Scaling studies and conceptual experiment designs for NGNP CFD assessment

The objective of this report is to document scaling studies and conceptual designs for flow and heat transfer experiments intended to assess CFD codes and their turbulence models proposed for application to prismatic NGNP concepts. The general approach of the project is to develop new benchmark experiments for assessment in parallel with CFD and coupled CFD/systems code calculations for the same geometry. Two aspects of the complex flow in an NGNP are being addressed: (1) flow and thermal mixing in the lower plenum ("hot streaking" issue) and (2) turbulence and resulting temperature distributions in reactor cooling channels ("hot channel" issue). Current prismatic NGNP concepts are being examined to identify their proposed flow conditions and geometries over the range from normal operation to decay heat removal in a pressurized cooldown. Approximate analyses have been applied to determine key non-dimensional parameters and their magnitudes over this operating range. For normal operation, the flow in the coolant channels can be considered to be dominant turbulent forced convection with slight transverse property variation. In a pressurized cooldown (LOFA) simulation, the flow quickly becomes laminar with some possible buoyancy influences. The flow in the lower plenum can locally be considered to be a situation of multiple hot jets into a confined crossflow -- with obstructions. Flow is expected to be turbulent with momentumdominated turbulent jets entering; buoyancy influences are estimated to be negligible in normal full power operation. Experiments are needed for the combined features of the lower plenum flows. Missing from the typical jet experiments available are interactions with nearby circular posts and with vertical posts in the vicinity of vertical walls - with near stagnant surroundings at one extreme and significant crossflow at the other. Two types of heat transfer experiments are being considered. One addresses the "hot channel" problem, if necessary. The second type will treat heated jets entering a model plenum. Unheated MIR (Matched-Index-of-Refraction) experiments are first steps when the geometry is complicated. One does not want to use a computational technique which will not even handle constant properties properly. The purpose of the fluid dynamics experiments is to develop benchmark databases for the assessment of CFD solutions of the momentum equations, scalar mixing and turbulence models for typical NGNP plenum geometries in the limiting case of negligible buoyancy and constant fluid properties. As indicated by the scaling studies, in normal full power operation of a typical NGNP conceptual design, buoyancy influences should be negligible in the lower plenum. The MIR experiment will simulate flow features of the paths of jets as they mix in flowing through the array of posts in a lower plenum en route to the single exit duct. Conceptual designs for such experiments are described

Initial Scaling Studies and Conceptual Thermal Fluids Experiments for the Prismatic NGNP Point Design

The objective of this report is to document the initial high temperature gas reactor scaling studies and conceptual experiment design for gas flow and heat transfer. The general approach of the project is to develop new benchmark experiments for assessment in parallel with CFD and coupled CFD/ATHENA/RELAP5-3D calculations for the same geometry. Two aspects of the complex flow in an NGNP are being addressed: (1) flow and thermal mixing in the lower plenum ("hot streaking" issue) and (2) turbulence and resulting temperature distributions in reactor cooling channels ("hot channel" issue). Current prismatic NGNP concepts are being examined to identify their proposed flow conditions and geometries over the range from normal operation to decay heat removal in a pressurized cooldown. Approximate analyses are being applied to determine key non-dimensional parameters and their magnitudes over this operating range. For normal operation, the flow in the coolant channels can be considered to be dominant forced convection with slight transverse property variation. The flow in the lower plenum can locally be considered to be a situation of multiple buoyant jets into a confined density-stratified crossflow -- with obstructions. Experiments are needed for the combined features of the lower plenum flows. Missing from the typical jet experiments are interactions with nearby circular posts and with vertical posts in the vicinity of vertical walls - with near stagnant surroundings at one extreme and significant crossflow at the other. Two heat transfer experiments are being considered. One addresses the "hot channel" problem, if necessary. The second experiment will treat heated jets entering a model plenum. Unheated MIR (Matched-Index-of-Refraction) experiments are first steps when the geometry is complicated. One does not want to use a computational technique which will not even handle constant properties properly. The MIR experiment will simulate flow features of the paths of jets as they mix in flowing through the array of posts in a lower plenum en route to the single exit duct. Initial conceptual designs for such experiments are described

Variability of postnatal ossification timing and evidence for a “dosage” effect

Although absolute variability in postnatal ossification timing is generally larger in boys than in girls, relative, conception-corrected variability is significantly larger in girls, suggestive of a “dosage” effect and consistent with the hypothesis of partial X-linkage. These findings, together with the excess of sister-sister over brother-brother timing similarities are inconsistent with the hypothesis of selective inactivation of either the paternal or the maternal X chromosome.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37498/1/1330320116_ftp.pd

Effects of Chromate and Chromate Conversion Coatings on Corrosion of Aluminum Alloy 2024-T3

Various effects of chromate conversion coatings (CCCs) and chromate in solution on the corrosion of AA2024-T3 and pure Al are studied in this work. Raman spectroscopy was used to investigate the nature of chromate in CCCs through a comparison with the spectra of known standards and artificial Cr(III)/Cr(VI) mixed oxides. Chromate was shown to be released from CCCs and to migrate to and protect a nearby, uncoated area in the artificial scratch cell. However, experiments investigating the effect of chromate in solution on anodic dissolution kinetics under potentiostatic control indicated that large chromate concentrations were needed to have an effect.This work was supported by Major H. DeLong at the United States Air Force Office of Scientific Research under contracts F49620-96-1-0479 and F49620-96-0042

