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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Brillouin Asymmetric Spatial Heterodyne Oceanographic Lidar Receiver for Profiling Temperature, Salinity, and Sound Velocity

No sensor today is capable of remotely sensing temperature and salinity at depth in oceanic waters, yet the physics to do so exists. Blue-green light (450-550 nm) can penetrate 10’s of meters into the water and interacts with water by the Brillouin scatter process. Temperature and salinity can be determined by analyzing the spectrum of Brillouin scatter. A host of scientific and operational drivers exist for such a sensor, from improved hurricane and red tide forecasting to studies of ocean fronts, eddies, and freshwater lenses. A low flying airborne light detection and ranging (lidar) instrument concept that exploits this physics is presented, along with simulation tools that potential data users can use to model its measurement performance, determine suitability for their application, and assess its implications.

John Anthony Smith↗
NASA NTRS1983

Remote measurements of ozone, water vapor and liquid water content, and vertical profiles of temperature in the lower troposphere

Several advanced atmospheric remote sensing systems developed at the Jet Propulsion Laboratory were demonstrated under various field conditions to determine how useful they would be for general use by the California Air Resources Board and local air quality districts. One of the instruments reported on is the Laser Absorption Spectrometer (LAS). It has a pair of carbon dioxide lasers with a transmitter and receiver and can be flown in an aircraft to measure the column abundance of such gases as ozone. From an aircraft, it can be used to rapidly survey a large region. The LAS is usually operated from an aircraft, although it can also be used at a fixed location on the ground. Some tests were performed with the LAS to measure ozone over a 2-km horizontal path. Another system reported on is the Microwave Atmospheric Remote Sensing System (MARS). It is tuned to microwave emissions from water vapor, liquid water, and oxygen molecules (for atmospheric temperature). It can measure water vapor and liquid water in the line-of-sight, and can measure the vertical temperature profile.

Grant, W. B.↗
NASA NTRS1986

Self-adaptive difference method for the effective solution of computationally complex problems of boundary layer theory

An implicit difference procedure for the solution of equations for a chemically reacting hypersonic boundary layer is described. Difference forms of arbitrary error order in the x and y coordinate plane were used to derive estimates for discretization error. Computational complexity and time were minimized by the use of this difference method and the iteration of the nonlinear boundary layer equations was regulated by discretization error. Velocity and temperature profiles are presented for Mach 20.14 and Mach 18.5; variables are velocity profiles, temperature profiles, mass flow factor, Stanton number, and friction drag coefficient; three figures include numeric data.

Schoenauer, W.↗
DOE OSTI2015

Simulating field conditions for the curing of salt-stone - 15501

salt-stone is a cementitious, low-level waste (LLW) material processed and stored at the Savannah River Site (SRS). It consists of fly ash (FA), blast furnace slag (BFS), and Portland cement that are blended with LLW salt solution. The dry feed materials and the salt solution are mixed at the salt-stone Production Facility (SPF), and the fresh grout subsequently pumped into a salt-stone Disposal Unit (SDU) in the salt-stone Disposal Facility (SDF) where it cures to form a rigid, cementitious monolith. In order to demonstrate the long-term performance of salt-stone, non-radioactive simulant samples are processed and cured in a laboratory environment and subsequently tested with respect to key performance properties. Of particular relevance to assessing the long-term stabilization and immobilization of radionuclides in salt-stone is the permeability, or saturated hydraulic conductivity, which determines the rate of infiltration for oxygen-bearing ground waters that can affect redox sensitive contaminants, such as {sup 99}Tc. Environmental conditions in the SDU, in particular temperature and humidity, are believed to affect the cured properties of salt-stone. With respect to humidity it has been determined that the average vapor space humidity in an SDU is at least 95%, and in addition the assumption can be made that underlying grout is subjected to a moisture-saturated environment by the grout poured over it. With respect to temperature, the SDUs contain thermo-well arrays that provide detailed vertical, and to a lesser degree radial, temperature profiles. Temperature data from the SDUs have subsequently been utilized to better simulate curing temperatures for simulant salt-stone in the laboratory. However, no two thermal profiles are the same, varying with respect to the following parameters: initial temperature, rate of temperature increase, maximum temperature attained, time at maximum temperature, and cooling rate. These temperature variables are dependent on the depth of grout (due to insulating effects of underlying and overlying grout), frequency of grout addition to the SDU (with more frequent additions causing grout temperatures to rise due to the exothermic hydration reactions), and, to a lesser degree, the ambient temperature of the external environment. Due to the variability in each thermal profile recorded in an SDU, the question arises as to which profile (or profiles) should be used in the simulated laboratory environment to best mimic the curing of field emplaced salt-stone, such that there is confidence that the properties measured for laboratory-prepared samples are representative of the grout in the SDU. Since the current SDU design contains sixty-six thermo-wells it is obviously not practical to process simulant samples according to each profile. Rather the aim would be to choose a reduced number of profiles that adequately encompass the range of recorded profiles, or to choose a single profile that is considered most conservative with respect to the resulting properties of interest. This is typically thought to be the profile exhibiting the highest peak temperature since for cement-based materials higher curing temperatures (> 60 deg. C), while resulting in enhanced reaction kinetics and strength development for short curing durations (∼28 days), have been shown to adversely affect the physical properties of the material after extended cure times. In choosing representative profiles it is important to consider not only the maximum temperature, but also the influence of rate of temperature rise to the maximum temperature, and time at or close to the maximum temperature on the post-cured properties. The intent of this paper is to consider the varied curing temperature profiles to which the salt-stone is exposed in an SDU, and to analyze the currently available data for elevated temperature curing of salt-stone to determine the potential thermal effects on the saturated hydraulic conductivity of salt-stone emplaced in an SDU. This may subsequently facilitate a more informed approach to simulating the curing of salt-stone in a laboratory environment. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