substantial geographical variations in temperature and wind speed can occur under specific wind directions. Therefore, the Applied Meteorology Unit (AMU), operated by ENSCO Inc., was tasked to develop a monthly and hourly climatology of temperatures and winds from the tower network, and identify the geographical variation, tower biases, and the magnitude of those biases. This paper presents a sub-set of results from a nine-year climatology of the KSC/CCAFS tower network, highlighting the geographical variations based on location, month, times of day, and specific wind direction regime. Section 2 provides a description of the tower mesonetwork and instrumentation characteristics. Section 3 presents the methodology used to construct the tower climatology including QC methods and data processing. The results of the tower climatology are presented in Section 4 and Section 5 summarizes the paper.

Research Based on the Acoustic Emission of Wind Power Tower Drum Dynamic Monitoring Technology

NASA Astrophysics Data System (ADS)

Zhang, Penglin; Sang, Yuan; Xu, Yaxing; Zhao, Zhiqiang

Wind power tower drum is one of the key components of the wind power equipment. Whether the wind tower drum performs safety directly affects the efficiency, life, and performance of wind power equipment. Wind power tower drum in the process of manufacture, installation, and operation may lead to injury, and the wind load and gravity load and long-term factors such as poor working environment under the action of crack initiation or distortion, which eventually result in the instability or crack of the wind power tower drum and cause huge economic losses. Thus detecting the wind power tower drum crack damage and instability is especially important. In this chapter, acoustic emission is used to monitor the whole process of wind power tower drum material Q345E steel tensile test at first, and processing and analysis tensile failure signal of the material. And then based on the acoustic emission testing technology to the dynamic monitoring of wind power tower drum, the overall detection and evaluation of the existence of active defects in the whole structure, and the acoustic emission signals collected for processing and analysis, we could preliminarily master the wind tower drum mechanism of acoustic emission source. The acoustic emission is a kind of online, efficient, and economic method, which has very broad prospects for work. The editorial committee of nondestructive testing qualification and certification of personnel teaching material of science and technology industry of national defense, "Acoustic emission testing" (China Machine Press, 2005.1).

Enhanced Precision Geolocation in 4G Wireless Networks

DTIC Science & Technology

2013-03-01

years has implemented a National Emergency Warning System using text messages delivered to cell phones [5]. The November 1999 FCC E911 regulations...statistical theory of passive geolocation of emitters may be found in [18]. Papers that survey methods of geolocation applied to cell phones include [4...where to put the tower % n: which tower to place %randomTowers(obj,dispersion, seperation ): generates % random towers for the network % obj: the network

Roughness Length Variability over Heterogeneous Surfaces

DTIC Science & Technology

2010-03-01

urban areas, marshes, temperate forests , barrier islands, sheltered inland waters, and the Atlantic Ocean . Depending upon the strength and direction of...32. Satellite photograph showing the proximity of Tower 0002 to the Atlantic Ocean . The tower is less than 1 km from the ocean in sector 120°–180...proximity of Tower 0110 to the Banana River and Atlantic Ocean . Red "X" marks the tower location. Image ©2010 Google

KSC-99pp1217

NASA Image and Video Library

1999-10-14

KENNEDY SPACE CENTER, FLA. -- Workers are dwarfed by the fallen 300-foot, five-million-pound Mobile Service Tower (MST) on Launch Complex 41, Cape Canaveral Air Force Station. The MST and a 200-foot-high umbilical tower nearby were demolished to make room for Lockheed Martin's 14-acre Vehicle Integration Facility (VIF), under construction. Only lightning protection towers remain standing at the site. About 200 pounds of linear-shaped charges were used to bring down the towers so that the materials can be recycled. The implosion and removal of the tower debris is expected to be completed in two months. The VIF will be used for Lockheed Martin's Atlas V Launch System.

Active tower damping and pitch balancing - design, simulation and field test

NASA Astrophysics Data System (ADS)

Duckwitz, Daniel; Shan, Martin

2014-12-01

The tower is one of the major components in wind turbines with a contribution to the cost of energy of 8 to 12% [1]. In this overview the load situation of the tower will be described in terms of sources of loads, load components and fatigue contribution. Then two load reduction control schemes are described along with simulation and field test results. Pitch Balancing is described as a method to reduce aerodynamic asymmetry and the resulting fatigue loads. Active Tower Damping is reducing the tower oscillations by applying appropiate pitch angle changes. A field test was conducted on an Areva M5000 wind turbine.

