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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Active control of asymmetric vortical flows around cones using injection and heating

The effectiveness of certain active-control methods for asymmetric flows around circular cones is investigated by using computational solution of the unsteady, compressible full Navier-Stokes equations. Two main methods of active control which include flow injection and surface heating are used. For the flow-injection-control method, flow injection is used either in the normal direction to the surface or in the tangential direction to the surface. For the surface-heating-control method, the temperature of the cone surface is increased. The effectiveness of a hybrid method of flow control which combines normal injection with surface heating has also been studied. The Navier-Stokes equations, subjected to various surface boundary conditions, are solved by using an implicit, upwind, flux-difference splitting, finite-volume scheme for locally-conical flow solutions.

Kandil, Osama A.↗
DOE OSTI2016

Axisymmetric flows from fluid injection into a confined porous medium

In this work, we study the axisymmetric flows generated from fluid injection into a horizontal confined porous medium that is originally saturated with another fluid of different density and viscosity. Neglecting the effects of surface tension and fluid mixing, we use the lubrication approximation to obtain a nonlinear advection-diffusion equation that describes the time evolution of the sharp fluid-fluid interface. The flow behaviors are controlled by two dimensionless groups: M , the viscosity ratio of displaced fluid relative to injected fluid, and Γ , which measures the relative importance of buoyancy and fluid injection. For this axisymmetric geometry, the similarity solution involving R 2 /T (where R is the dimensionless radial coordinate and T is the dimensionless time) is an exact solution to the nonlinear governing equation for all times. Four analytical expressions are identified as asymptotic approximations (two of which are new solutions): (i) injection-driven flow with the injected fluid being more viscous than the displaced fluid ( Γ $\ll$ 1 and M < 1) where we identify a self-similar solution that indicates a parabolic interface shape; (ii) injection-driven flow with injected and displaced fluids of equal viscosity ( Γ $\ll$ 1 and M = 1), where we find a self-similar solution that predicts a distinct parabolic interface shape; (iii) injection-driven flow with a less viscous injected fluid ( Γ $\ll$ 1 and M > 1) for which there is a rarefaction wave solution, assuming that the Saffman-Taylor instability does not occur at the reservoir scale; and (iv) buoyancy-driven flow ( Γ $\gg$ 1) for which there is a well-known self-similar solution corresponding to gravity currents in an unconfined porous medium [S. Lyle et al. “Axisymmetric gravity currents in a porous medium,” J. Fluid Mech. 543, 293–302 (2005)]. The various axisymmetric flows are summarized in a Γ - M regime diagram with five distinct dynamic behaviors including the four asymptotic regimes and an intermediate regime. The implications of the regime diagram are discussed using practical engineering projects of geological CO 2 sequestration, enhanced oil recovery, and underground waste disposal.

