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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Ignition Susceptibility of Additive Manufactured Inconel 718A® in Oxygen by Subsonic and Supersonic Particle Impact

Parts produced by additive manufacturing (AM), particularly Selective Laser Melting (SLM), have been shown to silt metal particulates even after undergoing stringent precision aerospace cleaning processes. The required pressures, temperatures, and flow rates in oxygen systems for human exploration are increasing, therefore, exacerbating the existing hazard of ignition mechanisms in these critical systems.

Tylka, Jonathan M.↗
NASA NTRS2020

Determination of Autogenous Ignition Temperature for Isopropyl Alcohol and Ethanol

As part of a recent liquid rocket engine shutdown investigation, a commercial partner requested that NASA provide the autogenous ignition (or autoignition) temperature (AIT) of isopropyl alcohol (IPA). NASA provided the available data, but the data were somewhat scattered, likely due to test configuration and test technique differences. NASA Engineering and Safety Center (NESC) support was requested to experimentally determine the AIT of IPA and ethanol, both of which are extensively applied to propulsion systems. This report contains the outcome of the NESC assessment.

Autoignition Temperature; Isopropyl Alcohol; Comme↗
NASA NTRSDate not supplied

Multiphase Computational Fluid Dynamics Simulation of Ignition Overpressure and Plume-Water Interaction in the SLS Scale Model Acoustics Test

The solid rocket boosters (SRBs) on the Space Launch System (SLS) generate powerful ignition overpressure (IOP) waves that can potentially damage the vehicle and surrounding ground structures. Based on historical Shuttle experience, the IOP will be mitigated by utilizing an IOP/Sound Suppression (SS) water system which sprays water in and around the SRB and RS-25 engine plumes. However, the complex multiphase physics of the resulting plume-water interaction can lead to undesirable effects, such as high velocity water spray onto the engine nozzles and SRB nozzle side loads. Prior to launch, insight into this environment can be achieved through scale model testing and predictive computational fluid dynamics (CFD) modeling. The Scale Model Acoustic Test (SMAT) was conducted at Marshall Space Flight Center to provide the data necessary to develop the SLS liftoff acoustic environments by using a 5% scale SLS vehicle, fully integrated with a scaled IOP/SS water system, mobile launcher (ML), and tower. NASA engineers have put forth significant effort in validating the Loci/CHEM-Real Fluids multiphase CFD solver on a wet hold down test from the SMAT series. In this paper, the IOP acoustics and plume-water interactions predicted by the CFD model are compared and validated against the experiment, enabling relatively inexpensive, rapid turnaround for multiphase launch environment analyses to support future flights and design evolutions of SLS and other launch vehicles.

John E. Soto↗
NASA NTRSDate not supplied

CFD Simulation of Ignition Overpressure and Plume-Water Interaction in the SLS Scale Model Acoustics Test

The solid rocket boosters (SRBs) on the Space Launch System (SLS) generate powerful ignition overpressure (IOP) waves that can potentially damage the vehicle and surrounding ground structures. Based on historical Shuttle experience, the IOP will be mitigated by utilizing an IOP/Sound Suppression (SS) water system which sprays water in and around the SRB and RS-25 engine plumes. However, the complex multiphase physics of the resulting plume-water interaction can lead to undesirable effects, such as high velocity water spray onto the engine nozzles and SRB nozzle side loads. Prior to launch, insight into this environment can be achieved through scale model testing and predictive computational fluid dynamics (CFD) modeling. The Scale Model Acoustic Test (SMAT) was conducted at Marshall Space Flight Center to provide the data necessary to develop the SLS liftoff acoustic environments by using a 5% scale SLS vehicle, fully integrated with a scaled IOP/SS water system, mobile launcher (ML), and tower. NASA engineers have put forth significant effort in validating the Loci/CHEM-Real Fluids multiphase CFD solver on a wet hold down test from the SMAT series. In this paper, the IOP acoustics and plume-water interactions predicted by the CFD model are compared and validated against the experiment, enabling relatively inexpensive, rapid turnaround for multiphase launch environment analyses to support future flights and design evolutions of SLS and other launch vehicles.

Computational Fluid Dynamics↗
DOE OSTI2011

X-Ray Line-Shape Diagnostics and Novel Stigmatic Imaging Schemes For the National Ignition Facility

In response to a recent solicitation from the US Department of Energy we proposed the development of a new x-ray line-shape diagnostic and novel stigmatic imaging schemes for the National Ignition Facility (NIF). These diagnostics are based on the imaging properties of spherically bent crystals, explained in Fig. 1, which have already been successfully applied to the diagnosis of extended tokamak plasmas for measurements of the ion-temperature and toroidal flow-velocity profiles [United States Patent: US 6, 259, 763 B1] and refs. [1, 2].

