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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Stagnation region gas film cooling: Spanwise angled injection from multiple rows of holes

The stagnation region of a cylinder in a cross flow was used in experiments conducted with both a single row and multiple rows of spanwise angled (25 deg) coolant holes for a range of the coolant blowing ratio with a freestream to wall temperature ratio approximately equal to 1.7 and R(eD) = 90,000. Data from local heat flux measurements are presented for injection from a single row located at 5 deg, 22.9 deg, 40.8 deg, 58.7 deg from stagnation using a hole spacing ratio of S/d(o) = 5 and 10. Three multiple row configurations were also investigated. Data are presented for a uniform blowing distribution and for a nonuniform blowing distribution simulating a plenum supply. The data for local Stanton Number reduction demonstrated a lack of lateral spreading by the coolant jets. Heat flux levels larger than those without film cooling were observed directly behind the coolant holes as the blowing ratio exceeded a particular value. The data were spanwise averaged to illustrate the influence of injection location, blowing ratio and hole spacing. The large values of blowing ratio for the blowing distribution simulating a plenum supply resulted in heat flux levels behind the holes in excess of the values without film cooling. An increase in freestream turbulence intensity from 4.4 to 9.5 percent had a negligible effect on the film cooling performance.

Luckey, D. W.↗
NASA NTRS1995

Impulsive ion injections in the morning auroral region

Low altitude (less than 1000 km) measurements of ions precipitating into the morning auroral region are presented and analyzed. The ion fluxes exhibited time-energy signatures consistent with impulsive injection onto high-altitude field lines, followed by time-of-flight dispersion. The origin of these ions is investigated through the detailed examination of these signatures in conjunction with simultaneous measurements of precipitating electrons and a magnetic field model. A model is developed which indicates that the source for these particles was located in or near the magnetopause boundary layer, with the position deduced to be in the midlatitude flank region about 20-30 R(sub E) tailward of the Earth. The model explains the existence of multiple injections on a given field line as due to a quasi-periodic source, with the periodicity being about 100-200 s at the source. Several mechanisms are examined in an attempt to explain the injections, with a mechanism related to the propagation of waves on the surface of the boundary layer found to be the most plausible. The observations and results are compared to those of similar experiments and some unifying ideas are discussed.

Clemmons, J. H.↗
DOE OSTI2020

Multiple injection for improving knock, gaseous and particulate matter emissions in direct injection SI engines

Advances in fuel injector technology have enabled research and development on a large variety of direct injection spark ignition (DISI) engine fueling strategies targeted to improve engine performance and reduce engine-out emissions. This study explores the effect of multiple injections on knock, engine efficiency and stability, and particulate number and gaseous emissions on a single-cylinder DISI research engine. Work to date on multiple injections in the literature is reviewed, and then two aspects of multiple injection strategies are experimentally investigated: the number of injections (up to five times in a cycle); and the timing of the injections (classified relative to the timing of intake valve opening and closing). A boosted, single-cylinder research engine equipped with a state-of-the-art piezoelectric hollow cone spray direct injector and research-grade E10 gasoline was used for the study. The results show multiple injections maintain torque and combustion stability compared with single injection and slightly increase the knock limits and indicated thermal efficiencies (maximum 0.7% absolute, 2.8% relative compared with single-injection baseline) due to improved heat release phasing, especially with an additional late injection during the intake valve closed (compression stroke) period. The gaseous pollutant emissions including nitrogen oxides and unburned hydrocarbons were reduced by 25% with multiple injections, particularly with injection during the compression stroke. In contrast, carbon monoxide emissions increased with multiple injections for all conditions. Increasing the number of injection events significantly reduced particulate number emissions (half with each additional injection), and the decrease in particulate number was not sensitive to the injection timing.

42 ENGINEERING↗
NASA NTRS1982

A wavelength scannable XeCl oscillator-ring amplifier laser system

A holographic grating at grazing angle of incidence was used to achieve tunable, narrow bandwidth (0.005 nm) operation of a XeCl oscillator for injection locking of a ring amplifier. The amplifier's narrow bandwidth output energy was constant and equal to the untuned, broadband output (approximately 15 mJ) in regions where injection locking was achieved. Scanning was provided by use of a stepping motor-driven differential micrometer on the tuning mirror. This system was used to produce a laser excitation spectrum of hydroxyl radicals (OH) in a flame.

