Science.gov

Sample records for shroud crack probe

  1. Single-point representative sampling with shrouded probes

    SciTech Connect

    McFarland, A.R.; Rodgers, J.C.

    1993-08-01

    The Environmental Protection Agency (EPA) prescribed methodologies for sampling radionuclides in air effluents from stacks and ducts at US Department of Energy (DOE) facilities. Requirements include use of EPA Method 1 for the location of sampling sites and use of American National Standards Institute (ANSI) N13.1 for guidance in design of sampling probes and the number of probes at a given site. Application of ANSI N13.1 results in sampling being performed with multiprobe rakes that have as many as 20 probes. There can be substantial losses of aerosol particles in such sampling that will degrade the quality of emission estimates from a nuclear facility. Three alternate methods, technically justified herein, are proposed for effluent sampling. First, a shrouded aerosol sampling probe should replace the sharp-edged elbowed-nozzle recommended by ANSI. This would reduce the losses of aerosol particles in probes and result in the acquisition of more representative aerosol samples. Second, the rakes of multiple probes that are intended to acquire representative samples through spatial coverage should be replaced by a single probe located where contaminant mass and fluid momentum are both well mixed. A representative sample can be obtained from a well-mixed flow. Some effluent flows will need to be engineered to achieve acceptable mixing. Third, sample extraction should be performed at a constant flow rate through a suitable designed shrouded probe rather than at a variable flow rate through isokinetic probes. A shrouded probe is shown to have constant sampling characteristics over a broad range of stack velocities when operated at a fixed flow rate.

  2. Fatigue induced cracking in aluminum LN-2 shroud of 39 foot vacuum chamber

    NASA Technical Reports Server (NTRS)

    Edwards, A. A.

    1984-01-01

    Fourteen years after completion of Ford's 39-foot space simulation chamber, leaks began to appear in its LN2 shroud. Although the shroud had been tight since its acceptance, cracks appeared in 1983 in some of the field welds of the one inch tubes which interconnect the LN2 panels. The resulting leaks were large enough to prevent pump down to high vacuum and could be heard easily when the chamber was at ambient conditions. New cracks appeared during each thermal cycle making it impossible to utilize the chamber for thermal vacuum testing. The analysis presented here implies that many, if not all, of the aluminum LN2 shrouds now in use may be in various stages of fatigue failure. The probability is high that fatigue cracks are working through the aluminum tubing in heat-affected zones of some field welds. The cracks may not be apparent yet, but after the shroud has experienced a certain number of thermal cycles these cracks will work through the material and become serious leaks. Fortunately, appropriate planning, analysis, and checking can, with a relatively small expenditure of money, help to avoid large and unexpected shroud failures and keep the chamber operational as long as it is needed.

  3. Stress corrosion cracking of type 304L stainless steel core shroud welds.

    SciTech Connect

    Chung, H. M.; Park, J.-H.; Sanecki, J. E.; Zaluzec, N. J.; Yu, M. S.; Yang, T. T.

    1999-10-26

    Microstructural analyses by advanced metallographic techniques were conducted on mockup welds and a cracked BWR core shroud weld fabricated from Type 304L stainless steel. heat-affected zones of the shroud weld and mockup shielded-metal-arc welds were free of grain-boundary carbide, martensite, delta ferrite, or Cr depletion near grain boundaries. However, as a result of exposure to welding fumes, the heat-affected zones of the welds were significantly contaminated by fluorine and oxygen which migrate to grain boundaries. Significant oxygen contamination promotes fluorine contamination and suppresses classical thermal sensitization, even in Type 304 steels. Results of slow-strain-rate tensile tests indicate that fluorine exacerbates the susceptibility of irradiated steels to intergranular stress corrosion cracking. These observations, combined with previous reports on the strong influence of weld flux, indicate that oxygen and fluorine contamination and fluorine-catalyzed stress corrosion play a major role in cracking of Type 304L stainless steel core shroud welds.

  4. Crack growth rate in core shroud horizontal welds using two models for a BWR

    NASA Astrophysics Data System (ADS)

    Arganis Juárez, C. R.; Hernández Callejas, R.; Medina Almazán, A. L.

    2015-05-01

    An empirical crack growth rate correlation model and a predictive model based on the slip-oxidation mechanism for Stress Corrosion Cracking (SCC) were used to calculate the crack growth rate in a BWR core shroud. In this study, the crack growth rate was calculated by accounting for the environmental factors related to aqueous environment, neutron irradiation to high fluence and the complex residual stress conditions resulting from welding. In estimating the SCC behavior the crack growth measurements data from a Boiling Water Reactor (BWR) plant are referred to, and the stress intensity factor vs crack depth throughout thickness is calculated using a generic weld residual stress distribution for a core shroud, with a 30% stress relaxation induced by neutron irradiation. Quantitative agreement is shown between the measurements of SCC growth rate and the predictions of the slip-oxidation mechanism model for relatively low fluences (5 × 1024 n/m2), and the empirical model predicted better the SCC growth rate than the slip-oxidation model for high fluences (>1 × 1025 n/m2). The relevance of the models predictions for SCC growth rate behavior depends on knowing the model parameters.

  5. Microstructural examination of the effect of surface machining on stress corrosion cracking in core shroud made of 316L

    SciTech Connect

    Sueishi, Y.; Kohyama, A.; Narui, M.; Asano, K.

    2006-07-01

    Cracks exhibited on the hardened surface region of the boiling water reactor (BWR) core shroud made of 316L were examined. The sample was removed from the circumference ring of a commercial power plant after about 9 years in service. On the surface with mechanical milling followed by grinding during the manufacturing process, micro-crack was found to propagate nearly perpendicular to the grinding direction. Cross-sectional transmission electron microscopy (TEM) observation of the micro-crack indicates that the crack has been initiated along the boundary of [111[<112> type deformation twins and the shear bands in Goss position [110]<001>. Along the crack wall, the Cr-Fe spinel and the grained magnetite were identified in inner and outer layer of the oxide thin film, respectively. The results suggest one potential mechanism of the cracking that the heavily deformed structure by surface machining is the origin or the factor for acceleration of the cracking. (authors)

  6. Reactor shroud joint

    DOEpatents

    Ballas, Gary J.; Fife, Alex Blair; Ganz, Israel

    1998-01-01

    A shroud for a nuclear reactor is described. In one embodiment, the shroud includes first and second shroud sections, and each shroud section includes a substantially cylindrical main body having a first end and a second end. With respect to each shroud section, a flange is located at the main body first end, and the flange has a plurality of bolt openings therein and a plurality of scalloped regions. The first shroud section is welded to the second shroud section, and at least some of the bolt openings in the first shroud section flange align with respective bolt openings in the second shroud section flange. In the event that the onset of inter-granular stress corrosion cracking is ever detected in the weld between the shroud section, bolts are inserted through bolt openings in the first shroud section flange and through aligned bolt openings the second shroud section flange. Each bolt, in one embodiment, has a shank section and first and second threaded end sections. Nuts are threadedly engaged to the threaded end sections and tightened against the respective flanges.

  7. Reactor shroud joint

    DOEpatents

    Ballas, G.J.; Fife, A.B.; Ganz, I.

    1998-04-07

    A shroud for a nuclear reactor is described. In one embodiment, the shroud includes first and second shroud sections, and each shroud section includes a substantially cylindrical main body having a first end and a second end. With respect to each shroud section, a flange is located at the main body first end, and the flange has a plurality of bolt openings therein and a plurality of scalloped regions. The first shroud section is welded to the second shroud section, and at least some of the bolt openings in the first shroud section flange align with respective bolt openings in the second shroud section flange. In the event that the onset of inter-granular stress corrosion cracking is ever detected in the weld between the shroud section, bolts are inserted through bolt openings in the first shroud section flange and through aligned bolt openings the second shroud section flange. Each bolt, in one embodiment, has a shank section and first and second threaded end sections. Nuts are threadedly engaged to the threaded end sections and tightened against the respective flanges. 4 figs.

  8. Crack detection by mobile photothermal probe

    SciTech Connect

    Bodnar, J.L.; Egee, M.; Menu, C.; Blanc, A. le; Besnard, R.; Sellier, J.Y.

    1994-12-31

    Within the frame of a previous study, encouraging results were obtained regarding the detection of microcracks by Photo Thermal Radiometry under sinusoidal excitation. However, the used method was too slow for an industrial application. It was therefore necessary to consider faster means of analysis. Such is the object of the present study. The authors show that, by using a mobile photothermal probe displaced relatively to the sample, it is possible to rapidly detect opened or non opened cracks, of a few tens of micrometers wide, and a few hundred of micrometers deep.

  9. Revolving Eddy-Current Probe Detects Cracks Near Rivets

    NASA Technical Reports Server (NTRS)

    Namkung, Min; Wincheski, Buzz; Fulton, James P.; Nath, Shridhar; Simpson, John

    1995-01-01

    Scanning eddy-current probe in circular pattern increases sensitivity with which probe indicates fatigue cracks and other defects in metal surfaces in vicinity of rivets. Technique devised to facilitate inspection of riveted joints in aircraft. Eddy-current probe in question described in "Electro-magnetic Flaw Detector Is Easier To Use" (LAR-15046).

  10. Crack detection and recognition using an eddy current differential probe

    SciTech Connect

    Chady, T.; Enokizono, M. . Faculty of Engineering); Sikora . Dept. of Theoretical Electrotechnics)

    1999-05-01

    This paper proposes a new eddy current differential sensor and a system for multi-frequency testing of conducting plates. Precise crack imaging was achieved by the use of spectrograms obtained from an eddy-current probe multi-frequency response and application of a neural network. Results of experiments with test specimens made of SUS304 showing very good sensitivity and spatial resolution are presented. The possibility of detection of an opposite side 20% crack was also confirmed.

  11. High speed rotor assembly shroud

    NASA Technical Reports Server (NTRS)

    Miller, Jeff H. (Inventor); Zheng, Xinhong J. (Inventor); Grota, Steven P. (Inventor); Phui, Khin C. (Inventor)

    2006-01-01

    An improved rotor assembly shroud includes at least one reinforcing flange on the upper surface of the shroud. The strength provided by the reinforcing flange allows for a smaller shroud thickness resulting in a net reduction of shroud mass. The lower shroud mass reduces the centrifugal stress on the rotor assembly blade during operation. The strength provided by the reinforcing flanges also significantly reduces the centrifugal bending stress on the shroud during operation. The shroud mass may be further reduced by tapering the shroud leading and trailing edges or, for shrouds incorporating a damper, by providing a damper cavity with a lower diameter surface defining an opening therethrough.

  12. Shroud leakage flow discouragers

    DOEpatents

    Bailey, Jeremy Clyde; Bunker, Ronald Scott

    2002-01-01

    A turbine assembly includes a plurality of rotor blades comprising a root portion, an airfoil having a pressure sidewall and a suction sidewall, and a top portion having a cap. An outer shroud is concentrically disposed about said rotor blades, said shroud in combination with said tip portions defining a clearance gap. At least one circumferential shroud leakage discourager is disposed within the shroud. The leakage discourager(s) increase the flow resistance and thus reduce the flow of hot gas flow leakage for a given pressure differential across the clearance gap to improve overall turbine efficiency.

  13. The Turin Shroud

    NASA Astrophysics Data System (ADS)

    Allday, Jonathan

    2005-01-01

    The Turin Shroud is a fascinating relic that has long intrigued many people. It is old—but how old? It has an image of a man's body—but how and when did the image get there? This article examines the scientific aspects of the debate about the Shroud, focusing on the image itself and on the radiocarbon dating performed in 1988.

  14. Core shroud corner joints

    DOEpatents

    Gilmore, Charles B.; Forsyth, David R.

    2013-09-10

    A core shroud is provided, which includes a number of planar members, a number of unitary corners, and a number of subassemblies each comprising a combination of the planar members and the unitary corners. Each unitary corner comprises a unitary extrusion including a first planar portion and a second planar portion disposed perpendicularly with respect to the first planar portion. At least one of the subassemblies comprises a plurality of the unitary corners disposed side-by-side in an alternating opposing relationship. A plurality of the subassemblies can be combined to form a quarter perimeter segment of the core shroud. Four quarter perimeter segments join together to form the core shroud.

  15. Turbine inner shroud and turbine assembly containing such inner shroud

    DOEpatents

    Bagepalli, Bharat Sampathkumaran; Corman, Gregory Scot; Dean, Anthony John; DiMascio, Paul Stephen; Mirdamadi, Massoud

    2001-01-01

    A turbine inner shroud and a turbine assembly. The turbine assembly includes a turbine stator having a longitudinal axis and having an outer shroud block with opposing and longitudinally outward facing first and second sides having open slots. A ceramic inner shroud has longitudinally inward facing hook portions which can longitudinally and radially surround a portion of the sides of the outer shroud block. In one attachment, the hook portions are engageable with, and are positioned within, the open slots.

  16. Shrouded inducer pump

    DOEpatents

    Meng, Sen Y.

    1989-01-01

    An improvement in a pump including a shrouded inducer, the improvement comprising first and second sealing means 32,36 which cooperate with a first vortex cell 38 and a series of secondary vortex cells 40 to remove any tangential velocity components from the recirculation flow.

  17. Detection of Fatigue Cracks at Rivets with Self-Nulling Probe

    NASA Technical Reports Server (NTRS)

    Wincheski, Buzz; Fulton, Jim; Nath, Shridhar; Namkung, Min

    1994-01-01

    A new eddy current probe developed at NASA Langley Research Center has been used to detect small cracks at rivets in aircraft lap splices [1]. The device has earlier been used to detect isolated fatigue cracks with a minimum detectable flaw size of roughly 1/2 to 1/3 the diameter of the probe [2]. The present work shows that the detectable flaw size for cracks originating at rivets can be greatly improved upon from that of isolated flaws. The use of a rotating probe method combined with spatial filtering has been used to detect 0.18 cm EDM notches, as measured from the rivet shank, with a 1.27 cm diameter probe and to detect flaws buried under the rivet head, down to a length of 0.076 cm, using a 0.32 cm diameter probe. The Self-Nulling Electromagnetic Flaw Detector induces a high density eddy current ring in the sample under test. A ferromagnetic flux focusing lens is incorporated such that in the absence of any inhomogeneities in the material under test only a minimal magnetic field will reach the interior of the probe. A magnetometer (pickup coil) located in the center of the probe therefore registers a null voltage in the absence of material defects. When a fatigue crack or other discontinuity is present in the test article the path of the eddy currents in the material is changed. The magnetic field associated with these eddy currents then enter into the interior of the probe, producing a large output voltage across the pickup coil leads. Further

  18. Improved high pressure turbine shroud

    NASA Technical Reports Server (NTRS)

    Bessen, I. I.; Rigney, D. V.; Schwab, R. C.

    1977-01-01

    A new high pressure turbine shroud material has been developed from the consolidation of prealloyed powders of Ni, Cr, Al and Y. The new material, a filler for cast turbine shroud body segments, is called Genaseal. The development followed the identification of oxidation resistance as the primary cause of prior shroud deterioration, since conversion to oxides reduces erosion resistance and increases spalling under thermal cycled engine conditions. The NICrAlY composition was selected in preference to NIAL and FeCRALY alloys, and was formulated to a prescribed density range that offers suitable erosion resistance, thermal conductivity and elastic modulus for improved behavior as a shroud.

  19. Rotating field eddy current probe for characterization of cracking in non-magnetic tubing

    SciTech Connect

    Capobianco, T.E.

    1998-07-01

    A rotating field eddy current probe was built and tested for use in small diameter, non-magnetic tubing. The rotating field probe is a driver/pickup style with two orthogonally wound drive coils and a pancake pickup coil. The driver coils are excited by two sine waves 90{degree} out of phase with each other. The physical arrangement of the drive coils and the 90{degree} phase shift of the excitation waveforms creates a field which rotates in the test piece under the drive coils. Preliminary tests on electrical discharge machined (EDM) notches show that phased based estimates of notch depth are possible. Probes currently used for detection of cracks in tubing produce responses that have proven unreliable for estimating defect depths. This recently developed version of the rotating field eddy current probe produces a bipolar response in the presence of a crack or a notch. Typically, the phase angle of a bipolar eddy current response is easily identified and measured and is used extensively for estimating depths of volumetric defects. Data are shown relating the phase angle of the rotating field probe`s bipolar response to the depth of circumferential EDM notches.

  20. Ceramic gas turbine shroud

    DOEpatents

    Shi, Jun; Green, Kevin E.

    2014-07-22

    An example gas turbine engine shroud includes a first annular ceramic wall having an inner side for resisting high temperature turbine engine gasses and an outer side with a plurality of radial slots. A second annular metallic wall is positioned radially outwardly of and enclosing the first annular ceramic wall and has a plurality of tabs in communication with the slot of the first annular ceramic wall. The tabs of the second annular metallic wall and slots of the first annular ceramic wall are in communication such that the first annular ceramic wall and second annular metallic wall are affixed.

  1. The Effect of Opening on Eddy Current Probe Response for an Idealized through Crack

    SciTech Connect

    Fu Fangwei; Bowler, J. R.; Theodoulidis, T. P.

    2006-03-06

    A structure representing an idealized through crack was formed by placing two coplanar aluminum rectangular plates next to one another with their edges separated by a small distance. The coil impedance variation with position was measured as a coil was moved over the adjacent plate edges. An analytical theory is used to evaluate the coil impedance change due to the gap between the plates. This theory is based on the truncated region eigenfunction expansion method. The difference between the eddy current probe signal due to a notch compared with that of a crack can be partly accounted for by the difference in the opening. We have investigated the effect of varying the opening of the simulated crack and shown theoretically and experimentally how the coil impedance changes with position, opening and frequency.

  2. Quantification of crack defect using a new pulsed eddy current probe

    NASA Astrophysics Data System (ADS)

    Yang, Binfeng; Zhao, Yufeng; Zhang, Weisi

    2011-06-01

    As one of the nondestructive testing (NDT) techniques, pulsed eddy current (PEC) NDT usually uses the reflection-type probe, which consists of a pancake exciting coil for generation of the incident magnetic field and a pick-up coil or a solid-state magnetic field sensor for detecting the perturbed magnetic field due to the presence of defects in conductors. Normally, during the signal processing, the difference process is needed, which involves the subtraction of reference signals from the testing transient signals to enhance the sensitivity of detection. In this paper, a new PEC probe is proposed for the quantification of cracks. The probe has the self-differential characteristic, and thus the difference process is no longer required. The principle of the new probe is analysed firstly. Following that, the performance of the new probe is compared with that of a traditional PEC probe by simulations and experiments. The results show that the proposed PEC probe is valid and advantageous over conventional probes in terms of higher accuracy in quantification of defects.

  3. Special Pyrheliometer Shroud Development

    NASA Technical Reports Server (NTRS)

    Dennison, E. W.

    1984-01-01

    To insure that the insolation values accurately represent the input power to a power conversion unit the field of view (FOV) of the concentrator aperture and the insolation radiometer must be the same. The calculations, implementation, and results of this approach are covered. Three instruments were used to measure the insolation: an Eppley Normal Incidence Radiometer (NIP) and two versions of the kendall cavity radiometer. The shrouds used to limit the FOV of the radiometers were designed to simulate the FOV of the PDC-1 concentrater with the cold water cavity calorimeter. This technique of matching the FOV of an insolation radiometer to the FOV of a specific concentrater and receiver aperture appears to be both practical and effective. The efficiency of a power conversion unit will be too low if the insolation is measured with a radiometer which has a FOV which is larger than the FOV of the concentrator.

  4. Detection of Cracks at Welds in Steel Tubing Using Flux Focusing Electromagnetic Probe

    NASA Technical Reports Server (NTRS)

    Wincheski, Buzz; Fulton, Jim; Nath, Shridhar; Simpson, John; Namkung, Min

    1994-01-01

    The inspection of weldments in critical pressure vessel joints is a major concern in the nuclear power industry. Corrosive environments can speed the fatigue process and access to the critical area is often limited. Eddy current techniques have begun to be used to help overcome these obstacles [1]. As direct contact and couplants are not required, remote areas can be inspected by simply snaking an eddy current coil into the intake tube of the vessel. The drawback of the eddy current method has been the high sensitivity to small changes in the conductivity and permeability of the test piece which are known to vary at weldments [1]. The flaw detection mechanism of the flux focusing electromagnetic probe can help alleviate these difficulties and provide a unique capability for detecting longitudinal fatigue cracks in critical tube structures. The Flux Focusing Electromagnetic Flaw Detector, originally invented for the detection of fatigue and corrosion damage in aluminum plates [2-3], has been adapted for use in testing steel tubing for longitudinal fatigue cracks. The modified design allows for the probe to be placed axisymmetrically into the tubing, inducing eddy currents in the tube wall. The pickup coil of the probe is fixed slightly below the primary windings and is rotated 90 so that its axis is normal to the tube wall. The magnetic flux of the primary coil is focused through the use of ferromagnetic material so that in the absence of fatigue damage there will be no flux linkage with the pickup coil. The presence of a longitudinal fatigue crack will cause the eddy currents induced in the tube wall to flow around the flaw and directly under the pickup coil. The magnetic field associated with these currents will then link the pickup coil and an unambiguous increase in the output voltage of the probe will be measured. The use of the flux focusing electromagnetic probe is especially suited for the detection of flaws originating at or near tube welds. The probe is

  5. Crack

    MedlinePlus

    ... sound the drug makes as it heats up. Short-Term Effects Crack is a stimulant that is absorbed through ... quickly, after about 5 or 10 minutes. Other short-term effects include: higher heart rate, breathing rate, blood pressure , ...

  6. Application of Self Nulling Eddy Current Probe Technique to the Detection of Fatigue Crack Initiation and Control of Test Procedures

    NASA Technical Reports Server (NTRS)

    Namkung, M.; Nath, S.; Wincheski, B.; Fulton, J. P.

    1994-01-01

    A major part of fracture mechanics is concerned with studying the initiation and propagation of fatigue cracks. This typically requires constant monitoring of crack growth during fatigue cycles and the knowledge of the precise location of the crack tip at any given time. One technique currently available for measuring fatigue crack length is the Potential Drop method. The method, however, may be inaccurate if the direction of crack growth deviates considerably from what was assumed initially or the curvature of the crack becomes significant. Another popular approach is to optically view the crack using a high magnification microscope, but this entails a person constantly monitoring it. The present proposed technique uses an automated scheme, in order to eliminate the need for a person to constantly monitor the experiment. Another technique under development elsewhere is to digitize an optical image of the test specimen surface and then apply a pattern recognition algorithm to locate the crack tip. A previous publication showed that the self nulling eddy current probe successfully tracked a simulated crack in an aluminum sample. This was the impetus to develop an online real time crack monitoring system. An automated system has been developed which includes a two axis scanner mounted on the tensile testing machine, the probe and its instrumentation and a personal computer (PC) to communicate and control all the parameters. The system software controls the testing parameters as well as monitoring the fatigue crack as it propagates. This paper will discuss the experimental setup in detail and demonstrate its capabilities. A three dimensional finite element model is utilized to model the magnetic field distribution due to the probe and how the probe voltage changes as it scans the crack. Experimental data of the probe for different samples under zero load, static load and high cycle fatigue load will be discussed. The final section summarizes the major accomplishments

  7. Airfoil nozzle and shroud assembly

    DOEpatents

    Shaffer, James E.; Norton, Paul F.

    1997-01-01

    An airfoil and nozzle assembly including an outer shroud having a plurality of vane members attached to an inner surface and having a cantilevered end. The assembly further includes a inner shroud being formed by a plurality of segments. Each of the segments having a first end and a second end and having a recess positioned in each of the ends. The cantilevered end of the vane member being positioned in the recess. The airfoil and nozzle assembly being made from a material having a lower rate of thermal expansion than that of the components to which the airfoil and nozzle assembly is attached.

  8. Airfoil nozzle and shroud assembly

    DOEpatents

    Shaffer, J.E.; Norton, P.F.

    1997-06-03

    An airfoil and nozzle assembly are disclosed including an outer shroud having a plurality of vane members attached to an inner surface and having a cantilevered end. The assembly further includes a inner shroud being formed by a plurality of segments. Each of the segments having a first end and a second end and having a recess positioned in each of the ends. The cantilevered end of the vane member being positioned in the recess. The airfoil and nozzle assembly being made from a material having a lower rate of thermal expansion than that of the components to which the airfoil and nozzle assembly is attached. 5 figs.

  9. Design of an electrochemical probe for monitoring susceptibility of steel in pickling to hydrogen-induced cracking

    SciTech Connect

    Cheng, Y.F.; Du, Y.L. . Corrosion Science Lab.)

    1993-09-01

    The relationship between the measured signals (hydrogen [H] permeating rate) of an electrochemical H sensor and the strength/embrittlement of plain carbon steel in acid solution as defined by slow strain rate tensile tests and scanning electron microscopy was studied. Critical parameters and criteria for hydrogen-induced cracking (HIC) reported may be useful in software design of an electrochemical probe for inspecting and monitoring the HIC susceptibility of steel in pickling.

  10. Wind turbine ring/shroud drive system

    DOEpatents

    Blakemore, Ralph W.

    2005-10-04

    A wind turbine capable of driving multiple electric generators having a ring or shroud structure for reducing blade root bending moments, hub loads, blade fastener loads and pitch bearing loads. The shroud may further incorporate a ring gear for driving an electric generator. In one embodiment, the electric generator may be cantilevered from the nacelle such that the gear on the generator drive shaft is contacted by the ring gear of the shroud. The shroud also provides protection for the gearing and aids in preventing gear lubricant contamination.

  11. Radiocarbon dating of the Shroud of Turin

    NASA Astrophysics Data System (ADS)

    Damon, P. E.; Donahue, D. J.; Gore, B. H.; Hatheway, A. L.; Jull, A. J. T.; Linick, T. W.; Sercel, P. J.; Toolin, L. J.; Bronk, C. R.; Hall, E. T.; Hedges, R. E. M.; Housley, R.; Law, I. A.; Perry, C.; Bonani, G.; Trumbore, S.; Woelfli, W.; Ambers, J. C.; Bowman, S. G. E.; Leese, M. N.; Tite, M. S.

    1989-02-01

    Very small samples from the Shroud of Turin have been dated by accelerator mass spectrometry in laboratories at Arizona, Oxford and Zurich. As controls, three samples whose ages had been determined independently were also dated. The results provide conclusive evidence that the linen of the Shroud of Turin is mediaeval.

  12. All-optical probing of the nonlinear acoustics of a crack.

    PubMed

    Mezil, Sylvain; Chigarev, Nikolay; Tournat, Vincent; Gusev, Vitalyi

    2011-09-01

    Experiments with an all-optical method for the study of the nonlinear acoustics of cracks in solids are reported. Nonlinear acoustic waves are initiated by the absorption of radiation from a pair of laser beams intensity modulated at two different frequencies. The detection of acoustic waves at mixed frequencies, absent in the frequency spectrum of the heating lasers, by optical interferometry or deflectometry provides unambiguous evidence of the elastic nonlinearity of the crack. The high contrast in crack imaging achieved by remote optical monitoring of the nonlinear acoustic processes is due to the strong dependence of the efficiency of optoacoustic conversion on the state of the crack. The highest acoustic nonlinearity is observed in the transitional state of the crack, which is intermediate between the open and the closed ones. PMID:21886240

  13. Vibration characteristics of mistuned shrouded blade assemblies

    NASA Technical Reports Server (NTRS)

    Bendiksen, O. O.; Valero, N. A.

    1985-01-01

    An investigation of the mode localization phenomenon associated with mistuning is presented for shrouded blade assemblies. The calculations are based on a generic finite element model, which permits modeling of arbitrary mistuning and both slipping and nonslipping shroud interfaces. The results presented indicate that interactions occur between mistuning and slip effects, with maximum mode localization occurring when the shrouds slip freely. Certain modes are found to be very sensitive to shroud slip, and in some cases completely change character when slip occurs. Mode localization is most pronounced in the predominantly bending modes, and varies considerably from mode to mode. As the ratio of interblade coupling strength to mistuning strength is increased, the effect of mistuning is observed to decrease significantly. This result has important implications for the flutter problem, since it suggests that the stabilization effect available from mistuning is significantly less for a shrouded rotor as compared to an unshrouded rotor.

  14. Centaur Standard Shroud (CSS) cryogenic unlatch tests

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Cryogenic tanking and partial jettison (unlatch) tests were performed on a full scale Centaur vehicle and Centaur Standard Shroud (CSS) to develop and qualify the CSS insulation system, the CSS and Centaur ground-hold purge systems, and the Centaur hydrogen tank flight vent system. Operation of the shroud/Centaur pyrotechnic systems, seals, and the shroud jettison springs, hinges, and other separation systems was demonstrated by a partial jettison of the shroud into catch nets. The Centaur tanks were filled with liquid hydrogen and liquid nitrogen. Prelaunch operations were performed, and data taken to establish system performances. Results from the initial tests showed a higher than expected heat transfer rate to the Centaur hydrogen tank. In addition, the release mechanism for the forward seal between the Centaur and the CSS did not function properly, and the seal was torn during jettison of the shroud.

  15. High-performance atom-probe field ion microscope study of segregation and hydrogen cracking in Fe-0. 29 Ti

    SciTech Connect

    Kuk, Y.; Pickering, H.W.; Sakurai, T.

    1980-01-01

    With the greatly improved resolution now available in energy focused atom probes, hydrogen can be readily resolved even when combined with metals having several isotopes. In addition to finding that H, H/sub 2/, FeH and TiH/sub 2/ accumulate at segregated grain boundaries in Fe-0.29 wt % Ti, a striking observation was made - the formation and propagation of a microcrack when the (field ion microscope) tip was exposed to hydrogen gas at elevated temperature. A small crack (approx. 200 A in length) was first noticed at a grain-boundary intersection during field ion imaging. This was an open crack, formed by detachment of metal between the intersecting grain boundaries, which was observed to be much larger after the tip was reheated to 1300/sup 0/K for 10 min. in the presence of 10/sup 2/ Pa (1 torr) H/sub 2/. This crack could be easily reduced in size by gradually field evaporating the surface. Its propagation was repeated several times and reproducible results were obtained. Hydrogen was identified in quantity in the crack surface, though not elsewhere. The observation of H/sub 2/ is taken to mean that H/sub 2/ gas was trapped in the grain boundary. The grain boundary was also observed to be enriched in Ti, O, C and S, in agreement with earlier results for Fe-Ti.