The Effects of Gravity on Wrinkled Laminar Flames

NASA Technical Reports Server (NTRS)

Kostiuk, Larry W.; Zhou, Liming; Cheng, Robert K.

1993-01-01

The effects of gravity are significant to the dynamics of idealized unconfined open premixed flames. Moderate to low turbulence Reynolds number flames, i.e., wrinkled laminar flames, of various unconfined geometries have been used extensively for investigating fundamental processes of turbulent flame propagation and to validate theoretical models. Without the wall constraints, the flames are free to expand and interact with surrounding ambient air. The flow field in which the flame exists is determined by a coupling of burner geometry, flame orientation and the gravity field. These complex interactions raise serious questions regarding the validity of comparing the experimental data of open flames with current theoretical and numerical models that do not include the effects of gravity nor effects of the larger aerodynamic flowfield. Therefore, studies of wrinkled laminar flame in microgravity are needed for a better understanding of the role of gravity on flame characteristics such as the orientation, mean aerodynamics stretch, flame wrinkle size and burning rate. Our approach to characterize and quantify turbulent flame structures under microgravity is to exploit qualitative and quantitative flow visualization techniques coupled with video recording and computer controlled image analysis technologies. The experiments will be carried out in the 2.2 second drop tower at the NASA Lewis Research Center. The longest time scales of typical wrinkled laminar flames in the geometries considered here are in the order of 10 msec. Hence, the duration of the drop is sufficient to obtain the amount of statistical data necessary for characterize turbulent flame structures.

Some Recent Observations on the Burning of Isolated N-Heptane and Alcohol Droplets

NASA Technical Reports Server (NTRS)

Dryer, F. L.

1999-01-01

In a joint program involving Prof F.A. Williams of the University of California, San Diego and Dr. Vedha Nayagam of the National Center for Microgravity Research on Fluid and Combustion, the combustion of liquid fuel droplets having initial diameters between about 1 mm and 6 mm is being studied. The objectives of the work are to improve fundamental knowledge of droplet combustion dynamics through microgravity experiments and theoretical analyses. The Princeton contributions to the collaborative program supports the engineering design, data analysis, and data interpretation requirements for the study of initially single component, spherically symmetric, isolated droplet combustion studies through experiments and numerical modeling. The complementary UCSD contributions apply asymptotic theoretical analyses and are described in the published literature and in a companion communication in this volume. Emphases of the Princeton work are on the study of simple alcohols (methanol, ethanol), alcohol/water mixtures, and pure alkanes (n-heptane, n-decane) as fuels, with time dependent measurements of drop size, flame-stand-off, liquid-phase composition, and finally, extinction. Ground based experiments have included bench-scale studies at Princeton and collaborative experimental studies in the 2.2 and 5.18 second drop towers at NASA-Glenn Research Center. Spacelab studies have included fiber-supported droplet combustion (FSDC) experiments in the Glovebox facility with accompanying numerical analyses. Experiments include FSDC-1, performed on the USML-2 mission in October, 1995 (STS-73) and FSDC-2, on the second flight of the MSL-1 mission in July, 1997 (STS-94).

1. View of north tower, facing northwest from dike on ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. View of north tower, facing northwest from dike on north bank of the Columbia River. - Pasco-Kennewick Transmission Line, Columbia River Crossing Towers, Columbia Drive & Gum Street, Kennewick, Benton County, WA

Interior of the mine observation tower building, showing the steel ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Interior of the mine observation tower building, showing the steel compass ring in the tower. View facing east - U.S. Naval Base, Pearl Harbor, Waipio Peninsula, Waipo Peninsula, Pearl City, Honolulu County, HI

Tower-supported solar-energy collector

NASA Technical Reports Server (NTRS)

Selcuk, M. K.

1977-01-01

Multiple-collector tower system supports three receiver/concentrators that absorb solar energy reflected from surrounding field of heliostats. System overcomes disadvantages of tower-supported collectors. Booms can be lowered during heavy winds to protect arms and collectors.

