Entry Systems Panel deliberations

The Entry Systems Panel was chaired by Don Rummler, LaRC and Dan Rasky, ARC. As requested, each panel participant prior to the workshop prepared and delivered presentations to: (1) identify technology needs; (2) assess current programs; (3) identify technology gaps; and (4) identify highest payoff areas R&D. Participants presented background on the entry systems R&D efforts and operations experiences for the Space Shuttle Orbiter. These participants represented NASA Centers involved in research (Ames Research Center), development (Johnson Space Center) and operations (Kennedy Space Center) and the Shuttle Orbiter prime contractor. The presentations lead to the discovery of several lessons learned

Entry Systems Panel

As general findings, lessons learned from shuttle are: (1) bridge established between development center (JSC) Research Centers (ARC, LARC), and industry (RI, LMSC, Corning, Mansville, 3M LTV, Union Carbide, Hexcel) for shuttle TPS; (2) not all test results adequately analyzed or in hindsight, completely encompassing all failure modes; (3) gap heating effects from ground facilities not totally indicative of flight experience; (4) need to design with operations in mind (not just to cost) example: moisture intrusion of GR/EP, many other examples; (5) RSI- developed as point design for maneuvering entry vehicle of high L/D; and (6) RSI - 15 years from invention to use on flight hardware

Thermal and Electromagnetic Stator Vent Design Optimisation for Synchronous Generators

© 2020 Institute of Electrical and Electronics Engineers Inc.. All rights reserved. This paper deals with the stator cooling of an air-cooled, synchronous generator with a power rating of 400 kVA, which has been improved by adding two radial vents to the stator. To ensure an optimal vent design, a novel combined thermal and electromagnetic modelling approach is developed. A parametric 3D Conjugate Heat Transfer Computational Fluid Dynamics (CFD) model is used for the thermal modelling. An electromagnetic 2D Finite Element Analysis determined the impact that venting the stator has on the loss distribution. The models are coupled by deriving analytical correlations between the combined vent width and rotor copper, rotor iron and stator iron losses. These correlations are implemented into the optimisation procedure of the parametric CFD model. Five design parameters are optimised simultaneously with the aim of minimising the peak stator winding temperature. The modelling approach was validated experimentally by thermal, torque and mass flow measurements on the benchmark machine, as well as the newly designed prototype

Two-pion correlations in Au+Au collisions at 10.8 GeV/c per nucleon

Two-particle correlation functions for positive and negative pions have been measured in Au+Au collisions at 10.8~GeV/c per nucleon. The data were analyzed using one- and three-dimensional correlation functions. From the results of the three-dimensional fit the phase space density of pions was calculated. It is consistent with local thermal equilibrium.Comment: 5 pages RevTeX (including 3 Figures

Proton and Pion Production in Au+Au Collisions at 10.8A GeV/c

We present proton and pion tranverse momentum spectra and rapidity distributions for Au+Au collisions at 10.8A GeV/c. The proton spectra exhibit collective transverse flow effects. Evidence of the influence of the Coulomb interaction from the fireball is found in the pion transverse momentum spectra. The data are compared with the predictions of the RQMD event generator.Comment: plain tex (revtex), 24 pages Submitted to Phys. Rev.

Proton and Pion Production Relative to the Reaction Plane in Au + Au Collisions at AGS Energies

Results are presented of an analysis of proton and charged pion azimuthal distributions measured with respect to the reaction plane in Au + Au collisions at a beam momentum of about 11 AGeV/c. The azimuthal anisotropy is studied as a function of particle rapidity and transverse momentum for different centralities of the collisions. The triple differential (in rapidity, transverse momentum, and azimuthal angle) distributions are reconstructed. A comparison of the results with a previous analysis of charged particle and transverse energy flow as well as with model predictions is presented.Comment: 23 pages (LaTeX), 12 figure

Two-Proton Correlations from 14.6A GeV/c Si+Pb and 11.5A GeV/c Au+Au Central Collisions

Two-proton correlation functions have been measured in Si+Pb collisions at 14.6A GeV/c and Au+Au collisions at 11.5A GeV/c by the E814/E877 collaboration. Data are compared with predictions of the transport model RQMD and the source size is inferred from this comparison. Our analysis shows that, for both reactions, the characteristic size of the system at freeze-out exceeds the size of the projectile, suggesting that the fireball created in the collision has expanded. For Au+Au reactions, the observed centrality dependence of the two-proton correlation function implies that more central collisions lead to a larger source sizes.Comment: RevTex, 12 pages, 5 figure

Directed flow of antiprotons in Au+Au collisions at AGS

Directed flow of antiprotons is studied in Au+Au collisions at a beam momentum of 11.5A GeV/c. It is shown that antiproton directed flow is anti-correlated to proton flow. The measured transverse momentum dependence of the antiproton flow is compared with predictions of the RQMD event generator.Comment: 16 pages, 6 figure

Hadron yields and spectra in Au+Au collisions at the AGS

Inclusive double differential multiplicities and rapidity density distributions of hadrons are presented for 10.8 A GeV/c Au+Au collisions as measured at the AGS by the E877 collaboration. The results indicate that large amounts of stopping and collective transverse flow effects are present. The data are also compared to the results from the lighter Si+Al system.Comment: 12 pages, latex, 10 figures, submitted to Nuclear Physics A (Quark Matter 1996 Proceedings

The role of salinity in the decadal variability of the North Atlantic meridional overturning circulation

Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Climate Dynamics 33 (2009): 777-793, doi:10.1007/s00382-008-0523-2.An OGCM hindcast is used to investigate the linkages between North Atlantic Ocean salinity and circulation changes during 1963–2003. The focus is on the eastern subpolar region consisting of the Irminger Sea and the eastern North Atlantic where a careful assessment shows that the simulated interannual to decadal salinity changes in the upper 1500 m reproduce well those derived from the available record of hydrographic measurements. In the model, the variability of the Atlantic meridional overturning circulation (MOC) is primarily driven by changes in deep water formation taking place in the Irminger Sea and, to a lesser extent, the Labrador Sea. Both are strongly influenced by the North Atlantic Oscillation (NAO). The modeled interannual to decadal salinity changes in the subpolar basins are mostly controlled by circulation-driven anomalies of freshwater flux convergence, although surface salinity restoring to climatology and other boundary fluxes each account for approximately 25% of the variance. The NAO plays an important role: a positive NAO phase is associated with increased precipitation, reduced northward salt transport by the wind-driven intergyre gyre, and increased southward flows of freshwater across the Greenland-Scotland ridge. Since the NAO largely controlled deep convection in the subpolar gyre, fresher waters are found near the sinking region during convective events. This markedly differs from the active influence on the MOC that salinity exerts at decadal and longer timescales in most coupled models. The intensification of the MOC that follows a positive NAO phase by about 2 years does not lead to an increase in the northward salt transport into the subpolar domain at low frequencies because it is cancelled by the concomitant intensification of the subpolar gyre which shifts the subpolar front eastward and reduces the northward salt transport by the North Atlantic Current waters. This differs again from most coupled models, where the gyre intensification precedes that of the MOC by several years.Support from NSF Grant 82677800 with the Woods Hole Oceanographic Institution, and (to CF) from the Institut universitaire de France and European FP6 project DYNAMITE (contract 003903-GOCE) and (to JD) from the NOAA Office of Hydrologic Development through a scientific appointment administered by UCAR is gratefully acknowledged