  16. Turbine assembly containing an inner shroud

    DOEpatents

    Bagepalli, Bharat Sampathkumaran; Corman, Gregory Scot; Dean, Anthony John; DiMascio, Paul Stephen; Mirdamadi, Massoud

    2000-01-01

    A turbine assembly having a turbine stator, a ceramic inner shroud, and a first spring. The stator has a longitudinal axis and an outer shroud block with opposing and longitudinally outward facing first and second sides. The first side has a longitudinally outward projecting first ledge and has a first side portion located radially outward of the first ledge. The ceramic inner shroud has a first hook portion longitudinally and radially surrounding the first ledge. The first spring is attached to one of the first side portion and the first hook portion and unattachedly and resiliently contacts the other of the first side portion and the first hook portion.

  17. Nozzle and shroud assembly mounting structure

    DOEpatents

    Faulder, Leslie J.; Frey, deceased, Gary A.; Nielsen, Engward W.; Ridler, Kenneth J.

    1997-01-01

    The present nozzle and shroud assembly mounting structure configuration increases component life and reduces maintenance by reducing internal stress between the mounting structure having a preestablished rate of thermal expansion and the nozzle and shroud assembly having a preestablished rate of thermal expansion being less than that of the mounting structure. The mounting structure includes an outer sealing portion forming a cradling member in which an annular ring member is slidably positioned. The mounting structure further includes an inner mounting portion to which a hooked end of the nozzle and shroud assembly is attached. As the inner mounting portion expands and contracts, the nozzle and shroud assembly slidably moves within the outer sealing portion.

  18. Nozzle and shroud assembly mounting structure

    DOEpatents

    Faulder, L.J.; Frey, G.A.; Nielsen, E.W.; Ridler, K.J.

    1997-08-05

    The present nozzle and shroud assembly mounting structure configuration increases component life and reduces maintenance by reducing internal stress between the mounting structure having a preestablished rate of thermal expansion and the nozzle and shroud assembly having a preestablished rate of thermal expansion being less than that of the mounting structure. The mounting structure includes an outer sealing portion forming a cradling member in which an annular ring member is slidably positioned. The mounting structure further includes an inner mounting portion to which a hooked end of the nozzle and shroud assembly is attached. As the inner mounting portion expands and contracts, the nozzle and shroud assembly slidably moves within the outer sealing portion. 3 figs.

  19. Compressor ported shroud for foil bearing cooling

    DOEpatents

    Elpern, David G.; McCabe, Niall; Gee, Mark

    2011-08-02

    A compressor ported shroud takes compressed air from the shroud of the compressor before it is completely compressed and delivers it to foil bearings. The compressed air has a lower pressure and temperature than compressed outlet air. The lower temperature of the air means that less air needs to be bled off from the compressor to cool the foil bearings. This increases the overall system efficiency due to the reduced mass flow requirements of the lower temperature air. By taking the air at a lower pressure, less work is lost compressing the bearing cooling air.

  20. The Shroud of Turin: Relic or icon?

    NASA Astrophysics Data System (ADS)

    Dale, W. S. A.

    1987-11-01

    The Shroud of Turin, a linen cloth on which appear the imprints of the front and back of a crucified man, can be historically traced to ca. 1354 a.d. Many believe it to be a true relic of the Passion of Christ. Many others regard it as a fake. This paper suggests a third alternative, that it is an icon dating from the 11th century. If future scientific tests, of which radiocarbon dating will be the most important, support this theory, the Shroud of Turin may well be recognized as one of the masterpieces of Christian art.

  1. Simulation and design of ECT differential bobbin probes for the inspection of cracks in bolts

    NASA Astrophysics Data System (ADS)

    Ra, S. W.; Im, K. H.; Lee, S. G.; Kim, H. J.; Song, S. J.; Kim, S. K.; Cho, Y. T.; Woo, Y. D.; Jung, J. A.

    2015-12-01

    All Various defects could be generated in bolts for a use of oil filters for the manufacturing process and then may affect to the safety and quality in bolts. Also, fine defects may be imbedded in oil filter system during multiple forging manufacturing processes. So it is very important that such defects be investigated and screened during the multiple manufacturing processes. Therefore, in order effectively to evaluate the fine defects, the design parameters for bobbin-types were selected under a finite element method (FEM) simulations and Eddy current testing (ECT). Especially the FEM simulations were performed to make characterization in the crack detection of the bolts and the parameters such as number of turns of the coil, the coil size and applied frequency were calculated based on the simulation results.

  2. FIB-SEM Tomography Probes the Mesoscale Pore Space of an Individual Catalytic Cracking Particle

    PubMed Central

    2016-01-01

    The overall performance of a catalyst particle strongly depends on the ability of mass transport through its pore space. Characterizing the three-dimensional structure of the macro- and mesopore space of a catalyst particle and establishing a correlation with transport efficiency is an essential step toward designing highly effective catalyst particles. In this work, a generally applicable workflow is presented to characterize the transport efficiency of individual catalyst particles. The developed workflow involves a multiscale characterization approach making use of a focused ion beam-scanning electron microscope (FIB-SEM). SEM imaging is performed on cross sections of 10.000 μm2, visualizing a set of catalyst particles, while FIB-SEM tomography visualized the pore space of a large number of 8 μm3 cubes (subvolumes) of individual catalyst particles. Geometrical parameters (porosity, pore connectivity, and heterogeneity) of the material were used to generate large numbers of virtual 3D volumes resembling the sample’s pore space characteristics, while being suitable for computationally demanding transport simulations. The transport ability, defined as the ratio of unhindered flow over hindered flow, is then determined via transport simulations through the virtual volumes. The simulation results are used as input for an upscaling routine based on an analogy with electrical networks, taking into account the spatial heterogeneity of the pore space over greater length scales. This novel approach is demonstrated for two distinct types of industrially manufactured fluid catalytic cracking (FCC) particles with zeolite Y as the active cracking component. Differences in physicochemical and catalytic properties were found to relate to differences in heterogeneities in the spatial porosity distribution. In addition to the characterization of existing FCC particles, our method of correlating pore space with transport efficiency does also allow for an up-front evaluation of

  3. Theoretical wave drag of shrouded airfoils and bodies

    NASA Technical Reports Server (NTRS)

    Byrd, Paul F

    1956-01-01

    Formulas for the wave drag of shrouded symmetrical airfoils and shrouded bodies of revolution of arbitrary shape are derived by means of linearized theory. In the case of the airfoils, the shroud consists of flat plates and for the bodies of revolution the shroud is a cylindrical shell. The results obtained hold for a Mach number range dependent on the geometry of the configuration. Expressions are also given for determining a class of body shapes for which the wave drag is theoretically zero.

  4. Cooling circuit for a gas turbine bucket and tip shroud

    DOEpatents

    Willett, Fred Thomas; Itzel, Gary Michael; Stathopoulos, Dimitrios; Plemmons, Larry Wayne; Plemmons, Helen M.; Lewis, Doyle C.

    2002-01-01

    An open cooling circuit for a gas turbine bucket wherein the bucket has an airfoil portion, and a tip shroud, the cooling circuit including a plurality of radial cooling holes extending through the airfoil portion and communicating with an enlarged internal area within the tip shroud before exiting the tip shroud such that a cooling medium used to cool the airfoil portion is subsequently used to cool the tip shroud.

  5. Prediction of Microporosity in Shrouded Impeller Castings

    SciTech Connect

    Viswanathan, S. Nelson, C.D.

    1998-09-01

    The purpose of this Cooperative Research and Development Agreement (CRADA) between the Oak Ridge National Laboratory (ORNL) and Morris Bean and Company was to link computer models of heat and fluid flow with previously developed quality criteria for the prediction of microporosity in a Al-4.5% Cu alloy shrouded impeller casting. The results may be used to analyze the casting process design for the commercial production of 206 o alloy shrouded impeller castings. Test impeller castings were poured in the laboratory for the purpose of obtaining thermal data and porosity distributions. Also, a simulation of the test impeller casting was conducted and the results validated with porosity measurements on the test castings. A comparison of the predicted and measured microporosity distributions indicated an excellent correlation between experiments and prediction. The results of the experimental and modeling studies undertaken in this project indicate that the quality criteria developed for the prediction of microporosity in Al-4.5% Cu alloy castings can accurately predict regions of elevated microporosity even in complex castings such as the shrouded impeller casting. Accordingly, it should be possible to use quality criteria for porosity prediction in conjunction with computer models of heat and fluid flow to optimize the casting process for the production of shrouded impeller castings. Since high levels of microporosity may be expected to result in poor fatigue properties, casting designs that are optimized for low levels of microporosity should exhibit superior fatigue life.

  6. Scientific investigation of the Shroud of Turin.

    PubMed

    Jumper, E J; Mottern, R W

    1980-06-15

    This article introduces three research papers discussing various scientific tests run on the Shroud of Turin-an ancient piece of linen that appears to bear faint images of a man's body. It also briefly reviews the chemical, photographic, and x-ray tests not dealt with in the three research papers, which are concerned with optical and IR spectroscopy and thermography. PMID:20221154

  7. PIONEER VENUS 1 SPACECRAFT PARTIALLY COVERED BY ENCAPSULATION SHROUD

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Segments of the shroud that will protect Pioneer Venus-A as it moves through the atmosphere following launch on a flight to Venus are moved into position to encapsulate the spacecraft. Pioneer Venus-A is scheduled for launch from Complex 36, Cape Canaveral, on May 20. Liftoff is scheduled during a opportunity extending from 9:13 to 9:28 a.m. Eastern Daylight Time. Pioneer Venus-A, to be renamed Pioneer Venus-1 after launch, will be placed in orbit around Venus on December 4. A second Pioneer Venus, a multi-probe spacecraft, is scheduled for launch August 4. The two scientific spacecraft are designed to sample Venusian weather patterns and hopefully provide answers for scientist to some of the unknown factors of the Venus atmosphere.

  8. Engine cooling fan and fan shrouding arrangement

    SciTech Connect

    Longhouse, R.E.; Vona, N.

    1987-08-11

    This patent describes a vehicle engine cooling fan and shrouding assembly for forcing cooling air through a radiator in which engine coolant is circulated comprising support means adjacent to the radiator, a fan shroud and mounting shell operatively secured to the support means adjacent to the radiator. The shell has a peripheral forwardly extending wall portion to provide an intake for air flowing through the radiator. The shell further has a generally cylindrical and rearwardly extending portion to provide a reduced dimensioned air ejector for the shell, spoke means extending inwardly from the air ejector, a fan drive motor supported by the spoke means extending axially into the shell, the motor having a rotatable output shaft extending outwardly therefrom toward the radiator and having a terminal end portion, and engine cooling fan operatively driven by the drive motor and rotatably mounted in the shell.

  9. Spectral properties of the Shroud of Turin.

    PubMed

    Pellicori, S F

    1980-06-15

    Spectrophotometric results from the 1978 investigation of the Shroud of Turin are presented. The goals of the investigation were to characterize spectrally the body image in a region extending from the near UV to the near IR, to determine if the blood stains are actually blood, and to recommend storage parameters to prevent further degradation of the image. The bloodstained areas have the spectral characteristics of human hemoglobin. The image shows monotonically increasing (featureless) absorption with decreasing wavelength. The contrast is low: R(550 nm) = 0.85 of that for the background linen. Simulated aging by air baking reproduced the color of the background linen. Simultaneously, an invisible deposit of perspiration plus skin oils became visible and displayed a reflection spectrum closely resembling that of the body image. Lightly scorched areas on the Shroud are also somewhat similar spectrally, suggesting that a similar resultant chemistry is possible for dissimilar causes. A likely cause for the bo y image is cellulose degradation stimulated locally by natural or applied substances transferred to the Shroud. PMID:20221155

  10. View-limiting shrouds for insolation radiometers

    NASA Technical Reports Server (NTRS)

    Dennison, E. W.; Trentelman, G. F.

    1985-01-01

    Insolation radiometers (normal incidence pyrheliometers) are used to measure the solar radiation incident on solar concentrators for calibrating thermal power generation measurements. The measured insolation value is dependent on the atmospheric transparency, solar elevation angle, circumsolar radiation, and radiometer field of view. The radiant energy entering the thermal receiver is dependent on the same factors. The insolation value and the receiver input will be proportional if the concentrator and the radiometer have similar fields of view. This report describes one practical method for matching the field of view of a radiometer to that of a solar concentrator. The concentrator field of view can be calculated by optical ray tracing methods and the field of view of a radiometer with a simple shroud can be calculated by using geometric equations. The parameters for the shroud can be adjusted to provide an acceptable match between the respective fields of view. Concentrator fields of view have been calculated for a family of paraboloidal concentrators and receiver apertures. The corresponding shroud parameters have also been determined.

  11. Experimental and analytical study of ceramic-coated turbine-tip shroud seals for small turbine engines

    NASA Technical Reports Server (NTRS)

    Biesiadny, T. J.; Mcdonald, G. E.; Hendricks, R. C.; Little, J. K.; Robinson, R. A.; Klann, G. A.; Lassow, E. S.

    1985-01-01

    The results of an experimental and analytical evaluation of ceramic turbine tip shrouds within a small turbine engine operating environment are presented. The ceramic shrouds were subjected to 1001 cycles between idle and high power and steady-state conditions for a total of 57.8 engine hr. Posttest engine inspection revealed mud-flat surface cracking, which was attributed to microcracking under tension with crack penetration to the ceramic and bond coat interface. Sections and micrographs tend to corroborate the thesis. The engine test data provided input to a thermomechanical analysis to predict temperature and stress profiles throughout the ceramic gas-path seal. The analysis predicts cyclic thermal stresses large enough to cause the seal to fail. These stresses are, however, mitigated by inelastic behavior of the shroud materials and by the microfracturing that tensile stresses produce. Microfracturing enhances shroud longevity during early life but provides the failure mechanism during life but provides the failure mechanism during extended life when coupled with the time dependent inelastic materials effects.

  12. Closed circuit steam cooled turbine shroud and method for steam cooling turbine shroud

    DOEpatents

    Burdgick, Steven Sebastian; Sexton, Brendan Francis; Kellock, Iain Robertson

    2002-01-01

    A turbine shroud cooling cavity is partitioned to define a plurality of cooling chambers for sequentially receiving cooling steam and impingement cooling of the radially inner wall of the shoud. An impingement baffle is provided in each cooling chamber for receiving the cooling media from a cooling media inlet in the case of the first chamber or from the immediately upstream chamber in the case of the second through fourth chambers and includes a plurality of impingement holes for effecting the impingement cooling of the shroud inner wall.

  13. Centaur Standard Shroud (CSS) static limit load structural tests

    NASA Technical Reports Server (NTRS)

    Eastwood, C.

    1975-01-01

    The structural capabilities of the jettisonable metal shroud were tested and the interaction of the shroud with the Centaur stage was evaluated. A flight-configured shroud and the assemblies of the associated Centaur stage were tested for applied axial and shear loads to flight limit values. The tests included various thermal, pressure, and load conditions to verify localized strength capabilities, to evaluate subsystem performance, and to determine the aging effect on insulation system properties. The tests series verified the strength capabilities of the shroud and of all associated flight assembles. Shroud deflections were shown to remain within allowable limits so long as load sharing members were connected between the shroud and the Centaur stage.

  14. Second heated jettison test on the Centaur standard shroud

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The second in a planned series of heated jettison tests on the Centaur Standard Shroud was conducted on January 16, 1974. The first 250-second portion of the test sequence involved heating the shroud with a specially-built fixture designed to provide a simulation of the heating environment encountered by the shroud during its ascent through the earth's atmosphere. The two heater halves, which were mounted on a rail system, were then retracted. This was followed by the jettison of the two shroud halves into catch nets positioned at 90 deg to the heater rails. The condition which made this test unique compared to the others in the test series was the alignment of the maximum thermal line with the shroud separation plane. Information on the test hardware, configuration, and sequence is presented. Shroud thermal and deflection data encountered during the heating portion of the test sequence are compared with free-skin design temperatures in various graphical formats.

  15. Pivotably mounted reactor shroud shield and shielding method

    SciTech Connect

    Hankinson, M.F.

    1987-03-31

    A method is described for shielding persons working around a nuclear reactor having a reactor head an a shroud extending upward from the reactor head, comprising: (a) mounting a plurality of swingout arms around the shroud, each swingout arm being pivotable about a respective axis that is substantially vertical and that is fixed with respect to the shroud; (b) positioning a shielding member adjacent a swingout arm with a hoist; (c) pivoting the swingout arm horizontally away from the shroud and toward the hoist; (d) transferring the shielding member from the hoist to the swingout arm so that the swingout arm supports the shielding member; (e) pivoting the swingout arm horizontally back toward the shroud; and (f) repeating steps (b) through (c) until the shroud is substantially surrounded by shielding members.

  16. Cleaning of a thermal vacuum chamber with shrouds in place

    NASA Technical Reports Server (NTRS)

    Bond, William R.

    1992-01-01

    In February, 1991, a failure of a rotary booster pump caused the diffusion pumps to backstream into a 10 ft x 15 ft thermal vacuum chamber. Concerns existed about the difficulty of removing and reinstalling the shrouds without causing leaks. The time required for the shroud removal was also of concern. These concerns prompted us to attempt to clean the chamber without removing the shrouds.

  17. Eddy current modeling by finite element method for evaluation of mechanical properties of the structure cracked in absolute probe

    NASA Astrophysics Data System (ADS)

    Harzallah, Salaheddine; Chabaat, Mohamed; Belgacem, Fethi Bin Muhammad

    2014-12-01

    In this paper, a nondestructive evaluation by sensor Eddy current is used as a tool to control cracks and micro-cracks in materials. A simulation by a numerical approach based on the finite element method is employed to detect cracks in materials and eventually to study their propagation using a crucial parameter such as a Stress Intensity Factor (SIF). This method has emerged as one of the most efficient techniques for prospecting cracks in materials, evaluating SIFs and analyzing crack's growth in the context of linear elastic fracture mechanics (LEFM). This technique uses extrapolation of displacements from results compared with those obtained by the integral interaction. On the other hand, crack's growth is analyzed as a model by combining the maximum circumferential stress criteria with the critical plane for predicting the direction of crack growth. Moreover, a constant crack growth increment is determined using the modified Paris's model. Furthermore, stress intensity factors needed for these models are calculated using the domain form of the J-integral interactions.

  18. Stress corrosion cracking of austenitic stainless steel core internal welds.

    SciTech Connect

    Chung, H. M.; Park, J.-H.; Ruther, W. E.; Sanecki, J. E.; Strain, R. V.; Zaluzec, N. J.

    1999-04-14

    Microstructural analyses by several advanced metallographic techniques were conducted on austenitic stainless steel mockup and core shroud welds that had cracked in boiling water reactors. Contrary to previous beliefs, heat-affected zones of the cracked Type 304L, as well as 304 SS core shroud welds and mockup shielded-metal-arc welds, were free of grain-boundary carbides, which shows that core shroud failure cannot be explained by classical intergranular stress corrosion cracking. Neither martensite nor delta-ferrite films were present on the grain boundaries. However, as a result of exposure to welding fumes, the heat-affected zones of the core shroud welds were significantly contaminated by oxygen and fluorine, which migrate to grain boundaries. Significant oxygen contamination seems to promote fluorine contamination and suppress thermal sensitization. Results of slow-strain-rate tensile tests also indicate that fluorine exacerbates the susceptibility of irradiated steels to intergranular stress corrosion cracking. These observations, combined with previous reports on the strong influence of weld flux, indicate that oxygen and fluorine contamination and fluorine-catalyzed stress corrosion play a major role in cracking of core shroud welds.

  19. Ceramic turbine stator vane and shroud support

    DOEpatents

    Glenn, Robert G.

    1981-01-01

    A support system for supporting the stationary ceramic vanes and ceramic outer shrouds which define the motive fluid gas path in a gas turbine engine is shown. Each individual segment of the ceramic component whether a vane or shroud segment has an integral radially outwardly projecting stem portion. The stem is enclosed in a split collet member of a high-temperature alloy material having a cavity configured to interlock with the stem portion. The generally cylindrical external surface of the collet engages a mating internal cylindrical surface of an aperture through a supporting arcuate ring segment with mating camming surfaces on the two facing cylindrical surfaces such that radially outward movement of the collet relative to the ring causes the internal cavity of the collet to be reduced in diameter to tightly engage the ceramic stem disposed therein. A portion of the collet extends outwardly through the ring segment opposite the ceramic piece and is threaded for receiving a nut and a compression washer for retaining the collet in the ring segment under a continuous biasing force urging the collet radially outwardly.

  20. A possible origin for the Turin shroud image.

    PubMed

    Clarkson, J D

    1983-09-01

    The image, of an apparently crucified corpse, on the Turin shroud is very possibly a scorch mark. One way a human body can produce intense but localised heat is by preternatural combustion. Many of the reported phenomena of the shroud and of preternatural combustion do correspond. PMID:6646006

  1. Deployable Shroud for the International X-Ray Observatory

    NASA Technical Reports Server (NTRS)

    Robinson, David W.

    2009-01-01

    A document describes the design of a lightweight (between 100 to 200 kg), light-tight shroud of about 3.9 meters in diameter that could be stowed into a very small volume, and be deployed to 12 meters. The shroud will consist of two concentric multi-layer blankets (MLIs) that are constructed in an accordion shape.

  2. Vibration characteristics analysis of rotating shrouded blades with impacts

    NASA Astrophysics Data System (ADS)

    Ma, Hui; Xie, Fangtao; Nai, Haiqiang; Wen, Bangchun

    2016-09-01

    A dynamic model of rotating shrouded blades with impacts among adjacent shrouded blades is established considering the effects of the centrifugal stiffening, spin softening and Coriolis force, and the model is validated using finite element method. In the proposed model, the shrouded blade is simplified as a cantilever Euler-Bernoulli beam with a mass point at the free end, and the flexural dynamic stiffness of shrouded blade is selected as contact stiffness during collision. Based on the developed model, the effects of symmetric and asymmetric shroud gaps, rotational speeds, and aerodynamic force amplitudes on the dynamic characteristics of shrouded blades are analyzed through Newmark-β numerical method. The results indicate that (1) the vibro-impact responses of shrouded blades under some asymmetric gaps are more complicated than that under symmetric gap. (2) With the increase of rotational speed from 6000 to 10,000 rev/min, the system vibration experiences from period-three motion, through chaotic motion, finally to period-one motion during collision process because the increasing rotational speed changes the flexural dynamic stiffness of rotating blade. (3) The vibration displacements of shrouded blades increase linearly, and impact force increases linearly with the increase of aerodynamic force amplitude.

  3. Cooling circuit for a gas turbine bucket and tip shroud

    SciTech Connect

    Willett, Fred Thomas

    2004-07-13

    An open cooling circuit for a gas turbine airfoil and associated tip shroud includes a first group of cooling holes internal to the airfoil and extending in a radially outward direction generally along a leading edge of the airfoil; a second group of cooling holes internal to the airfoil and extending in a radially outward direction generally along a trailing edge of the airfoil. A common plenum is formed in the tip shroud in direct communication with the first and second group of cooling holes, but a second plenum may be provided for the second group of radial holes. A plurality of exhaust holes extends from the plenum(s), through the tip shroud and opening along a peripheral edge of the tip shroud.

  4. Fluid-dynamic and aeroacoustic investigations of shrouded jets

    NASA Astrophysics Data System (ADS)

    Veerasamy, V.

    1980-08-01

    The fluid dynamic and aeroacoustic characteristics of a high subsonic jet discharging from a shrouded nozzle were investigated theoretically and experimentally to explore the possibility of jet noise reduction and thrust augmentation for STOL/VTOL aircraft. The preliminary design calculations of an adiabatic shrouded nozzle were performed by solving iteratively the one dimensional fluid dynamic equations governing the compressible flow. A two dimensional flow model, consisting of second order partial differential equations of a parabolic type, was used to find the effect of shroud length on the ejector performance. This model consists of the conservation laws with thin shear layer assumptions incorporating the Prandtl's mixing length hypothesis for turbulence closure. A numerical integration method was used to solve the governing fluid dynamic equations of motion. The aeroacoustic characteristics of the shrouded jet were analyzed based on the Lighthill's V(8) law.

  5. Centaur Standard Shroud (CSS) static ultimate load structural tests

    NASA Technical Reports Server (NTRS)

    1975-01-01

    A series of tests were conducted on the jettisonable metallic shroud used on the Titan/Centaur launch vehicle to verify its structural capabilities and to evaluate its structural interaction with the Centaur stage. A flight configured shroud and the interfacing Titan/Centaur structural assemblies were subjected to tests consisting of combinations of applied axial and shear loads to design ultimate values, including a set of tests on thermal conditions and two dynamic response tests to verify the analytical stiffness model. The strength capabilities were demonstrated at ultimate (125 percent of design limit) loads. It was also verified that the spring rate of the flight configured shroud-to-Centaur forward structural deflections of the specimen became nonlinear, as expected, above limit load values. This test series qualification program verified that the Titan/Centaur shroud and the Centaur and Titan interface components are qualified structurally at design ultimate loads.

  6. Fluidized-bed calciner with combustion nozzle and shroud

    DOEpatents

    Wielang, Joseph A.; Palmer, William B.; Kerr, William B.

    1977-01-01

    A nozzle employed as a burner within a fluidized bed is coaxially enclosed within a tubular shroud that extends beyond the nozzle length into the fluidized bed. The open-ended shroud portion beyond the nozzle end provides an antechamber for mixture and combustion of atomized fuel with an oxygen-containing gas. The arrangement provides improved combustion efficiency and excludes bed particles from the high-velocity, high-temperature portions of the flame to reduce particle attrition.

  7. Ladle Shroud as a Flow Control Device for Tundish Operations

    NASA Astrophysics Data System (ADS)

    Morales-Higa, Ken; Guthrie, R. I. L.; Isac, M.; Morales, R. D.

    2013-02-01

    The performance characteristics of a tundish, such as the flotation of inclusions and slag entrainment, are largely influenced by the fluid-flow phenomena. Physical modeling in water is widely used to understand the fluid flows in a tundish and as a tool to improve, control, and design procedures for high-quality steel processing operations. These approaches were used to study the performance of fluid flow for a new design of ladle shroud. The new design for a dissipative ladle shroud (DLS) was studied, using a one-third scale, delta shaped, four-strand tundish. The results were compared with those achieved with the conventional ladle shroud. Different cases have been analyzed, including a conventional ladle shroud (LS) with a bare tundish and a tundish furnished with an impact pad. Similarly, the new design of the shroud (DLS) was studied under equivalent conditions. The physical experiments included the use of particle image velocimetry (PIV) and conductivity tracer techniques. The PIV measured the instantaneous velocities at the outlet of the DLS and the LS at different flow rates, showing the detailed jetting characteristics of water leaving the two types of ladle shroud. Residence time distribution (RTD) curves were also obtained for the different flow arrangements previously mentioned, and the dispersion of a colored dye tracer was observed at different intervals of time during tundish operation and analyzed using the video visualization technique.

  8. Quantitative analysis of trace Pb(II) by a DNAzyme cracking-rhodamine 6G SERRS probe on AucoreAgshell nanosol substrate

    NASA Astrophysics Data System (ADS)

    Liu, Qingye; Wei, Yanyan; Luo, Yanghe; Liang, Aihui; Jiang, Zhiliang

    2014-07-01

    In pH 7.2 Tris-HCl buffer solution containing 0.09 mol/L NaCl at 80 °C, the single-stranded substrate DNA hybrids with the enzyme DNA to form double-stranded DNA (dsDNA). The substrate chain of dsDNA could be cracked catalytically by Pb2+ to produce a short single-stranded DNA (ssDNA) that adsorbed on the AucoreAgshell nanoparticle (Au/AgNP) surface to form stable Au/AgNP-ssDNA conjugate to prevent aggregation by NaCl, and it combined with rhodamine 6G (RhG) to form RhG-Au/AgNP-ssDNA probe that exhibited a strong surface-enhanced resonance Raman scattering (SERRS) peak at 1510 cm-1. With the increase of Pb2+ concentration, the SERRS peak increased linearly due to the more RhG-Au/AgNP-ssDNA probe forming. Under the selected conditions, the increased SERRS intensity ΔI was linear to Pb2+ concentration in the range of 5.0 × 10-8-7.0 × 10-7 mol/L, with a detection limit of 7 × 10-9 mol/L Pb2+.