TOWER, WEST ELEVATION, SHOWING CONNECTION PIPES FOR TURNOUTS 22 (FOREGROUND) ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

TOWER, WEST ELEVATION, SHOWING CONNECTION PIPES FOR TURNOUTS 22 (FOREGROUND) AND 24. NOTE “LAZY JACK” TEMPERATURE COMPENSATOR IN FOREGROUND. - Baltimore & Ohio Railroad, Z Tower, State Route 46, Keyser, Mineral County, WV

6. Detail of windows in north wall of Signal Tower. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. Detail of windows in north wall of Signal Tower. - Delaware, Lackawanna & Western Railroad, Scranton Yards, Mattes Street Signal Tower, 80 feet Southwest of Railroad Alley & Cedar Avenue, Scranton, Lackawanna County, PA

4. VIEW, LOOKING SOUTHEAST, SHOWING NORTHWEST ELEVATION OF TOWER ND ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. VIEW, LOOKING SOUTHEAST, SHOWING NORTHWEST ELEVATION OF TOWER ND SIGNAL BRIDGE No. 6 AND DWARF SIGNAL IN FOREGROUND - South Station Tower No. 1 & Interlocking System, Dewey Square, Boston, Suffolk County, MA

Potentially pathogenic amoeba-associated microorganisms in cooling towers and their control.

PubMed

Pagnier, Isabelle; Merchat, Michèle; La Scola, Bernard

2009-06-01

Cooling towers provide a favorable environment for the proliferation of microorganisms. Cooling towers generate a biofilm and often aerosolize contaminated water, thereby increasing the risk of microorganism dissemination by human inhalation. This pathogen dissemination was first revealed by the epidemics of Legionnaires' disease that were directly related to the presence of cooling towers, and since then, the ecology of Legionella pneumophila has been well studied. Each country has specific standards regarding the acceptable amount of microorganisms in cooling tower systems. However, those standards typically only concern L. pneumophila, even though many other microorganisms can also be isolated from cooling towers, including protozoa, bacteria and viruses. Microbiological control of the cooling tower system can be principally achieved by chemical treatments and also by improving the system's construction. Several new treatments are being studied to improve the efficiency of disinfection. However, as most of these treatments continue to focus solely on L. pneumophila, reports of other types of pathogens continue to increase. Therefore, how their dissemination affects the human populous health should be addressed now.

8. LOOKING EAST FROM TOP OF WATER TOWER: VIEW SHOWS ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. LOOKING EAST FROM TOP OF WATER TOWER: VIEW SHOWS BUILDING #626 AND PORTION OF QUADRANGLE - Fort Sam Houston, San Antonio Depot, Water-Watch Tower, Grayson Street & New Braunfels Avenue, San Antonio, Bexar County, TX

3. View of north tower, facing north across the main ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. View of north tower, facing north across the main channel of the Columbus River from Clover Island. - Pasco-Kennewick Transmission Line, Columbia River Crossing Towers, Columbia Drive & Gum Street, Kennewick, Benton County, WA

29. Photocopy of 1921 photograph. Glass Negative Box IX, Tower ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

29. Photocopy of 1921 photograph. Glass Negative Box IX, Tower Grove, Missouri Botanical Garden. ITALIAN GARDEN AND NEW PALM HOUSE (DEMOLISHED), LOOKING NORTHEAST - Missouri Botanical Garden, 2345 Tower Grove Avenue, Saint Louis, Independent City, MO

Oblique view of the mine observation tower and transformer buildings, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Oblique view of the mine observation tower and transformer buildings, with the tower building behind. View facing south-southeast - U.S. Naval Base, Pearl Harbor, Waipio Peninsula, Waipo Peninsula, Pearl City, Honolulu County, HI

4. View of center tower at Clover Island, facing northeast. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. View of center tower at Clover Island, facing northeast. Pasco-Kennewick automobile bridge in background, lower right. - Pasco-Kennewick Transmission Line, Columbia River Crossing Towers, Columbia Drive & Gum Street, Kennewick, Benton County, WA

