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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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Ignition of Metals in Heated Supersonic Particle Impact with Inert Particulate

The conventional understanding of particle impact ignition characteristic elements relies on the following principles: 1) flammable particulate (except in the case of titanium and aluminum target materials); 2) gas velocity greater than 100 ft/s; 3) Impact point ranging from 45° to perpendicular to the path of the particle [1]; 4) flammable target material. To test assumptions about particulate flammability being necessary for particle impact ignition of less reactive target materials, such as Inconel 718, testing was performed with inert particulate. Supersonic particle impact testing was conducted with heated gas and 1500-µm sapphire particulate on various target materials: 304 stainless steel, wrought and selective laser melted Inconel 718, and Monel 400. Posttest characterization of impact craters was performed on each type of metallic target sample, including surface characterization performed by light optical microscopy and scanning electron microscopy with energy dispersive spectroscopy. Full consumption of the stainless steel and wrought Inconel 718 targets were noted to occur with sequential impacts. The results of testing will be discussed in detail, as well as recommendations for updating the understanding of the particle impact ignition mechanism.

Particle Impact↗
DOE OSTI2025

Evaluating Chemical Kinetics Predictions for Propane Using 3-D and 0-D Models in a Boosted Spark-Ignited Engine

Propane has been shown to be a promising alternative fuel to reduce emissions while simultaneously achieving high efficiencies in medium- and heavy-duty engines. These high-power density applications require boosted engines which, combined with high compression ratio, can lead to auto-ignition and knock. While three-dimensional (3-D) computational fluid dynamics (CFD) models are often used for resolving the complex fluid flow in engines, these models can become computationally expensive when simulating detailed chemical kinetics. Likewise, zero-dimensional (0-D) models are computationally concise enough for kinetics development, but lack any flow-field information which governs the flame propagation processes in spark ignition (SI) engines. This work presents a comprehensive comparison between 3-D and 0-D closed cycle simulations at knocking conditions in a high compression ratio high stroke-to-bore ratio propane engine. In order to initialize the flow-field for the 3-D closed cycle (intake valve closing, (IVC) to exhaust valve opening, (EVO)) simulation, a motored multi-cycle 3-D model was run using Converge to create a map at IVC, reducing the computational time. The map allowed a non-homogeneous 3-D closed cycle simulation to be satisfactorily validated against experiments, while a homogeneous case using only the turbulence field mapping was also simulated, mimicking 0-D modeling. The 3-D simulations were used to prescribe the initial conditions (e.g., IVC thermodynamics, speciation, burn-rate profile) for a 2-zone 0-D SI engine model in Chemkin Pro for both cases. It was found that 2-zone 0-D modeling underpredicted the knock onset timing, likely due to the lack of thermal stratification in the unburned gas region. Future work will carry multi-zone 0-D modeling to capture the fuel auto-ignition in the unburned region.

Douvry-Rabjeau, Julien [Oakland University, Roches↗
DOE OSTI2025

60 years of science in ICF: from conception to scientific breakeven on the National Ignition Facility

The recent achievements of a burning plasma, fusion ignition, and scientific energy gain with deuterium-tritium (DT) fuel at Lawrence Livermore National Laboratory’s National Ignition Facility (NIF) represents a major milestone in the development of inertial confinement fusion (ICF) and all of fusion research. In these experiments, fuel pressures well in excess of hundreds of GBars were achieved in the compressed fuel, and robust alpha heating of the fuel, far in excess of the energy provided by the implosion, were demonstrated for the first time. These achievements occurred 60 years after the inception of ICF and the first laser demonstration, and were made possible by more than five decades of research at laser facilities around the world. Advances in laser technology both in wavelength and precision, motivated by improved understanding of laser-plasma interaction physics and the demands of targets; improvements in target fabrication inspired by the need to control and minimize hydrodynamic instabilities in the implosion; and multi-dimensional simulations and diagnostics have been critical to this achievement. This paper will summarize the scientific and technical advances, the surprises, and the challenges that had to be overcome to achieve these goals.