Pacala, T. J.↗
DOE OSTI2021

MRCSP Final Technical Report

Final technical report discussing the project background, the Michigan Basin large scale injection test, regional analyses, and additional studies.

background↗
DOE OSTI2024

Constraining induced seismicity hazard on the Neck of the Desert fault for the proposed Iron Mountain, Utah carbon sequestration project

As significantly more focus is placed on carbon sequestration as a means to help mitigate the progression of climate change, the need to adequately characterize an injection target for its induced seismicity potential becomes more apparent. In the Iron Mountain project in Southern Utah, a single fault is identified in the Neck of the Desert near Iron Mountain. The dip of the fault is unknown, and the geomechanical stability of the fault (i.e., distribution of Coulomb failure functions (CFFs)) is highly dependent upon the dip. For some dips, such as 15 degrees, the hazard from injection is low. For other dips, such as 75 degrees, the hazard is high. Another key consideration is the depth of penetration of the fault. Should the fault not penetrate the stress and pressure perturbed region from injection, it will not be induced to fail. Thus, understanding the dip and the depth of penetration of the fault will greatly improve our understanding of the likelihood of inducing an earthquake.

58 GEOSCIENCES↗
NASA NTRS1988

MHD simulation of mass injection - A mechanism for the formation of active region loops

A two-dimensional nonlinear MHD numerical code is used to simulate the formation and dynamic evolution of active regions loops subjected to mass injections at the footpoints. The UV and X-ray signatures of the plasmas are also calculated. It is found that it is possible to form loops in a low beta plasma that occurs in the solar active regions.

Cheng, Chung-Chieh↗
NASA NTRS1981

Sensitivity tests of two-dimensional model predictions of corridor effects

Future aerospace-vehicle systems, such as supersonic transport fleets, the Space Shuttle (SS), and the Heavy-Lift Launch Vehicle (HLLV) system will inject substantial amounts of pollutants into the stratosphere. It is, therefore, pertinent to ask whether the operation of these systems will lead to deleterious effects in the atmosphere. The current investigation is concerned with the development of criteria to assess the likelihood of a detectable corridor effect being caused by the long-term deposition of pollutants at a single latitude. The sources are assumed to operate continuously and at a uniform rate for periods of many years. It is found that transport by meridional winds and by eddy processes acts to diminish the corridor effect by advecting the pollutants out of the region of injection and by mixing them with the ambient air. Attention is given to the altitude for which a detectable corridor effect can be expected for the hypothetical launching of 400 HLLV's per year for 10 years.

Borucki, W. J.↗
DOE OSTI2020

Chemo‐mechanical Alterations Induced From CO 2 Injection in Carbonate‐Cemented Sandstone: An Experimental Study at 71 °C and 29 MPa

Abstract Carbon capture, utilization, and storage may lead to mechanical degradation of the subsurface reservoir from fluid‐rock interaction, which could lead to wellbore instability or reservoir compaction. To better understand potential relationship between mechanical degradation with various carbonate cement textures and compositions in sandstone reservoirs, six flow‐through experiments were conducted. Formation water (TDS = 5,390 mg/L) enriched with CO 2 flowed through two types of Pennsylvanian Morrow B Sandstone: an ankerite‐siderite‐cemented sandstone (disseminated cement texture) and a calcite‐cemented sandstone (poikilotopic cement texture). The experiments produced little change in permeability in the ankerite‐siderite‐cemented sandstone, but permeability increased up to more than 1 order of magnitude in the calcite‐cemented sandstone. Ultrasonic measurements and cylinder‐splitting tests (also known as Brazilian tests) suggested negligible mechanical degradation of the ankerite‐siderite‐cemented sandstone. Variable changes, with significant mechanical degradation in the static moduli, were observed in the calcite‐cemented sandstone. Thus, dissolution of the disseminated ankerite‐siderite cement (0.28–0.30%) had minimal impact on modifying the flow network and the mechanical integrity of the sandstone, whereas dissolution of the poikilotopic calcite cement (0.89–1.13%, quantified with fluid chemistry and visualized with X‐ray microcomputed tomography) impacted the mechanical strength of the sandstone by disconnecting framework grains. With the high water‐to‐rock mass ratios (7.3–8.2) and number of pore volumes (147–675) employed in these experiments, potential risks are most relevant to regions near injection wells. Ultimately, the chemo‐mechanical effects induced by CO 2 injection are strongly influenced by the cement texture and composition and the burial history of the reservoir rock.