Metal-polymer functionally graded materials for removing guided wave reflections at beam end boundaries

This paper investigates the potential of a metal-polymer functionally graded material (FGM) to remove beam end boundary wave reflections that produce complicated interference patterns in the response signals used for guided wave damage identification methodologies. The metal-polymer FGM matches the material properties to a metal beam for total wave transmission on one side and is continuously graded to a viscoelastic polymer on the other side. An Aluminium-Polycarbonate (Al-PC) FGM was fabricated and characterised using microscopy, hardness testing and through-transmission ultrasonics to verify the continuous gradient. Measurements of guided waves on an aluminium beam attached to the FGM on one end show reduction in boundary wave reflections that varies with wave frequency. A damaged aluminium beam attached with the FGM produced promising improvements in a damage identification system

Key Thermal Fluid Phenomena In Prismatic Gas-Cooled Reactors

Several types of gas-cooled nuclear reactors have been suggested as part of the international Generation IV initiative with the proposed NGNP (Next Generation Nuclear Plant) as one of the main concepts [MacDonald et al., 2003]. Meaningful studies for these designs will require accurate, reliable predictions of material temperatures to evaluate the material capabilities; these temperatures depend on the thermal convection in the core and in other important components. Some of these reactors feature complex geometries and wide ranges of temperatures, leading to significant variations of the gas thermodynamic and transport properties plus possible effects of buoyancy during normal and reduced power operations and loss-of-flow (LOFA) and loss-of-coolant scenarios. Potential issues identified to date include ''hot streaking'' in the lower plenum evolving from ''hot channels'' in prismatic cores. In order to predict thermal hydraulic behavior of proposed designs effectively and efficiently, it is useful to identify the dominant phenomena occurring

Relationship of skinfolds and muscle size to growth of children. I. Costa Rica

The relationships between triceps skinfolds and stature and between upper arm muscle size and stature were studied on 874 pairs matched for age derived from a cross-sectional sample of 2,445 Costa Rican rural subjects, aged 0 to 20 years. The results indicate that fatter children for their age, on the average, are not taller than their leaner counterparts. On the other hand, more muscular children, on the average, are taller than their less muscular counterparts of the same age.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37511/1/1330350110_ftp.pd

Raman Optical Activity Using Twisted Photons

Raman optical activity underpins a powerful vibrational spectroscopic technique for obtaining detailed structural information about chiral molecular species. The effect centers on the discriminatory interplay between the handedness of material chirality with that of circularly polarized light. Twisted light possessing an optical orbital angular momentum carries helical phase fronts that screw either clockwise or anticlockwise and, thus, possess a handedness that is completely distinct from the polarization. Here a novel form of Raman optical activity that is sensitive to the handedness of the incident twisted photons through a spin-orbit interaction of light is identified, representing a new chiroptical spectroscopic technique

Mid-ocean microseisms

Author Posting. © American Geophysical Union, 2005. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 6 (2005): Q04009, doi:10.1029/2004GC000768.The Hawaii-2 Observatory (H2O) is an excellent site for studying the source regions and propagation of microseisms since it is located far from shorelines and shallow water. During Leg 200 of the Ocean Drilling Program, the officers of the JOIDES Resolution took wind and wave measurements for comparison with double-frequency (DF) microseism data collected at nearby H2O. The DF microseism band can be divided into short period and long period bands, SPDF and LPDF, respectively. Comparison of the ship’s weather log with the seismic data in the SPDF band from about 0.20 to 0.45 Hz shows a strong correlation of seismic amplitude with wind speed and direction, implying that the energy reaching the ocean floor is generated locally by ocean gravity waves. Near-shore land seismic stations see similar SPDF spectra, also generated locally by wind seas. At H2O, SPDF microseism amplitudes lag sustained changes in wind speed and direction by several hours, with the lag increasing with wave period. This lag may be associated with the time necessary for the development of opposing seas for DF microseism generation. Correlation of swell height above H2O with the LPDF band from 0.085 to 0.20 Hz is often poor, implying that a significant portion of this energy originates at distant locations. Correlation of the H2O seismic data with NOAA buoy data, with hindcast wave height data from the North Pacific, and with seismic data from mainland and island stations, defines likely source areas of the LPDF signals. Most of the LPDF energy at H2O appears to be generated by high amplitude storm waves impacting long stretches of coastline nearly simultaneously, and the Hawaiian Islands appear to be a significant source of LPDF energy in the North Pacific when waves arrive from particular directions. The highest DF levels observed at mid-ocean site H2O occur in the SPDF band when two coincident nearby storm systems develop. Mid-ocean generated DF microseisms are not observed at interior continental sites, indicating high attenuation of these signals. At near-coastal seismic stations, both SPDF and LPDF microseism levels are generally dominated by local generation at nearby shorelines.This work was supported by the U.S. Science Support Program (User Reference: 418920-BA372; Task Order F001602) associated with the Ocean Drilling Program and is sponsored by the National Science Foundation and the Joint Oceanographic Institutions, Inc. Additional support was provided by the California Energy Commission and the California Department of Boating and Waterways as part of their program to improve boating facilities, access, safety, and education. Support for Ralph Stephen was also provided by the National Science Foundation under Grant #OCE-0424633