fusion↗
DOE OSTI2025

Time-resolved measurements of OH during auto-ignition of syngas with trimethylsilanol and hexamethyldisiloxane

The effects of trimethylsilanol (TMSO) and hexamethyldisiloxane (HMDSO) addition on OH time histories during syngas (H 2 and CO) ignition were investigated using the University of Michigan rapid compression facility. Experiments spanned temperatures of 1010–1080 K, at a pressure of approximately 5 atm. Syngas mixtures of 1.2 % H 2 /2.8 % CO/20 % O 2 by volume (balance N 2 and Ar) provided a baseline for comparison with mixtures that included 100, 200, and 1000 ppm of the TMSO and 100 ppm of HMDSO. Narrow-line ultraviolet laser-absorption was used to measure OH mole-fraction during ignition. The addition of TMSO and HMDSO significantly shifted the OH time-histories earlier in time, by up to 51 %, compared with the baseline syngas mixture. The value of the maximum OH mole fraction was consistent between the 100 and 200 ppm TMSO mixtures and the 100 ppm HMDSO mixtures, but the maximum OH increased significantly with the 1000 ppm TMSO mixtures. Here, the OH data indicate TMSO and HMDSO were not direct sources of OH radicals. Analysis further indicates the TMSO and HMDSO decompose rapidly followed by reactions that enhance the production of H atoms, and the increased reactivity observed is via the H + O 2 = OH + O reaction.

Hexamethyldisiloxane↗
DOE OSTI2024

How ignition and target gain > 1 were achieved in inertial fusion

For many decades the running joke in fusion research has been that “fusion” is twenty years away and always will be. Yet, in 2023 we find ourselves in a position where we can talk about the milestones of burning plasmas, fusion ignition, and target energy gain greater than unity in the past tense – a situation that is remarkable! Herein this paper tells some of the story of the applied physics challenges that needed to be overcome to achieve these milestones and the strategy our team followed. Things did not always go well and some practical lessons learned are part of this story. The data shows, getting to a burning plasma in late 2020 and early 2021 was a key tipping-point, after which ignition (August 8, 2021) and target gain (December 5, 2022) were rapidly achieved.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2026

High-Efficiency Mixing Controlled Compression Ignition Combustion of Propane DME Blends

The program is a multi-institutional effort led by the University of Wisconsin-Madison Engine Research Center, partnered with WM International and the University of Central Florida, aiming to revolutionize combustion technology for medium-duty commercial vehicles. The project’s primary objective is to develop a high-efficiency mixing controlled compression ignition (MCCI) combustion strategy utilizing propane and propane/DME blends. This development is crucial because current propane-fueled spark-ignited (SI) engines operate at substantially lower efficiencies (BTE of 31.5%) than comparable modern diesel engines (37.1%).

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS1925

Determination of ignition points of liquid fuels under pressure

Two series of experiments were tried, in order to determine the ignition point at any desired pressure, the first series at constant and the second at varying pressure. The results differ greatly and indicate that testing under pressure, in the investigation of liquid fuels, can be done best in the laboratory and that the determination of the ignition points in an open vessel furnishes no certain indication of the behavior of the fuel in the engine.

FUELS↗
NASA NTRS1952

Ignition Delay Experiments with Small-scale Rocket Engine at Simulated Altitude Conditions Using Various Fuels with Nitric Acid Oxidants / Dezso J. Ladanyi

Ignition delay determinations of several fuels with nitric oxidants were made at simulated altitude conditions utilizing a small-scale rocket engine of approximately 50 pounds thrust. Included in the fuels were aniline, hydrazine hydrate, furfuryl alcohol, furfuryl mercaptan, turpentine, and mixtures of triethylamine with mixed xylidines and diallyaniline. Red fuming, white fuming, and anhydrous nitric acids were used with and without additives. A diallylaniline - triethylamine mixture and a red fuming nitric acid analyzing 3.5 percent water and 16 percent NO2 by weight was found to have a wide temperature-pressure ignition range, yielding average delays from 13 milliseconds at 110 degrees F to 55 milliseconds at -95 degrees F regardless of the initial ambient pressure that ranged from sea-level pressure altitude of 94,000 feet.