Wu, Z.↗
NASA NTRS1986

DE-1 observations of solar wind-magnetosphere coupling processes in the polar cusp

Measurements of hot plasma distribution functions in the midaltitude polar cusp by the Dynamics Explorer-1 spacecraft have provided new information on the processes of magnetosheath plasma injection and transport and the dependence of these phenomena on solar-wind parameters. Results on magnetosheath plasma injection have included: (1) localization of the region of plasma injection to the high-latitude cusp-magnetosheath interface, (2) movement of this region toward lower latitudes as B(z) becomes more southward, (3) maintenance of quasi-neutrality of suprathermal plasmas within the cusp, and (4) support for merging-type injection at the high-latitude cusp boundary for northward IMF. Plasma flow measurements from Dynamics Explorer-1 have led to a global IMF-dependent convection model which contains both merging and viscous driving forces.

Burch, J. L.↗
DOE OSTI2021

Deep Kronecker neural networks: A general framework for neural networks with adaptive activation functions

Here we propose a new type of neural networks, Kronecker neural networks (KNNs), that form a general framework for neural networks with adaptive activation functions. KNNs employ the Kronecker product, which provides an efficient way of constructing a very wide network while keeping the number of parameters low. Our theoretical analysis reveals that under suitable conditions, KNNs induce a faster decay of the loss than that by the feed-forward networks. This is also empirically verified through a set of computational examples. Furthermore, under certain technical assumptions, we establish global convergence of gradient descent for KNNs. As a specific case, we propose the Rowdy activation function that is designed to get rid of any saturation region by injecting sinusoidal fluctuations, which include trainable parameters. The proposed Rowdy activation function can be employed in any neural network architecture like feed-forward neural networks, Recurrent neural networks, Convolutional neural networks etc. The effectiveness of KNNs with Rowdy activation is demonstrated through various computational experiments including function approximation using feed-forward neural networks, solution inference of partial differential equations using the physics-informed neural networks, and standard deep learning benchmark problems using convolutional and fully-connected neural networks.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2023

A Search for Technosignatures Around 11,680 Stars with the Green Bank Telescope at 1.15–1.73 GHz

We conducted a search for narrowband radio signals over four observing sessions in 2020–2023 with the $L$-band receiver (1.15–1.73 GHz) of the 100 m diameter Green Bank Telescope. We pointed the telescope in the directions of 62 TESS Objects of Interest, capturing radio emissions from a total of ~11,680 stars and planetary systems in the ~9' beam of the telescope. All detections were either automatically rejected or visually inspected and confirmed to be of anthropogenic nature. We also quantified the end-to-end efficiency of radio SETI pipelines with a signal injection and recovery analysis. The UCLA SETI pipeline recovers 94.0% of the injected signals over the usable frequency range of the receiver and 98.7% of the injections when regions of dense radio frequency interference are excluded. In another pipeline that uses incoherent sums of 51 consecutive spectra, the recovery rate is ~15 times smaller at ~6%. The pipeline efficiency affects calculations of transmitter prevalence and SETI search volume. Accordingly, we developed an improved Drake figure of merit and a formalism to place upper limits on transmitter prevalence that take the pipeline efficiency and transmitter duty cycle into account. Based on our observations, we can state at the 95% confidence level that fewer than 6.6% of stars within 100 pc host a transmitter that is continuously transmitting a narrowband signal with an equivalent isotropic radiated power (EIRP) > 10 13 W. For stars within 20,000 ly, the fraction of stars with detectable transmitters (EIRP > 5 × 10 16 W) is at most 3 × 10 -4 . Finally, we showed that the UCLA SETI pipeline natively detects the signals detected with AI techniques by Ma et al.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1983

