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At least 361 records · Page 20

Hydrogen no-vent fill testing in a 34 liter (1.2 cubic foot) tank

Experimental results of no-vent fill testing with liquid hydrogen in a 34 liter stainless steel tank are presented. More than 40 tests were performed with various liquid inlet temperatures, inlet flowrates, initial tank wall temperatures, and liquid injection techniques. Maximum pressure within the receiver tank was limited to 0.207 MPa (30 psia), and fill levels equal to or exceeding 90 percent by volume were achieved in 40 percent of the tests. Three liquid injection techniques were employed; top spray, upward pipe discharge, and bottom diffuser. Effects of each of the various parameters on the tank pressure history and final fill level are evaluated. The final fill level is found to be indirectly proportional to the initial wall and inlet liquid temperatures and directly proportional to the inlet liquid flowrate. Furthermore, the top spray is the most efficient no-vent fill method of the three configurations examined. The success of this injection method is primarily due to condensation of the ullage vapor onto the incoming liquid droplets. Ullage condensation counteracts the tank pressure rise resulting from energy exchange between the fluid and the warmer tank walls and from ullage compression.

Moran, Matthew E.↗

Ground testing for the no-vent fill of cryogenic tanks - Results of tests for a 71 cubic foot tank

NASA Lewis Research has been investigating the no-vent till method, since it is a promising approach to transfer liquid while handling the problems of low-g venting. This paper reports the results of a test series for filling a 71 cu ft tank with liquid hydrogen without venting. Twenty two tests were conducted, ten with a bottom orifice as the inlet and 12 with a spray bar. Parameters investigated included inlet saturation pressures of approximately 5, 15, and 25 psia; transfer pressures of 20, 30, and 45 psia; and various starting wall temperatures. Of the tests, only the one run at the highest wall temperature (238 R) failed to fill the tank. Test results are compared to a thermodynamic equilibrium model. Overall model-data agreement was good except for the tendency of the model to overshoot during the initial wall cool-down of the higher starting wall temperature fills.

Chato, David J.↗

Correlation of cylinder-head temperatures and coolant heat rejections of a multicylinder, liquid-cooled engine of 1710-cubic-inch displacement

Data obtained from an extensive investigation of the cooling characteristics of four multicylinder, liquid-cooled engines have been analyzed and a correlation of both the cylinder-head temperatures and the coolant heat rejections with the primary engine and coolant variables was obtained. The method of correlation was previously developed by the NACA from an analysis of the cooling processes involved in a liquid-cooled-engine cylinder and is based on the theory of nonboiling, forced-convection heat transfer. The data correlated included engine power outputs from 275 to 1860 brake horsepower; coolant flows from 50 to 320 gallons per minute; coolants varying in composition from 100 percent water to 97 percent ethylene glycol and 3 percent water; and ranges of engine speed, manifold pressure, carburetor-air temperature, fuel-air ratio, exhaust-gas pressure, ignition timing, and coolant temperature. The effect on engine cooling of scale formation on the coolant passages of the engine and of boiling of the coolant under various operating conditions is also discussed.

Lundin, Bruce T↗

Ground testing for the no-vent fill of cryogenic tanks: Results of tests for a 71 cubic foot tank

NASA Lewis Research has been investigating the no-vent fill method, since it is a promising approach to transfer liquid while handling the problems of low-g venting. This paper reports the results of a test series for filling a 71 cu ft tank with liquid hydrogen without venting. 22 tests were conducted, 10 with a bottom orifice as the inlet and 12 with a spray bar. Parameters investigated included inlet saturation pressures of approximately 5, 15, and 25 psia, transfer pressures of 20, 30, and 45 psia, and various starting wall temperatures. Of the tests, only the one run at the highest wall temperature (238 R) failed to fill the tank. Test results are compared to a thermodynamic equilibrium model. Overall model-data agreement was good except for the tendency of the model to overshoot during the initial wall cool down of the higher starting wall temperature fills.