OVERVIEW OF VALVE TOWER FROM EASTERN SIDE OF BASIN SHOWING ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

OVERVIEW OF VALVE TOWER FROM EASTERN SIDE OF BASIN SHOWING BRIDGE SUPPORTS ON HILLTOP. VIEW FACING WEST - Schofield Barracks Military Reservation, Ku Tree Reservoir, Valve Tower, Kalakoa Stream, East Range, Wahiawa, Honolulu County, HI

View of the southwest guard tower, cell blocks seven and ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View of the southwest guard tower, cell blocks seven and eight, administration building west tower, and Fairmount Avenue, looking from the administration building facing west - Eastern State Penitentiary, 2125 Fairmount Avenue, Philadelphia, Philadelphia County, PA

12. GENERAL INTERIOR VIEW OF SIGNAL TOWER OFFICE FACING NORTH. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

12. GENERAL INTERIOR VIEW OF SIGNAL TOWER OFFICE FACING NORTH. - U.S. Naval Base, Pearl Harbor, Signal Tower, Corner of Seventh Street & Avenue D east of Drydock No. 1, Pearl City, Honolulu County, HI

ETR COOLING TOWER. PUMP HOUSE (TRA645) IN SHADOW OF TOWER ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

ETR COOLING TOWER. PUMP HOUSE (TRA-645) IN SHADOW OF TOWER ON LEFT. AT LEFT OF VIEW, HIGH-BAY BUILDING IS ETR. ONE STORY ATTACHMENT IS ETR ELECTRICAL BUILDING. STACK AT RIGHT IS ETR STACK; MTR STACK IS TOWARD LEFT. CAMERA FACING NORTHEAST. INL NEGATIVE NO. 56-3799. Jack L. Anderson, 11/26/1956 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

DOE Office of Scientific and Technical Information (OSTI.GOV)

Danguy des Deserts, L.M.J.; Michael, D.; Sedillot, F.G.

An oscillating platform is described for work at sea, the platform having a weight, comprising a deck, a lattice tower having an upper part and a lower part, the tower further having a total buoyancy center, and a center of gravity, an articulation formed by flexible piles. The articulation has a center; the flexible piles are driven into the sea bed and fixed to the upper part of the tower; the tower comprising floaters in its upper part and a ballast compartment in its lower part, as well as means for resisting shear forces; the product of the total buoyancymore » of the tower by the distance between the buoyancy center of the tower and the center of the articulation are at least equal to 1.25 times the product of the weight of the platform by the distance between the center of gravity of the platform and the center of the articulation.« less

Antenna structures and cloud-to-ground lightning location: 1995-2015

NASA Astrophysics Data System (ADS)

Kingfield, Darrel M.; Calhoun, Kristin M.; de Beurs, Kirsten M.

2017-05-01

Spatial analyses of cloud-to-ground (CG) lightning occurrence due to a rapid expansion in the number of antenna towers across the United States are explored by gridding 20 years of National Lightning Detection Network data at 500 m spatial resolution. The 99.8% of grid cells with ≥100 CGs were within 1 km of an antenna tower registered with the Federal Communications Commission. Tower height is positively correlated with CG occurrence; towers taller than 400 m above ground level experience a median increase of 150% in CG lightning density compared to a region 2 km to 5 km away. In the northern Great Plains, the cumulative CG lightning density near the tower was around 138% (117%) higher than a region 2 to 5 km away in the September-February (March-August) months. Higher CG frequencies typically also occur in the first full year following new tower construction, creating new lightning hot spots.

Modified shape of the Eiffel Tower determined for an atmospheric boundary-layer wind profile

NASA Astrophysics Data System (ADS)

Weidman, P. D.

2009-06-01

The design and construction of the Eiffel Tower was based, in part, on a uniform horizontal wind model giving 300 kg m-2 kinematic pressure acting on the surface of the tower. Eiffel received a patent for his method of construction that eliminates the need for diagonal trellis bars used to resist the moment of an oncoming wind. At the end of the 19th century boundary-layer theory, laminar or turbulent, was nonexistent. Now, however, models for atmospheric flow over rough landscapes are available, the simplest being a power-law distribution of velocity with height. In this paper we deduce the shape of the tower had Eiffel incorporated this information into the design and construction of his world famous tower. Moreover, we prove Eiffel's observation that the tower profile conforms to the moment distribution wrought by the wind.