Development of compact excimer lasers for remote sensing

The capabilities of excimer lasers for remote sensing applications are illustrated in a discussion of the development of a compact tunable XeCl excimer laser for the detection of atmospheric OH radicals. Following a brief review of the operating principles and advantages of excimer lasers, measurements of the wavelength dependence of the net small signal gain coefficient of a discharge excited XeCl laser are presented which demonstrate the overlap of several absorption lines of the A-X(0,0) transition of OH near 308 nm with the wavelengths of the XeCl laser. A range of continuous narrow bandwidth tunability of from 307.6 to 308.4 nm with only a 30 percent variation in output is reported for an XeCl laser used as a double-pass amplifier for a frequency-doubled dye laser, and measurements demonstrating the detection of laser-induced fluorescence from OH in a methane-oxygen flame are also noted. The design of an oscillator-amplifier excimer system comprising a corona-preionized, transverse-discharge oscillator and amplifier is then presented. Output energies of 12-15 mJ have been achieved in the regions where injection locking was established, with energies of 8-10 mJ elsewhere.

Laudenslager, J. B.↗
NASA NTRS2005

Shock Interaction Control for Scramjet Cowl Leading Edges

An experimental study was conducted to qualitatively determine the effectiveness of stagnation-region gas injection in protecting a scramjet cowl leading edge from the intense heating produced by Type III and Type IV shock interactions. The model consisted of a two-dimensional leading edge, representative of that of a scramjet cowl. Tests were conducted at a nominal freestream Mach number of 6. Gaseous nitrogen was supersonically injected through the leading-edge nozzles at various mass flux ratios and with the model pitched at angles of 0deg and -20deg relative to the freestream flow. Qualitative data, in the form of focusing and conventional schlieren images, were obtained of the shock interaction patterns. Results indicate that large shock displacements can be achieved and both the Type III and IV interactions can be altered such that the interaction does not impinge on the leading edge surface.

Albertson, Cindy W.↗
NASA NTRS2010

Airborne Dust, "The Good Guy or the Bad Guy": How Much do We Know?

Processes in generating, transporting, and dissipating the airborne dust particles are global phenomena -African dust regularly reaching the Alps; Asian dust seasonally crossing the Pacific into North America, and ultimately the Atlantic into Europe. One of the vital biogeochemical roles dust storms play in Earth's ecosystem is routinely mobilizing mineral dust, as a source of iron, from deserts into oceans for fertilizing the growth of phytoplankton -the basis of the oceanic food chain. Similarly, these dust-laden airs also supply crucial nutrients for the soil of tropical rain forests, the so-called womb of life that hosts 50-90% of the species on Earth. With massive amounts of dust lifted from desert regions and injected into the atmosphere, however, these dust storms often affect daily activities in dramatic ways: pushing grit through windows and doors, forcing people to stay indoors, causing breathing problems, reducing visibility and delaying flights, and by and large creating chaos. Thus, both increasing and decreasing concentrations of doses result in harmful biological effects; so do the airborne dust particles to our Living Earth. Since 1997 NASA has been successfully launching a series of satellites - the Earth Observing System - to intensively study, and gain a better understanding of, the Earth as an integrated system. Through participation in many satellite remote-sensing/retrieval and validation projects over the years, we have gradually developed and refined the SMART (Surface-sensing Measurements for Atmospheric Radiative Transfer) and COMMIT (Chemical, Optical & Microphysical Measurements of In-situ Troposphere) mobile observatories, a suite of surface remote sensing and in-situ instruments that proved to be vital in providing high temporal measurements, which complement the satellite observations. In this talk, we will present SMART-COMMIT which has played key roles, serving as network or supersite, in major international research projects such as the Joint Aerosol Monsoon Experiment (JAMEX), a core element of the Asian Monsoon Years (AMY, 2008-2012). SMART-COMMIT deployments during 2008 AMY/JAMEX were conducted in northwestern China to characterize the properties of dust-laden aerosols. In 2009, SMART-COMMIT also participated in the JAMEX/RAJO-MEGHA (Radiation, Aerosol Joint Observations-Monsoon Experiment in the Gangetic-Himalayan Area; Sanskrit for Dust-Cloud) to study the aerosol properties, solar absorption and the associated atmospheric warming, and the climatic impact of elevated aerosols during the premonsoon season in South Asia. To fully characterize the properties of airborne dust in the field is an important but challenging task. In this seminar, we will present our recent measurements and retrievals of airborne dust properties.