Chato, David J.↗

Achieving high data reduction with integral cubic B-splines

During geometry processing, tangent directions at the data points are frequently readily available from the computation process that generates the points. It is desirable to utilize this information to improve the accuracy of curve fitting and to improve data reduction. This paper presents a curve fitting method which utilizes both position and tangent direction data. This method produces G(exp 1) non-rational B-spline curves. From the examples, the method demonstrates very good data reduction rates while maintaining high accuracy in both position and tangent direction.

Chou, Jin J.↗

Analysis of the Erosion of Cubic Centered and Face Centered Metallic Materials [Analyse de L'erosion de Matereaux Metalliques de Structures Cubiques Centree et Face Centree]

A generalized law of erosion, in nondimensional form, is proposed. The aforementioned explicitly gives an account of the nature and the microstructure of the material impacted, the angle of impact of the particles, and their hardness. The erosion behavior of various steels, pig iron, and cast iron is examined as well as the behavior of new ordered intermetallic materials, Fe-25% Al-(Zr, Cr, B). The concern of such alloys in an erosion-corrosion environment is shown. --- Une loi généralisée d'usure par érosion, sous forme non dimensionnelle, est proposée. Celle-ci rend compte explicitement de la nature et de la microstructure du matériau impacté, de l'angle d'impact des particules, de leur acuité at de leur durete. Le comportement à l'érosion de divers aciers et fontes est examiné ainsi que la tenue de nouveaux matériaux intermétalliques ordonnés Fe-25% Al - (Zr, Cr, B). L'interet de tels alliages dans des environnements agressifs du type érosion-corrosion est montré. Mots clés: usure, érosion, modèle, matériaux métalliques, intermétalliques Fe-Al.

A Magnée↗

Reproducible Growth of High-Quality Cubic-SiC Layers

Semiconductor electronic devices and circuits based on silicon carbide (SiC) are being developed for use in high-temperature, high-power, and/or high-radiation conditions under which devices made from conventional semiconductors cannot adequately perform. The ability of SiC-based devices to function under such extreme conditions is expected to enable significant improvements in a variety of applications and systems. These include greatly improved high-voltage switching for saving energy in public electric power distribution and electric motor drives; more powerful microwave electronic circuits for radar and communications; and sensors and controls for cleaner-burning, more fuel-efficient jet aircraft and automobile engines.