42 ENGINEERING↗
NASA NTRS2011

Separation of Single-Walled Carbon Nanotubes with DEP-FFF

A process using a modified dielectrophoresis device separates single-walled carbon nanotubes (SWNTs) according to their polarizability in electric fields. This depends on the size and dielectric constant of individual nanotubes and easily separates metallic from semiconducting nanotubes. Separation by length has also been demonstrated. Partial separation (enrichment) according to bandgap (which is linked to polarizability) has also been shown and can be improved to full separation of individual types of semiconducting SWNTs with better control over operational parameters and the length of SWNT starting material. This process and device can be scaled affordably to generate useful amounts of semiconducting SWNTs for electronic device development and production. In this study, a flow injection dielectrophoresis technique was used with a modified dielectrophoresis device. The length, width, and height of the modified chamber were 28, 2.5, and 0.025 cm, respectively. On the bottom of the chamber, there are two arrays of 50-m-wide, 2-m-thick gold electrodes, which are connected to an AC voltage generator and are alternately arranged so that every electrode is adjacent to two electrodes of the opposite polar. There is an additional plate electrode on the top of the chamber that is negatively biased. During the experiment, a syringe pump constantly pumps in the mobile phase, 1-percent sodium dodecylbenzene sulfonate (SDBS) solution, into the chamber. The frequency and voltage are set to 1 MHz and 10 V peak-to-peak, respectively. About 150 micro-L of SWNTs in 1- percent SDBS decanted solution are injected to the mobile phase through a septum near the entrance of the chamber. The flow rate of the mobile phase is set to 0.02 cu cm/min. The injected SWNTs sample flows through the chamber before it is lead into a fluorescence flow-through cell and collected for further analysis. The flow-through cell has three windows, thus allowing the fluorometer to collect fluorescence spectrum and visible absorption spectrums simultaneously. Dielectrophoresis field-flow fractionation (DEP-FFF) generally depends on interaction of a sedimentation force and DEP force for particle separation, and SWNTs are neutrally buoyant in water. In this innovation, the third electrode was added to create a sedimentation force based on DC electrophoresis. This makes this particular device applicable to separations on any neutrally buoyant particles in solution and a more general process for a broad range of nanomaterials sorting and separations.

Schmidt, Howard K.↗
DOE OSTI2022

Aero-thermal numerical characterization of blunt fin-induced shock wave–boundary layer interaction and its control through leading-edge cooling injection

This study represents a novel evaluation of active flow control to alleviate the aerothermal penalties created by the blunt fin-induced shock wave–boundary layer interaction. The manuscript analyzes the effect of flow injection on a blunt fin-induced shock wave–boundary layer interaction via computational fluid dynamics simulations with various degrees of resolution. The impact on the mean flow topology and wall variables was investigated utilizing Reynolds-averaged Navier–Stokes simulations. Detached-eddy simulations revealed the low-frequency shock motion, shock wave–boundary layer, and horseshoe vortex interaction. The test article was exposed to two different incoming boundary layer thicknesses; the thicker boundary layer led to the appearance of larger turbulent scales. The Detached-eddy simulations revealed the time history of the shock wave–boundary layer interaction, focusing on the inception and development of the recirculated flow regions. Ultimately, spectral proper orthogonal decomposition was employed to identify the structures associated with the low-frequency shock motion caused by the shock wave–boundary layer interaction.

Lozano, Francisco (ORCID:0000000277871125)↗
DOE OSTI2022

ThunderSecure: deploying real-time intrusion detection for 100G research networks by leveraging stream-based features and one-class classification network

Nowadays, data generated by large-scale scientific experiments are on the scale of petabytes per month. These data are transferred through dedicated high-bandwidth networks (40/100G) across distributed sites for processing, storage, and analysis. Like general purpose networks, research networks experience intrusions. However, monitoring anomalies in such high-speed network traffics is challenging given current cyber-infrastructure. Moreover, traditional network intrusion detection systems (NIDS) are signature based. However, anomaly patterns are difficult to define and that rulesets are often not updated frequently enough to reflect the changes of attack behaviors. We present ThunderSecure, a high-throughput, unsupervised learning-based intrusions detection system for 100G research networks. ThunderSecure implements an efficient packet processing and detection pipeline using multi-cores and GPUs. It extracts statistical and temporal features from real-time network data streams and feeds them to a one-class anomaly detection network. A baseline of normal distribution will be created based on the training observation. Testing traffic deviated from the learned profile will be marked as anomalies. We trained ThunderSecure on hundreds of billions of science data packets mirrored from two 100G network connections at Fermi National Accelerator Laboratory. The detection performance was evaluated on traffic captured from the same research network days and weeks after the training with different types of attack flows injected. Results show that ThunderSecure can recognize science data traffic captured long after the training and made nearly certain detection on the segment of the streams where anomalous flows were injected.