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2014

Compression ignition engine having fuel system for non-sooting combustion and method

A direct injection compression ignition internal combustion engine includes a fuel system having a nozzle extending into a cylinder of the engine and a plurality of spray orifices formed in the nozzle. Each of the spray orifices has an inner diameter dimension of about 0.09 mm or less, and define inter-orifice angles between adjacent spray orifice center axes of about 36.degree. or greater such that spray plumes of injected fuel from each of the spray orifices combust within the cylinder according to a non-sooting lifted flame and gas entrainment combustion pattern. Related methodology is also disclosed.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2015

Near Field Intensity Trends of Main Laser Alignment Images in the National Ignition Facility (NIF)

The National Ignition Facility (NIF) utilizes 192 high-energy laser beams focused with enough power and precision on a hydrogen-filled spherical, cryogenic target to potentially initiate a fusion reaction. NIF has been operational for six years; during that time, thousands of successful laser firings or shots have been executed. Critical instrument measurements and camera images are carefully recorded for each shot. The result is a massive and complex database or ‘big data’ archive that can be used to investigate the state of the laser system at any point in its history or to locate and track trends in the laser operation over time. In this study, the optical light throughput for more than 1600 NIF shots for each of the 192 main laser beams and 48 quads was measured over a three year period from January 2009 to October 2012. The purpose was to verify that the variation in the transmission of light through the optics over time performed within design expectations during this time period. Differences between average or integrated intensity from images recorded by the input sensor package (ISP) and by the output sensor package (OSP) in the NIF beam-line were examined. A metric is described for quantifying changes in the integrated intensity measurements and was used to view potential trends. Results are presented for the NIF input and output sensor package trends and changes over the three year time-frame.

42 ENGINEERING↗
DOE OSTI2015

Method for operating a spark-ignition, direct-injection internal combustion engine

A spark-ignition, direct-injection internal combustion engine is coupled to an exhaust aftertreatment system including a three-way catalytic converter upstream of an NH3-SCR catalyst. A method for operating the engine includes operating the engine in a fuel cutoff mode and coincidentally executing a second fuel injection control scheme upon detecting an engine load that permits operation in the fuel cutoff mode.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2016

Recent progress on the National Ignition Facility advanced radiographic capability

The National Ignition Facility (NIF) is a megajoule (million-joule)-class laser and experimental facility built for Stockpile Stewardship and High Energy Density (HED) science research [1]. Up to several times a day, 192 laser pulses from NIF's 192 laser beamlines converge on a millimeter-scale target located at the center of the facility's 10-meter diameter target chamber. The carefully synchronized pulses, typically a few nanoseconds (billionths of a second) in duration and co-times to better than 20 picoseconds (trillionths of a second), a deliver a combined energy of up to 1.8 megajoules and a peak power of 500 terawatts (trillion watts). Furthermore, this drives temperatures inside the target to tens of millions of degrees and pressures to many billion times greater than Earth's atmosphere.

42 ENGINEERING↗
DOE OSTI2016

FUEL EFFECTS ON COMBUSTION WITH EGR DILUTION IN SPARK IGNITED ENGINES

The use of EGR as a diluent allows operation with an overall stoichiometric charge composition, and the addition of cooled EGR results in well-understood thermodynamic benefits for improved fuel consumption. This study investigates the effect of fuel on the combustion and emission response of EGR dilution in spark ignited engines. A 2.0 L GM Ecotec LNF engine equipped with the production side-mounted direct injection (DI) fueling system is used in this study. Ethanol, isooctane and certified gasoline are investigated with EGR from 0% to the EGR dilution tolerance. Constant BMEP at 2000 rpm was operated with varying CA50 from 8 CAD to 16 CAD aTDCf. The results show that ethanol gives the largest EGR tolerance at a given combustion phasing, engine load and speed. The improved EGR dilution tolerance with ethanol is attributed to a faster flame speed, which manifests itself as shorter combustion duration. Data shows that the combustion stability limit occurs at a critical combustion duration that is fuel independent. Due to different flame speeds, this critical combustion duration occurs at different EGR levels for the different fuels.

COV↗
DOE OSTI2017

Co-Optimization of Fuels & Engines (Co-Optima) Initiative: Recent Progress on Light-Duty Boosted Spark-Ignition Fuels/Engines

This presentation reports recent progress on light-duty boosted spark-ignition fuels/engines being developed under the Co-Optimization of Fuels and Engines initiative (Co-Optima). Co-Optima is focused on identifying fuel properties that optimize engine performance, independent of composition, allowing the market to define the best means to blend and provide these fuels. However, in support of this, we are pursuing a systematic study of blendstocks to identify a broad range of feasible options, with the objective of identifying blendstocks that can provide target ranges of key fuel properties, identifying trade-offs on consistent and comprehensive basis, and sharing information with stakeholders.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2018