  9. Cryogenic Shrouds for Testing Thermal-Insulation Panels

    NASA Technical Reports Server (NTRS)

    Norris, Jeffrey; Carroll, Robert; Kirch, Charles

    2007-01-01

    Cryogenic shrouds have been designed and built for use in thermomechanical testing of samples of thermalinsulation panels on cryogenic vessels. In the original application for which these shrouds were specifically designed, the samples are representative of the large-area thermal-insulation panels on the space-shuttle external tanks that hold liquid hydrogen and liquid oxygen, and the purpose of the testing is to demonstrate the ability of bonded layers in the panels to resist delamination under a combination of applied uniaxial mechanical loads and realistic operational temperatures. Presumably, the shrouds and the tests performed by use of them could be modified to enable similar evaluation of thermomechanical properties of thermal-insulation panels for cryogenic vessels other than the external tanks of the space shuttles. The shrouds are required to enable maintenance of required temperatures on the inner and outer surfaces of the thermal-insulation-panel samples, to enable visual observation of the outer surfaces of the samples, and not to introduce any measurable loads into the panels. For each panel sample, there are two shrouds: one to be mounted on the inner surface (the surface that would be in contact with a tank containing a cryogenic liquid during normal use) and one to be mounted on the outer surface (the surface that would be exposed to ambient air or other warmer environment during normal use). The shrouds for testing specimens of thermal-insulation- panels for the liquid-hydrogen tank are made largely of titanium; the shrouds for testing specimens of thermal- insulation-panels for the liquid-oxygen tank are made largely of an aluminum- lithium alloy. The specific temperature requirements are the following: The inner shroud must make it possible to maintain a temperature of 321 degrees F (196 degrees C) [the approximate temperature of liquid nitrogen] or 453 F (about 269 C) [the approximate temperature of liquid helium] on the inner face of the

  10. Shroud debris modeling techniques for IR sensors in space

    NASA Astrophysics Data System (ADS)

    VanderWyst, Anton; Jenkins, David G.; Ahmad, Anees

    2007-09-01

    Space-based surveillance sensors are covered by a shroud to protect the delicate optics from adverse environments (aerothermal heating and contamination) during hypersonic flight through the atmosphere. Once the sensor payload reaches a safe altitude, the shroud is deployed and then sensor operation begins. When the pyrotechnic actuators are fired to deploy the shroud or nosecone, large and microscopic particles are dislodged. The source of these particles is the charred thermal protection insulation material on outer surface of the shroud, and particulate contaminants deposited on the inside surface of shroud and on sensor components during assembly process. These dislodged particles can end up within the sensor field of view (FOV), and remain there for extended periods of time, with the duration depending on the air density and vehicle velocity. These undesirable particles within the sensor FOV can degrade infrared sensor performance in several ways. These particles can cause obscuration, scattering and produce spurious thermal signature, thus making it difficult to image the objects of interest. This paper presents the aeromodeling techniques used to estimate the number and size of particles, and the duration these particles can stay within the sensor FOV. This information can then be used to predict the resulting degradation in sensor performance.

  11. How was the Turin Shroud Man crucified?

    PubMed

    Bevilacqua, M; Fanti, G; D'Arienzo, M; Porzionato, A; Macchi, V; De Caro, R

    2014-12-01

    As the literature is not exhaustive with reference to the way the Turin Shroud (TS) Man was crucified, and it is not easy to draw significant information from only a "photograph" of a man on a linen sheet, this study tries to add some detail on this issue based on both image processing of high resolution photos of the TS and on experimental tests on arms and legs of human cadavers. With regard to the TS Man hands, a first hypothesis states that the left hand of the TS Man was nailed twice at two different anatomical sites: the midcarpal joint medially to the pisiform between the lunate/pyramidal and capitate/uncinate bones (Destot's space) and the radiocarpal joint between the radio, lunate and scaphoid; also the right hand would have been nailed twice. A second hypothesis, preferred by the authors, states that the hands were nailed only once in the Destot's space with partial lesion of the ulnar nerve and flexion of the metacarpophalangeal joint of the thumbs. With regard to the TS Man feet, the imprint of the sole of the right foot leads to the conclusion that TS Man suffered a dislocation at the ankle just before the nailing. The entrance hole of the nail on the right foot is a few inches from the ankle, and excludes a double nailing. The nail has been driven between the tarsal bones. The TS Man suffered the following tortures during crucifixion: a very serious and widespread causalgia due to total paralysis of the upper right limb (paradoxical causalgia); a nailing of the left wrist with damage to the ulnar nerve; a similar nailing of the right wrist; and a nailing to both feet using one only nail that injured the plantaris medialis nerves. The respiratory limitation was probably not sufficient to cause death by asphyxiation. Also considering the hypovolemia produced by scourging and the many other tortures detectable on the TS, the principal cause of death can be attributed to a myocardial infarction. PMID:25457335

  12. Helium-Cooled Black Shroud for Subscale Cryogenic Testing

    NASA Technical Reports Server (NTRS)

    Tuttle, James; Jackson, Michael; DiPirro, Michael; Francis, John

    2011-01-01

    This shroud provides a deep-space simulating environment for testing scaled-down models of passively cooling systems for spaceflight optics and instruments. It is used inside a liquid-nitrogen- cooled vacuum chamber, and it is cooled by liquid helium to 5 K. It has an inside geometry of approximately 1.6 m diameter by 0.45 m tall. The inside surfaces of its top and sidewalls have a thermal absorptivity greater than 0.96. The bottom wall has a large central opening that is easily customized to allow a specific test item to extend through it. This enables testing of scale models of realistic passive cooling configurations that feature a very large temperature drop between the deepspace-facing cooled side and the Sun/Earth-facing warm side. This shroud has an innovative thermal closeout of the bottom wall, so that a test sample can have a hot (room temperature) side outside of the shroud, and a cold side inside the shroud. The combination of this closeout and the very black walls keeps radiated heat from the sample s warm end from entering the shroud, reflecting off the walls and heating the sample s cold end. The shroud includes 12 vertical rectangular sheet-copper side panels that are oriented in a circular pattern. Using tabs bent off from their edges, these side panels are bolted to each other and to a steel support ring on which they rest. The removable shroud top is a large copper sheet that rests on, and is bolted to, the support ring when the shroud is closed. The support ring stands on four fiberglass tube legs, which isolate it thermally from the vacuum chamber bottom. The insides of the cooper top and side panels are completely covered with 25- mm-thick aluminum honeycomb panels. This honeycomb is painted black before it is epoxied to the copper surfaces. A spiral-shaped copper tube, clamped at many different locations to the outside of the top copper plate, serves as part of the liquid helium cooling loop. Another copper tube, plumbed in a series to the

  13. Shroud boundary condition characterization experiments at the Radiant Heat Facility.

    SciTech Connect

    Suo-Anttila, Jill Marie; Nakos, James Thomas; Gill, Walter

    2004-10-01

    A series of experiments was performed to better characterize the boundary conditions from an inconel heat source ('shroud') painted with Pyromark black paint. Quantifying uncertainties in this type of experimental setup is crucial to providing information for comparisons with code predictions. The characterization of this boundary condition has applications in many scenarios related to fire simulation experiments performed at Sandia National Laboratories Radiant Heat Facility (RHF). Four phases of experiments were performed. Phase 1 results showed that a nominal 1000 C shroud temperature is repeatable to about 2 C. Repeatability of temperatures at individual points on the shroud show that temperatures do not vary more than 10 C from experiment to experiment. This variation results in a 6% difference in heat flux to a target 4 inches away. IR camera images showed the shroud was not at a uniform temperature, although the control temperature was constant to about {+-}2 C during a test. These images showed that a circular shaped, flat shroud with its edges supported by an insulated plate has a temperature distribution with higher temperatures at the edges and lower temperatures in the center. Differences between the center and edge temperatures were up to 75 C. Phase 3 results showed that thermocouple (TC) bias errors are affected by coupling with the surrounding environment. The magnitude of TC error depends on the environment facing the TC. Phase 4 results were used to estimate correction factors for specific applications (40 and 63-mil diameter, ungrounded junction, mineral insulated, metal-sheathed TCs facing a cold surface). Correction factors of about 3.0-4.5% are recommended for 40 mil diameter TCs and 5.5-7.0% for 63 mil diameter TCs. When mounted on the cold side of the shroud, TCs read lower than the 'true' shroud temperature, and the TC reads high when on the hot side. An alternate method uses the average of a cold side and hot side TC of the same size to

  14. Double-ended metal halide arc discharge lamp with electrically isolated containment shroud

    NASA Technical Reports Server (NTRS)

    Muzeroll, Martin M. (Inventor)

    1994-01-01

    A double-ended arc discharge lamp includes a sealed, light-transmissive outer jacket, a light-transmissive shroud mounted within the outer jacket and directly supported by the outer jacket, and an arc discharge tube mounted within the shroud. The arc tube is typically a metal halide arc discharge tube. In a preferred embodiment, the shroud includes an outwardly flared portion at each end. The outwardly flared portions space the shroud from the outer jacket and support the shroud within the outer jacket. The outwardly flared portions of the shroud can be affixed to the outer jacket by fusing. The outer jacket can be provided with inwardly extending dimples for locating the shroud with respect to the outer jacket. In another embodiment, the outer jacket includes reduced diameter portions near each end which are attached to the shroud.

  15. The Most Luminous Object in the Universe: Shrouded Quasar or Proto-Galaxy

    NASA Technical Reports Server (NTRS)

    Heckman, Timothy M.

    1999-01-01

    We have used ASCA to observe the IRAS source FSC 10214+4724, which is identified with a galaxy at a redshift of 2.286. When first discovered, it was believed to be the most luminous object in the universe. Subsequent HST images have established that it is gravitationally-lensed by a foreground cluster. It is still a very powerful object, but not extraordinarily so. Observations at other wavebands have not established whether it is a dust-shrouded quasar or a young, massive galaxy in the process of formation. Since quasars are strong emitters of hard X-rays, while proto-galaxies would not be, and since the opacity of gas and dust is relatively small in the energy regime probed by ASCA (3 to 30 keV in the galaxy rest frame), we undertook these observations to search for a heavily shrouded quasar that might be invisible at lower energies. However, the observations did not detect any emission from this object. This either means that the galaxy is in fact powered by a starburst or that the putative quasar is located behind a very high column density of absorbing gas (N_H > 10(exp 25)/sq cm), so that not even hard X-rays are transmitted. A hidden quasar should be visible in reflected light in X-ray data of higher sensitivity. Observations with NASA's Chandra X-ray Observatory or ESA's XMM are required to settle the matter. No publication resulted from our null result.

  16. Measurements of the rotordynamic shroud forces for centrifugal pumps

    NASA Technical Reports Server (NTRS)

    Guinzburg, A.; Brennen, C. E.; Acosta, A. J.; Caughey, T. K.

    1990-01-01

    An experiment was designed to measure the rotordynamic shroud forces on a centrifugal pump impeller. The measurements were done for various whirl/impeller speed ratios and for different flow rates. A destabilizing tangential force was measured for small positive whirl ratios and this force decreased with increasing flow rate.

  17. 15. VIEW OF THE SPECIAL SHROUDING AND AIR HANDLING SYSTEM ...

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

    15. VIEW OF THE SPECIAL SHROUDING AND AIR HANDLING SYSTEM USED IN BERYLLIUM PRODUCTION. (3/30/89) - Rocky Flats Plant, Non-Nuclear Production Facility, South of Cottonwood Avenue, west of Seventh Avenue & east of Building 460, Golden, Jefferson County, CO

  18. Corrosion cracking

    SciTech Connect

    Goel, V.S.

    1986-01-01

    Various papers on corrosion cracking are presented. The topics addressed include: unique case studies on hydrogen embrittlement failures in components used in aeronautical industry; analysis of subcritical cracking in a Ti-5Al-2.5Sn liquid hydrogen control valve; corrosion fatigue and stress corrosion cracking of 7475-T7351 aluminum alloy; effects of salt water environment and loading frequency on crack initiation in 7075-T7651 aluminum alloy and Ti-6Al-4V; stress corrosion cracking of 4340 steel in aircraft ignition starter residues. Also discussed are: stress corrosion cracking of a titanium alloy in a hydrogen-free environment; automation in corrosion fatigue crack growth rate measurements; the breaking load method, a new approach for assessing resistance to growth of early stage stress corrosion cracks; stress corrosion cracking properties of 2090 Al-Li alloy; repair welding of cracked free machining Invar 36; radial bore cracks in rotating disks.

  19. BWR Vessel and Internals Project Removal and Analysis of Material Samples from Core Shroud and Top Guide at Susquehanna Unit 2

    SciTech Connect

    Howell, D; Haertel, T; Lindberg, J; Oliver, B; Greenwood, L

    2005-04-15

    Fast and thermal fluence were determined by a laboratory analysis of the samples. Fluence in the upper regions of the shroud (between the H1 and H2 welds) was substantially lower than that in the belt line region (near the H4 weld). Fluence in the top guide was significantly higher than fluence on the core shroud. As expected, helium concentrations were highest in regions where fluence was highest. Estimates of the initial boron concentration were similar to measurements made on materials removed from other reactors. A technical justification evaluated the acceptability of the sampling process with respect to structural consequences of material removal and to increased cracking susceptibility due to the as-left condition. It was determined that the sampling process was acceptable on both counts.

  20. Investigation of eddy current examination on OD fatigue crack for steam generator tubes

    NASA Astrophysics Data System (ADS)

    Kong, Yuying; Ding, Boyuan; Li, Ming; Liu, Jinhong; Chen, Huaidong; Meyendorf, Norbert G.

    2015-03-01

    The opening width of fatigue crack was very small, and conventional Bobbin probe was very difficult to detect it in steam generator tubes. Different sizes of 8 fatigue cracks were inspected using bobbin probe rotating probe. The analysis results showed that, bobbin probe was not sensitive for fatigue crack even for small through wall crack mixed with denting signal. On the other hand, the rotating probe was easily to detect all cracks. Finally, the OD phase to depth curve for fatigue crack using rotating probe was established and the results agreed very well with the true crack size.

  1. Heat transfer and flow characteristics on a gas turbine shroud.

    PubMed

    Obata, M; Kumada, M; Ijichi, N

    2001-05-01

    The work described in this paper is an experimental investigation of the heat transfer from the main flow to a turbine shroud surface, which may be applicable to ceramic gas turbines. Three kinds of turbine shrouds are considered with a flat surface, a taper surface and a spiral groove surface opposite to the blades in an axial flow turbine of actual turbo-charger. Heat transfer measurements were performed for the experimental conditions of a uniform heat flux or a uniform wall temperature. The effects of the inlet flow angle, rotational speed, and tip clearance on the heat transfer coefficient were clarified under on- and off-design flow conditions. The mean heat transfer coefficient was correlated to the blade Reynolds number and tip clearance, and compared with an experimental correlation and measurements of a flat surface. A comparison was also made for the measurement of static pressure distributions. PMID:11460639

  2. High voltage transmission microscopy of Surveyor 3 camera shrouds

    NASA Technical Reports Server (NTRS)

    Fisher, R. M.; Duff, W. R.; Thomas, L. E.; Radcliffe, S. V.

    1972-01-01

    The internal structure of painted and unpainted aluminum alloy sheet samples from the TV camera shrouds were examined by high-voltage transmission electron microscopy. No clear-cut evidence of radiation damage effects was observed. Noticeable differences in microstructures between the upper visor and the sides and bottom of the lower shroud suggest different thermal histories, and the maximum temperatures due to solar heating are estimated to be between 164 and 319 C. Some correlation between microstructures and maximum estimated temperature is noted. It is felt that the apparent temperature rise due to solar heating will not affect the structural integrity of spacecraft components except possibly for very long periods of exposure. However, substantial thermal diffusion could affect interpretation of solar wind rare gas studies.

  3. Sequence of Assembly of OAO Shroud at SPC

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Sequence of assembly of OAO Shroud at Space Power Facility, Plum Brook Station, Lewis Research Center, Sandusky Ohio. Lewis is now known as the John H. Glenn Research Center at Lewis Field. At the time it was built, the SPF was the world's largest vacuum chamber, measuring more than 100 feet in diameter and 122 feet high. The OAO or Orbiting Astronomical Observatory was used for astronomical research.

  4. Design and performance of a small shrouded Cretan windwheel

    NASA Astrophysics Data System (ADS)

    Fleming, P. D.; Probert, S. D.

    1982-02-01

    Test data for the performance of a shrouded Cretan-type sail mill are reported. The mill was chosen because of simplicity and low-cost considerations, for applications in developing countries. The mill had 9 sails, a 0.64 m diam cycle wheel as a rotor, and was tested in rim-attached and sail-with-pole configurations. Winds shape the sails into airfoil shapes, and the addition of the shroud to augment the wind flow boosted the power coefficient to close to the Betz limit. The sail-with-pole form, comprising a loosely sheeted sail with the leading edge wrapped around the spoke and fastened to itself was found to be a practical configuration for driving a peristaltic pump. Maximum power was obtained with a higher rotor speed than the rotor speed for maximum torque. Prospective uses for the shrouded sail mill are given as irrigation and land drainage, and for boosting the thermo-syphon in a domestic solar heating circuit.

  5. Dynamically tuned shroud for gun barrel vibration attenuation

    NASA Astrophysics Data System (ADS)

    Littlefield, Andrew G.; Kathe, Eric L.; Durocher, Robert

    2002-06-01

    Modern tank guns, such as the one on the Abrams, are stabilized to allow fire on the move while traversing uneven terrain. The current barrel is short enough that treating as a rigid beam allows engagement of another tank at ranges of over a kilometer. However, as the length of the tube is extended, to meet required muzzle exit velocities, the terrain induced vibrations lead to increased muzzle pointing errors. A method to reduce these vibrations is to use the forward thermal shroud as part of a mass tuned damper. In this case the system under study is an extended length version of the gun currently fielded. This extended length increases its susceptibility to terrain-induced vibrations. The forward thermal shroud has been shortened and additional mass has been added onto its forward collar. This collar is then supported by springs, which are preloaded so that they stay in contact through the full range of the shroud's movement. Varying the stiffness of these springs allows for tuning of the absorber. Different types of springs and attachments have been tried. The current version uses leaf springs and a wedge collar. This system has been modeled and experiments conducted to validate the model.

  6. The Release of Trapped Gases from Amorphous Solid Water Films: I. “Top-Down” Crystallization-Induced Crack Propagation Probed using the Molecular Volcano

    SciTech Connect

    May, Robert A.; Smith, R. Scott; Kay, Bruce D.

    2013-03-14

    In this (Paper I) and the companion paper (Paper II) we investigate the mechanisms for the release of trapped gases from underneath of amorphous solid water (ASW) films. In prior work, we reported the episodic release of trapped gases in concert with the crystallization ASW, a phenomenon that we termed the "molecular volcano". The observed abrupt desorption is due to the formation of cracks that span the film to form a connected pathway for release. In this paper we utilize the "molecular volcano" desorption peak to characterize the formation of crystallization-induced cracks. We find that the crack length and distribution are independent of the trapped gas (Ar, Kr, Xe, CH4, N2, O2 or CO). Selective placement of the inert gas layer is used to show that cracks form near the top of the film and propagate downward into the film. Isothermal experiments reveal that, after some induction time, cracks propagate linearly in time with an Arrhenius dependent velocity corresponding to an activation energy of 54 kJ/mol. This value is consistent with the crystallization growth rate reported by others and establishes a direct connection between crystallization growth rate and the crack propagation rate. A two-step model in which nucleation and crystallization occurs in an induction zone near the top of the film followed by the propagation of a crystallization/crack front into the film is in good agreement with the temperature programmed desorption results.

  7. Energy efficient engine high pressure turbine ceramic shroud support technology report

    NASA Technical Reports Server (NTRS)

    Nelson, W. A.; Carlson, R. G.

    1982-01-01

    This work represents the development and fabrication of ceramic HPT (high pressure turbine) shrouds for the Energy Efficient Engine (E3). Details are presented covering the work performed on the ceramic shroud development task of the NASA/GE Energy Efficient Engine (E3) component development program. The task consists of four phases which led to the selection of a ZrO2-BY2O3 ceramic shroud material system, the development of an automated plasma spray process to produce acceptable shroud structures, the fabrication of select shroud systems for evaluation in laboratory, component, and CF6-50 engine testing, and finally, the successful fabrication of ZrO2-8Y2O3/superpeg, engine quality shrouds for the E3 engine.

  8. Environmentally assisted cracking of LWR materials.

    SciTech Connect

    Chopra, O. K.; Chung, H. M.; Kassner, T. F.; Park, J. H.; Shack, W. J.; Zhang, J.; Brust, F. W.; Dong, P.

    1997-12-05

    The effect of dissolved oxygen level on fatigue life of austenitic stainless steels is discussed and the results of a detailed study of the effect of the environment on the growth of cracks during fatigue initiation are presented. Initial test results are given for specimens irradiated in the Halden reactor. Impurities introduced by shielded metal arc welding that may affect susceptibility to stress corrosion cracking are described. Results of calculations of residual stresses in core shroud weldments are summarized. Crack growth rates of high-nickel alloys under cyclic loading with R ratios from 0.2-0.95 in water that contains a wide range of dissolved oxygen and hydrogen concentrations at 289 and 320 C are summarized.

  9. Environmentally assisted cracking in LWR materials

    SciTech Connect

    Chopra, O.K.; Chung, H.M.; Kassner, T.F.; Park, J.H.; Shack, W.J.; Zhang, J.; Brust, F.W.; Dong, P.

    1998-03-01

    The effect of dissolved oxygen level on fatigue life of austenitic stainless steels is discussed and the results of a detailed study of the effect of the environment on the growth of cracks during fatigue initiation are presented. Initial test results are given for specimens irradiated in the Halden reactor. Impurities introduced by shielded metal arc welding that may affect susceptibility to stress corrosion cracking are described. Results of calculations of residual stresses in core shroud weldments are summarized. Crack growth rates of high-nickel alloys under cyclic loading with R ratios from 0.2--0.95 in water that contains a wide range of dissolved oxygen and hydrogen concentrations at 289 and 320 C are summarized.

  10. NK-1 Removable Cryogenic Shroud (A Study of the Bimba Pneumatic Cylinder)

    SciTech Connect

    Anderson, K; Stefanescu, D

    2003-02-07

    The Mark 1 Cryostat requires a cryogenic shroud that must be retracted immediately before firing the NIF laser. This paper evaluates a pneumatic cylinder that has been chosen to open and close the shroud. After a variety of motion control and vacuum compatibility experiments, we concluded that the Bimba feedback control cylinder may be used to retract the shroud with certain modifications to its control system and additional rod seals.

  11. Analysis of Shroud Options in Support of the Human Exploration of Mars

    NASA Technical Reports Server (NTRS)

    Feldman, Stuart; Borowski, Stanley; Engelund, Walter; Hundley, Jason; Monk, Timothy; Munk, Michelle

    2010-01-01

    In support of the Mars Design Reference Architecture (DRA) 5.0, the NASA study team analyzed several shroud options for use on the Ares V launch vehicle.1,2 These shroud options included conventional "large encapsulation" shrouds with outer diameters ranging from 8.4 to 12.9 meters (m) and overall lengths of 22.0 to 54.3 meters, along with a "nosecone-only" shroud option used for Mars transfer vehicle component delivery. Also examined was a "multi-use" aerodynamic encapsulation shroud used for launch, Mars aerocapture, and entry, descent, and landing of the cargo and habitat landers. All conventional shroud options assessed for use on the Mars launch vehicles were the standard biconic design derived from the reference shroud utilized in the Constellation Program s lunar campaign. It is the purpose of this paper to discuss the technical details of each of these shroud options including material properties, structural mass, etc., while also discussing both the volume and mass of the various space transportation and surface system payload elements required to support a "minimum launch" Mars mission strategy, as well as the synergy, potential differences and upgrade paths that may be required between the Lunar and Mars mission shrouds.

  12. Leaf seal for gas turbine stator shrouds and a nozzle band

    DOEpatents

    Burdgick, Steven Sebastian; Sexton, Brendan Francis

    2002-01-01

    A leaf seal assembly is secured to the trailing edge of a shroud segment for sealing between the shroud segment and the leading edge side wall of a nozzle outer band. The leaf seal includes a circumferentially elongated seal plate biased by a pair of spring clips disposed in a groove along the trailing edge of the shroud segment to maintain the seal plate in engagement with the flange on the leading edge side wall of the nozzle outer band. The leaf seal plate and spring clips receive pins tack-welded to the shroud segment to secure the leaf seal assembly in place.

  13. Ultraviolet-visible reflectance and fluorescence spectra of the Shroud of Turin.

    PubMed

    Gilbert, R; Gilbert, M M

    1980-06-15

    The Shroud of Turin is a partially scorched linen cloth containing an apparently bloodstained sepia image of a man lying in a state of repose. It is believed by some to be the burial cloth of Jesus of Nazareth. A team of scientists, under the auspices of The Shroud of Turin Research Project, Inc., performed nondestructive measurements on the Shroud with electromagnetic energy from x ray to the IR to develop data leading to the analysis of the substances making up the body image stains and bloodstains. Presented here are UV-visible reflectance and fluoroescence spectra of the sepia body image area and scorched and bloodstained areas on the shroud. PMID:20221157

  14. Analysis, Verification, and Application of Equations and Procedures for Design of Exhaust-pipe Shrouds

    NASA Technical Reports Server (NTRS)

    Ellerbrock, Herman H.; Wcislo, Chester R.; Dexter, Howard E.

    1947-01-01

    Investigations were made to develop a simplified method for designing exhaust-pipe shrouds to provide desired or maximum cooling of exhaust installations. Analysis of heat exchange and pressure drop of an adequate exhaust-pipe shroud system requires equations for predicting design temperatures and pressure drop on cooling air side of system. Present experiments derive such equations for usual straight annular exhaust-pipe shroud systems for both parallel flow and counter flow. Equations and methods presented are believed to be applicable under certain conditions to the design of shrouds for tail pipes of jet engines.

  15. Detecting Cracks in Rough Metal Surfaces

    NASA Technical Reports Server (NTRS)

    Zuver, N. T.; Sugg, F. E.; Stuckenberg, F. H.; Morrissey, E. T.

    1985-01-01

    Test based on eddy-current probe technique identifies cracks in swaged metals. Hinged collar with spring-loaded latch holds probe in place on part tested. For repeated measurements on same or similar parts, collar loosened and moved to various measuring positions. Method suitable for many kinds of metal parts, including swaged fittings, tubing, and pipes. Used for rapid crack/no-crack determinations in suspect parts already installed.

  16. Turin workshop on radiocarbon dating the Turin Shroud

    NASA Astrophysics Data System (ADS)

    Gove, H. E.

    1987-11-01

    A workshop to explore the procedures for making carbon-14 measurements on the cloth of the Shroud of Turin was held in Turin, Italy on September 29, 30 and October 1, 1986. It was sponsored by the Pontifical Academy of Sciences whose president chaired the workshop and by the Archbishop of Turin. Twenty-two people participated including representatives from seven laboratories who have indicated a willingness to carry out the measurements if a request to do so from the Vatican is forthcoming. A protocol for carrying out this task was agreed upon by the workshop delegates and has been presented to Vatican authorities.

  17. TOTAL SOLAR ECLIPSE OBSERVATIONS OF HOT PROMINENCE SHROUDS

    SciTech Connect

    Habbal, S. Rifai; Morgan, H.; Scholl, I.; Druckmueller, M.; Rusin, V.; Daw, A.; Johnson, J.; Arndt, M.

    2010-08-20

    Using observations of the corona taken during the total solar eclipses of 2006 March 29 and 2008 August 1 in broadband white light and in narrow bandpass filters centered at Fe X 637.4 nm, Fe XI 789.2 nm, Fe XIII 1074.7 nm, and Fe XIV 530.3 nm, we show that prominences observed off the solar limb are enshrouded in hot plasmas within twisted magnetic structures. These shrouds, which are commonly referred to as cavities in the literature, are clearly distinct from the overlying arch-like structures that form the base of streamers. The existence of these hot shrouds had been predicted by model studies dating back to the early 1970s, with more recent studies implying their association with twisted magnetic flux ropes. The eclipse observations presented here, which cover a temperature range of 0.9 to 2 x10{sup 6} K, are the first to resolve the long-standing ambiguity associated with the temperature and magnetic structure of prominence cavities.

  18. User manual for SPLASH (Single Panel Lamp and Shroud Helper).

    SciTech Connect

    Larsen, Marvin Elwood

    2006-02-01

    The radiant heat test facility develops test sets providing well-characterized thermal environments, often representing fires. Many of the components and procedures have become standardized to such an extent that the development of a specialized design tool to determine optimal configurations for radiant heat experiments was appropriate. SPLASH (Single Panel Lamp and Shroud Helper) is that tool. SPLASH is implemented as a user-friendly, Windows-based program that allows a designer to describe a test setup in terms of parameters such as number of lamps, power, position, and separation distance. This document is a user manual for that software. Any incidental descriptions of theory are only for the purpose of defining the model inputs. The theory for the underlying model is described in SAND2005-2947 (Ref. [1]). SPLASH provides a graphical user interface to define lamp panel and shroud designs parametrically, solves the resulting radiation enclosure problem for up to 2500 surfaces, and provides post-processing to facilitate understanding and documentation of analyzed designs.

  19. Uncovering the sources of DNA found on the Turin Shroud

    PubMed Central

    Barcaccia, Gianni; Galla, Giulio; Achilli, Alessandro; Olivieri, Anna; Torroni, Antonio

    2015-01-01

    The Turin Shroud is traditionally considered to be the burial cloth in which the body of Jesus Christ was wrapped after his death approximately 2000 years ago. Here, we report the main findings from the analysis of genomic DNA extracted from dust particles vacuumed from parts of the body image and the lateral edge used for radiocarbon dating. Several plant taxa native to the Mediterranean area were identified as well as species with a primary center of origin in Asia, the Middle East or the Americas but introduced in a historical interval later than the Medieval period. Regarding human mitogenome lineages, our analyses detected sequences from multiple subjects of different ethnic origins, which clustered into a number of Western Eurasian haplogroups, including some known to be typical of Western Europe, the Near East, the Arabian Peninsula and the Indian sub-continent. Such diversity does not exclude a Medieval origin in Europe but it would be also compatible with the historic path followed by the Turin Shroud during its presumed journey from the Near East. Furthermore, the results raise the possibility of an Indian manufacture of the linen cloth. PMID:26434580

  20. Modeling shrouded stator cavity flows in axial-flow compressors

    SciTech Connect

    Wellborn, S.R.; Tolchinsky, I.; Okiishi, T.H.