100G research network↗
DOE OSTI2020

Airfoil leading edge blowing to control bow shock waves

Abstract This manuscript presents a detailed characterization of active control of bow shock waves via leading edge injection, including subsonic coolant ejection and the appearance of Coanda effects. The flow phenomena occurring at steady and pulsating flow injection regimes were analyzed using steady and unsteady two-dimensional Reynolds-Averaged Navier Stokes, leading to a precise evaluation of the thermal load and drag reductions. Steady supersonic injection yields the largest abatement in thermal load and aerodynamic drag, while subsonic or fluctuating ones can also provide significant improvements at reduced cooling mass flow rates. Furthermore, a Coanda effect, causing a non-symmetric flow topology, was observed and analyzed for reduced injection port size. This Coanda effect is due to the sudden expansion happening from the injection port to the main flow and it causes the flow topology at the leading edge to become non-symmetric despite the complete symmetry of the problem. This is the first time in the literature such a phenomenon is documented for a supersonic airfoil leading edge injection. Furthermore, it enables the design of novel flow control strategies for the leading edge shock topology and flow structures in supersonic flows.

42 ENGINEERING↗
DOE OSTI2011

A Pneumatic Actuated Microfluidic Beads-Trapping Device

The development of a polydimethylsiloxane (PDMS) microfluidic microbeads trapping device is reported in this paper. Besides fluid channels, the proposed device includes a pneumatic control chamber and a beads-trapping chamber with a filter array structure. The pneumatic flow control chamber and the beads-trapping chamber are vertically stacked and separated by a thin membrane. By adjusting the pressure in the pneumatic control chamber, the membrane can either be pushed against the filter array to set the device in trapping mode or be released to set the device in releasing mode. In this paper, a computational fluid dynamics simulation was conducted to optimize the geometry design of the filter array structure; the device fabrication was also carried out. The prototype device was tested and the preliminary experimental results showed that it can be used as a beads-trapping unit for various biochemistry and analytical chemistry applications, especially for flow injection analysis systems.

42 ENGINEERING↗
DOE OSTI2018

A Physical Model Study of Two-Phase Gas–Liquid Flows in a Ladle Shroud

Argon-steel flows inside a ladle shroud during teeming from a ladle to a tundish have been modelled physically. To this end, full-scale Perspex models of bloom as well as slab casting shrouds (BCS and SCS), operating with air and water, have been applied. Both open to air as well as immersed conditions were investigated with and without gas injection. Flows inside a ladle shroud under open to air and immersed conditions were found to be substantially different with a strong function of gas and liquid flow rates, collector nozzle and shroud diameters. Depending on the volumetric gas injection rate relative to liquid flow rate, different flow regimes have been observed in an immersed shroud [i.e., 0<(((d s )/(L s )))≤0.24]. At extremely low gas flow rates, [i.e., (((Q g )/(Q L )))≤0.02], injected gas is completely entrained as bubbles by the down-flowing liquid resulting in a bubbly two-phase flow over the entire length of a shroud. However, with an increasing gas flow rate, two distinctly different regions start to develop within the shroud body: a free liquid jet in the upper part and a gas–liquid mixing zone below. The length of the free jet increases with an increasing gas flow rate and at significantly higher gas to liquid flow rates [viz., (((Q g )/(Q L ))) BCS ≥0.42] and [viz., (((Q g )/(Q L ))) SCS ≥0.30], and the free jet is found to prevail over the entire length of the shroud. Within the range of conditions studied, it is observed that the free jet length or the line of demarcation between the jetting and two-phase mixing zone depends on gas and liquid flow rates and is specific to a particular shroud-collector nozzle system. Physical model results further indicate that a sufficiently large free jet length (~ shroud length) tends to create a high pressure region inside a shroud and prevent ingression of air. Possible implications of the present findings with reference to industrial teeming practices are also discussed in the text.