Wind tower service lift

DOEpatents

Oliphant, David; Quilter, Jared; Andersen, Todd; Conroy, Thomas

2011-09-13

An apparatus used for maintaining a wind tower structure wherein the wind tower structure may have a plurality of legs and may be configured to support a wind turbine above the ground in a better position to interface with winds. The lift structure may be configured for carrying objects and have a guide system and drive system for mechanically communicating with a primary cable, rail or other first elongate member attached to the wind tower structure. The drive system and guide system may transmit forces that move the lift relative to the cable and thereby relative to the wind tower structure. A control interface may be included for controlling the amount and direction of the power into the guide system and drive system thereby causing the guide system and drive system to move the lift relative to said first elongate member such that said lift moves relative to said wind tower structure.

Hospital-acquired legionellosis originating from a cooling tower during a period of thermal inversion.

PubMed

Engelhart, Steffen; Pleischl, Stefan; Lück, Christian; Marklein, Günter; Fischnaller, Edith; Martin, Sybille; Simon, Arne; Exner, Martin

2008-07-01

A case of hospital-acquired legionellosis occurred in a 75-year-old male patient who underwent surgery due to malignant melanoma. Legionellosis was proven by culture of Legionella pneumophila serogroup 1 from bronchoalveolar lavage (BAL) fluid. Being a chronic smoker the patient used to visit the sickroom balcony that was located about 90 m to the west of a hospital cooling tower. Routine cooling tower water samples drawn during the presumed incubation period revealed 1.0x10(4) CFU/100 ml (L. pneumophila serogroup 1). One of three isolates from the cooling tower water matched the patient's isolate by monoclonal antibody (mab)- and genotyping (sequence-based typing). Horizontal transport of cooling tower aerosols probably was favoured by meteorological conditions with thermal inversion. The case report stresses the importance of routine maintenance and microbiological control of hospital cooling towers.

Analysis of Wind Characteristics at United States Tall Tower Measurement Sites

NASA Astrophysics Data System (ADS)

Elliott, D.; Schwartz, M.; Scott, G.; Haymes, S.

2008-12-01

A major initiative of the U.S. Department of Energy (DOE) is to ensure that 20% of the country's electricity is produced by wind energy by the year 2030. An understanding of the boundary layer characteristics, especially at elevated heights greater than 80 meters (m) above the surface is a key factor for wind turbine design, wind plant layout, and identifying potential markets for advanced wind technology. The wind resource group at the DOE National Renewable Energy Laboratory is analyzing wind data collected at tall (80+ m) towers across the United States. The towers established by both public and private initiative, measure wind characteristics at multiple levels above the surface, with the highest measurement levels generally between 80 and 110 m. A few locations have measurements above 200 m. Measurements of wind characteristics over a wide range of heights are useful to: (1) characterize the local and regional wind climate; (2) validate wind resource estimates derived from numerical models; and (3) directly assess and analyze specific wind resource characteristics such as wind speed shear over the turbine blade swept area. The majority of the available public tall tower measurement sites are located between the Appalachian and Rocky Mountains. The towers are not evenly distributed among the states. The states with the largest number of towers include Indiana, Iowa, Missouri, and Kansas. These states have five or six towers collecting data. Other states with multiple tower locations include Texas, Oklahoma, Minnesota, and Ohio. The primary consideration when analyzing the data from the tall towers is identifying tower flow effects that not only can produce slightly misleading average wind speeds, but also significantly misleading wind speed shear values. In addition, the periods-of-record of most tall tower data are only one to two years in length. The short data collection time frame does not significantly affect the diurnal wind speed pattern though it does complicate analysis of seasonal wind patterns. The tall tower data analysis revealed some distinct regional features of wind shear climatology. For example, the wind shear exponent (alpha) at the towers in the Central Plains is generally between 0.15 and 0.25, greater than the commonly used 1/7 power law exponent value of 0.143. Another characteristic of Central Plains wind climatology was that winds from the south had alpha values of 0.2 to 0.3, while northerly winds had lower alpha values from 0.1 to 0.2. The wind resource at a particular tower is affected not only by the regional climatology but also by local conditions such as terrain, surface roughness, and structure of the lower boundary layer.