    2000-01-01

    Experiments and computational analyses were completed to understand the nature of shrouded stator cavity flows. From this understanding, a one-dimensional model of the flow through shrouded stator cavities was developed. This model estimates the leakage mass flow, temperature rise, and angular momentum increase through the cavity, given geometry parameters and the flow conditions at the interface between the cavity and primary flow path. This cavity model consists of two components, one that estimates the flow characteristics through the labyrinth seals and the other that predicts the transfer of momentum due to windage. A description of the one-dimensional model is given. The incorporation and use of the one-dimensional model in a multistage compressor primary flow analysis tool is described. The combination of this model and the primary flow solver was used to reliably simulate the significant impact on performance of the increase of hub seal leakage in a twelve-stage axial-flow compressor. Observed higher temperatures of the hub region fluid, different stage matching, and lower overall efficiencies and core flow than expected could be correctly linked to increased hub seal clearance with this new technique. The importance of including these leakage flows in compressor simulations is shown.

  1. Uncovering the sources of DNA found on the Turin Shroud.

    PubMed

    Barcaccia, Gianni; Galla, Giulio; Achilli, Alessandro; Olivieri, Anna; Torroni, Antonio

    2015-01-01

    The Turin Shroud is traditionally considered to be the burial cloth in which the body of Jesus Christ was wrapped after his death approximately 2000 years ago. Here, we report the main findings from the analysis of genomic DNA extracted from dust particles vacuumed from parts of the body image and the lateral edge used for radiocarbon dating. Several plant taxa native to the Mediterranean area were identified as well as species with a primary center of origin in Asia, the Middle East or the Americas but introduced in a historical interval later than the Medieval period. Regarding human mitogenome lineages, our analyses detected sequences from multiple subjects of different ethnic origins, which clustered into a number of Western Eurasian haplogroups, including some known to be typical of Western Europe, the Near East, the Arabian Peninsula and the Indian sub-continent. Such diversity does not exclude a Medieval origin in Europe but it would be also compatible with the historic path followed by the Turin Shroud during its presumed journey from the Near East. Furthermore, the results raise the possibility of an Indian manufacture of the linen cloth. PMID:26434580

  2. Design of Shrouded Airborne Wind Turbine & CFD Analysis

    NASA Astrophysics Data System (ADS)

    Anbreen, Faiqa; Faiqa Anbreen Collaboration

    2015-11-01

    The focus is to design a shrouded airborne wind turbine, capable to generate 70 kW to propel a leisure boat. The idea of designing an airborne turbine is to take the advantage of different velocity layers in the atmosphere. The blades have been designed using NREL S826 airfoil, which has coefficient of lift CL of 1.4 at angle of attack, 6°. The value selected for CP is 0.8. The rotor diameter is 7.4 m. The balloon (shroud) has converging-diverging nozzle design, to increase the mass flow rate through the rotor. The ratio of inlet area to throat area, Ai/At is 1.31 and exit area to throat area, Ae/At is1.15. The Solidworks model has been analyzed numerically using CFD. The software used is StarCCM +. The Unsteady Reynolds Averaged Navier Stokes Simulation (URANS) K- ɛ model has been selected, to study the physical properties of the flow, with emphasis on the performance of the turbine. Stress analysis has been done using Nastran. From the simulations, the torque generated by the turbine is approximately 800N-m and angular velocity is 21 rad/s.

  3. Corrosion fatigue crack propagation in metals

    SciTech Connect

    Gangloff, R.P.

    1990-06-01

    This review assesses fracture mechanics data and mechanistic models for corrosion fatigue crack propagation in structural alloys exposed to ambient temperature gases and electrolytes. Extensive stress intensity-crack growth rate data exist for ferrous, aluminum and nickel based alloys in a variety of environments. Interactive variables (viz., stress intensity range, mean stress, alloy composition and microstructure, loading frequency, temperature, gas pressure and electrode potential) strongly affect crack growth kinetics and complicate fatigue control. Mechanistic models to predict crack growth rates were formulated by coupling crack tip mechanics with occluded crack chemistry, and from both the hydrogen embrittlement and anodic dissolution/film rupture perspectives. Research is required to better define: (1) environmental effects near threshold and on crack closure; (2) damage tolerant life prediction codes and the validity of similitude; (3) the behavior of microcrack; (4) probes and improved models of crack tip damage; and (5) the cracking performance of advanced alloys and composites.

  4. Corrosion fatigue crack propagation in metals

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.

    1990-01-01

    This review assesses fracture mechanics data and mechanistic models for corrosion fatigue crack propagation in structural alloys exposed to ambient temperature gases and electrolytes. Extensive stress intensity-crack growth rate data exist for ferrous, aluminum and nickel based alloys in a variety of environments. Interactive variables (viz., stress intensity range, mean stress, alloy composition and microstructure, loading frequency, temperature, gas pressure and electrode potential) strongly affect crack growth kinetics and complicate fatigue control. Mechanistic models to predict crack growth rates were formulated by coupling crack tip mechanics with occluded crack chemistry, and from both the hydrogen embrittlement and anodic dissolution/film rupture perspectives. Research is required to better define: (1) environmental effects near threshold and on crack closure; (2) damage tolerant life prediction codes and the validity of similitude; (3) the behavior of microcrack; (4) probes and improved models of crack tip damage; and (5) the cracking performance of advanced alloys and composites.

  5. SHED: A program for three-dimensional, rigid body, shroud ejection dynamics

    SciTech Connect

    Segalman, D.J.

    1988-03-01

    The computer program SHED (for SHroud Ejection Dynamics) which calculates the exoatmospheric trajectory of a missile shroud is described. This rigid body dynamics program follows the motion of the shroud as its motors accelerate it ahead and away form the missile. Of particular interest is the ability of SHED to accommodate the forces produced by the motors which are ''fixed'' to the body in the sense that they both translate and rotate along with the body. The code as written has the following capabilities: The resulting program can accommodate an arbitrary number of motors, arranged in an arbitrary manner on the shroud, and each imposing an arbitrary schedule of thrust; The shroud may have any arbitrary shape; and Guides can be accommodated which protect the payload by preventing shroud rotation or lateral motion until the shroud has passed over the guide. Limitations are that all bodies are assumed to be rigid and aerodynamic loads are not included. SHED has proven itself sufficiently robust and versatile to permit a critical comparison of a large range of shroud separation strategies in selecting a separation strategy for the Strategic TARgeting System (STARS) funded by the Army SDI Office. 8 refs., 9 figs.

  6. On Wind Tunnel Tests and Computations Concerning the Problem of Shrouded Propellers

    NASA Technical Reports Server (NTRS)

    Kruger, W.

    1949-01-01

    Results of measurements on a shrouded propeller are given. The propeller is designed for the high ratio of advance and high thrust loading. The effect of the shape of propeller and shroud upon the aerodynamic coefficients of the propulsion unit can be seen from the results. The highest efficiency measured is 0.71. The measurements permit the conclusion that the maximum efficiency can be essentially improved by shroud profiles of small chord and thickness. The largest static thrust factor of merit measured reaches according to Bendemann, a value of about zeta = 1.1. By the use of a nose split flap the static thrust for thin shroud profiles with small nose radius can be about doubled. In a separate section numerical investigations of the behavior of shrouded propellers for the ideal case and for the case with energy losses are carried out. The calculations are based on the assumption that the slipstream cross section depends solely on the shape of the shroud and not on the propeller loading. The reliability of this hypothesis is confirmed experimentally and by flow photographs for a shroud with small circulation. Calculation and test are also in good agreement concerning efficiency and static thrust factor of merit. The prospects of applicability for shrouded propellers and their essential advantages are discussed.

  7. Internal Performance of Several Divergent-Shroud Ejector Nozzles with High Divergence Angles

    NASA Technical Reports Server (NTRS)

    Trout, Arthur M.; Papell, S. Stephen; Povolny, John H.

    1957-01-01

    Nine divergent-shroud ejector configurations were investigated to determine the effect of shroud divergence angle on ejector internal performance. Unheated dry air was used for both the primary and secondary flows. The decrease in the design-point thrust coefficient with increasing flow divergence angle (angle measured from primary exit to shroud exit) followed very closely a simple relation involving the cosine of the angle. This indicates that design-point thrust performance for divergent-shroud ejectors can be predicted with reasonable accuracy within the range investigated. The decrease in design-point thrust coefficient due to increasing the flow divergence engle from 120deg to 30deg (half-singles) was approximately 6 percent. Ejector air-handling characteristics and the primary-nozzle flow coefficient were not significantly affected by change in shroud divergence angle.

  8. Measurement of Total Condensation on a Shrouded Cryogenic Surface using a Single Quart Crystal Microbalance

    SciTech Connect

    Haid, B J; Malsbury, T N; Gibson, C R; Warren, C T

    2008-06-10

    A single quartz crystal microbalance (QCM) is cooled to 18 K to measure condensation rates inside of a retractable ''shroud'' enclosure. The shroud is of a design intended to minimize condensate on fusion targets to be fielded at the National Ignition Facility (NIF). The shroud has a double-wall construction with an inner wall that may be cooled to 75-100 K. The QCM and the shroud system were mounted in a vacuum chamber and cooled using a cryocooler. Condensation rates were measured at various vacuum levels and compositions, and with the shroud open or closed. A technique for measuring total condensate during the cooldown of the system with an accuracy of better than 1.0 x 10{sup -6} g/cm{sup 2} was also demonstrated. The technique involved a separate measurement of the condensate-free crystal frequency as a function of temperature that was later applied to the measurement of interest.

  9. Investigation of the HPFTP first stage impeller crack

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The occurrence of a crack in the HPFTP first stage impeller of pump 2608 R2 during test 750-245 prompted this analysis to examine possible causes of the failure. Preliminary analysis, using an existing NASTRAN model of the impeller, showed a deficiency in the model's ability to reliably calculate stress in the area of concern (outboard edge of the impeller shroud). A new NASTRAN model was constructed to better define the stress state in the area of crack initiations. Static stress analysis and normal models analysis were performed on the new model. Results are presented.

  10. Seal with Integrated Shroud for Androgynous Docking and Berthing

    NASA Technical Reports Server (NTRS)

    Daniels, Christopher C.

    2010-01-01

    A specially configured seal system (see figure) has been developed and produced that provides a barrier to gas leakage between a pressurized module and its external environment. The seal system includes a shroud covering that both protects the sealing surface from its environment when not in use and retracts to expose the sealing surface when engaged. The seal system is constructed and arranged to mate with a replicate seal system or with a flat surface. When mated with a replicate seal system, the seal system functions when the two sealing surfaces are aligned or misaligned. The seal system can operate over a wide range of temperatures, limited only by the glass transition and melt temperatures of the material from which the sealing surface is manufactured.

  11. Internal Performance Evaluation of a Two Position Divergent Shroud Ejector

    NASA Technical Reports Server (NTRS)

    Mihaloew, James R.; Stofan, Andrew J.

    1960-01-01

    A two-position divergent shroud ejector was investigated in an unheated quiescent-air facility over a range of operational variables applicable to a Mach 2.5 aircraft. The performance data are shown in terms of hypothetical engine operating conditions to illustrate variations of performance with Mach number. The overall thrust performance was reasonably good, with ejector thrust ratios ranging from 0.97 to 0.98 for all conditions except that corresponding to acceleration with afterburning through the transonic flight Mach number region from 0.9 to 1.1, where the ejector thrust ratio decreased to as low as 0.945 for an ejector corrected weight-flow ratio of 0.105.

  12. Investigation of flow in axial turbine stage without shroud-seal

    NASA Astrophysics Data System (ADS)

    Straka, Petr; Němec, Martin; Jelínek, Thomáš

    2015-05-01

    This article deals with investigation of the influence of the radial gaps on the efficiency of the axial turbine stage. The investigation was carried out for the axial stage of the low-power turbine with the drum-type rotor without the shroud. In this configuration the flow through the radial gap under the hub-end of the stator blades and above the tip-end of the rotor blades leads to generation of the strong secondary flows, which decrease the efficiency of the stage. This problem was studied by experiment as well as by numerical modelling. The experiment was performed on the test rig equipped with the water brake dynamometer, torque meter and rotatable stator together with the linear probe manipulator. Numerical modelling was carried out for both the steady flow using the "mixing plane" interface and the unsteady flow using the "sliding mesh" interface between the stator and rotor wheels. The influence of the radial gap was studied in two configuration a) positive and b) negative overlapping of the tip-ends of the rotor blades. The efficiency of the axial stage in dependence on the expansion ratio, velocity ratio and the configuration as well as the details of the flow fields are presented in this paper.

  13. Hover and wind-tunnel testing of shrouded rotors for improved micro air vehicle design

    NASA Astrophysics Data System (ADS)

    Pereira, Jason L.

    The shrouded-rotor configuration has emerged as the most popular choice for rotary-wing Micro Air Vehicles (MAVs), because of the inherent safety of the design and the potential for significant performance improvements. However, traditional design philosophies based on experience with large-scale ducted propellers may not apply to the low-Reynolds-number (˜20,000) regime in which MAVs operate. An experimental investigation of the effects of varying the shroud profile shape on the performance of MAV-scale shrouded rotors has therefore been conducted. Hover tests were performed on seventeen models with a nominal rotor diameter of 16 cm (6.3 in) and various values of diffuser expansion angle, diffuser length, inlet lip radius and blade tip clearance, at various rotor collective angles. Compared to the baseline open rotor, the shrouded rotors showed increases in thrust by up to 94%, at the same power consumption, or reductions in power by up to 62% at the same thrust. These improvements surpass those predicted by momentum theory, due to the additional effect of the shrouds in reducing the non-ideal power losses of the rotor. Increasing the lip radius and decreasing the blade tip clearance caused performance to improve, while optimal values of diffuser angle and length were found to be 10 and 50% of the shroud throat diameter, respectively. With the exception of the lip radius, the effects of changing any of the shrouded-rotor parameters on performance became more pronounced as the values of the other parameters were changed to degrade performance. Measurements were also made of the wake velocity profiles and the shroud surface pressure distributions. The uniformity of the wake was improved by the presence of the shrouds and by decreasing the blade tip clearance, resulting in lower induced power losses. For high net shroud thrust, a favorable pressure distribution over the inlet was seen to be more important than in the diffuser. Strong suction pressures were observed

  14. Convective heat transfer from circular cylinders located within perforated cylindrical shrouds

    NASA Technical Reports Server (NTRS)

    Daryabeigi, K.; Ash, R. L.

    1986-01-01

    The influence of perforated cylindrical shrouds on the convective heat transfer to circular cylinders in transverse flow has been studied experimentally. Geometries studied were similar to those used in industrial platinum resistance thermometers. The influence of Reynolds number, ventilation factor (ratio of the open area to the total surface area of shroud), radius ratio (ratio of shroud's inside radius to bare cylinder's radius), and shroud orientation with respect to flow were studied. The experiments showed that perforated shrouds with ventilation factors in the range 0.1 to 0.4 and radius ratios in the range 1.1 to 2.1 could enhance the convective heat transfer to bare cylinders up to 50%. The maximum enhancement occurred for a radius ratio of 1.4 and ventilation factors between 0.2 and 0.3. It was found that shroud orientation influenced the heat transfer, with maximum heat transfer generally occurring when the shroud's holes were centered on either side of the stagnation line. However, the hole orientation effect is of second order compared to the influence of ventilation factor and radius ratio.

  15. Experimental investigation of the hydrodynamic forces on the shroud of a centrifugal pump impeller. Thesis

    NASA Technical Reports Server (NTRS)

    Zhuang, Fei

    1989-01-01

    Fluid-induced forces acting on a rotating impeller are known to cause rotor-dynamic problems in turbomachines. The forces generated by leakage flow along the front shroud surface of a centrifugal turbomachine impeller play an important role among these fluid-induced forces. The present research was aimed to gain a better understanding of these shroud forces. An experimental apparatus was designed and constructed to simulate the impeller shroud leakage flow. Hydrodynamic forces and steady and unsteady pressure distributions on the rotating shroud were measured as functions of eccentricity, width of shroud clearance, face seal clearance and shaft rotating speed. The forces measured from the dynamometer and manometers agreed well. The hydrodynamic force matrices were found skew-symmetric and statically unstable. This is qualitatively similar to the result of previous hydrodynamic volute force measurements. Nondimensionalized normal and tangential forces decrease slightly as Reynolds number increases. As the width of the shroud clearance decreases and/or the eccentricity increases, the hydrodynamic forces increase nonlinearly. There was some evidence found that increased front seal clearance could reduce the radial shroud forces and the relative magnitude of the destabilizing tangential force. Subharmonic pressure fluctuations were also observed which may adversely affect the behavior of the rotor system.

  16. Analysis of Gas Turbine Rotor Blade Tip and Shroud Heat Transfer

    NASA Technical Reports Server (NTRS)

    Ameri, A. A.; Steinthorsson, E.

    1996-01-01

    Predictions of the rate of heat transfer to the tip and shroud of a gas turbine rotor blade are presented. The simulations are performed with a multiblock computer code which solves the Reynolds Averaged Navier-Stokes equations. The effect of inlet boundary layer thickness as well as rotation rate on the tip and shroud heat transfer is examined. The predictions of the blade tip and shroud heat transfer are in reasonable agreement with the experimental measurements. Areas of large heat transfer rates are identified and physical reasoning for the phenomena presented.

  17. Features of the stress state and vibration of shrouded turbine blades

    SciTech Connect

    Borishanskii, K.N.

    1986-01-01

    This paper shows that the features of the stress state of shrouded blades are connected with the need to allow for constraint of torsion during static deformatin and vibration of the blades. The authors approximate the cross-section by an element of a thin-walled tube which is sufficiently close in dimensions to the peripheral section of the blade. The magnitude of the stresses in a shrouded blade under the influence of the moment ''M /SUB z/ '' are determined. The results of measurement of the strain in a shrouded blade in the last stage of a powerful steam turbine are presented.

  18. Fluid-structure interaction forces at pump-impeller-shroud surfaces for axial vibration analysis

    NASA Technical Reports Server (NTRS)

    Childs, D. W.

    1991-01-01

    The axial forces developed on a pump impeller shroud surfaces are analyzed using a bulk-flow model of the leakage path between the impeller and the housing. Shear stresses at the impeller and the housing surfaces are modeled according to Hirs's turbulent lubrication model. The calculated results yield predictions of resonance peaks of the fluid within the annulus formed by the impeller shroud and housing. Numerical results are presented for a double-suction single-stage pump, showing that the direct stiffness of the perturbed impeller shroud forces is negligible; the forces become important only for pumps with very low axial natural frequencies in comparison to the running speed.

  19. Knuckle Cracking

    MedlinePlus

    ... older obese people. Question: Can cracking knuckles / joints lead to arthritis? Answer: There is no evidence of ... or damaged joints due to arthritis could potentially lead more easily to ligament injury or acute trauma ...

  20. The electrical conductivities of candidate beam-waveguide antenna shroud materials

    NASA Technical Reports Server (NTRS)

    Otoshi, T. Y.; Franco, M. M.

    1994-01-01

    The shroud on the beam-waveguide (BWG) antenna at DSS 13 is made from highly magnetic American Society for Testing and Materials (ASTM) A36 steel. Measurements at 8.42 GHz showed that this material (with paint) has a very poor electrical conductivity that is 600 times worse than aluminum. In cases where the BWG mirrors might be slightly misaligned, unintentional illumination and poor electrical conductivity of the shroud walls can cause system noise temperature to be increased significantly. This potential increase of noise temperature contribution can be reduced through the use of better conductivity materials for the shroud walls. An alternative is to attempt to improve the conductivity of the currently used ASTM A36 steel by means of some type of plating, surface treatment, or high-conductivity paints. This article presents the results of a study made to find improved materials for future shrouds and mirror supports.

  1. Measurement of convective heat transfer to solid cylinders inside ventilated shrouds

    NASA Technical Reports Server (NTRS)

    Daryabeigi, K.; Germain, E. F.; Ash, R. L.

    1984-01-01

    The influence of ventilated cylindrical shrouds on the convective heat transfer to circular cylinders has been studied experimentally. Geometries studied were similar to those used in commercially available platinum resistance thermometers. Experiments showed that thermal response (convection) was enhanced when the shroud ventilation factor was approximately 20 percent (80 percent solid), and that maximum enhancement occurred when the ventilation holes were located symmetrically on either side of the stagnation lines.

  2. Influence of impeller shroud forces on turbopump rotor dynamics

    NASA Technical Reports Server (NTRS)

    Williams, Jim P.; Childs, Dara W.

    1989-01-01

    The shrouded-impeller leakage path forces calculated by Childs (1987) have been analyzed to answer two questions. First, because of certain characteristics of the results of Childs, the forces could not be modeled with traditional approaches. Therefore, an approach has been devised to include the forces in conventional rotordynamic analyses. The forces were approximated by traditional stiffness, damping and inertia coefficients with the addition of whirl-frequency-dependent direct and cross-coupled stiffness terms. The forces were found to be well-modeled with this approach. Finally, the effect these forces had on a simple rotor-bearing system was analyzed, and, therefore, they, in addition to seal forces, were applied to a Jeffcott rotor. The traditional methods of dynamic system analysis were modified to incorporate the impeller forces and yielded results for the eigenproblem, frequency response, critical speed, transient response and an iterative technique for finding the frequency of free vibration as well as system stability. All results lead to the conclusion that the forces have little influence on natural frequency but can have appreciable effects on system stability. Specifically, at higher values of fluid swirl at the leakage path entrance, relative stability is reduced. The only unexpected response characteristics that occurred are attributed to the nonlinearity of the model.

  3. Influence of impeller shroud forces on turbopump rotor dynamics

    NASA Technical Reports Server (NTRS)

    Williams, J. P.; Childs, Dara W.

    1993-01-01

    The shrouded-impeller leakage path forces calculated by Childs have been analyzed to answer two questions. First, because of certain characteristics or the results of Childs, the forces could not be modeled with traditional approaches. Therefore, an approach has been devised to include the forces in conventional rotordynamic analyses. The forces were found to be well-modeled with this approach. Finally, the effect these forces had on a simple rotor-bearing system was analyzed, and, therefore, they, in addition to seal forces, were applied to a Jeffcott rotor. The traditional methods of dynamic system analysis were modified to incorporate the impeller forces and yielded results for the eigenproblem, frequency response, critical speed, transient response, and an iterative technique for finding the frequency of free vibration as well as system stability. All results lead to the conclusion that the forces have little influence on natural frequency but can have appreciable effects on system stability. Specifically, at higher values of fluid swirl at the leakage path entrance, relative stability is reduced. The only unexpected response characteristics that occurred are attributed to the nonlinearity of the model.

  4. Centaur Standard Shroud (CSS) Heated Altitude Jettison Tests

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Altitude jettison tests, at a pressure of 20 torr (0.39 psia), were performed on the Centaur Standard Shroud (CSS) in a 100-foot diameter vacuum chamber. These jettison tests were part of a series of flight qualification tests which were performed on the new CSS system in preparation for the Helios and Viking missions. The first two tests subjected the CSS to a thermal cycle which simulated aerodynamic heating during ascent flight and the third test was performed at altitude pressure and in ambient temperature conditions. The purpose of the ambient temperature test was to provide base line data by which the separate machanical and thermal factors that influence jettison performance could be evaluated individually. The CSS was successfully jettisoned in each of the three tests. Also, thermal, stress, and structural deflection data were obtained which verified the analytical predictions of CSS response to flight environmental conditions and performance during jettison. In addition, much important information was obtained on critical CSS-to-payload clearance losses due to shell motions prior to and during jettison. The effectiveness of the separation system was successfully demonstrated at maximum flight temperatures.

  5. Structure interaction due to thermal bowing of shrouds in steam generator of gas-cooled reactor

    SciTech Connect

    Woo, H.H.

    1981-01-01

    The design of the gas-cooled reactor steam generators includes a tube bundle support plate system which restrains and supports the helical tubes in the steam generator. The support system consists of an array of radially oriented, perforated plates through which the helical tube coils are wound. These support plates have tabs on their edges which fit into vertical slots in the inner and outer shrouds. When the helical tube bundle and support plates are installed in the steam generator, they most likely cannot fit evenly between the inner and outer shrouds. This imperfection leads to different gaps between two extreme sides of the tube bundle and the shrouds. With different gaps through the tube bundle height, the helium flow experiences different cooling effects from the tube bundle. Hence, the temperature distribution in the shrouds will be non-uniform circumferentially since their surrounding helium flow temperatures are varied. These non-uniform temperatures in the shrouds result in the phenomenon of thermal bowing of shrouds.

  6. Effect of honeycomb seals on loss characteristics in shroud cavities of an axial turbine

    NASA Astrophysics Data System (ADS)

    Gao, Jie; Zheng, Qun; Wang, Zheng

    2013-01-01

    The loss in efficiency due to shroud leakage or tip clearance flow accounts for a substantial part of the overall losses in turbomachinery. It is important to identify the leakage loss characteristics in order to optimize turbomachinery. At present, little information is available in the open literature concerning the effect of honeycomb seals on the loss characteristics in shroud cavities of an axial turbine, despite of the widespread use of the honeycomb seals. Therefore, interaction between rotor labyrinth seal leakage flow with and without honeycomb facings and main flow is investigated to provide the loss characteristics of the mixing process of the re-entering leakage flow into the main flow. The effects of honeycomb seals on the flow in shroud cavities and interaction with the main flow are analyzed. An additional study on the impact of subtle shroud cavity exit geometry is also presented. The investigation results indicate that the honeycomb seal affects the over tip leakage flow and reduces mixing losses when compared to the solid labyrinth seal. The leakage flow interactions with the main flow have considerably changed the flow fields in the endwall regions. The proposed research reveals the effects of honeycomb seals on the loss characteristics in shroud cavities and the impact of subtle shroud cavity exit geometry, and it is helpful for the design optimization of turbomachinery.

  7. Experimental Investigation of a Shrouded Rotor Micro Air Vehicle in Hover and in Edgewise Gusts

    NASA Astrophysics Data System (ADS)

    Hrishikeshavan, Vikram

    Due to the hover capability of rotary wing Micro Air Vehicles (MAVs), it is of interest to improve their aerodynamic performance, and hence hover endurance (or payload capability). In this research, a shrouded rotor configuration is studied and implemented, that has the potential to offer two key operational benefits: enhanced system thrust for a given input power, and improved structural rigidity and crashworthiness of an MAV platform. The main challenges involved in realising such a system for a lightweight craft are: design of a lightweight and stiff shroud, and increased sensitivity to external flow disturbances that can affect flight stability. These key aspects are addressed and studied in order to assess the capability of the shrouded rotor as a platform of choice for MAV applications. A fully functional shrouded rotor vehicle (disk loading 60 N/ m2) was designed and constructed with key shroud design variables derived from previous studies on micro shrouded rotors. The vehicle weighed about 280 g (244 mm rotor diameter). The shrouded rotor had a 30% increase in power loading in hover compared to an unshrouded rotor. Due to the stiff, lightweight shroud construction, a net payload benefit of 20-30 g was achieved. The different components such as the rotor, stabilizer bar, yaw control vanes and the shroud were systematically studied for system efficiency and overall aerodynamic improvements. Analysis of the data showed that the chosen shroud dimensions was close to optimum for a design payload of 250 g. Risk reduction prototypes were built to sequentially arrive at the final configuration. In order to prevent periodic oscillations in ight, a hingeless rotor was incorporated in the shroud. The vehicle was successfully ight tested in hover with a proportional-integralderivative feedback controller. A flybarless rotor was incorporated for efficiency and control moment improvements. Time domain system identification of the attitude dynamics of the flybar and

  8. ACT Payload Shroud Structural Concept Analysis and Optimization

    NASA Technical Reports Server (NTRS)

    Zalewski, Bart B.; Bednarcyk, Brett A.

    2010-01-01

    Aerospace structural applications demand a weight efficient design to perform in a cost effective manner. This is particularly true for launch vehicle structures, where weight is the dominant design driver. The design process typically requires many iterations to ensure that a satisfactory minimum weight has been obtained. Although metallic structures can be weight efficient, composite structures can provide additional weight savings due to their lower density and additional design flexibility. This work presents structural analysis and weight optimization of a composite payload shroud for NASA s Ares V heavy lift vehicle. Two concepts, which were previously determined to be efficient for such a structure are evaluated: a hat stiffened/corrugated panel and a fiber reinforced foam sandwich panel. A composite structural optimization code, HyperSizer, is used to optimize the panel geometry, composite material ply orientations, and sandwich core material. HyperSizer enables an efficient evaluation of thousands of potential designs versus multiple strength and stability-based failure criteria across multiple load cases. HyperSizer sizing process uses a global finite element model to obtain element forces, which are statistically processed to arrive at panel-level design-to loads. These loads are then used to analyze each candidate panel design. A near optimum design is selected as the one with the lowest weight that also provides all positive margins of safety. The stiffness of each newly sized panel or beam component is taken into account in the subsequent finite element analysis. Iteration of analysis/optimization is performed to ensure a converged design. Sizing results for the hat stiffened panel concept and the fiber reinforced foam sandwich concept are presented.

  9. Blood stains of the Turin Shroud 2015: beyond personal hopes and limitations of techniques.

    PubMed

    Di Minno, Giovanni; Scala, Rosanna; Ventre, Itala; de Gaetano, Giovanni

    2016-06-01

    In the early '80s, evidence was provided that, rather than a dye (red okra), hemoglobin was indeed responsible for the alleged blood stains of the Turin Shroud. Such stains were shown to belong to an MNS positive individual of the AB group, and the halos surrounding the blood stains were compatible with serum containing trace amounts of bilirubin, albumin and immunoglobulins. However, being only based on indirect and circumstantial evidence, most of these data were challenged. In the late '90s, together with the evidence of the gene coding β-globin, contamination between male and female DNA was documented on the Turin Shroud. Although the presence of male was more noticeable than female DNA, these data were considered null and void. These days, to establish that blood indisputably belongs to an MNS positive individual of the AB group, and to exclude DNA contamination, high-specificity techniques with monoclonal antibodies and molecular studies on nuclear and mitochondrial DNA are needed. Indeed, consistent with DNA contamination on the Turin Shroud, sequences from multiple subjects of different ethnic origins have been recently detected on the human mitochondrial genome extracted from dust particles of the linen. Innovative concepts are likely to come up using modern research approaches to evaluate the issue of blood stains of the Turin Shroud. Nor can we rule out the possibility that religious implications of the new findings on the Turin Shroud might be envisaged. Conceivably enough, the ongoing debate will be fierce and passionate, especially in the media. PMID:27001889

  10. Molecular Exploration of the First-Century Tomb of the Shroud in Akeldama, Jerusalem

    PubMed Central

    Matheson, Carney D.; Vernon, Kim K.; Lahti, Arlene; Fratpietro, Renee; Spigelman, Mark; Gibson, Shimon; Greenblatt, Charles L.; Donoghue, Helen D.