42 ENGINEERING↗
DOE OSTI2011

Development of a dynamic flow imaging phantom for dynamic contrast-enhanced CT

Purpose: Dynamic contrast enhanced CT (DCE-CT) studies with modeling of blood flow and tissue perfusion are becoming more prevalent in the clinic, with advances in wide volume CT scanners allowing the imaging of an entire organ with sub-second image frequency and sub-millimeter accuracy. Wide-spread implementation of perfusion DCE-CT, however, is pending fundamental validation of the quantitative parameters that result from dynamic contrast imaging and perfusion modeling. Therefore, the goal of this work was to design and construct a novel dynamic flow imaging phantom capable of producing typical clinical time-attenuation curves (TACs) with the purpose of developing a framework for the quantification and validation of DCE-CT measurements and kinetic modeling under realistic flow conditions. Methods: The phantom is based on a simple two-compartment model and was printed using a 3D printer. Initial analysis of the phantom involved simple flow measurements and progressed to DCE-CT experiments in order to test the phantoms range and reproducibility. The phantom was then utilized to generate realistic input TACs. A phantom prediction model was developed to compute the input and output TACs based on a given set of five experimental (control) parameters: pump flow rate, injection pump flow rate, injection contrast concentration, and both control valve positions. The prediction model is then inversely applied to determine the control parameters necessary to generate a set of desired input and output TACs. A protocol was developed and performed using the phantom to investigate image noise, partial volume effects and CT number accuracy under realistic flow conditionsResults: This phantom and its surrounding flow system are capable of creating a wide range of physiologically relevant TACs, which are reproducible with minimal error between experiments ({sigma}/{mu} < 5% for all metrics investigated). The dynamic flow phantom was capable of producing input and output TACs using either step function based or typical clinical arterial input function (AIF) inputs. The measured TACs were in excellent agreement with predictions across all comparison metrics with goodness of fit (R{sup 2}) for the input function between 0.95 and 0.98, while the maximum enhancement differed by no more than 3.3%. The predicted output functions were similarly accurate producing R{sup 2} values between 0.92 and 0.99 and maximum enhancement to within 9.0%. The effect of ROI size on the arterial input function (AIF) was investigated in order to determine an operating range of ROI sizes which were minimally affected by noise for small dimensions and partial volume effects for large dimensions. It was possible to establish the measurement sensitivity of both the Toshiba (ROI radius range from 1.5 to 3.2 mm ''low dose'', 1.4 to 3.0 mm ''high dose'') and GE scanner (1.5 to 2.6 mm ''low dose'', 1.1 to 3.4 mm ''high dose''). This application of the phantom also provides the ability to evaluate the effect of the AIF error on kinetic model parameter predictions. Conclusions: The dynamic flow imaging phantom is capable of producing accurate and reproducible results which can be predicted and quantified. This results in a unique tool for perfusion DCE-CT validation under realistic flow conditions which can be applied not only to compare different CT scanners and imaging protocols but also to provide a ground truth across multimodality dynamic imaging given its MRI and PET compatibility.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1995

Aqueous nitrite ion determination by selective reduction and gas phase nitric oxide chemiluminescence

An improved method of flow injection analysis for aqueous nitrite ion exploits the sensitivity and selectivity of the nitric oxide (NO) chemilluminescence detector. Trace analysis of nitrite ion in a small sample (5-160 microL) is accomplished by conversion of nitrite ion to NO by aqueous iodide in acid. The resulting NO is transported to the gas phase through a semipermeable membrane and subsequently detected by monitoring the photoemission of the reaction between NO and ozone (O3). Chemiluminescence detection is selective for measurement of NO, and, since the detection occurs in the gas-phase, neither sample coloration nor turbidity interfere. The detection limit for a 100-microL sample is 0.04 ppb of nitrite ion. The precision at the 10 ppb level is 2% relative standard deviation, and 60-180 samples can be analyzed per hour. Samples of human saliva and food extracts were analyzed; the results from a standard colorimetric measurement are compared with those from the new chemiluminescence method in order to further validate the latter method. A high degree of selectivity is obtained due to the three discriminating steps in the process: (1) the nitrite ion to NO conversion conditions are virtually specific for nitrite ion, (2) only volatile products of the conversion will be swept to the gas phase (avoiding turbidity or color in spectrophotometric methods), and (3) the NO chemiluminescence detector selectively detects the emission from the NO + O3 reaction. The method is free of interferences, offers detection limits of low parts per billion of nitrite ion, and allows the analysis of up to 180 microL-sized samples per hour, with little sample preparation and no chromatographic separation. Much smaller samples can be analyzed by this method than in previously reported batch analysis methods, which typically require 5 mL or more of sample and often need chromatographic separations as well.