XYLIDINE↗
NASA NTRS1953

Ignition Delays of Alkyl Thiophosphites with White and Red Fuming Nitric Acids Within Temperature Range 80 to -105 F

Ignition delays of alkyl thiophosphites were obtained in a modified open-cup apparatus and a small-scale rocket engine apparatus. At -40 F, mixed alkyl thiophosphites gave short delays with white fuming nitric acid containing 2 percent water and red fuming nitric acids of widely varying compositions. At -40 F and higher, triethyl trithiophosphite blended with as much as 40 percent n-heptane gave satisfactory self-igniting properties at temperatures as low as -76 F.

FUELS - PROPERTIES PHYSICAL AND CHEMICAL↗
NASA NTRS1946

Analysis of Spark-Ignition Engine Knock as Seen in Photographs Taken at 200,000 Frames Per Second

A motion picture of the development of knock in a spark-ignition engine, is presented, which consists of 20 photographs taken at intervals of 5 microseconds, or at a rate of 200,000 photographs a second, with an equivalent wide-open exposure time of 6.4 microseconds for each photograph. A motion picture of a complete combustion process, including the development of knock, taken at the rate of 40,000 photographs a second is also presented to assist the reader in orienting the photographs of the knock development taken at 200,000 frames per second. The photographs taken at 200,000 frames per second are analyzed and the conclusion is made that the type of knock in the spark-ignition engine involving violent gas vibration originates as self-propagating disturbance starting at a point in the.burn1ig or autoigniting gases and spreading out from that point through the incompletely burned gases at a rate as high as 6800 feet per second, or about twice the speed of sound in the burned gases. Apparent formation of free carbon particles in both the burning and the burned gas is observed within 10 microseconds after passage of the knock disturbance through the gases.

CAMERAS-NACA (MOVING PICTURE)(HIGH SPEED)↗
NASA NTRSDate not supplied

Hydroxyl Tagging Velocimetry Demonstration in an Augmented Spark Igniter

Hydroxyl tagging velocimetry (HTV) involves tagging a flow by “writing” a line of OH molecules using a laser beam to dissociate H2O molecules and capturing an image of the line after a short delay using laser-induced fluorescence. Velocity is obtained by a time-of-flight analysis of the data. In this effort, HTV was used for obtaining both instantaneous and average velocity profiles in the flow of an augmented spark igniter. Two modes of camera readout were investigated, called conventional full frame mode and dual image mode feature (DIF) mode. In DIF mode, two images are captured in quick succession and therefore the measurement is immune to vibration effects. Measurement uncertainty for the DIF case varied from 3% at the centerline to 10% at the edges of the profile in a 1000-m/s flow. For the full-frame case, measurement uncertainty varied from 3% at the centerline to 7% at the edges. This demonstration provides evidence that the HTV technique is well suited for obtaining velocity profiles in the challenging environment of either a rocket engine or rocket engine igniter.

Augmented Spark Igniter↗
NASA NTRSDate not supplied

Particle Impact Simulation and Ignition Prediction

An experimentally calibrated tool is needed to predict if a system is susceptible to failure by particle impact ignition (PI) based on use conditions, materials, and flow geometry. This tool will accelerate new components, evaluating existing hardware, and help disposition anomalies. Conduct particle impact testing with in-situ diagnostics and complementary simulations on subset of key engineering materials (IN718, M400, 316L, 6061, Ti64, Zr) to develop a proof-of-concept predictive tool for assessing the risk of PI for idealized geometries (spherical particles) in realistic environments. Assess particle/target interactions (coefficient of restitution, ignition, kindling) using instrumented particle impact rigs while systematically varying key parameters (materials, particle size, environment, target configuration). Determine key field variables (temperature, strain, stress) in particle impacts using Multiphysics finite element and hydrocode simulations validated through comparison with experimental measurements and observations. Synthesize experiments and simulations into constitutive models for PI that can be integrated with existing computational fluid dynamics (CFD) and Debris Transport Analysis (DTA) tools in future efforts

particle impact↗
NASA NTRSDate not supplied

SLS Ignition Overpressure-Sound Suppression System Performance Evaluated Against Historical Configurations