Neudeck, Philip G.↗

Materials Data on Y2Zr24O51 by Materials Project

Y2Zr24O51 crystallizes in the orthorhombic Pmm2 space group. The structure is three-dimensional. there are two inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Y–O bond distances ranging from 2.16–2.42 Å. In the second Y3+ site, Y3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are two shorter (2.09 Å) and four longer (2.37 Å) Y–O bond lengths. There are twenty-four inequivalent Zr4+ sites. In the first Zr4+ site, Zr4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Zr–O bond distances ranging from 2.17–2.33 Å. In the second Zr4+ site, Zr4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Zr–O bond distances ranging from 2.11–2.42 Å. In the third Zr4+ site, Zr4+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are four shorter (2.10 Å) and four longer (2.44 Å) Zr–O bond lengths. In the fourth Zr4+ site, Zr4+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Zr–O bond distances ranging from 2.09–2.46 Å. In the fifth Zr4+ site, Zr4+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Zr–O bond distances ranging from 2.09–2.46 Å. In the sixth Zr4+ site, Zr4+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are four shorter (2.09 Å) and four longer (2.45 Å) Zr–O bond lengths. In the seventh Zr4+ site, Zr4+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Zr–O bond distances ranging from 2.09–2.45 Å. In the eighth Zr4+ site, Zr4+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Zr–O bond distances ranging from 2.09–2.45 Å. In the ninth Zr4+ site, Zr4+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Zr–O bond distances ranging from 2.09–2.45 Å. In the tenth Zr4+ site, Zr4+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Zr–O bond distances ranging from 2.09–2.45 Å. In the eleventh Zr4+ site, Zr4+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Zr–O bond distances ranging from 2.10–2.45 Å. In the twelfth Zr4+ site, Zr4+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Zr–O bond distances ranging from 2.10–2.43 Å. In the thirteenth Zr4+ site, Zr4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Zr–O bond distances ranging from 2.20–2.27 Å. In the fourteenth Zr4+ site, Zr4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Zr–O bond distances ranging from 2.13–2.39 Å. In the fifteenth Zr4+ site, Zr4+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Zr–O bond distances ranging from 2.10–2.44 Å. In the sixteenth Zr4+ site, Zr4+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Zr–O bond distances ranging from 2.09–2.45 Å. In the seventeenth Zr4+ site, Zr4+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Zr–O bond distances ranging from 2.09–2.45 Å. In the eighteenth Zr4+ site, Zr4+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Zr–O bond distances ranging from 2.09–2.45 Å. In the nineteenth Zr4+ site, Zr4+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Zr–O bond distances ranging from 2.09–2.45 Å. In the twentieth Zr4+ site, Zr4+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Zr–O bond distances ranging from 2.09–2.45 Å. In the twenty-first Zr4+ site, Zr4+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Zr–O bond distances ranging from 2.09–2.45 Å. In the twenty-second Zr4+ site, Zr4+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Zr–O bond distances ranging from 2.09–2.44 Å. In the twenty-third Zr4+ site, Zr4+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Zr–O bond distances ranging from 2.09–2.44 Å. In the twenty-fourth Zr4+ site, Zr4+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Zr–O bond distances ranging from 2.10–2.43 Å. There are fifty-one inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Y3+ and two equivalent Zr4+ atoms to form OY2Zr2 tetrahedra that share corners with fourteen OZr4 tetrahedra and edges with five OY2Zr2 tetrahedra. In the second O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of corner and edge-sharing OZr4 tetrahedra. In the third O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of corner and edge-sharing OZr4 tetrahedra. In the fourth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the fifth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the sixth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the seventh O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the eighth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the ninth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the tenth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the eleventh O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the twelfth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the thirteenth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the fourteenth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the fifteenth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the sixteenth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the seventeenth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the eighteenth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the nineteenth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the twentieth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the twenty-first O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the twenty-second O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the twenty-third O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the twenty-fourth O2- site, O2- is bonded to four Zr4+ atoms to form distorted OZr4 tetrahedra that share corners with sixteen OY2Zr2 tetrahedra and edges with six OZr4 tetrahedra. In the twenty-fifth O2- site, O2- is bonded to two equivalent Y3+ and two equivalent Zr4+ atoms to form distorted OY2Zr2 tetrahedra that share corners with fourteen OZr4 tetrahedra and edges with five OY2Zr2 tetrahedra. In the twenty-sixth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of corner and edge-sharing OZr4 tetrahedra. In the twenty-seventh O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the twenty-eighth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the twenty-ninth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the thirtieth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the thirty-first O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the thirty-second O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the thirty-third O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the thirty-fourth O2- site, O2- is bonded to four Zr4+ atoms to form OZr4 tetrahedra that share corners with sixteen OY2Zr2 tetrahedra and edges with six OZr4 tetrahedra. In the thirty-fifth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the thirty-sixth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the thirty-seventh O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the thirty-eighth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the thirty-ninth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the fortieth O2- site, O2- is bonded to two equivalent Y3+ and two equivalent Zr4+ atoms to form a mixture of distorted corner and edge-sharing OY2Zr2 tetrahedra. In the forty-first O2- site, O2- is bonded to two equivalent Y3+ and two equivalent Zr4+ atoms to form OY2Zr2 tetrahedra that share corners with twelve OZr4 tetrahedra and edges with six OY4 tetrahedra. In the forty-second O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the forty-third O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the forty-fourth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the forty-fifth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the forty-sixth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the forty-seventh O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the forty-eighth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the forty-ninth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra. In the fiftieth O2- site, O2- is bonded to four Y3+ atoms to form a mixture of corner and edge-sharing OY4 tetrahedra. In the fifty-first O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted corner and edge-sharing OZr4 tetrahedra.

36 MATERIALS SCIENCE↗