NASA Discipline Environmental Health↗
DOE OSTI2012

Assessing the Thermal Environmental Impacts of an Groundwater Heat Pump in Southeastern Washington State

A thermal analysis of a large-scale (e.g., 1900 gpm), open-loop ground source heat pump (GSHP) installed on the Pacific Northwest National Laboratory (PNNL) campus in southeastern Washington State has been performed using a numerical modeling approach. Water temperature increases at the upgradient extraction wells in the system and at the downgradient Columbia River are potential concerns, especially since heat rejection to the subsurface will occur year-round. Hence, thermal impacts of the open-loop GSHP were investigated to identify operational scenarios that minimized downgradient environmental impacts at the river, and upgradient temperature drift at the production wells. Simulations examined the sensitivity of the system to variations in pumping rates and injected water temperatures, as well as to hydraulic conductivity estimates of the aquifer. Results demonstrated that both downgradient and upgradient thermal impacts were more sensitive to injection flow rates than estimates of hydraulic conductivity. Higher injection rates at lower temperatures resulted in higher temperature increases at the extraction wells but lower increases at the river. Conversely, lower pumping rates and higher injected water temperatures resulted in a smaller temperature increase at the extraction wells, but higher increases at the river. The scenario with lower pumping rates is operationally more efficient, but does increase the likelihood of a thermal plume discharging into the Columbia River. However, this impact would be mitigated by mixing within the hyporheic zone and the Columbia River. The impact under current operational conditions is negligible, but future increases in heat rejection could require a compromise between maximizing operational efficiency and minimizing temperature increases at the shoreline.

15 GEOTHERMAL ENERGY↗
DOE OSTI2020

Leveraging operational information from wastewater injection wells to evaluate CO 2 injection performance for carbon storage applications in the Appalachian Basin

Abstract Geologic parameters, geophysical logging, injection testing, and operational metrics from wastewater injection wells were integrated to develop a preliminary design of a carbon storage facility in the Appalachian Basin. A scattered group of 10–20 commercial wastewater injection wells dispose off produced water from oil and gas wells in the region, utilizing a sequence of stacked deep saline formations for injection zones. These wastewater injection wells provide practical benchmarks for understanding the feasibility of carbon dioxide (CO 2 ) storage. Geologic models were developed based on characterization data from the wastewater injection wells. Reservoir simulations were calibrated according to injection testing and operational data from the wastewater injection wells. Long‐term operational data on injection flow rates and pressures measured in the wastewater injection wells were especially useful to evaluate the performance of carbon storage applications. The simulations were used to estimate injection pressures, radius of CO 2 saturation, and pressure response for industrial scale CO 2 storage applications. Results were also used to provide a design basis in terms of number of injection wells, well spacing, area of review, injection system components, monitoring plan, and CO 2 pipeline distribution system. The analysis demonstrates that there is sufficient injectivity in the deep saline formations in the west‐central Appalachian Basin to store commercial volumes of anthropogenic CO 2 . The geologic system appears suitable for supporting CO 2 injection rates of 0.5–1.0 million metric tons per year at injection pressures below formation fracture pressure in a single well. The long‐term operational data of wastewater injection wells within the study area suggested a lower permeability‐thickness values than indicated by initial reservoir tests. A workflow for developing realistic permeability values for input into reservoir simulations is presented. © 2020 Society of Chemical Industry and John Wiley & Sons, Ltd.

Valluri, Manoj↗