    2009-01-01

    The Tomb of the Shroud is a first-century C.E. tomb discovered in Akeldama, Jerusalem, Israel that had been illegally entered and looted. The investigation of this tomb by an interdisciplinary team of researchers began in 2000. More than twenty stone ossuaries for collecting human bones were found, along with textiles from a burial shroud, hair and skeletal remains. The research presented here focuses on genetic analysis of the bioarchaeological remains from the tomb using mitochondrial DNA to examine familial relationships of the individuals within the tomb and molecular screening for the presence of disease. There are three mitochondrial haplotypes shared between a number of the remains analyzed suggesting a possible family tomb. There were two pathogens genetically detected within the collection of osteological samples, these were Mycobacterium tuberculosis and Mycobacterium leprae. The Tomb of the Shroud is one of very few examples of a preserved shrouded human burial and the only example of a plaster sealed loculus with remains genetically confirmed to have belonged to a shrouded male individual that suffered from tuberculosis and leprosy dating to the first-century C.E. This is the earliest case of leprosy with a confirmed date in which M. leprae DNA was detected. PMID:20016819

  11. Melt Infiltrated Ceramic Matrix Composites for Shrouds and Combustor Liners of Advanced Industrial Gas Turbines

    SciTech Connect

    Gregory Corman; Krishan Luthra; Jill Jonkowski; Joseph Mavec; Paul Bakke; Debbie Haught; Merrill Smith

    2011-01-07

    This report covers work performed under the Advanced Materials for Advanced Industrial Gas Turbines (AMAIGT) program by GE Global Research and its collaborators from 2000 through 2010. A first stage shroud for a 7FA-class gas turbine engine utilizing HiPerComp{reg_sign}* ceramic matrix composite (CMC) material was developed. The design, fabrication, rig testing and engine testing of this shroud system are described. Through two field engine tests, the latter of which is still in progress at a Jacksonville Electric Authority generating station, the robustness of the CMC material and the shroud system in general were demonstrated, with shrouds having accumulated nearly 7,000 hours of field engine testing at the conclusion of the program. During the latter test the engine performance benefits from utilizing CMC shrouds were verified. Similar development of a CMC combustor liner design for a 7FA-class engine is also described. The feasibility of using the HiPerComp{reg_sign} CMC material for combustor liner applications was demonstrated in a Solar Turbines Ceramic Stationary Gas Turbine (CSGT) engine test where the liner performed without incident for 12,822 hours. The deposition processes for applying environmental barrier coatings to the CMC components were also developed, and the performance of the coatings in the rig and engine tests is described.

  12. Electrochemical reduction of UO2 in LiCl-Li2O molten salt using porous and nonporous anode shrouds

    NASA Astrophysics Data System (ADS)

    Choi, Eun-Young; Won, Chan Yeon; Cha, Ju-Sun; Park, Wooshin; Im, Hun Suk; Hong, Sun-Seok; Hur, Jin-Mok

    2014-01-01

    Electrochemical reductions of uranium oxide in a molten LiCl-Li2O electrolyte were carried out using porous and nonporous anode shrouds. The study focused on the effect of the type of anode shroud on the current density by running experiments with six anode shrouds. Dense ceramics, MgO, and MgO (3 wt%) stabilized ZrO2 (ZrO2-MgO) were used as nonporous shrouds. STS 20, 100, and 300 meshes and ZrO2-MgO coated STS 40 mesh were used as porous shrouds. The current densities (0.34-0.40 A cm-2) of the electrolysis runs using the nonporous anode shrouds were much lower than those (0.76-0.79 A cm-2) of the runs using the porous shrouds. The ZrO2-MgO shroud (600-700 MPa at 25 °C) showed better bending strength than that of MgO (170 MPa at 25 °C). The high current densities achieved in the electrolysis runs using the porous anode shrouds were attributed to the transport of O2- ions through the pores in meshes of the shroud wall. ZrO2-MgO coating on STS mesh was chemically unstable in a molten LiCl-Li2O electrolyte containing Li metal. The electrochemical reduction runs using STS 20, 100, and 300 meshes showed similar current densities in spite of their different opening sizes. The STS mesh shrouds which were immersed in a LiCl-Li2O electrolyte were stable without any damage or corrosion.

  13. An investigation of the vibration characteristics of shrouded-bladed-disk rotor stages

    NASA Technical Reports Server (NTRS)

    Chen, L.-T.; Dugundji, J.

    1979-01-01

    Coupled differential equations of motion are given for application to a rotating, pretwisted and heated beam under the effects of thermal stresses and gas bending loads. The circumferential modes of the multi-blade vibration of a bladed-disk rotor stage were studied. A finite element method was developed for the dynamic and static deformation analysis of the blade. The deformations of a bladed disk and a shrouded-bladed disk were studied by introducing a special bladed-disk element and a special shrouded-blade element. Some features of the vibration of part-span-shrouded, bladed-disk rotor stages are discussed. The static deformation, thermal stress and gas bending effects on the blade vibration were presented previously.

  14. Integrity testing of brush seal in shroud ring of T-700 engine

    NASA Astrophysics Data System (ADS)

    Hendricks, Robert C.; Griffin, Thomas A.; Bobula, George B.; Bill, Robert C.; Howe, Harold W.

    1992-08-01

    A split-ring brush seal was fabricated, installed between two labyrinth-honeycomb shroud seals, and tested in the fourth-stage turbine of a T-700 engine. The annealed Haynes 25 bristles rubbed directly against the nonconditioned, irregular Rene 80 turbine blade shroud surface. A total of 30 hr of cyclic and steady-state data were taken with surface speeds to 335 m/s (1100 ft/s) and shroud temperatures to 620 C (1150 F). Wear appeared to be rapid initially, with an orange flash of hot brush fragments during the first engine startup, to minimal after 10 hr of operation. The brush survived the testing but experienced some bristle pullouts and severe bristle wear; some turbine interface wear and possible material transfer was noted. Future design concerns center on tribological behavior at the interface with or without lubricants.

  15. Coloring linens with excimer lasers to simulate the body image of the Turin Shroud.

    PubMed

    Baldacchini, Giuseppe; Di Lazzaro, Paolo; Murra, Daniele; Fanti, Giulio

    2008-03-20

    The body image of the Turin Shroud has not yet been explained by traditional science; so a great interest in a possible mechanism of image formation still exists. We present preliminary results of excimer laser irradiation (wavelength of 308 nm) of a raw linen fabric and of a linen cloth. The permanent coloration of both linens is a threshold effect of the laser beam intensity, and it can be achieved only in a narrow range of irradiation parameters, which are strongly dependent on the pulse width and time sequence of laser shots. We also obtained the first direct evidence of latent images impressed on linen that appear in a relatively long period (one year) after laser irradiation that at first did not generate a clear image. The results are compared with the characteristics of the Turin Shroud, reflecting the possibility that a burst of directional ultraviolet radiation may have played a role in the formation of the Shroud image. PMID:18709075

  16. Experimental determination of residual stress by neutron diffraction in a boiling water reactor core shroud

    SciTech Connect

    Payzant, A.; Spooner, S.; Zhu, Xiaojing; Hubbard, C.R.

    1996-06-01

    Residual strains in a 51 mm (2-inch) thick 304L stainless steel plate have been measured by neutron diffraction and interpreted in terms of residual stress. The plate, measuring (300 mm) in area, was removed from a 6m (20-ft.) diameter unirradiated boiling water reactor core shroud, and included a multiple-pass horizontal weld which joined two of the cylindrical shells which comprise the core shroud. Residual stress mapping was undertaken in the heat affected zone, concentrating on the outside half of the plate thickness. Variations in residual stresses with location appeared consistent with trends expected from finite element calculations, considering that a large fraction of the residual hoop stress was released upon removal of the plate from the core shroud cylinder.

  17. Anode shroud for off-gas capture and removal from electrolytic oxide reduction system

    SciTech Connect

    Bailey, James L.; Barnes, Laurel A.; Wiedmeyer, Stanley G.; Williamson, Mark A.; Willit, James L.

    2014-07-08

    An electrolytic oxide reduction system according to a non-limiting embodiment of the present invention may include a plurality of anode assemblies and an anode shroud for each of the anode assemblies. The anode shroud may be used to dilute, cool, and/or remove off-gas from the electrolytic oxide reduction system. The anode shroud may include a body portion having a tapered upper section that includes an apex. The body portion may have an inner wall that defines an off-gas collection cavity. A chimney structure may extend from the apex of the upper section and be connected to the off-gas collection cavity of the body portion. The chimney structure may include an inner tube within an outer tube. Accordingly, a sweep gas/cooling gas may be supplied down the annular space between the inner and outer tubes, while the off-gas may be removed through an exit path defined by the inner tube.

  18. Electrochemical machining process for forming surface roughness elements on a gas turbine shroud

    DOEpatents

    Lee, Ching-Pang; Johnson, Robert Alan; Wei, Bin; Wang, Hsin-Pang

    2002-01-01

    The back side recessed cooling surface of a shroud defining in part the hot gas path of a turbine is electrochemically machined to provide surface roughness elements and spaces therebetween to increase the heat transfer coefficient. To accomplish this, an electrode with insulating dielectric portions and non-insulating portions is disposed in opposition to the cooling surface. By passing an electrolyte between the cooling surface and electrode and applying an electrical current between the electrode and a shroud, roughness elements and spaces therebetween are formed in the cooling surface in opposition to the insulating and non-insulating portions of the electrode, hence increasing the surface area and heat transfer coefficient of the shroud.

  19. Colouring fabrics with excimer lasers to simulate encoded images: the case of the Shroud of Turin

    NASA Astrophysics Data System (ADS)

    Di Lazzaro, P.; Baldacchini, G.; Fanti, G.; Murra, D.; Santoni, A.

    2008-10-01

    The faint body image embedded into the Turin Shroud has not yet explained by traditional science. We present experimental results of excimer laser irradiation (wavelengths 308 nm and 193 nm) of a raw linen fabric and of a linen cloth, seeking for a possible mechanism of image formation. The permanent coloration of both linens is a threshold effect on the laser beam intensity and it can be achieved only in a surprisingly narrow range of irradiation parameters: the shorter the wavelength, the narrower the range. We also obtained the first direct evidence of latent images impressed on linen that appear in a relatively long period (one year) after a laser irradiation that at first did not generate a clear image. The results are compared to the characteristics of the Turin Shroud, commenting the possibility that a burst of directional ultraviolet radiation may have played a role in the formation of the Shroud image.

  20. Coloring linens with excimer lasers to simulate the body image of the Turin Shroud

    NASA Astrophysics Data System (ADS)

    Baldacchini, Giuseppe; di Lazzaro, Paolo; Murra, Daniele; Fanti, Giulio

    2008-03-01

    The body image of the Turin Shroud has not yet been explained by traditional science; so a great interest in a possible mechanism of image formation still exists. We present preliminary results of excimer laser irradiation (wavelength of 308 nm) of a raw linen fabric and of a linen cloth. The permanent coloration of both linens is a threshold effect of the laser beam intensity, and it can be achieved only in a narrow range of irradiation parameters, which are strongly dependent on the pulse width and time sequence of laser shots. We also obtained the first direct evidence of latent images impressed on linen that appear in a relatively long period (one year) after laser irradiation that at first did not generate a clear image. The results are compared with the characteristics of the Turin Shroud, reflecting the possibility that a burst of directional ultraviolet radiation may have played a role in the formation of the Shroud image.

  1. Corrosion and oxidation properties of NiCr coatings sprayed in presence of gas shroud system

    NASA Astrophysics Data System (ADS)

    Morks, M. F.; Berndt, C. C.

    2010-04-01

    The oxidation of a NiCr bond coat during air plasma spraying was controlled by designing a gas shroud system attached to the plasma torch nozzle. Two nozzles, termed as "normal" and "high-speed" nozzles examined the effect of nozzle internal design on the microstructure and phase structure of coatings. X-ray diffraction and SEM morphologies showed that the shroud system reduced the oxidation of NiCr particles during the spray process. Compared with conventional air plasma spraying, the argon gas shroud reduced the coating hardness because the volume fraction of partially melted particles increased. The high-speed nozzle reduced the oxidation and hardness of NiCr coatings due to the increase of partially melted particles in the coatings.

  2. Crack tip deformation and fatigue crack growth

    NASA Technical Reports Server (NTRS)

    Liu, H.-W.

    1981-01-01

    Recent research on fatigue crack growth is summarized. Topics discussed include the use of the differential stress intensity factor to characterize crack tip deformation, the use of the unzipping model to study the growth of microcracks and the fatigue crack growth in a ferritic-martensitic steel, and the development of a model of fatige crack growth threshold. It is shown that in the case of small yielding, the differential stress intensity factor provides an adequate description of cyclic plastic deformation at the crack tip and correlates well with the crack growth rate. The unzipping model based on crack tip shear decohesion process is found to be in good agreement with the measured crack growth and striation spacing measurements. The proposed model of crack growth threshold gives correct predictions of the crack growth behavior in the near-threshold region.

  3. Composite wall concept for high temperature turbine shrouds: Heat transfer analysis

    NASA Technical Reports Server (NTRS)

    Stepka, F. S.; Ludwig, L. P.

    1980-01-01

    A heat transfer analysis was made of a composite wall shroud consisting of a ceramic thermal barrier layer bonded to a porous metal layer which, in turn, is bonded to a metal base. The porous metal layer serves to mitigate the strain differences between the ceramic and the metal base. Various combinations of ceramic and porous metal layer thicknesses and of porous metal densities and thermal conductivities were investigated to determine the layer thicknesses required to maintain a limiting temperature in the porous metal layer. Analysis showed that the composite wall offered significant air cooling flow reductions compared to an all impingement air cooled, all metal shroud.

  4. The double superficiality of the frontal image of the Turin Shroud

    NASA Astrophysics Data System (ADS)

    Fanti, Giulio; Maggiolo, Roberto

    2004-06-01

    Photographs of the back surface of the Turin Shroud were analysed to verify the existence of a double body image of a man. The body image is very faint and the background not uniform; i.e., the signal-to-noise ratio is lower than one. Therefore, image processing, developed ad hoc, was necessary to highlight body features. This was based on convolution with Gaussian filters, summation of images, and filtering in spatial frequency by direct and inverse bidimensional Fourier transformations. Body features were identified by template matching. The face and probably also the hands are visible on the back of the Turin Shroud, but not features related to the dorsal image.

  5. Discovery of inscriptions on the shroud of Turin by digital image processing

    NASA Astrophysics Data System (ADS)

    Marion, Andre

    1998-08-01

    Almost invisible Latin and Greek inscriptions were discovered on the shroud of Turin around the image of the face. This result was obtained by using digital image processing techniques. An original method is developed to eliminate the texture of the cloth and also to combine data from different photographs or from the same plate digitized under various conditions. According to some paleographists, the revealed characters are thought to date back to before the Middle Ages. This conclusion could be a new argument in favor of the authenticity of the shroud.

  6. Infrared reflectance spectroscopy and thermographic investigations of the Shroud of Turin.

    PubMed

    Accetta, J S; Baumgart, J S

    1980-06-15

    In this paper we present the results of the IR investigations of the controversial Turin Shroud. Reflectance spectroscopy in the 3-5- and 8-14-microm bands was attempted in situ using commercial equipment with moderate success. Spectral comparisons are made between laboratory reflectance data and selected Shroud features. Infrared thermographic imaging was accomplished with an enhanced contrast technique using external illumination. Due to the spectral similarities of most features observed, we show that the results are inconclusive. The IR imagery yielded results that are consistent with expectations with no anomalies observed. PMID:20221156

  7. Superficial and Shroud-like coloration of linen by short laser pulses in the vacuum ultraviolet.

    PubMed

    Di Lazzaro, Paolo; Murra, Daniele; Nichelatti, Enrico; Santoni, Antonino; Baldacchini, Giuseppe

    2012-12-20

    We present a survey on five years of experiments of excimer laser irradiation of linen fabrics, seeking a coloration mechanism able to reproduce the microscopic complexity of the body image embedded onto the Shroud of Turin. We achieved a superficial, Shroud-like coloration in a narrow range of irradiation parameters. We also obtained latent coloration that appears after artificial or natural aging of linen following laser irradiations that, at first, did not generate any visible effect. Most importantly, we have recognized photochemical processes that account for both coloration and latent coloration. PMID:23262596

  8. Stochastic distribution of the fibrils that yielded the Shroud of Turin body image

    NASA Astrophysics Data System (ADS)

    Fazio, G.; Mandaglio, G.

    2011-07-01

    The fibrils that yielded the Shroud body image show a stochastic distribution on the Linen of Turin. In fact, the probability of a fibril yellowing is a function of the energy, while this is not the case for the optical density value. This means that the above image is a latent image. We suggest thermal radiation or low-temperature chemical processes as possible natural energy sources to explain, by stochastic effects, the Shroud body image formation. Unfortunately, due to the nature of the phenomenon, we are not able to extract the energy source.

  9. Concepts for a Shroud or Propellant Tank Derived Deep Space Habitat

    NASA Technical Reports Server (NTRS)

    Howard, Robert L.

    2012-01-01

    Long duration human spaceflight missions beyond Low Earth Orbit will require much larger spacecraft than capsules such as the Russian Soyuz or American Orion Multi-Purpose Crew Vehicle. A concept spacecraft under development is the Deep Space Habitat, with volumes approaching that of space stations such as Skylab, Mir, and the International Space Station. This paper explores several concepts for Deep Space Habitats constructed from a launch vehicle shroud or propellant tank. It also recommends future research using mockups and prototypes to validate the size and crew station capabilities of such a habitat. Keywords: Exploration, space station, lunar outpost, NEA, habitat, long duration, deep space habitat, shroud, propellant tank.

  10. Assessment of low-order theories for analysis and design of shrouded wind turbines using CFD

    NASA Astrophysics Data System (ADS)

    Aranake, Aniket C.; Lakshminarayan, Vinod K.; Duraisamy, Karthik

    2014-06-01

    The use of a shroud around the rotor of a wind turbine has been known to augment the airflow through the rotor plane and hence result in improved performance. This work uses Computational Fluid Dynamics (CFD) to assess the validity of several simple theories which attempt to extend Betz theory to shrouded turbines. Two CFD models are employed and compared to predictions of previously published models. The first makes use of a fixed pressure-drop actuator disk, while the second incorporates the twist and chord distribution of the turbine blade as well as an airfoil polar using a technique much like the classical blade element momentum (BEM) method. Calculations are performed for a sweep of turbine loadings using the fixed pressure-drop model and a sweep of tip speed ratios using the BEM model for both an open and shrouded turbine. Power is computed using a control volume approach for the fixed pressure-drop model and by integrating tangential forces for the BEM model. Information including mass flow ratio, power coefficient ratio, axial induction, and shroud force is extracted from the solution fields and compared against the predictions of low-order theories. Finally, the blade element model is used to redesign the turbine twist distribution to achieve greater performance across a range of tip speed ratios.

  11. 124. Pre1911. View forward from mizzen shrouds, starboard side; Chinese ...

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

    124. Pre-1911. View forward from mizzen shrouds, starboard side; Chinese cannery workers boarding ship from barge, S/V BENJAMIN F. PACKARD in background. Note main fife rail with fresh water pump. Fred Heick Collection. (G12.799) - Ship BALCLUTHA, 2905 Hyde Street Pier, San Francisco, San Francisco County, CA

  12. Dynamics of cracking in drying colloidal sheets.

    PubMed

    Sengupta, Rajarshi; Tirumkudulu, Mahesh S

    2016-04-01

    Colloidal dispersions are known to display a fascinating network of cracks on drying. We probe the fracture mechanics of free-standing films of aqueous polymer-particle dispersions. Thin films of the dispersion are cast between a pair of plain steel wires and allowed to dry under ambient conditions. The strain induced on the particle network during drying is relieved by cracking. The stress which causes the films to crack has been calculated by measuring the deflection of the wires. The critical cracking stress varied inversely to the two-thirds' power of the film thickness. We also measure the velocity of the tip of a moving crack. The motion of a crack has been modeled as a competition between the release of the elastic energy stored in the particle network, the increase in surface energy as a result of the growth of a crack, the rate of viscous dissipation of the interstitial fluid and the kinetic energy associated with a moving crack. There is fair agreement between the measured crack velocities and predictions. PMID:26924546

  13. The electrical conductivities of the DSS-13 beam-waveguide antenna shroud material and other antenna reflector surface materials

    NASA Technical Reports Server (NTRS)

    Otoshi, T. Y.; Franco, M. M.; Reilly, H. F., Jr.

    1992-01-01

    A significant amount of noise temperature can potentially be generated by currently unknown dissipative losses in the beam waveguide (BWG) shroud. The amount of noise temperature contribution from this source is currently being studied. In conjunction with this study, electrical conductivity measurements were made on samples of the DSS-13 BWG shroud material at 8.420 GHz. The effective conductivities of unpainted and painted samples of the BWG shroud were measured to be 0.01 x 10(exp 7) and 0.0036 x 10(exp 7) mhos/m, respectively. This value may be compared with 5.66 x 10(exp 7) mhos/m for high conductivity copper.

  14. Mechanics of fatigue crack closure

    NASA Technical Reports Server (NTRS)

    Newman, J. C., Jr. (Editor); Elber, Wolf (Editor)

    1988-01-01

    Papers are presented on plasticity induced crack closure, crack closure in fatigue crack growth, the dependence of crack closure on fatigue loading variables, and a procedure for standardizing crack closure levels. Also considered are a statistical approach to crack closure determination, the crack closure behavior of surface cracks under pure bending, closure measurements on short fatigue cracks, and crack closure under plane strain conditions. Other topics include fatigue crack closure behavior at high stress ratios, the use of acoustic waves for the characterization of closed fatigue cracks, and the influence of fatigue crack wake length and state of stress on crack closure.

  15. Nondestructive Test Probe

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Under the Aircraft Structural Integrity program, Langley Research Center invented a device to detect fatigue cracks in aluminum alloy plates. Krautkramer Branson obtained an exclusive license and commercialized a hand-held device, the "CrackFinder," an electromagnetic probe for nondestructive evaluation, used to scan aircraft skins for surface breaks. The technology involves an eddy current, which is an electrical current induced by an alternating magnetic field. The CrackFinder also employs an innovative self-nulling feature, where the device automatically recalibrates to zero so that each flaw detected produces a reading. Compared to conventional testing systems, the CrackFinder is affordable, small, simple to use, and needs no calibration.

  16. Crack, crack house sex, and HIV risk.

    PubMed

    Inciardi, J A

    1995-06-01

    Limited attention has been focused on HIV risk behaviors of crack smokers and their sex partners, yet there is evidence that the crack house and the crack-using life-style may be playing significant roles in the transmission of HIV and other sexually transmitted diseases. The purposes of this research were to study the attributes and patterns of "sex for crack" exchanges, particularly those that occurred in crack houses, and to assess their potential impact on the spread of HIV. Structured interviews were conducted with 17 men and 35 women in Miami, Florida, who were regular users of crack and who had exchanged sex for crack (or for money to buy crack) during the past 30 days. In addition, participant observation was conducted in 8 Miami crack houses. Interview and observational data suggest that individuals who exchange sex for crack do so with considerable frequency, and through a variety of sexual activities. Systematic data indicated that almost a third of the men and 89% of the women had had 100 or more sex partners during the 30-day period prior to study recruitment. Not only were sexual activities anonymous, extremely frequent, varied, uninhibited (often undertaken in public areas of crack houses), and with multiple partners but, in addition, condoms were not used during the majority of contacts. Of the 37 subjects who were tested for HIV and received their test results 31% of the men and 21% of the women were HIV seropositive. PMID:7611845

  17. Internal-Performance Evaluation of Two Fixed-Divergent-Shroud Ejectors

    NASA Technical Reports Server (NTRS)

    Mihaloew, James R.

    1960-01-01

    Ejectors designed for use in a Mach 2.2 aircraft were evaluated over a range of representative primary pressure ratios and ejector corrected weight-flow ratios. Basic thrust and pumping characteristics are discussed in terms of an assumed engine operating schedule to illustrate the variation of performance with Mach number. The two designs differed about 16 percent in the shroud longitudinal spacing ratio. For corrected ejector weight-flow ratios up to 0.10, the performance of the fixed-shroud ejector designs is comparable with that of a similar continuously variable ejector except at conditions corresponding to acceleration with afterburning from Mach 0.4 to 1.2. In this region, the ejector thrust ratio decreased to a minimum of 0.96.

  18. Mixer-Ejector Wind Turbine: Breakthrough High Efficiency Shrouded Wind Turbine

    SciTech Connect

    2010-02-22

    Broad Funding Opportunity Announcement Project: FloDesign Wind Turbine’s innovative wind turbine, inspired by the design of jet engines, could deliver 300% more power than existing wind turbines of the same rotor diameter by extracting more energy over a larger area. FloDesign Wind Turbine’s unique shrouded design expands the wind capture area, and the mixing vortex downstream allows more energy to flow through the rotor without stalling the turbine. The unique rotor and shrouded design also provide significant opportunity for mass production and simplified assembly, enabling mid-scale turbines (approximately 100 kW) to produce power at a cost that is comparable to larger-scale conventional turbines.

  19. Some results in the processing of the holy shroud of turin.

    PubMed

    Tamburelli, G

    1981-06-01

    We illustrate some new developments in the three-dimensional (3-D) processing of the image of the Shroud of Turin. After analyzing the various possibilities of obtaining a ``clean'' two-dimensional (2-D) image, i.e., without noise due to rows and spots, we present the processed image used as a starting point for the three-dimensional processing. Moreover, we describe the mathematical methods used for the processing and show the relief image of the face. This image enhances a number of new details, which were not apparent on the two-dimensional image. To obtain a woundless natural face image of the Man of the Shroud, we processed the previous image suppressing the smaller and attenuating the larger wounds without substantially changing the features. The image shown in this article will probably recall the natural face of Jesus Christ. Also the processing of the body image is shown. PMID:21868987

  20. Effect of shroud temperature on performance of a cryogenic loop heat pipe

    NASA Astrophysics Data System (ADS)

    Zhao, Ya'nan; Yan, Tao; Liang, Jingtao

    2012-06-01

    Cryogenic loop heat pipe (CLHP) is considered as highly efficient two-phase thermal control device in satellites, spacecrafts, electronics and structures. The initial thermal capacitance of the CLHP components has an important effect on the startup and operation of the CLHP, especially in case of a low heat load. It is difficult for the CLHP to start up with a warm shroud. This paper presents a CLHP operated in the liquid-nitrogen temperature range with nitrogen as the working fluid. Thermal conductance of the CLHP is tested at different shroud temperatures, and the measured temperatures with the heat load on the primary evaporator ranging from 0 W to 19 W are shown and discussed.

  1. Bladed-shrouded-disc aeroelastic analyses: Computer program updates in NASTRAN level 17.7

    NASA Technical Reports Server (NTRS)

    Gallo, A. M.; Elchuri, V.; Skalski, S. C.

    1981-01-01

    In October 1979, a computer program based on the state-of-the-art compressor and structural technologies applied to bladed-shrouded-disc was developed. The program was more operational in NASTRAN Level 16. The bladed disc computer program was updated for operation in NASTRAN Level 17.7. The supersonic cascade unsteady aerodynamics routine UCAS, delivered as part of the NASTRAN Level 16 program was recorded to improve its execution time. These improvements are presented.

  2. Seal with integrated shroud for androgenous docking and berthing in contaminated environments

    NASA Technical Reports Server (NTRS)

    Daniels, Christopher C. (Inventor)

    2012-01-01

    The present invention is directed to a specially configured seal system which provides a barrier to gas leakage flow between a pressurized module and its external environment. The seal includes a shroud covering which protects the sealing interface from its environment when not in use, and retracts to expose the sealing interface when mated. The seal system is constructed and arranged to mate with a seal of identical construction and arrangement or to mate with a flat surface.

  3. The mystery of the shroud of turin challenges 20th-century science.

    PubMed

    Culliton, B J

    1978-07-21

    On the face of it, the very idea that the linen cloth in which Jesus Christ was wrapped in the tomb should have survived to this day would seem incredible. It demands even more of human credulity that the cloth bears a photographic likeness which would seem to be that of Jesus as he lay in the tomb. [From The Shroud of Turin by IAN WILSON]. PMID:17778647

  4. Eddy-Current Detection of Cracks in Tubes

    NASA Technical Reports Server (NTRS)

    Parent, R.; Kettering, D.

    1987-01-01

    Nondestructive device tests narrow, sharply-bent metal tubes. Eddycurrent probe detects incipient cracks inside small metal tubes. Tube-centering device consisting of pair of opposed bars ensures tube centered on eddy-current coil. Probe moves along length of bent tube to inspect repeatably for cracks. Compatible with tubes of different cross sections, oval, flattened, square, rectangular,or irregular. Adapts for inspecting formed tubes in petrochemical, automotive, nuclear, and medical equipment.

  5. Theory and experimental validation of SPLASH (Single Panel Lamp and Shroud Helper).

    SciTech Connect

    Larsen, Marvin Elwood; Porter, Jason M.