During the start-up of a number of launch vehicles that include solid rocket motor (SRM), the ignition transient and acoustic environments are mitigated by the implementation of a water spray system located immediately below the SRM nozzle exit plane (NEP). For NASA’s Space Launch System (SLS), this water system is referred to as the Ignition Overpressure / Sound Suppression (IOP/SS) system. The SLS Induced Environments (IE) technical discipline conducted a comprehensive evaluation of the design and as-tested performance of the IOP/SS water that will operate underneath both Boosters during the Artemis I launch. As part of this evaluation, flow rates and imagery from a number of integrated launch pad / mobile launcher IOP/SS flow tests were studied. Additional insight was leveraged from the Shuttle heritage IOP/SS system that includes data and imagery from a number of Flight Readiness Firings (FRF) and water flow tests. Lastly, the IE study included a qualitive comparison of the Shuttle and SLS systems to the equivalent water flow systems for Titan and Atlas V and determined that the NASA water flow systems are substantially different than those supporting other launch vehicles.

Ignition Overpressure↗
NASA NTRSDate not supplied

SLS Ignition Overpressure-Sound Suppression System Performance Evaluated Against Historical Configurations

During the start-up of a number of launch vehicles that include solid rocket motor (SRM), the ignition transient and acoustic environments are mitigated by the implementation of a water spray system located immediately below the SRM nozzle exit plane (NEP). For NASA’s Space Launch System (SLS), this water system is referred to as the Ignition Overpressure / Sound Suppression (IOP/SS) system. The SLS Induced Environments (IE) technical discipline conducted a comprehensive evaluation of the design and as-tested performance of the IOP/SS water that will operate underneath both Boosters during the Artemis I launch. As part of this evaluation, flow rates and imagery from a number of integrated launch pad / mobile launcher IOP/SS flow tests were studied. Additional insight was leveraged from the Shuttle heritage IOP/SS system that includes data and imagery from a number of Flight Readiness Firings (FRF) and water flow tests. Lastly, the IE study included a qualitive comparison of the Shuttle and SLS systems to the equivalent water flow systems for Titan and Atlas V and determined that the NASA water flow systems are substantially different than those supporting other launch vehicles.

Ignition Overpressure↗
NASA NTRS2024

Reliable Ignition of LOX-LCH4 Propellants

No cryogenic Reaction Control System (RCS) has ever flown in space. Cryogenic propellants are baselined by HLS and CLPS partners and are the key use case for future ISRU manufactured propellants. A reliable LOX/LCH 4 RCS is an enabling technology for human Lunar and Mars exploration. In previous thermal vacuum (<275 F, <10 torr) testing at NASA GRC Plum Brook, the team uncovered anomalous LOX/LCH4 engine ignition phenomena where flame kernels quenched at these ultra cold hardware temperatures, leading to many pulses where the engines would not light. In 2022, the project was able to recreate the no light condition with an upgraded Frost-Mint test stand at JSC. This project implemented test stand improvements and procured propellants and follow on engine components for a hot fire campaign beginning in November 2024 which will attempt to ignite the RCS engine at ultra cold vacuum conditions by modifying the engine mixture ratio. New modeling techniques were implemented to account for past no lights and are an enabling method to make lunar surface go no go predictions based on hardware conditions. This was enabled by significant improvements to the Frost Mint system, which reduced moisture build up and leaks, increased propellant availability, leading to more attempts at thermal vacuum hot-fires.

Propulsion↗