Tsay, Si-Chee↗
NASA NTRS2021

The Long-term Transport and Radiative Impacts of the 2017 British Columbia Pyrocumulonimbus Smoke Aerosols in the Stratosphere

Interactions of meteorology with wildfires in British Columbia, Canada during August 2017 led to three major pyrocumulonimbus (pyroCb) events that resulted in the injection of large amounts of smoke aerosols and other combustion products at the local upper troposphere and lower stratosphere (UTLS). These plumes of UTLS smoke with elevated values of aerosol extinction and backscatter compared to the background state were readily tracked by multiple satellite-based instruments as they spread across the Northern Hemisphere (NH). The plumes were observed in the lower stratosphere for about 8-10 months following the fire injections, with a stratospheric aerosol e-folding time of about 5 months. To investigate the radiative impacts of these events on the Earth system, we performed a number of simulations with the Goddard Earth Observing System (GEOS) atmospheric general circulation model (AGCM). Observations from multiple remote-sensing instruments were used to calibrate the injection parameters (location, amount, composition and heights) and optical properties of the smoke aerosols in the model. The resulting simulations of three-dimensional smoke transport were evaluated for a year from the day of injections using daily observations from OMPS-LP (Ozone Mapping Profiler Suite Limb Profiler). The model simulated rate of ascent, hemispheric spread and residence time (or e-folding time) of the smoke aerosols in the stratosphere are in close agreement with OMPS-LP observations. We found that both aerosol self-lofting and the large-scale atmospheric motion play important roles in lifting the smoke plumes from near the tropopause altitudes (~12 km) to about 22-23 km into the atmosphere. Further, our estimations of the radiative impacts of the pyroCb-emitted smoke aerosols showed that the smoke caused an additional warming of the atmosphere by about 0.6-1 W/m2 (zonal mean) that persisted for about 2-3 months after the injections in regions north of 40oN. The surface experienced a comparable magnitude of cooling. The atmospheric warming is mainly located in the stratosphere, coincident with the location of the smoke plumes, leading to an increase in zonal mean shortwave (SW) heating rates of 0.02-0.04 K/day during September 2017.

pyrocumulonimbus (pyroCb) events↗
NASA NTRS2023

Deriving Large Coronal Magnetic Loop Parameters Using LOFAR J Burst Observations

Large coronal loops around one solar radius in altitude are an important connection between the solar wind and the low solar corona. However, their plasma properties are ill-defined, as standard X-ray and UV techniques are not suited to these low-density environments. Diagnostics from type J solar radio bursts at frequencies above 10 MHz are ideally suited to understand these coronal loops. Despite this, J-bursts are less frequently studied than their type III cousins, in part because the curvature of the coronal loop makes them unsuited for using standard coronal density models. We used LOw-Frequency-ARray (LOFAR) and Parker Solar Probe (PSP) solar radio dynamic spectrum to identify 27 type III bursts and 27 J-bursts during a solar radio noise storm observed on 10 April 2019. We found that their exciter velocities were similar, implying a common acceleration region that injects electrons along open and closed magnetic structures. We describe a novel technique to estimate the density model in coronal loops from J-burst dynamic spectra, finding typical loop apex altitudes around 1.3 solar radius. At this altitude, the average scale heights were 0.36 solar radius, the average temperature was around 1 MK, the average pressure was 0.7mdyn cm -2 , and the average minimum magnetic field strength was 0.13 G. We discuss how these parameters compare with much smaller coronal loops.

Jinge Zhang↗