    2005-06-01

    The radiant heat test facility develops test sets providing well-characterized thermal environments, often representing fires. Many of the components and procedures have become standardized to such an extent that the development of a specialized design tool was appropriate. SPLASH (Single Panel Lamp and Shroud Helper) is that tool. SPLASH is implemented as a user-friendly program that allows a designer to describe a test setup in terms of parameters such as lamp number, power, position, and separation distance. Thermal radiation is the dominant mechanism of heat transfer and the SPLASH model solves a radiation enclosure problem to estimate temperature distributions in a shroud providing the boundary condition of interest. Irradiance distribution on a specified viewing plane is also estimated. This document provides the theoretical development for the underlying model. A series of tests were conducted to characterize SPLASH's ability to analyze lamp and shroud systems. The comparison suggests that SPLASH succeeds as a design tool. Simplifications made to keep the model tractable are demonstrated to result in estimates that are only approximately as uncertain as many of the properties and characteristics of the operating environment.

  6. Steady computational analysis of shrouded plug nozzle flows using unequal stream pressures

    NASA Astrophysics Data System (ADS)

    Ruhs, Kevin Paul

    This study focuses on the effects of unequal core and bypass stream feed pressures in a high pressure ratio, two-stream nozzle notionally designed for supersonic business jet applications. Whereas previous analysis used a measured mass average pressure of the core and bypass streams, equal pressures were not exactly maintained in the experimental work and the effect of the imbalance is the primary motivation for the present study. The plug nozzle geometry used is a sub-scale model of a Gulfstream Aerospace Corporation concept that features an extended shroud. It uses two inlet streams, representing core and bypass streams from a turbofan engine. Nozzle pressure ratios range from unity to 6.23. Experimental measurements included pressure taps on the plug and shroud, schlieren and shadowgraph figures, mass flows for both streams, and thrust values. The computational analysis employed the General Equation and Mesh Solver, or GEMS code. Previous computational analysis was performed by Kapilavai, giving a basis analysis involving grid generation and refinement, error convergence studies, axisymmetric analysis, and unsteady computations. Unequal core and bypass stream pressure or swirl in the core stream is used to replicate experimental data and assess performance. The results of using these conditions were explored, including pressure on the plug and shroud, shock characteristics, separation and recirculation zones, mass flows and discharge coefficients, and thrust efficiencies.

  7. Experimental analysis of dynamic characteristics for vibration-impact process of steam turbine blades with integral shroud

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Li, Lu-ping; Lu, Xu-xiang; Rao, Hong-de; Liu, Yu-jing

    2008-11-01

    Integral shroud is an advanced technique used to improve reliability of steam turbine blades. In this paper, dynamic characteristics of vibration-impact process of steam turbine blades with integral shroud are studied. To test and verify the reliability of calculation result, a series of experiments are well performed on the platform of contracting and impacting of blades tips. The dynamic strain data under different gaps, different loads and different rotating speeds are surveyed through which the log decrement at each condition is obtained, and the effects of vibration damping are obtained by comparing the log decrement. The results of experimental study show that larger log decrement means larger system damping and better effectives of vibration reduction. Besides, the effects of vibro-impact reduction of different parameters are got and the experimental study results show that the vibro-impact structure is a good vibration damper. The dynamic stress of the blade with integral shroud is insensitive to loads when the gap between adjacent integral shrouds is small. In short, the achievements gained in the paper have revealed dynamic characteristics for vibro-impact process of steam turbine blades with integral shroud, which will bring important engineering application to development and modification design of the integrally shrouded blades.

  8. Variation in the Scattering Shroud Surrounding Markarian 231

    NASA Astrophysics Data System (ADS)

    Gallagher, S. C.; Schmidt, Gary D.; Smith, Paul S.; Brandt, W. N.; Chartas, G.; Hylton, Shavonne; Hines, D. C.; Brotherton, M. S.

    2005-11-01

    We present a detailed study of the nuclear structure of the highly polarized broad absorption line quasar, Mrk 231, through a multiwavelength campaign of Chandra observations, optical spectroscopy, optical spectropolarimetry, and imaging polarimetry. This campaign was designed to extend the 40 ks Chandra study of Gallagher and coworkers and the optical and UV spectropolarimetric study of Smith and coworkers to probe variability on multiple timescales. As direct emission from the nucleus is heavily obscured at optical through X-ray wavelengths, the detailed study of scattered emission has lead to insights into the stratified and complex central region of this active galaxy. Although significant continuum variability is not detected in any of the three new 40 ks Chandra observations, we investigate Fe Kα emission features in the individual and combined spectra. Comparing echelle spectra of the Na I D absorption lines with the literature, we show that one system disappeared in 2000 only to reappear in later epochs. Notably, we detect a large decrease in polarization across the entire optical spectrum of Mrk 231 from 1995 to 2003. Although the polarization fraction fell, e.g., from 4% to 3% at λobs~6000 Å, the polarization position angle spectrum remained unchanged. The optical polarization behavior is consistent with a decrease in the flux scattered by circumnuclear material on spatial scales where the broad-line region is resolved by the scattering material. Ultraviolet imaging polarimetry of Mrk 231 by the Hubble Space Telescope sets an upper limit on the distance between the active nucleus and the scattering regions of <20 pc. Some of the data presented here were obtained with the MMT Observatory, a facility operated jointly by the University of Arizona and the Smithsonian Institution. Based on observations obtained with the Upgraded Fiber Optic Echelle Spectrograph on the Hobby-Eberly Telescope, which is operated by McDonald Observatory on behalf of the

  9. Gear Crack Propagation Investigation

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Reduced weight is a major design goal in aircraft power transmissions. Some gear designs incorporate thin rims to help meet this goal. Thin rims, however, may lead to bending fatigue cracks. These cracks may propagate through a gear tooth or into the gear rim. A crack that propagates through a tooth would probably not be catastrophic, and ample warning of a failure could be possible. On the other hand, a crack that propagates through the rim would be catastrophic. Such cracks could lead to disengagement of a rotor or propeller from an engine, loss of an aircraft, and fatalities. To help create and validate tools for the gear designer, the NASA Lewis Research Center performed in-house analytical and experimental studies to investigate the effect of rim thickness on gear-tooth crack propagation. Our goal was to determine whether cracks grew through gear teeth (benign failure mode) or through gear rims (catastrophic failure mode) for various rim thicknesses. In addition, we investigated the effect of rim thickness on crack propagation life. A finite-element-based computer program simulated gear-tooth crack propagation. The analysis used principles of linear elastic fracture mechanics, and quarter-point, triangular elements were used at the crack tip to represent the stress singularity. The program had an automated crack propagation option in which cracks were grown numerically via an automated remeshing scheme. Crack-tip stress-intensity factors were estimated to determine crack-propagation direction. Also, various fatigue crack growth models were used to estimate crack-propagation life. Experiments were performed in Lewis' Spur Gear Fatigue Rig to validate predicted crack propagation results. Gears with various backup ratios were tested to validate crack-path predictions. Also, test gears were installed with special crack-propagation gages in the tooth fillet region to measure bending-fatigue crack growth. From both predictions and tests, gears with backup ratios

  10. Surface-crack detection by microwave methods

    NASA Technical Reports Server (NTRS)

    Feinstein, L.; Hruby, R.

    1967-01-01

    Microwave surface-crack detection system examines metallic surfaces with a noncontacting probe. The change in the microwave signal reflected from the surface under investigation is an indication of the existence of surface flaws. This technique can detect flaws and scratches as small as 100 microinches.

  11. Crack spectra analysis

    SciTech Connect

    Tiernan, M.

    1980-09-01

    Crack spectra derived from velocity data have been shown to exhibit systematics which reflect microstructural and textural differences between samples (Warren and Tiernan, 1980). Further research into both properties and information content of crack spectra have yielded the following: Spectral features are reproducible even at low pressures; certain observed spectral features may correspond to non-in-situ crack populations created during sample retrieval; the functional form of a crack spectra may be diagnostic of the sample's grain texture; hysteresis is observed in crack spectra between up and down pressure runs - it may be due to friction between the faces of closed crack populations.

  12. Gear crack propagation investigations

    NASA Technical Reports Server (NTRS)

    Lewicki, David G.; Ballarini, Roberto

    1996-01-01

    Analytical and experimental studies were performed to investigate the effect of gear rim thickness on crack propagation life. The FRANC (FRacture ANalysis Code) computer program was used to simulate crack propagation. The FRANC program used principles of linear elastic fracture mechanics, finite element modeling, and a unique re-meshing scheme to determine crack tip stress distributions, estimate stress intensity factors, and model crack propagation. Various fatigue crack growth models were used to estimate crack propagation life based on the calculated stress intensity factors. Experimental tests were performed in a gear fatigue rig to validate predicted crack propagation results. Test gears were installed with special crack propagation gages in the tooth fillet region to measure bending fatigue crack growth. Good correlation between predicted and measured crack growth was achieved when the fatigue crack closure concept was introduced into the analysis. As the gear rim thickness decreased, the compressive cyclic stress in the gear tooth fillet region increased. This retarded crack growth and increased the number of crack propagation cycles to failure.

  13. Cocaine (Coke, Crack) Facts

    MedlinePlus

    ... That People Abuse » Cocaine (Coke, Crack) Facts Cocaine (Coke, Crack) Facts Listen Cocaine is a white ... Version Download "My life was built around getting cocaine and getting high." Stacey is recovering from her ...

  14. Crack propagation in graphene

    NASA Astrophysics Data System (ADS)

    Budarapu, P. R.; Javvaji, B.; Sutrakar, V. K.; Roy Mahapatra, D.; Zi, G.; Rabczuk, T.

    2015-08-01

    The crack initiation and growth mechanisms in an 2D graphene lattice structure are studied based on molecular dynamics simulations. Crack growth in an initial edge crack model in the arm-chair and the zig-zag lattice configurations of graphene are considered. Influence of the time steps on the post yielding behaviour of graphene is studied. Based on the results, a time step of 0.1 fs is recommended for consistent and accurate simulation of crack propagation. Effect of temperature on the crack propagation in graphene is also studied, considering adiabatic and isothermal conditions. Total energy and stress fields are analyzed. A systematic study of the bond stretching and bond reorientation phenomena is performed, which shows that the crack propagates after significant bond elongation and rotation in graphene. Variation of the crack speed with the change in crack length is estimated.

  15. Short crack growth behavior

    SciTech Connect

    Sadananda, K.; Vasudevan, A.K.

    1997-12-01

    The authors have re-evaluated short crack growth behavior using concepts developed recently, and they show that these concepts provide a unified framework that can explain both short and long crack growth behavior without resorting to the crack closure effect. They consider that the behavior of long cracks, including the effects of load ratio, R, is fundamental. they had shown previously that, since fatigue is at least a two-parameter problem in that at least two load parameters are required for an unambiguous description, there are two critical driving forces required simultaneously for fatigue cracks to grow. In extending this analysis to the growth of short cracks, they reject the current notion of the lack of similitude for short cracks and express the similitude as a fundamental postulate that, for a given crack growth mechanism, equal crack tip driving forces result in equal crack growth rates. Short crack growth behavior confirms the concept that two parameters are required to define fatigue; consequently, for fatigue cracks to grow, two thresholds need to be satisfied simultaneously. The authors present examples from the literature to illustrate the concepts discussed.

  16. Seeing Inscriptions on the Shroud of Turin: The Role of Psychological Influences in the Perception of Writing.

    PubMed

    Jordan, Timothy R; Sheen, Mercedes; Abedipour, Lily; Paterson, Kevin B

    2015-01-01

    The Shroud of Turin (hereafter the Shroud) is one of the most widely known and widely studied artifacts in existence, with enormous historical and religious significance. For years, the Shroud has inspired worldwide interest in images on its fabric which appear to be of the body and face of a man executed in a manner consistent with crucifixion, and many believe that these images were formed in the Shroud's fibers during the Resurrection of Jesus of Nazareth. But, more recently, other reports have suggested that the Shroud also contains evidence of inscriptions, and these reports have been used to add crucial support to the view that the Shroud is the burial cloth of Jesus. Unfortunately, these reports of inscriptions are based on marks that are barely visible on the Shroud, even when images are enhanced, and the actual existence of writing on the Shroud is still a matter of considerable debate. Here we discuss previous evidence concerning the psychological processes involved generally in the perception of writing, and especially when letters and words are indistinct. We then report two experiments in which the influence of religious context on perception of inscriptions was addressed specifically, using an image of woven fabric (modern linen) containing no writing and with no religious provenance. This image was viewed in two different contexts: in the Religious Context, participants were informed that the image was of a linen artifact that was important to the Christian faith whereas, in the non-religious Neutral Context, participants were informed that the image was of a simple piece of linen. Both groups were told that the image may contain faint words and were asked to report any words they could see. All participants detected words on the image, and indicated that these words were visible and were able to trace on the image the words they detected. In each experiment, more religious words were detected in the Religious Context condition than in the Neutral

  17. Effects of Hydrocarbon-Based Grease on Rapid Prototype Material Used for Grease Retention Shrouds

    NASA Technical Reports Server (NTRS)

    Zakrajsek, Andrew J.; Valco, Daniel J.; Street, Kenneth W., Jr.

    2010-01-01

    Effects of hydrocarbon-based greases on specific rapid prototype (RP) materials used to fabricate grease retention shrouds (GRS) were explored in this study. Grease retention shrouds are being considered as a way to maintain adequate grease lubrication at the gear mesh in a prototype research transmission system. Due to their design and manufacturing flexibility, rapid prototype materials were chosen for the grease retention shrouds. In order to gain a better understanding of the short and long term effects grease pose on RP materials, research was conducted on the interaction of hydrocarbon-based grease with RP materials. The materials used in this study were durable polyamide (nylon), acrylonitrile butadiene styrene (ABS), and WaterClear 10120. Testing was conducted using Mobilgrease 28 and Syn-Tech 3913G grease (gear coupling grease). These greases were selected due to their regular use with mechanical components. To investigate the effect that grease has on RP materials, the following methods were used to obtain qualitative and quantitative data: Fourier transform infrared spectroscopy (FT-IR), interference profilometer measurements, digital camera imaging, physical shape measurement, and visual observations. To record the changes in the RP materials due to contact with the grease, data was taken before and after the grease application. Results showed that the WaterClear 10120 RP material provided the best resistance to grease penetration as compared to nylon and ABS RP materials. The manufacturing process, and thus resulting surface conditions of the RP material, played a key role in the grease penetration properties and resilience of these materials.

  18. Environmentally assisted cracking in light water reactors. Semiannual report July 1996--December 1996

    SciTech Connect

    Chopra, O.K.; Chung, H.M.; Gavenda, D.J.

    1997-10-01

    This report summarizes work performed by Argonne National Laboratory on fatigue and environmentally assisted cracking (EAC) in light water reactors from July 1996 to December 1996. Topics that have been investigated include (a) fatigue of carbon, low-alloy, and austenitic stainless steels (SSs) used in reactor piping and pressure vessels, (b) irradiation-assisted stress corrosion cracking of Type 304 SS, (c) EAC of Alloy 600, and (d) characterization of residual stresses in welds of boiling water reactor (BWR) core shrouds by numerical models. Fatigue tests were conducted on ferritic and austenitic SSs in water that contained various concentrations of dissolved oxygen to determine whether a slow strain rate applied during various portions of a tensile-loading cycle are equally effective in decreasing fatigue life. Slow-strain-rate-tensile tests were conducted in simulated BWR water at 288 C on SS specimens irradiated to a low fluence in the Halden reactor and the results were compared with similar data from a control-blade sheath and neutron-absorber tubes irradiated in BWRs to the same fluence level. Crack-growth-rate tests were conducted on compact-tension specimens from a low-carbon content heat of Alloy 600 in high-purity oxygenated water at 289 C. Residual stresses and stress intensity factors were calculated for BWR core shroud welds.

  19. GTD analysis of the radiation patterns of a prime focus paraboloid with shroud

    NASA Astrophysics Data System (ADS)

    Narasimhan, M. S.; Raghavan, K.; Ramanujam, P.

    1983-09-01

    The uniform geometrical theory of diffraction (UGTD) is employed to analyze the far-field radiation patterns of a prime focus paraboloid with a cylindrical shroud. The blockage of the aperture illumination of the dish by the gooseneck and the primary feed is also taken into account in the analysis. Far-field radiation patterns (theta = 0-180 deg), calculated for a typical prime focus paraboloid with 2 m aperture diameter, designed and fabricated, are compared with the experimentally derived patterns at 8.8 GHz in the E- and H-planes. There is a satisfactory agreement between the two results.

  20. Effects of Shrouded Stator Cavity Flows on Multistage Axial Compressor Aerodynamic Performance

    NASA Technical Reports Server (NTRS)

    Wellborn, Steven R.; Okiishi, Theodore H.

    1996-01-01

    Experiments were performed on a low-speed multistage axial-flow compressor to assess the effects of shrouded stator cavity flows on aerodynamic performance. Five configurations, which involved changes in seal-tooth leakage rates and/or elimination of the shrouded stator cavities, were tested. Data collected enabled differences in overall individual stage and the third stage blade element performance parameters to be compared. The results show conclusively that seal-tooth leakage ran have a large impact on compressor aerodynamic performance while the presence of the shrouded stator cavities alone seemed to have little influence. Overall performance data revealed that for every 1% increase in the seal-tooth clearance to blade-height ratio the pressure rise dropped up to 3% while efficiency was reduced by 1 to 1.5 points. These observed efficiency penalty slopes are comparable to those commonly reported for rotor and cantilevered stator tip clearance variations. Therefore, it appears that in order to correctly predict overall performance it is equally important to account for the effects of seal-tooth leakage as it is to include the influence of tip clearance flows. Third stage blade element performance data suggested that the performance degradation observed when leakage was increased was brought about in two distinct ways. First, increasing seal-tooth leakage directly spoiled the near hub performance of the stator row in which leakage occurred. Second, the altered stator exit now conditions caused by increased leakage impaired the performance of the next downstream stage by decreasing the work input of the downstream rotor and increasing total pressure loss of the downstream stator. These trends caused downstream stages to progressively perform worse. Other measurements were acquired to determine spatial and temporal flow field variations within the up-and-downstream shrouded stator cavities. Flow within the cavities involved low momentum fluid traveling primarily

  1. Accelerated aging of cellulose by laser irradiation. [Development for Shroud of Turin

    SciTech Connect

    Jackson, J.P.; Arthurs, E.; Schwalbe, L.A.; Sega, R.M.; Windish, D.; Long, W.H.; Stappaerts, E.A.

    1988-01-01

    We describe a new technique for studying thermally-induced chemical transformations in cellulose developed for the Shroud of Turin. The apparatus consists of a carbon dioxide laser for heating, an infrared thermometer, and an optical reflectance spectrometer for tracking the progressive discoloration of the sample. To illustrate the technique, we present measurements from a single piece of sample linen along five isotherms in the range 200-290/degree/C. The results are explained in terms of first-order chemical rate theory and a four-step model. From the measurements we derive the activation energies, Arrhenius constants, and reflectivities of the chromophoric states. 4 refs., 2 figs., 1 tab.

  2. Determining the propagation angle for non-vertical surface-breaking cracks and its effect on crack sizing using an ACFM sensor

    NASA Astrophysics Data System (ADS)

    Shen, J. L.; Zhou, L.; Rowshandel, H.; Nicholson, G. L.; Davis, C. L.

    2015-11-01

    Alternating current field measurement (ACFM) probes are used to detect and size cracks in a range of engineering components. Crack sizing for this, and other electromagnetic (EM) based NDT systems, relies on relating the signal obtained to the actual crack length. For cracks that do not propagate vertically, such as rolling contact fatigue cracks in rails, predicting the crack depth, which determines the rail depth to be removed by grinding, requires an assumed propagation angle into the material as no method to determine crack vertical angle from the EM signals has been reported. This paper discusses the relationship between ACFM signals and propagation angles for surface-breaking cracks using a COMSOL model. The Bx signal accurately predicts the crack pocket length when the vertical angle is 30-90° but underestimates pocket length for shallower angles, e.g. a 50% underestimate is seen for a 3.2 mm pocket length crack propagating at a vertical angle of 10°. A new measure, the Bz trough-peak ratio, is proposed to determine the crack vertical angle. These are verified by experimental measurements using a commercial ACFM pencil probe for cracks with a range of vertical angles between 10° and 90°.

  3. Effects of Contextual Information on Seeing Pareidolic Religious Inscriptions on an Artifact: Implications for the Shroud of Turin.

    PubMed

    Sheen, Mercedes; Jordan, Timothy R

    2015-12-01

    Several reports suggest that images of the Shroud of Turin contain faint religious inscriptions that support the view that the Shroud has special religious significance. Against this background, we investigated effects of contextual information on detecting religious inscriptions using an image of plain modern linen with no religious provenance and containing no writing. The image was viewed in three contexts: In the Neutral Context, participants were told that the image was of a simple piece of linen; in the Religious Context, participants were told that the image was of an important religious artifact; and in the Religious Context + Options condition, participants were also given plausible word options. Very few words were detected in the Neutral Context, significantly more in the Religious Context, and most in the Religious Context+Options condition. Some implications of these findings for reports of inscriptions in the context-laden conditions surrounding the Shroud of Turin are discussed. PMID:26562867

  4. Determination of crack depth in aluminum using eddy currents and GMR sensors

    NASA Astrophysics Data System (ADS)

    Lopes Ribeiro, A.; Pasadas, D.; Ramos, H. G.; Rocha, T.

    2015-03-01

    In this paper we use eddy currents to determine the depth of linear cracks in aluminum plates. A constant field probe is used to generate the spatially uniform excitation field and a single axis giant magneto-resistor (GMR) sensor is used to measure the eddy currents magnetic field. Different depths were machined in one aluminum plate with 4 mm of thickness. By scanning those cracks the magnetic field components parallel and perpendicular to the crack's line were measured when the eddy currents were launched perpendicularly to the crack's line. To characterize one crack in a plate of a given thickness and material, the experimental procedure was defined. The plate surface is scanned to detect and locate one crack. The acquired data enables the determination of the crack's length and orientation. A second scanning is performed with the excitation current perpendicular to the crack and the GMR sensing axis perpendicular and parallel to the crack's line.

  5. Investigation of Helicopter Longeron Cracks

    NASA Technical Reports Server (NTRS)

    Newman, John A.; Baughman, James; Wallace, Terryl A.

    2009-01-01

    Four cracked longerons, containing a total of eight cracks, were provided for study. Cracked regions were cut from the longerons. Load was applied to open the cracks, enabling crack surface examination. Examination revealed that crack propagation was driven by fatigue loading in all eight cases. Fatigue crack initiation appears to have occurred on the top edge of the longerons near geometric changes that affect component bending stiffness. Additionally, metallurgical analysis has revealed a local depletion in alloying elements in the crack initiation regions that may be a contributing factor. Fatigue crack propagation appeared to be initially driven by opening-mode loading, but at a crack length of approximately 0.5 inches (12.7 mm), there is evidence of mixed-mode crack loading. For the longest cracks studied, shear-mode displacements destroyed crack-surface features of interest over significant portions of the crack surfaces.

  6. Laser velocimeter measurements in shrouded and unshrouded radial flow pump impellers

    NASA Technical Reports Server (NTRS)

    Hamkins, C. P.; Flack, R. D.

    1986-01-01

    Shrouded and unshrouded versions of a four-vaned radial flow impeller with a design flow coefficient of 0.063 were tested in a volute pump using a two-component frequency-shifted laser velocimeter. Velocity profiles were measured at six flow rates and at four radial and six circumferential positions in the volute. The variations of the velocity from blade to blade and in the axial direction were measured and are presented. A passage vortex caused by tip leakage and relative casing wall velocity was found in the unshrouded impeller. The tip leakage did not accumulate in the suction wake region; the suction wake region was only 30 to 50 percent as large in the unshrouded impeller as compared to the shrouded impeller. The slip was 30 percent higher in the unshrouded impeller and the variation of slip with flow rate is presented. At no measured position in the impellers did the slip factor reach unity; the closest approach was 0.90. Reverse loadings of the vanes at outer radii were found for flow rates below the impeller/volute matching point for both impellers.

  7. Physical Modeling of Slag `Eye' in an Inert Gas-Shrouded Tundish Using Dimensional Analysis

    NASA Astrophysics Data System (ADS)

    Chatterjee, Saikat; Chattopadhyay, Kinnor

    2016-02-01

    The formation of an exposed eye in the gas-stirred metallurgical vessels such as ladle or tundish is a common observation. Although gas stirring results in proper homogenization of melt composition and temperature, the resulting exposed eye leads to higher heat losses, re-oxidation of liquid steel, and formation of inclusions. Most of the previous research related to slag eye were carried out explicitly for ladles. In the present work, a large number of experiments were performed to measure the slag eye area in full scale and one-third scale water models of an inert gas-shrouded tundish under various operating conditions. Based on the polynomial regression of experimental data, and the method of dimensional analysis, correlations for diameter of gas bubbles and plume velocity were developed. Subsequently, these results were used to obtain correlations for the slag eye area, and critical gas flow rate in an inert gas-shrouded tundish in terms of the operational parameters viz., gas flow rate, thickness of the slag and melt baths, along with the physical properties of the liquids viz., kinematic viscosity and density. It was observed that the dimensionless slag eye area can be expressed in terms of dimensionless numbers such as the density ratio, Froude number, and Reynolds number.

  8. Image formation mechanism on the Shroud of Turin: a solar reflex radiation model (the optical aspect).

    PubMed

    Mouraviev, S N

    1997-12-01

    Unprejudiced logical analysis of the main available data, in the first instance, those collected in 1978 by the American interdisciplinary team known as STURP, suggests that the image of the dead man on the Shroud of Turin resulted from (a) the reflection by the anointed body of transmitted solar rays and their projection onto the inner side of the cloth and (b) the chemical registration of this reflex image by the topmost fibers of the linen, probably with a water or oil solution of aloes and myrrh acting as a catalyzer. This reflex radiation model requires the following: (1) action at the shortest possible distance (i.e., a maximum clinging of the Shroud to the body except for a narrow intervening liquid film), which explains the high resolution and the absence of serious distortions, and (2) double exposure-of both the face and the back-of the enveloped corpse to the sun, which accounts for the presence and optical symmetry of both the frontal and the dorsal images. An attempt is also made to reinterpret the so-called three-dimensional information encoded in the image. Although some chemical issues are also mentioned and a historical reconstruction of the burial procedure is suggested, first and foremost the optical aspect of this mechanism is addressed here. PMID:18264452

  9. Force and moment rotordynamic coefficients for pump-impeller shroud surfaces

    NASA Technical Reports Server (NTRS)

    Childs, Dara W.

    1987-01-01

    Governing equations of motion are derived for a bulk-flow model of the leakage path between an impeller shroud and a pump housing. The governing equations consist of a path-momentum, a circumferential - momentum, and a continuity equation. The fluid annulus between the impeller shroud and pump housing is assumed to be circumferentially symmetric when the impeller is centered; i.e., the clearance can vary along the pump axis but does not vary in the circumferential direction. A perturbation expansion of the governing equations in the eccentricity ratio yields a set of zeroth and first-order governing equations. The zeroth-order equations define the leaking rate and the circumferential and path velocity distributions and pressure distributions for a centered impeller position. The first-order equations define the perturbations in the velocity and pressure distributions due to either a radial-displacement perturbation or a tilt perturbation of the impeller. Integration of the perturbed pressure and shear-stress distribution acting on the rotor yields the reaction forces and moments acting on the impeller face.

  10. Design and performance of a centimetre-scale shrouded wind turbine for energy harvesting

    NASA Astrophysics Data System (ADS)

    Howey, D. A.; Bansal, A.; Holmes, A. S.

    2011-08-01

    A miniature shrouded wind turbine aimed at energy harvesting for power delivery to wireless sensors in pipes and ducts is presented. The device has a rotor diameter of 2 cm, with an outer diameter of 3.2 cm, and generates electrical power by means of an axial-flux permanent magnet machine built into the shroud. Fabrication was accomplished using a combination of traditional machining, rapid prototyping, and flexible printed circuit board technology for the generator stator, with jewel bearings providing low friction and start up speed. Prototype devices can operate at air speeds down to 3 m s-1, and deliver between 80 µW and 2.5 mW of electrical power at air speeds in the range 3-7 m s-1. Experimental turbine performance curves, obtained by wind tunnel testing and corrected for bearing losses using data obtained in separate vacuum run-down tests, are compared with the predictions of an elementary blade element momentum (BEM) model. The two show reasonable agreement at low tip speed ratios. However, in experiments where a maximum could be observed, the maximum power coefficient (~9%) is marginally lower than predicted from the BEM model and occurs at a lower than predicted tip speed ratio of around 0.6.

  11. Seeing Inscriptions on the Shroud of Turin: The Role of Psychological Influences in the Perception of Writing

    PubMed Central

    Jordan, Timothy R.; Sheen, Mercedes; Abedipour, Lily; Paterson, Kevin B.

    2015-01-01

    The Shroud of Turin (hereafter the Shroud) is one of the most widely known and widely studied artifacts in existence, with enormous historical and religious significance. For years, the Shroud has inspired worldwide interest in images on its fabric which appear to be of the body and face of a man executed in a manner consistent with crucifixion, and many believe that these images were formed in the Shroud’s fibers during the Resurrection of Jesus of Nazareth. But, more recently, other reports have suggested that the Shroud also contains evidence of inscriptions, and these reports have been used to add crucial support to the view that the Shroud is the burial cloth of Jesus. Unfortunately, these reports of inscriptions are based on marks that are barely visible on the Shroud, even when images are enhanced, and the actual existence of writing on the Shroud is still a matter of considerable debate. Here we discuss previous evidence concerning the psychological processes involved generally in the perception of writing, and especially when letters and words are indistinct. We then report two experiments in which the influence of religious context on perception of inscriptions was addressed specifically, using an image of woven fabric (modern linen) containing no writing and with no religious provenance. This image was viewed in two different contexts: in the Religious Context, participants were informed that the image was of a linen artifact that was important to the Christian faith whereas, in the non-religious Neutral Context, participants were informed that the image was of a simple piece of linen. Both groups were told that the image may contain faint words and were asked to report any words they could see. All participants detected words on the image, and indicated that these words were visible and were able to trace on the image the words they detected. In each experiment, more religious words were detected in the Religious Context condition than in the Neutral

  12. Ultrasonic Study of Crack Under a Dynamic Thermal Load

    NASA Astrophysics Data System (ADS)

    Pitkänen, J.; Kemppainen, M.; Virkkunen, I.