Development of Platforms for Nuclear Science Experiments at the National Ignition Facility

When neutrons are produced in nuclear processes such as fission or fusion, they can interact with any surrounding materials, inducing radioactivity through neutron capture reactions. Neutron reactions are fundamental to many areas of nuclear science, including studies of nuclear reactors, determining the formation of matter in stars, nuclear forensics, medical radiotherapy, and assessing the safety of our nuclear stockpile. The National Ignition Facility (NIF) offers a unique opportunity to use the inertial confinement fusion platform to measure neutron reactions essential to national security or fundamental and applied science applications. A typical fusion experiment at NIF currently produces approximately 10 16 neutrons through the fusion of deuterium and tritium in a target capsule. Materials introduced into the NIF target chamber in close proximity to the capsule will undergo neutron reactions such as capture or fission, and the resultant reaction rates can be evaluated. While neutron reactions can be measured at other facilities, NIF offers unique advantages. The flux of neutrons produced (number of neutrons per square centimeter per second) is much higher than any other available neutron source due to both the small size of the NIF capsule (2-mm diameter before implosion) and the short time (roughly 100 ps) over which the neutrons are produced. This results in less target material required to perform a reaction-rate study (less than or equal to 10 16 atoms) as compared to traditional particle accelerators, which require targets that are approximately 1 mg or roughly 10 20 atoms. Also, the NIF neutron spectrum is peaked at thermonuclear (14 MeV) neutron energy, which means that nuclear reactions with nonthermal energy thresholds can be studied at NIF, whereas neutron energies at a nuclear reactor are generally insufficient for studying higher-energy neutron reactions. Several experimental configurations have been developed that enable the use of NIF fusion capsules as powerful neutron sources for nuclear reaction measurements.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2018

Nonlinear model-based controller for premixed charge compression ignition combustion timing in diesel engines

Advanced combustion modes, such as PCCI, operate near the system stability limits. In PCCI, the combustion event begins without a direct combustion trigger in contrast to traditional spark-ignited gasoline engines and direct-injected diesel engines. The lack of a direct combustion trigger encourages the usage of model-based controls to provide robust control of the combustion phasing. The nonlinear relationships between the control inputs and the combustion system response often limit the effectiveness of traditional, non-model-based controllers. Accurate knowledge of the system states and inputs is helpful for implementation of an effective nonlinear controller. A nonlinear controller is developed and implemented to control the engine combustion timing during diesel PCCI operation by targeting desired values of the in-cylinder oxygen concentration, pressure, and temperature during early fuel injection.

42 ENGINEERING↗
DOE OSTI2019

Towards improved mesh-designing techniques of spark-ignition engines in the framework of spectral element methods

In the current paper we present an advanced meshing technique to perform high-fidelity numerical simulations in spark ignition (SI) engines. The design of the mesh is critical towards generating physically consistent, high fidelity data especially in regions of complex boundaries inside the cylinder, e.g., near the spark plugs. This is primarily due to the mesh deformation caused by the motion of the valve near the plug and also finer mesh sizes in the spark plug region. In the current work, we demonstrate the use of an overlapping grid (overset) methodology to design the mesh in the spark-plug region in a 2D SI engine-like geometry for a high-order simulation, based on the spectral element method (SEM). The data in the overlapping region is exchanged between the spark-plug geometry and the geometry containing rest of the objects like the piston, cylinder head, valve etc., using a high order spectral interpolation technique. The numerical simulations have been further compared against the standard, single (non-overset) grid, meshing technique for the whole 2D domain. The results further illustrate the capability of overlapping grid methodology in handling mesh deformation compared to the standard grid case and also the ability to capture the flow dynamics with a similar level of fidelity as the standard one

overlapping grids↗
DOE OSTI2016

Considerations for a PDV diagnostic capability on the National Ignition Facility

Photonic Doppler Velocimetry (PDV) has become widely and routinely used in many high-velocity experimental applications due to its improved ease of use, cost, experimental flexibility, data return, and robustness compared to earlier velocimetric methods. However, these earlier methods have advantages in applications with requirements beyond PDV’s current capabilities. Various classes of experiments at the National Ignition Facility (NIF) that are characterized by extremely high velocity or acceleration, or diagnostic requirements for high precision in timing and/or velocity, have historically seen a VISAR (velocity interferometer system for any surface) diagnostic employed due to such advantages. VISAR, however, requires specific, and sometimes challenging, experimental features, including planar geometry and normal incidence, high-reflectivity surface treatment, and a relatively large and inflexible diagnostic footprint. Therefore, the potential for implementing a PDV diagnostic at NIF has been evaluated by researchers from National Security Technologies, LLC and Lawrence Livermore National Laboratory. We present the results of this study, weigh the relative merits of the two methodologies with consideration of experimental phenomena and requirements, and discuss possible implementations and future directions.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

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