    2004-02-01

    In piping the defects play a key role for determining the life of component. Also the risk for pipe failure combined to the defects has to be taken into account. In this study thermal dynamic load has been applied to austenitic material (AISI 304) in order to introduce dynamic behaviour into the crack. The studied crack (˜20 mm × 7 mm) has been produced by thermal fatigue in advance. Different ultrasonic techniques were used to reveal information from interaction of ultrasonic waves from dynamic behaviour of a crack face in the sonified volume. The ultrasonic probes in the study are typical probes for defect detection and sizing on site inspections This information helps us to understand some effects in nuclear piping such as detection of cracks with special techniques and difficulties in sizing of the cracks in real situations. In this case the material is loaded to exceed the yield strength. The thermal cycles used caused high variations in the temperature scale from 20°C (68 F) to 600°C (1112 F) in the crack volume especially on the crack surface area. These factors cause large stress variations in the vicinity of the crack. Effects which have been detected during analysis from the measurements explain well difficulties in ultrasonic inspections of those materials on site. Experimental work explains reasons why some defects are missed in the real piping. Ultrasonic techniques used are described in details and conclusion for applicability of those techniques has been drawn.

  13. Ultrasonic Study of Crack Under a Dynamic Thermal Load

    SciTech Connect

    Pitkaenen, J.; Kemppainen, M.; Virkkunen, I.

    2004-02-26

    In piping the defects play a key role for determining the life of component. Also the risk for pipe failure combined to the defects has to be taken into account. In this study thermal dynamic load has been applied to austenitic material (AISI 304) in order to introduce dynamic behaviour into the crack. The studied crack ({approx}20 mm x 7 mm) has been produced by thermal fatigue in advance. Different ultrasonic techniques were used to reveal information from interaction of ultrasonic waves from dynamic behaviour of a crack face in the sonified volume. The ultrasonic probes in the study are typical probes for defect detection and sizing on site inspections This information helps us to understand some effects in nuclear piping such as detection of cracks with special techniques and difficulties in sizing of the cracks in real situations. In this case the material is loaded to exceed the yield strength. The thermal cycles used caused high variations in the temperature scale from 20 deg. C (68 F) to 600 deg. C (1112 F) in the crack volume especially on the crack surface area. These factors cause large stress variations in the vicinity of the crack. Effects which have been detected during analysis from the measurements explain well difficulties in ultrasonic inspections of those materials on site. Experimental work explains reasons why some defects are missed in the real piping. Ultrasonic techniques used are described in details and conclusion for applicability of those techniques has been drawn.

  14. Elevated temperature crack growth

    NASA Technical Reports Server (NTRS)

    Kim, K. S.; Vanstone, R. H.

    1992-01-01

    The purpose of this program was to extend the work performed in the base program (CR 182247) into the regime of time-dependent crack growth under isothermal and thermal mechanical fatigue (TMF) loading, where creep deformation also influences the crack growth behavior. The investigation was performed in a two-year, six-task, combined experimental and analytical program. The path-independent integrals for application to time-dependent crack growth were critically reviewed. The crack growth was simulated using a finite element method. The path-independent integrals were computed from the results of finite-element analyses. The ability of these integrals to correlate experimental crack growth data were evaluated under various loading and temperature conditions. The results indicate that some of these integrals are viable parameters for crack growth prediction at elevated temperatures.

  15. CRACK MODELLING FOR RADIOGRAPHY

    SciTech Connect

    Chady, T.; Napierala, L.

    2010-02-22

    In this paper, possibility of creation of three-dimensional crack models, both random type and based on real-life radiographic images is discussed. Method for storing cracks in a number of two-dimensional matrices, as well algorithm for their reconstruction into three-dimensional objects is presented. Also the possibility of using iterative algorithm for matching simulated images of cracks to real-life radiographic images is discussed.

  16. Thermal cracking of butadiene

    SciTech Connect

    Duisters, H.A.M. )

    1994-01-01

    This paper presents experimental data on the thermal cracking of butadiene in a pilot plant, under conditions representative of industrial operation. The product distribution of pure-butadiene cracking is shown. Results from cocracking experiments in naphtha and C[sub 4]-raffinate are also presented. It is shown that butadiene cracking can be an interesting outlet for the increasing butadiene overcapacity in steam crackers. Some aspects of coke formation during butadiene pyrolysis are addressed as well.

  17. Crack Modelling for Radiography

    NASA Astrophysics Data System (ADS)

    Chady, T.; Napierała, L.

    2010-02-01

    In this paper, possibility of creation of three-dimensional crack models, both random type and based on real-life radiographic images is discussed. Method for storing cracks in a number of two-dimensional matrices, as well algorithm for their reconstruction into three-dimensional objects is presented. Also the possibility of using iterative algorithm for matching simulated images of cracks to real-life radiographic images is discussed.

  18. Automatic crack propagation tracking

    NASA Technical Reports Server (NTRS)

    Shephard, M. S.; Weidner, T. J.; Yehia, N. A. B.; Burd, G. S.

    1985-01-01

    A finite element based approach to fully automatic crack propagation tracking is presented. The procedure presented combines fully automatic mesh generation with linear fracture mechanics techniques in a geometrically based finite element code capable of automatically tracking cracks in two-dimensional domains. The automatic mesh generator employs the modified-quadtree technique. Crack propagation increment and direction are predicted using a modified maximum dilatational strain energy density criterion employing the numerical results obtained by meshes of quadratic displacement and singular crack tip finite elements. Example problems are included to demonstrate the procedure.

  19. Electromagnetic Detection of Fatigue Cracks under Protruding Head Ferromagnetic Fasteners

    NASA Technical Reports Server (NTRS)

    Wincheski, Buzz; Namkung, Min

    2004-01-01

    The detection of fatigue cracks under installed fasteners has been a major goal of the aging aircraft NDE community. The Sliding Probe, Magneto-Optic Imager, Rotating Self-Nulling Probe, Low Frequency Eddy Current Array, and Eddyscan systems are among the instruments developed for this inspection. It has been verified that the detection of fatigue cracks under flush head aluminum and titanium fasteners can be accomplished with a high resolution by the above techniques. The detection of fatigue cracks under ferromagnetic and protruding head fasteners, however, has been found to be much more difficult. For the present work, the inspection for fatigue cracks under SAE 4340 Steel Hi-Lok fasteners is explored. Modifications to the Rotating Self-Nulling Eddy Current Probe System are presented which enable the detection of fatigue cracks hidden under the protruding head of the ferromagnetic fastener. Inspection results for samples with varying length EDM notches are shown, as well as a comparison between the signature from an EDM notch and an actual fatigue crack. Finite Element Modeling is used to investigate the effect of the ferromagnetic fastener on the induced eddy current distribution in order to help explain the detection characteristics of the system. This paper will also introduce a modification to the Rotating Probe System designed specifically for the detection of deeply buried flaws in multilayer conductors. The design change incorporates a giant magnetoresistive (GMR) sensor as the pickup device to improve the low frequency performance of the probe. The flaw detection capabilities of the GMR based Self- Nulling Probe are presented along with the status of the GMR based Rotating Probe System for detection of deeply buried flaws under installed fasteners.

  20. Probe assembly

    SciTech Connect

    Avera, C.J.

    1981-01-06

    A hand-held probe assembly, suitable for monitoring a radioactive fibrinogen tracer, is disclosed comprising a substantially cylindrically shaped probe handle having an open end. The probe handle is adapted to be interconnected with electrical circuitry for monitoring radioactivity that is sensed or detected by the probe assembly. Mounted within the probe handle is a probe body assembly that includes a cylindrically shaped probe body inserted through the open end of the probe handle. The probe body includes a photomultiplier tube that is electrically connected with a male connector positioned at the rearward end of the probe body. Mounted at the opposite end of the probe body is a probe head which supports an optical coupler therewithin. The probe head is interconnected with a probe cap which supports a detecting crystal. The probe body assembly, which consists of the probe body, the probe head, and the probe cap is supported within the probe handle by means of a pair of compressible o-rings which permit the probe assembly to be freely rotatable, preferably through 360*, within the probe handle and removable therefrom without requiring any disassembly.

  1. Diagnostic methods of a bladed disc mode shape evaluation used for shrouded blades in steam turbines

    NASA Astrophysics Data System (ADS)

    Strnad, Jaromir; Liska, Jindrich

    2015-11-01

    This paper deals with advanced methods for the evaluation of a bladed disc behavior in terms of the wheel vibration and blade service time consumption. These methods are developed as parts of the noncontact vibration monitoring system of the steam turbine shrouded blades. The proposed methods utilize the time-frequency processing (cross spectra) and the method using least squares to analyse the data from the optical and magnetoresistive sensors, which are mounted in the stator radially above the rotor blades. Fundamentally, the blade vibrations are detected during the blade passages under the sensors and the following signal processing, which covers also the proposed methods, leads to the estimation of the blade residual service life. The prototype system implementing above mentioned techniques was installed into the last stage of the new steam turbine (LP part). The methods for bladed disc mode shape evaluation were successfully verified on the signals, which were obtained during the commission operation of the turbine.

  2. The effect of inlet swirl on the rotordynamic shroud forces in a centrifugal pump

    NASA Astrophysics Data System (ADS)

    Ginzburg, A.; Brennen, C. E.; Acosta, A. J.; Caughey, T. K.

    1992-06-01

    The role played by fluid forces in determining the rotordynamic stability of a centrifugal pump is gaining increasing attention. The present research investigates the contributions to the rotordynamic forces from the discharge-to-suction leakage flows between the front shroud of the rotating impeller and the stationary pump casing. In particular, the dependency of the rotordynamic characteristics of leakage flows on the swirl at the inlet to the leakage path was examined. An inlet guide vane was designed for the experiment so that swirl could be introduced at the leakage flow inlet. The data demonstrates substantial rotordynamic effects and a destabilizing tangential force for small positive whirl ratios; this force decreased with increasing flow rate. The effect of swirl on the rotordynamic forces was found to be destabilizing.

  3. The Turin Shroud face: the evidence of maxillo-facial trauma.

    PubMed

    Majorana, A; Bardellini, E; Gulino, G; Conti, G; Farronato, G; Rodella, L

    2015-01-01

    The Turin Shroud (TS) is a linen cloth commonly associated with Jesus Christ, his crucifixion and burial. Several medical specialists have debated the injuries of the TS Man, nevertheless there are no detailed and quantitative data about the anatomy of the TS face. The purpose of this study was to analyse the cephalometric measurements of the face image of the TS. The TS face image was acquired by a picture and processed using a cephalometric software, Oris Ceph® (Up to date 2012). The image of the soft tissues was processed in order to obtain skeletal points and a cephalometric analysis of the soft and skeletal tissues was performed. Image processing of the TS face shows that the Man represented in it has undergone a maxillo-facial trauma, especially a left displacement of the mandible, probably due to temporo-mandibular joint lesions. This condition has not been described before, despite several studies on the subject. PMID:26050809

  4. The effect of inlet swirl on the rotordynamic shroud forces in a centrifugal pump

    NASA Technical Reports Server (NTRS)

    Ginzburg, A.; Brennen, C. E.; Acosta, A. J.; Caughey, T. K.

    1992-01-01

    The role played by fluid forces in determining the rotordynamic stability of a centrifugal pump is gaining increasing attention. The present research investigates the contributions to the rotordynamic forces from the discharge-to-suction leakage flows between the front shroud of the rotating impeller and the stationary pump casing. In particular, the dependency of the rotordynamic characteristics of leakage flows on the swirl at the inlet to the leakage path was examined. An inlet guide vane was designed for the experiment so that swirl could be introduced at the leakage flow inlet. The data demonstrates substantial rotordynamic effects and a destabilizing tangential force for small positive whirl ratios; this force decreased with increasing flow rate. The effect of swirl on the rotordynamic forces was found to be destabilizing.

  5. Effect of Helmholtz Oscillation on Auto-shroud for APS Tungsten Carbide Coating

    NASA Astrophysics Data System (ADS)

    Jin, Younggil; Choi, Sooseok; Yang, Seung Jae; Park, Chong Rae; Kim, Gon-Ho

    2013-06-01

    The atmospheric-pressure plasma spray (APS) of tungsten coating was performed using tungsten carbide (WC) powder by means of DC plasma torch equipped with a stepped anode nozzle as a potential method of W coating on graphite plasma-facing component of fusion reactors. This nozzle configuration allows Helmholtz oscillation mode dominating in APS arc fluctuation, and the variation of auto-shroud effect with Helmholtz oscillation characteristics can be investigated. Tungsten coating made from WC powder has lower porosity and higher tungsten purity than that made from pure tungsten powder. The porosity and chemical composition of coatings were investigated by mercury intrusion porosimetry and x-ray photoelectron spectroscopy, respectively. The purity of tungsten coating layer is increased with the increasing frequency of Helmholtz oscillation and the increasing arc current. The modulation of Helmholtz oscillation frequency and magnitude may enhance the decarburization of WC to deposit tungsten coating without W-C and W-O bond from WC powder.

  6. Crack layer theory

    NASA Technical Reports Server (NTRS)

    Chudnovsky, A.

    1987-01-01

    A damage parameter is introduced in addition to conventional parameters of continuum mechanics and consider a crack surrounded by an array of microdefects within the continuum mechanics framework. A system consisting of the main crack and surrounding damage is called crack layer (CL). Crack layer propagation is an irreversible process. The general framework of the thermodynamics of irreversible processes are employed to identify the driving forces (causes) and to derive the constitutive equation of CL propagation, that is, the relationship between the rates of the crack growth and damage dissemination from one side and the conjugated thermodynamic forces from another. The proposed law of CL propagation is in good agreement with the experimental data on fatigue CL propagation in various materials. The theory also elaborates material toughness characterization.

  7. Crack layer theory

    NASA Technical Reports Server (NTRS)

    Chudnovsky, A.

    1984-01-01

    A damage parameter is introduced in addition to conventional parameters of continuum mechanics and consider a crack surrounded by an array of microdefects within the continuum mechanics framework. A system consisting of the main crack and surrounding damage is called crack layer (CL). Crack layer propagation is an irreversible process. The general framework of the thermodynamics of irreversible processes are employed to identify the driving forces (causes) and to derive the constitutive equation of CL propagation, that is, the relationship between the rates of the crack growth and damage dissemination from one side and the conjugated thermodynamic forces from another. The proposed law of CL propagation is in good agreement with the experimental data on fatigue CL propagation in various materials. The theory also elaborates material toughness characterization.

  8. The influence of shrouded stator cavity flows on multistage compressor performance

    SciTech Connect

    Wellborn, S.R.; Okiishi, T.H.

    1999-07-01

    Experiments were performed on a low-speed multistage axial-flow compressor to assess the effects of shrouded stator cavity flows on aerodynamic performance. Five configurations, which involved systematic changes in seal-tooth leakage rates and/or elimination of the shrouded stator cavities, were tested. Rig data indicate increasing seal-tooth leakage substantially degraded compressor performance. For every 1 percent increase in seal-tooth clearance-to-span ratio, the decrease in pressure rise was 3 percent and the reduction in efficiency was 1 point. These observed performance penalties are comparable to those commonly reported for rotor and cantilevered stator tip clearance variations. The performance degradation observed with increased leakage was brought about in two distinct ways. First, increasing seal-tooth leakage directly spoiled the near-hub performance of the stator row in which leakage occurred. Second, the altered stator exit flow conditions, caused by increased leakage, impaired the performance of the next downstream stage by decreasing the work input of the rotor and increasing total pressure loss of the stator. These trends caused the performance of downstream stages to deteriorate progressively. Numerical simulations of the test rig stator flow field were also conducted to help resolve important fluid mechanic details associated with the interaction between the primary and cavity flows. Simulation results show that fluid originating in the upstream cavity collected on the stator suction surface when the cavity tangential momentum was low and on the pressure side when it was high. The convection of cavity fluid to the suction surface was a mechanism that reduced stator performance when leakage increased.

  9. Electrical Impedance Spectroscopy-Based Defect Sensing Technique in Estimating Cracks

    PubMed Central

    Zhang, Tingting; Zhou, Liangdong; Ammari, Habib; Seo, Jin Keun

    2015-01-01

    A defect sensing method based on electrical impedance spectroscopy is proposed to image cracks and reinforcing bars in concrete structures. The method utilizes the frequency-dependent behavior of thin insulating cracks: low-frequency electrical currents are blocked by insulating cracks, whereas high-frequency currents can pass through thin cracks to probe the conducting bars. From various frequency-dependent electrical impedance tomography (EIT) images, we can show its advantage in terms of detecting both thin cracks with their thickness and bars. We perform numerical simulations and phantom experiments to support the feasibility of the proposed method. PMID:26007713

  10. Small-crack test methods

    NASA Astrophysics Data System (ADS)

    Larsen, James M.; Allison, John E.

    This book contains chapters on fracture mechanics parameters for small fatigue cracks, monitoring small-crack growth by the replication method, measurement of small cracks by photomicroscopy (experiments and analysis), and experimental mechanics of microcracks. Other topics discussed are the real-time measurement of small-crack-opening behavior using an interferometric strain/displacement gage; direct current electrical potential measurement of the growth of small cracks; an ultrasonic method for the measurement of the size and opening behavior of small fatigue cracks; and the simulation of short crack and other low closure loading conditions, utilizing constant K(max) Delta-K-decreasing fatigue crack growth procedures.

  11. Effect of crack surface geometry on fatigue crack closure

    SciTech Connect

    Drury, W.J.; Gokhale, A.M.; Antolovich, S.D.

    1995-10-01

    The geometry of crack faces often plays a critical role in reducing crack extension forces when crack closure occurs during fatigue crack growth. Most previous studies of fatigue crack closure are concerned with mechanical measure of closure as related to the crack growth rate; very little attention has been given to the geometry of the crack surfaces. The objective is to identify those aspects of crack surface geometry that are important in the closure process, to develop quantitative fractographic techniques to estimate such attributes in a statistically significant and robust manner, and to correlate them to the physical process of crack closure. For this purpose, fatigue crack propagation experiments were performed on a Ni-base superalloy and crack growth rates and crack closure loads were measured. Digital image profilometry and software-based analysis techniques were used for statistically reliable and detailed quantitative characterization of fatigue crack profiles. It is shown that the dimensionless, scale-independent attributes, such a height-to-width ratio of asperities, fractal dimensions, dimensionless roughness parameters, etc., do not represent the aspects of crack geometry that are of primary importance in the crack closure phenomena. Furthermore, it is shown that the scale-dependent characteristics, such as average asperity height, do represent the aspects of crack geometry that play an interactive role in the closure process. These observations have implications concerning the validity of geometry-dependent, closure-based models for fatigue crack growth.

  12. Effect of crack surface geometry on fatigue crack closure

    NASA Astrophysics Data System (ADS)

    Drury, W. J.; Gokhale, Arun M.; Antolovich, S. D.

    1995-10-01

    The geometry of crack faces often plays a critical role in reducing crack extension forces when crack closure occurs during fatigue crack growth. Most previous studies of fatigue crack closure are concerned with mechanical measures of closure as related to the crack growth rate; very little attention has been given to the geometry of the crack surfaces. Our objective is to identify those aspects of crack surface geometry that are important in the closure process, to develop quantitative fractographic techniques to estimate such attributes in a statistically significant and robust manner, and to correlate them to the physical process of crack closure. For this purpose, fatigue crack propagation experiments were performed on a Ni-base superalloy and crack growth rates and crack closure loads were measured. Digital image profilometry and software-based analysis techniques were used for statistically reliable and detailed quantitative characterization of fatigue crack profiles. It is shown that the dimensionless, scale-independent attributes, such as height-to-width ratio of asperities, fractal dimensions, dimensionless roughness parameters, etc., do not represent the aspects of crack geometry that are of primary importance in the crack closure phenomena. Furthermore, it is shown that the scaledependent characteristics, such as average asperity height, do represent the aspects of crack geometry that play an interactive role in the closure process. These observations have implications concerning the validity of geometry-dependent, closure-based models for fatigue crack growth.

  13. Catalytic cracking process

    SciTech Connect

    Gladrow, E.M.; Winter, W.E.

    1980-04-29

    The octane number of a cracked naphtha can be significantly improved in a catalytic cracking unit, without significant decrease in naphtha yield, by maintaining certain critical concentrations of metals on the catalyst, suitably by blending or adding a heavy metals-containing component to the gas oil feed. Suitably, in a catalytic cracking process unit wherein a gas oil feed is cracked in a cracking reactor (Zone) at an elevated temperature in the presence of a cracking catalyst, the cracking catalyst is regenerated in a regenerator (Regeneration zone) by burning coke off the catalyst, and catalyst is circulated between the reactor and regenerator, sufficient of a metals-containing heavy feedstock is admixed, intermittantly or continuously, with the gas oil feed to deposit metals on said catalyst and raise the metals-content of said catalyst to a level of from about 1500 to about 6000 parts per million, preferably from about 2500 to about 4000 parts per million expressed as equivalent nickel, base the weight of the catalyst, and said metals level is maintained on the catalyst throughout the operation by withdrawing high metals-containing catalyst and adding low metals-containing catalyst to the regenerator.

  14. Modelling of hydride cracking

    SciTech Connect

    Zheng, X.J.; Metzger, D.R.; Glinka, G.; Dubey, R.N.

    1996-12-01

    Zirconium alloys may be susceptible to hydride formation under certain service conditions, due to hydrogen diffusion and precipitation in the presence of stress concentrations and temperature gradients. The inhomogeneous brittle hydride platelets that form are modeled as plane defects of zero thickness, with fracture toughness less than that of the matrix. A fracture criterion based on sufficient energy and stress is proposed for either delayed hydride cracking (DHC) under constant loading conditions, or hydride cracking at rising loads, such as in a fracture toughness test. The fracture criterion is validated against available experimental data concerning initiation of hydride fracture in smooth specimens, and DHC in cracked specimens under various loading and temperature conditions.

  15. Fracture mechanics by three-dimensional crack-tip synchrotron X-ray microscopy.

    PubMed

    Withers, P J

    2015-03-01

    To better understand the relationship between the nucleation and growth of defects and the local stresses and phase changes that cause them, we need both imaging and stress mapping. Here, we explore how this can be achieved by bringing together synchrotron X-ray diffraction and tomographic imaging. Conventionally, these are undertaken on separate synchrotron beamlines; however, instruments capable of both imaging and diffraction are beginning to emerge, such as ID15 at the European Synchrotron Radiation Facility and JEEP at the Diamond Light Source. This review explores the concept of three-dimensional crack-tip X-ray microscopy, bringing them together to probe the crack-tip behaviour under realistic environmental and loading conditions and to extract quantitative fracture mechanics information about the local crack-tip environment. X-ray diffraction provides information about the crack-tip stress field, phase transformations, plastic zone and crack-face tractions and forces. Time-lapse CT, besides providing information about the three-dimensional nature of the crack and its local growth rate, can also provide information as to the activation of extrinsic toughening mechanisms such as crack deflection, crack-tip zone shielding, crack bridging and crack closure. It is shown how crack-tip microscopy allows a quantitative measure of the crack-tip driving force via the stress intensity factor or the crack-tip opening displacement. Finally, further opportunities for synchrotron X-ray microscopy are explored. PMID:25624521

  16. Fracture mechanics by three-dimensional crack-tip synchrotron X-ray microscopy

    PubMed Central

    Withers, P. J.

    2015-01-01

    To better understand the relationship between the nucleation and growth of defects and the local stresses and phase changes that cause them, we need both imaging and stress mapping. Here, we explore how this can be achieved by bringing together synchrotron X-ray diffraction and tomographic imaging. Conventionally, these are undertaken on separate synchrotron beamlines; however, instruments capable of both imaging and diffraction are beginning to emerge, such as ID15 at the European Synchrotron Radiation Facility and JEEP at the Diamond Light Source. This review explores the concept of three-dimensional crack-tip X-ray microscopy, bringing them together to probe the crack-tip behaviour under realistic environmental and loading conditions and to extract quantitative fracture mechanics information about the local crack-tip environment. X-ray diffraction provides information about the crack-tip stress field, phase transformations, plastic zone and crack-face tractions and forces. Time-lapse CT, besides providing information about the three-dimensional nature of the crack and its local growth rate, can also provide information as to the activation of extrinsic toughening mechanisms such as crack deflection, crack-tip zone shielding, crack bridging and crack closure. It is shown how crack-tip microscopy allows a quantitative measure of the crack-tip driving force via the stress intensity factor or the crack-tip opening displacement. Finally, further opportunities for synchrotron X-ray microscopy are explored. PMID:25624521

  17. Characteristics of lead induced stress corrosion cracking of alloy 690 in high temperature

    SciTech Connect

    Chung, K.K.; Lim, J.K.; Watanabe, Yutaka; Shoji, Tetsuo

    1996-10-01

    Slow strain rate tests (SSRT) were conducted on alloy 690 in various lead chloride solutions and metal lead added to 100 ppm chloride solution at 288 C. The corrosion potential (rest potential) for the alloy was measured with SSRT tests. The cracking was observed by metallographic examination and electron probe micro analyzer. Also, the corrosion behavior of the alloy was evaluated by anodic polarized measurement at 30 C. Resulting from the tests, cracking was characterized by cracking behavior, crack length and crack growth rate, and lead effects on cracking. The cracking was mainly intergranular in mode, approximately from 60 um to 450 um in crack length, and approximately 10{sup {minus}6} to 10{sup {minus}7} mmS-1 in crack velocity. The cracking was evaluated through the variation the corrosion potential in potential-time and lead behavior during SSRTs. The lead effect in corrosion was evaluated through active to passive transition behavior in anodic polarized curves. The corrosion reactions in the cracking region were confirmed by electron probe microanalysis. Alloy 690 is used for steam generation tubes in pressurized water reactors.

  18. Quantity Effect of Radial Cracks on the Cracking Propagation Behavior and the Crack Morphology

    PubMed Central

    Chen, Jingjing; Xu, Jun; Liu, Bohan; Yao, Xuefeng; Li, Yibing

    2014-01-01

    In this letter, the quantity effect of radial cracks on the cracking propagation behavior as well as the circular crack generation on the impacted glass plate within the sandwiched glass sheets are experimentally investigated via high-speed photography system. Results show that the radial crack velocity on the backing glass layer decreases with the crack number under the same impact conditions during large quantities of repeated experiments. Thus, the “energy conversion factor” is suggested to elucidate the physical relation between the cracking number and the crack propagation speed. Besides, the number of radial crack also takes the determinative effect in the crack morphology of the impacted glass plate. This study may shed lights on understanding the cracking and propagation mechanism in laminated glass structures and provide useful tool to explore the impact information on the cracking debris. PMID:25048684

  19. Rotating concave eddy current probe

    DOEpatents

    Roach, Dennis P.; Walkington, Phil; Rackow, Kirk A.; Hohman, Ed

    2008-04-01

    A rotating concave eddy current probe for detecting fatigue cracks hidden from view underneath the head of a raised head fastener, such as a buttonhead-type rivet, used to join together structural skins, such as aluminum aircraft skins. The probe has a recessed concave dimple in its bottom surface that closely conforms to the shape of the raised head. The concave dimple holds the probe in good alignment on top of the rivet while the probe is rotated around the rivet's centerline. One or more magnetic coils are rigidly embedded within the probe's cylindrical body, which is made of a non-conducting material. This design overcomes the inspection impediment associated with widely varying conductivity in fastened joints.

  20. Ethylene by Naphta Cracking

    ERIC Educational Resources Information Center

    Wiseman, Peter

    1977-01-01

    Presents a discussion of the manufacture of ethylene by thermal cracking of hydrocarbon feedstocks that is useful for introducing the subject of industrial chemistry into a chemistry curriculum. (MLH)

  1. Elevated temperature crack growth

    NASA Technical Reports Server (NTRS)

    Kim, K. S.; Vanstone, R. H.; Malik, S. N.; Laflen, J. H.

    1988-01-01

    A study was performed to examine the applicability of path-independent (P-I) integrals to crack growth problems in hot section components of gas turbine aircraft engines. Alloy 718 was used and the experimental parameters included combined temperature and strain cycling, thermal gradients, elastic-plastic strain levels, and mean strains. A literature review was conducted of proposed P-I integrals, and those capable of analyzing hot section component problems were selected and programmed into the postprocessor of a finite element code. Detailed elastic-plastic finite element analyses were conducted to simulate crack growth and crack closure of the test specimen, and to evaluate the P-I integrals. It was shown that the selected P-I integrals are very effective for predicting crack growth for isothermal conditions.

  2. Thermal cracking of hydrocarbons

    SciTech Connect

    Braun, R.L.; Burnham, A.K.

    1988-09-01

    Knowledge of thermal cracking of hydrocarbons is important in understanding and modeling petroleum maturation. We have reviewed the literature on the thermal cracking of pure hydrocarbons and mixtures of hydrocarbons, with particular attention given to dependence of the kinetics on temperature, pressure, and phase. Major uncertainties remain with regard to pressure dependence. Based on this review, we developed a simple, four-component, three-reaction model for oil-cracking. We also developed a simple, kerogen-maturation, kinetic model that incorporates hydrogen and carbon balance and includes the most important oil- and gas-forming reactions: kerogen pyrolysis, three oil-cracking reactions, and three coke-pyrolysis reactions. Tentative stoichiometry parameters are given for lacustrine and marine kerogens. 35 refs., 5 figs., 5 tabs.

  3. Elevated Temperature Crack Propagation

    NASA Technical Reports Server (NTRS)

    Orange, Thomas W.

    1994-01-01

    This paper is a summary of two NASA contracts on high temperature fatigue crack propagation in metals. The first evaluated the ability of fairly simple nonlinear fracture parameters to correlate crack propagation. Hastelloy-X specimens were tested under isothermal and thermomechanical cycling at temperatures up to 980 degrees C (1800 degrees F). The most successful correlating parameter was the crack tip opening displacement derived from the J-integral. The second evaluated the ability of several path-independent integrals to correlate crack propagation behavior. Inconel 718 specimens were tested under isothermal, thermomechanical, temperature gradient, and creep conditions at temperatures up to 650 degrees C (1200 degrees F). The integrals formulated by Blackburn and by Kishimoto correlated the data reasonably well under all test conditions.

  4. Crack-growth analysis

    NASA Technical Reports Server (NTRS)

    Bianca, C.; Creager, M.

    1976-01-01

    Flexible, adaptable, integrative routine, computer program incorporates Collipriest-Ehret and Paris-Forman equations. Calculates growth from initial defect size and terminates calculation when crack is sufficiently large for critical condition. Wheeler, Willenborg, and Grumman Closure models are available.

  5. Single point aerosol sampling: Evaluation of mixing and probe performance in a nuclear stack

    SciTech Connect

    Rodgers, J.C.; Fairchild, C.I.; Wood, G.O.

    1995-02-01

    Alternative Reference Methodologies (ARMs) have been developed for sampling of radionuclides from stacks and ducts that differ from the methods required by the U.S. EPA. The EPA methods are prescriptive in selection of sampling locations and in design of sampling probes whereas the alternative methods are performance driven. Tests were conducted in a stack at Los Alamos National Laboratory to demonstrate the efficacy of the ARMs. Coefficients of variation of the velocity tracer gas, and aerosol particle profiles were determined at three sampling locations. Results showed numerical criteria placed upon the coefficients of variation by the ARMs were met at sampling stations located 9 and 14 stack diameters from flow entrance, but not at a location that is 1.5 diameters downstream from the inlet. Experiments were conducted to characterize the transmission of 10 {mu}m aerodynamic equivalent diameter liquid aerosol particles through three types of sampling probes. The transmission ratio (ratio of aerosol concentration at the probe exit plane to the concentration in the free stream) was 107% for a 113 L/min (4-cfm) anisokinetic shrouded probe, but only 20% for an isokinetic probe that follows the EPA requirements. A specially designed isokinetic probe showed a transmission ratio of 63%. The shrouded probe performance would conform to the ARM criteria; however, the isokinetic probes would not.

  6. Single point aerosol sampling: Evaluation of mixing and probe performance in a nuclear stack

    SciTech Connect

    Rodgers, J.C.; Fairchild, C.I.; Wood, G.O.; Ortiz, C.A.; Muyshondt, A.; McFarland, A.R. |

    1994-12-31

    Alternative Reference Methodologies (ARMS) have been developed for sampling of radionuclide; from stacks and ducts that differ from the methods required by the US EPA. The EPA methods are prescriptive in selection of sampling locations and in design of sampling probes whereas the alternative methods are performance driven. Tests were conducted in a stack at Los Alamos National Laboratory to demonstrate the efficacy of the ARMS. Coefficients of variation of the velocity tracer gas, and aerosol particle profiles were determined at three sampling locations. Results showed numerical criteria placed upon the coefficients of variation by the ARMs were met at sampling stations located 9 and 14 stack diameters from flow entrance, but not at a location that is 1.5 diameters downstream from the inlet. Experiments were conducted to characterize the transmission of 10 {mu}m aerodynamic equivalent diameter liquid aerosol particles through three types of sampling probes. The transmission ratio (ratio of aerosol concentration at the probe exit plane to the concentration in the free stream) was 107% for a 113 L/min (4-cfm) an isokinetic shrouded probe, but only 20% for an isokinetic probe that follows the EPA requirements. A specially designed isokinetic probe showed a transmission ratio of 63%. The shrouded probe performance would conform to the ARM criteria; however, the isokinetic probes would not.

  7. The kinked interface crack

    NASA Astrophysics Data System (ADS)

    Heitzer, Joerg

    1992-05-01

    Two methods for the numerical solution of the integral equation describing the kinked interface crack, one proposed by Erdogan et al. (1973) and the other by Theokaris and Iokimidis (1979), are examined. The method of Erdogan et al. is then used to solve the equation in order to determine the kinking angle of the interface crack. Results are presented for two material combinations, aluminum/epoxy and glass/ceramic, under uniaxial tension in the direction normal to the interface.

  8. Effect of engine shroud configuration on the static aerodynamic characteristics of a 0.00563 scale 142-inch diameter solid rocket booster (SA10F)

    NASA Technical Reports Server (NTRS)

    Johnson, J. D.; Braddock, W. F.

    1974-01-01

    A test of a 0.563 percent scale space shuttle Solid Rocket Booster (SRB) model, MSFC Model 449, was conducted in a trisonic wind tunnel. Test Mach numbers were 0.4, 0.6, 0.9, 1.2, 1.96, 3.48, 4.0, 4.45, and 4.96. Test angles-of-attack ranged from minus 10 degrees to 190 degrees. Test Reynolds numbers ranged from 3.0 million per foot to 8.6 million per foot. Test roll angles were 0, 11.25, 22.5, 45, and 90 degrees. In addition to the static stability evaluation of the primary SRB configuration, five parametric investigations were made: (1) effect of Reynolds number, (2) effect of engine shroud flare angle, (3) effect of engine shroud length, (4) effect of engine shroud strakes, and (5) effect of engine shroud strakes and trust vector control bottles.

  9. Evaluation of the impeller shroud performance of an axial flow ventricular assist device using computational fluid dynamics.

    PubMed

    Su, Boyang; Chua, Leok P; Lim, Tau M; Zhou, Tongming

    2010-09-01

    Generally, there are two types of impeller design used in the axial flow blood pumps. For the first type, which can be found in most of the axial flow blood pumps, the magnet is embedded inside the impeller hub or blades. For the second type, the magnet is embedded inside the cylindrical impeller shroud, and this design has not only increased the rotating stability of the impeller but has also avoided the flow interaction between the impeller blade tip and the pump casing. Although the axial flow blood pumps with either impeller design have been studied individually, the comparisons between these two designs have not been conducted in the literature. Therefore, in this study, two axial flow blood pumps with and without impeller shrouds were numerically simulated with computational fluid dynamics and compared with each other in terms of hydraulic and hematologic performances. For the ease of comparison, these two models have the same inner components, which include a three-blade straightener, a two-blade impeller, and a three-blade diffuser. The simulation results showed that the model with impeller shroud had a lower static pressure head with a lower hydraulic efficiency than its counterpart. It was also found that the blood had a high possibility to deposit on the impeller shroud inner surface, which greatly enhanced the possibility of thrombus formation. The blood damage indices in both models were around 1%, which was much lower than the 13.1% of the axial flow blood pump of Yano et al. with the corresponding experimental hemolysis of 0.033 g/100 L. PMID:20883393

  10. Centrifugal acceleration modes for incompressible fluid in the leakage annulus between a shrouded pump impeller and its housing

    NASA Technical Reports Server (NTRS)

    Childs, D. W.

    1991-01-01

    An algorithm is developed for calculating complex eigenvalues and eigenvectors associated with the fluid resonances and is used to analyze the perturbed flow in the leakage path between a shrouded-pump impeller and its housing. The eigenvalues obtained are consistent with the forced-response curves. First- and second-natural-frequency eigensolutions are presented for mode shapes corresponding to lateral excitations, and first-natural-frequency eigensolutions are presented for mode shapes corresponding to axial excitation.

  11. An experimental investigation on the tip leakage noise in axial-flow fans with rotating shroud

    NASA Astrophysics Data System (ADS)

    Canepa, Edward; Cattanei, Andrea; Mazzocut Zecchin, Fabio; Milanese, Gabriele; Parodi, Davide

    2016-08-01

    The tip leakage noise generated by a shrouded rotor of an axial-flow fan has been experimentally studied. The measurements have been taken at high flow rate and at the design point in a hemi-anechoic chamber, at constant rotational speed and during speed ramps. A test plenum designed according to ISO 10302 has been employed to modify the operating conditions and different inlet configurations, ducted and unducted with standard and reduced tip gap, have been considered. The basic features of the inflow have been studied by means of aerodynamic measurements taken upstream of the rotor. To separate the noise generating mechanisms from the acoustic propagation effects, the acoustic response function of the test configuration has been computed employing the spectral decomposition method, and then it has been compared with the velocity-scaled, constant-Strouhal number SPL. In this way, the noise components related to the tip leakage flow have been identified and their connection with geometry have been highlighted. The broadband part of the spectra and the peaks related to the tip leakage flow are affected by the same propagation effects, but show a different dependence on the rotational speed and on the operating point. The upstream geometry affects the radiated noise much more than the performance and even a strong reduction in the tip-gap cannot completely eliminate the related noise.

  12. Do we really need new medical information about the Turin Shroud?

    PubMed

    Bevilacqua, M; Fanti, G; D'Arienzo, M; De Caro, R

    2014-02-01

    Image processing of the Turin Shroud (TS) shows that the Man represented in it has undergone an under glenoidal dislocation of the humerus on the right side and lowering of the shoulder, and has a flattened hand and enophthalmos; conditions that have not been described before, despite several studies on the subject. These injuries indicate that the Man suffered a violent blunt trauma to the neck, chest and shoulder from behind, causing neuromuscular damage and lesions of the entire brachial plexus. The posture of the left claw-hand is indicative of an injury of the lower brachial plexus, as is the crossing of the hands on the pubis, not above the pubis as it would normally be, and are related to traction of the limbs as a result of the nailing to the patibulum. The disappearance of the thumbprints is because of entrainment of the flexor pollicis longus tendons while the nails were driven through the wrists. The blunt chest trauma, which resulted in the body falling forwards, was the direct cause of a lung contusion and haemothorax, confirmed by the post-mortem leakage of clots and serum from the chest caused by the stabbing with the spear, and was a likely cause of cardiac contusion. All the evidence is in favour of the hypothesis that the TS Man is Jesus of Nazareth. PMID:24135252

  13. Computational study of the effects of shroud geometric variation on turbine performance in a 1.5-stage high-loaded turbine

    NASA Astrophysics Data System (ADS)

    Jia, Wei; Liu, Huoxing

    2013-10-01

    Generally speaking, main flow path of gas turbine is assumed to be perfect for standard 3D computation. But in real engine, the turbine annulus geometry is not completely smooth for the presence of the shroud and associated cavity near the end wall. Besides, shroud leakage flow is one of the dominant sources of secondary flow in turbomachinery, which not only causes a deterioration of useful work but also a penalty on turbine efficiency. It has been found that neglect shroud leakage flow makes the computed velocity profiles and loss distribution significantly different to those measured. Even so, the influence of shroud leakage flow is seldom taken into consideration during the routine of turbine design due to insufficient understanding of its impact on end wall flows and turbine performance. In order to evaluate the impact of tip shroud geometry on turbine performance, a 3D computational investigation for 1.5-stage turbine with shrouded blades was performed in this paper. The following geometry parameters were varied respectively: Inlet cavity length and exit cavity length

  14. Refinery ring groove cracking experience

    SciTech Connect

    Ehmke, E.F.

    1982-05-01

    This paper presents the results of a questionnaire on the problem of ring groove cracking in reactors. The results were found to be inconclusive in providing any information on correcting the problem. One report pertaining to a ring groove crack on a 24-inch reactor nozzle served as a warning that cracks may progress beyond the overlay, through it is not known if the base metal can easily crack at low temperatures. The results did not indicate at what point the cracks occurred, but what was common to almost all cracks was that the flange had been in high-temperature, high-pressure hydrogen suggesting that dissolved hydrogen or environmental hydrogen assisted the cracking. The type of stress that contributes in the cracking has not been determined. It is indicated that many cracks were found after the questionnaire was done.

  15. Navier-Stokes analysis of an oxidizer turbine blade with tip clearance with and without a mini-shroud

    NASA Astrophysics Data System (ADS)

    Chan, Tony; Dejong, Frederik J.

    1993-07-01

    The Gas Generator Oxidizer Turbine (GGOT) Blade is being analyzed by various investigators under the NASA MSFC-sponsored Turbine Stage Technology Team design effort. The present work concentrates on the tip clearance region flow and associated losses; however, flow details for the passage region are also obtained in the simulations. The present calculations simulate the rotor blade row in a rotating reference frame with the appropriate coriolis and centrifugal acceleration term included in the momentum equations. The upstream computational boundary is located about one axial chord from the blade leading edge. The boundary conditions at this location have been determined by Pratt & Whitney using an Euler analysis without the vanes to obtain approximately the same flow profiles at the rotor as were obtained with the Euler stage analysis including the vanes. Inflow boundary layer profiles are then constructed assuming the skin friction coefficient at both the hub and the casing. The downstream computational boundary is located about one axial chord from the blade trailing edge, and the circumferentially averaged static pressure at this location was also obtained from the P&W Euler analysis. Results obtained for the 3-D baseline GGOT geometry at the full scale design Reynolds number show a region of high loss in the region near the casing. Particle traces in the near tip region show vortical flow behavior of the fluid which passes through the clearance region and exits at the downstream edge of the gap. In an effort to reduce clearance flow losses, the mini-shroud concept was proposed by the Pratt & Whitney design team. Calculations were performed on the GGO geometry with the mini-shroud. Results of these calculations indicate that the mini-shroud does not significantly affect the flow in the passage region, and although the tip clearance flow is different, the mini-shroud does not seem to prevent the above-mentioned vortical flow behavior. Since both flow distortion

  16. Navier-Stokes analysis of an oxidizer turbine blade with tip clearance with and without a mini-shroud

    NASA Technical Reports Server (NTRS)

    Chan, Tony; Dejong, Frederik J.

    1993-01-01

    The Gas Generator Oxidizer Turbine (GGOT) Blade is being analyzed by various investigators under the NASA MSFC-sponsored Turbine Stage Technology Team design effort. The present work concentrates on the tip clearance region flow and associated losses; however, flow details for the passage region are also obtained in the simulations. The present calculations simulate the rotor blade row in a rotating reference frame with the appropriate coriolis and centrifugal acceleration term included in the momentum equations. The upstream computational boundary is located about one axial chord from the blade leading edge. The boundary conditions at this location have been determined by Pratt & Whitney using an Euler analysis without the vanes to obtain approximately the same flow profiles at the rotor as were obtained with the Euler stage analysis including the vanes. Inflow boundary layer profiles are then constructed assuming the skin friction coefficient at both the hub and the casing. The downstream computational boundary is located about one axial chord from the blade trailing edge, and the circumferentially averaged static pressure at this location was also obtained from the P&W Euler analysis. Results obtained for the 3-D baseline GGOT geometry at the full scale design Reynolds number show a region of high loss in the region near the casing. Particle traces in the near tip region show vortical flow behavior of the fluid which passes through the clearance region and exits at the downstream edge of the gap. In an effort to reduce clearance flow losses, the mini-shroud concept was proposed by the Pratt & Whitney design team. Calculations were performed on the GGO geometry with the mini-shroud. Results of these calculations indicate that the mini-shroud does not significantly affect the flow in the passage region, and although the tip clearance flow is different, the mini-shroud does not seem to prevent the above-mentioned vortical flow behavior. Since both flow distortion

  17. Spectrophotometric probe

    DOEpatents

    Prather, W.S.; O'Rourke, P.E.

    1994-08-02

    A support structure is described bearing at least one probe for making spectrophotometric measurements of a fluid using a source of light and a spectrophotometer. The probe includes a housing with two optical fibers and a planoconvex lens. A sleeve bearing a mirror surrounds the housing. The lens is separated from the mirror by a fixed distance, defining an interior space for receiving a volume of the fluid sample. A plurality of throughholes extending through the sleeve communicate between the sample volume and the exterior of the probe, all but one hole bearing a screen. A protective jacket surrounds the probe. A hollow conduit bearing a tube is formed in the wall of the probe for venting any air in the interior space when fluid enters. The probe is held at an acute angle so the optic fibers carrying the light to and from the probe are not bent severely on emergence from the probe. 3 figs.

  18. Spectrophotometric probe

    DOEpatents

    Prather, William S.; O'Rourke, Patrick E.

    1994-01-01

    A support structure bearing at least one probe for making spectrophotometric measurements of a fluid using a source of light and a spectrophotometer. The probe includes a housing with two optical fibers and a planoconvex lens. A sleeve bearing a mirror surrounds the housing. The lens is separated from the mirror by a fixed distance, defining an interior space for receiving a volume of the fluid sample. A plurality of throughholes extending through the sleeve communicate between the sample volume and the exterior of the probe, all but one hole bearing a screen. A protective jacket surrounds the probe. A hollow conduit bearing a tube is formed in the wall of the probe for venting any air in the interior space when fluid enters. The probe is held at an acute angle so the optic fibers carrying the light to and from the probe are not bent severely on emergence from the probe.

  19. Surface crack problems in plates

    NASA Technical Reports Server (NTRS)

    Joseph, P. F.; Erdogan, F.

    1989-01-01

    The mode I crack problem in plates under membrane loading and bending is reconsidered. The purpose is to examine certain analytical features of the problem further and to provide some new results. The formulation and the results given by the classical and the Reissner plate theories for through and part-through cracks are compared. For surface cracks the three-dimensional finite element solution is used as the basis of comparison. The solution is obtained and results are given for the crack/contact problem in a plate with a through crack under pure bending and for the crack interaction problem. Also, a procedure is developed to treat the problem of subcritical crack growth and to trace the evolution of the propagating crack.

  20. Catalytic cracking process

    DOEpatents

    Lokhandwala, Kaaeid A.; Baker, Richard W.

    2001-01-01

    Processes and apparatus for providing improved catalytic cracking, specifically improved recovery of olefins, LPG or hydrogen from catalytic crackers. The improvement is achieved by passing part of the wet gas stream across membranes selective in favor of light hydrocarbons over hydrogen.

  1. Cracking the Credit Hour

    ERIC Educational Resources Information Center

    Laitinen, Amy

    2012-01-01

    The basic currency of higher education--the credit hour--represents the root of many problems plaguing America's higher education system: the practice of measuring time rather than learning. "Cracking the Credit Hour" traces the history of this time-based unit, from the days of Andrew Carnegie to recent federal efforts to define a credit hour. If…

  2. Crack patterns over uneven substrates.

    PubMed

    Nandakishore, Pawan; Goehring, Lucas

    2016-02-28

    Cracks in thin layers are influenced by what lies beneath them. From buried craters to crocodile skin, crack patterns are found over an enormous range of length scales. Regardless of absolute size, their substrates can dramatically influence how cracks form, guiding them in some cases, or shielding regions from them in others. Here we investigate how a substrate's shape affects the appearance of cracks above it, by preparing mud cracks over sinusoidally varying surfaces. We find that as the thickness of the cracking layer increases, the observed crack patterns change from wavy to ladder-like to isotropic. Two order parameters are introduced to measure the relative alignment of these crack networks, and, along with Fourier methods, are used to characterise the transitions between crack pattern types. Finally, we explain these results with a model, based on the Griffith criteria of fracture, that identifies the conditions for which straight or wavy cracks will be seen, and predicts how well-ordered the cracks will be. Our metrics and results can be applied to any situation where connected networks of cracks are expected, or found. PMID:26762761

  3. Random loading fatigue crack growth: Crack closure considerations

    NASA Technical Reports Server (NTRS)

    Ortiz, Keith

    1987-01-01

    The prediction of fatigue crack growth is an important element of effective fracture control for metallic structures and mechanical components, especially in the aerospace industry. The prediction techniques available and applied today are mostly based on fatigue crack growth measurements determined in constant amplitude testing. However, while many service loadings are constant amplitude, many more loadings are random amplitude. An investigation to determine which statistics of random loadings are relevant to fatigue crack closure was conducted. The fundamentals of random processes and crack closure are briefly reviewed, then the relevance of certain random process parameters to the crack closure calculation are discussed qualitatively. A course for further research is outlined.

  4. Heat-affected zone liquation crack on resistance spot welded TWIP steels

    SciTech Connect

    Saha, Dulal Chandra; Chang, InSung; Park, Yeong-Do

    2014-07-01

    In this study, the heat affected zone (HAZ) liquation crack and segregation behavior of the resistance spot welded twinning induced plasticity (TWIP) steel have been reported. Cracks appeared in the post-welded joints that originated at the partially melted zone (PMZ) and propagated from the PMZ through the heat affected zone (HAZ) to the base metal (BM). The crack length and crack opening widths were observed increasing with heat input; and the welding current was identified to be the most influencing parameter for crack formation. Cracks appeared at the PMZ when nugget diameter reached at 4.50 mm or above; and the liquation cracks were found to occur along two sides of the notch tip in the sheet direction rather than in the electrode direction. Cracks were backfilled with the liquid films which has lamellar structure and supposed to be the eutectic constituent. Co-segregation of alloy elements such as, C and Mn were detected on the liquid films by electron-probe microanalysis (EPMA) line scanning and element map which suggests that the liquid film was enrich of Mn and C. The eutectic constituent was identified by analyzing the calculated phase diagram along with thermal temperature history of finite element simulation. Preliminary experimental results showed that cracks have less/no significant effect on the static cross-tensile strength (CTS) and the tensile-shear strength (TSS). In addition, possible ways to avoid cracking were discussed. - Highlights: • The HAZ liquation crack during resistance spot welding of TWIP steel was examined. • Cracks were completely backfilled and healed with divorced eutectic secondary phase. • Co-segregation of C and Mn was detected in the cracked zone. • Heat input was the most influencing factor to initiate liquation crack. • Cracks have less/no significant effect on static tensile properties.

  5. Cascaded image analysis for dynamic crack detection in material testing

    NASA Astrophysics Data System (ADS)

    Hampel, U.; Maas, H.-G.

    Concrete probes in civil engineering material testing often show fissures or hairline-cracks. These cracks develop dynamically. Starting at a width of a few microns, they usually cannot be detected visually or in an image of a camera imaging the whole probe. Conventional image analysis techniques will detect fissures only if they show a width in the order of one pixel. To be able to detect and measure fissures with a width of a fraction of a pixel at an early stage of their development, a cascaded image analysis approach has been developed, implemented and tested. The basic idea of the approach is to detect discontinuities in dense surface deformation vector fields. These deformation vector fields between consecutive stereo image pairs, which are generated by cross correlation or least squares matching, show a precision in the order of 1/50 pixel. Hairline-cracks can be detected and measured by applying edge detection techniques such as a Sobel operator to the results of the image matching process. Cracks will show up as linear discontinuities in the deformation vector field and can be vectorized by edge chaining. In practical tests of the method, cracks with a width of 1/20 pixel could be detected, and their width could be determined at a precision of 1/50 pixel.

  6. A Comparative Study of Fluid Flow and Mass Transfer in a Trumpet-Shaped Ladle Shroud Using Large Eddy Simulation

    NASA Astrophysics Data System (ADS)

    Zhang, Jiangshan; Li, Jingshe; Yan, Yi; Chen, Zhixin; Yang, Shufeng; Zhao, Jingwei; Jiang, Zhengyi

    2016-02-01

    The advantages of trumpet-shaped ladle shrouds (TLS) have been frequently demonstrated over conventional straight-bore ladle shrouds (CLS) with respect to production efficiency and molten steel quality in continuous casting practices. The present study is to shed some lights on why the TLS are better than the CLS design by examining the fluid dynamics and mass transfer using large eddy simulation. The obtained numerical results were validated with particle imaging velocimetry experiments. Flow velocity, deformation, turbulent energy dissipation, and mixing kinetics of tracer were discussed. The results showed that the entering jet of the CLS flowed straight down into the tundish with a relatively high speed (average at 0.710 to 0.815 m/s) and turbulent kinetic energy. However, the trumpet section of a TLS intensified velocity differences, strain rates, and vortices, and promoted an increase on turbulence dissipation rate in the interior of the ladle shroud. The average speed of the entering jet to the tundish was decreased to 0.270 to 0.410 m/s from the 0.708 m/s of the inlet speed. The entering jet from the TLS swung, twisted and well mixed with surrounding fluid in the tundish, and dissipated its kinetic energy. Consequently, the turbulence of the whole flow field as well as the mean skin friction coefficient of tundish wall and the velocity of free liquid surface were reduced. A tracer experiment was carried out to study mass transfer and flow mixing behavior, and the results demonstrated that the use of the TLS increased the plug volume and decreased the dead zone, thereby enhancing inclusion flotation.

  7. Elevated temperature crack growth

    NASA Technical Reports Server (NTRS)

    Yau, J. F.; Malik, S. N.; Kim, K. S.; Vanstone, R. H.; Laflen, J. H.

    1985-01-01

    The objective of the Elevated Temperature Crack Growth Project is to evaluate proposed nonlinear fracture mechanics methods for application to combustor liners of aircraft gas turbine engines. During the first year of this program, proposed path-independent (P-I) integrals were reviewed for such applications. Several P-I integrals were implemented into a finite-element postprocessor which was developed and verified as part of the work. Alloy 718 was selected as the analog material for use in the forthcoming experimental work. A buttonhead, single-edge notch specimen was designed and verified for use in elevated-temperature strain control testing with significant inelastic strains. A crack mouth opening displacement measurement device was developed for further use.

  8. Statistical crack mechanics

    SciTech Connect

    Dienes, J.K.

    1983-01-01

    An alternative to the use of plasticity theory to characterize the inelastic behavior of solids is to represent the flaws by statistical methods. We have taken such an approach to study fragmentation because it offers a number of advantages. Foremost among these is that, by considering the effects of flaws, it becomes possible to address the underlying physics directly. For example, we have been able to explain why rocks exhibit large strain-rate effects (a consequence of the finite growth rate of cracks), why a spherical explosive imbedded in oil shale produces a cavity with a nearly square section (opening of bedding cracks) and why propellants may detonate following low-speed impact (a consequence of frictional hot spots).

  9. Replica-based Crack Inspection

    NASA Technical Reports Server (NTRS)

    Newman, John A.; Smith, Stephen W.; Piascik, R. S.; Willard, Scott A.; Dawicke, David S.

    2007-01-01

    A surface replica-based crack inspection method has recently been developed for use in Space Shuttle main engine (SSME) hydrogen feedline flowliners. These flowliners exist to ensure favorable flow of liquid hydrogen over gimble joint bellows, and consist of two rings each containing 38 elongated slots. In the summer of 2002, multiple cracks ranging from 0.1 inches to 0.6 inches long were discovered; each orbiter contained at least one cracked flowliner. These long cracks were repaired and eddy current inspections ensured that no cracks longer than 0.075 inches were present. However, subsequent fracture-mechanics review of flight rationale required detection of smaller cracks, and was the driving force for development of higher-resolution inspection method. Acetate tape surface replicas have been used for decades to detect and monitor small cracks. However, acetate tape replicas have primarily been limited to laboratory specimens because complexities involved in making these replicas - requiring acetate tape to be dissolved with acetone - are not well suited for a crack inspection tool. More recently developed silicon-based replicas are better suited for use as a crack detection tool. A commercially available silicon-based replica product has been determined to be acceptable for use in SSME hydrogen feedlines. A method has been developed using this product and a scanning electron microscope for analysis, which can find cracks as small as 0.005 inches and other features (e.g., pits, scratches, tool marks, etc.) as small as 0.001 inches. The resolution of this method has been validated with dozens of cracks generated in a laboratory setting and this method has been used to locate 55 cracks (ranging in size from 0.040 inches to 0.004 inches) on space flight hardware. These cracks were removed by polishing away the cracked material and a second round of replicas confirmed the repair.

  10. Double shroud delivery of silica precursor for reducing hexavalent chromium in welding fume.

    PubMed

    Wang, Jun; Kalivoda, Mark; Guan, Jianying; Theodore, Alexandros; Sharby, Jessica; Wu, Chang-Yu; Paulson, Kathleen; Es-Said, Omar

    2012-01-01

    The welding process yields a high concentration of nanoparticles loaded with hexavalent chromium (Cr(6+)), a known human carcinogen. Previous studies have demonstrated that using tetramethylsilane (TMS) as a shielding gas additive can significantly reduce the Cr(6+) concentration in welding fume particles. In this study, a novel insulated double shroud torch (IDST) was developed to further improve the reduction of airborne Cr(6+) concentration by separating the flows of the primary shielding gas and the TMS carrier gas. Welding fumes were collected from a welding chamber in the laboratory and from a fixed location near the welding arc in a welding facility. The Cr(6+) content was analyzed with ion chromatography and X-ray photoelectron spectroscopy (XPS). Results from the chamber sampling demonstrated that the addition of 3.2 ≈ 5.1% of TMS carrier gas to the primary shielding gas resulted in more than a 90% reduction of airborne Cr(6+) under all shielding gas flow rates. The XPS result confirmed complete elimination of Cr(6+) inside the amorphous silica shell. Adding 100 ≈ 1000 ppm of nitric oxide or carbon monoxide to the shielding gas could also reduce Cr(6+) concentrations up to 57% and 35%, respectively; however, these reducing agents created potential hazards from the release of unreacted agents. Results of the field test showed that the addition of 1.6% of TMS carrier gas to the primary shielding gas reduced Cr(6+) concentration to the limitation of detection (1.1 μg/m(3)). In a worst-case scenario, if TMS vapor leaked into the environment without decomposition and ventilation, the estimated TMS concentration in the condition of field sampling would be a maximum 5.7 ppm, still well below its flammability limit (1%). Based on a previously developed cost model, the use of TMS increases the general cost by 3.8%. No visual deterioration of weld quality caused by TMS was found, although further mechanical testing is necessary. PMID:23113576