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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 NTRS1975

Manufacture and static firing of X259-E6 rocket motor serial number XJ04/0001

A single motor was cast and static fired to demonstrate the performance of high energy crosslinked double base (XLDB) propellant in standard X259 rocket motor hardware. Prior to motor fabrication, the motor was analyzed to predict the results of static firing the X259 motor loaded with XLDB propellant. As a result of the analyses, a forward dome shrinkage liner was added to the design. With this design change it was determined that adequate margins of safety existed. The motor, designated the X259-E6 model with serial number XJ04/0001, was fabricated using a slurry-casting technique and was assembled with a standard X259-B4 nozzle which had the nozzle throat machined to a smaller inside diameter than the B4 model and the exit cone cut short for Bacchus Works altitude expansion. The motor was static fired on 20 February 1974 with the nozzle failing during motor operation. Nozzle failure was attributed to spalling of the throat material leading to complete nozzle break-up. However, the propellant functioned as predicted in the motor chamber, ignition was normal, and char and erosion of the internal insulator were as expected.

Robertson, D. R.↗
NASA NTRS2001

Rocket Launch-Induced Vibration and Ignition Overpressure Response

Rocket-induced vibration and ignition overpressure response environments are predicted in the low-frequency (5 to 200 hertz) range. The predictions are necessary to evaluate their impact on critical components, structures, and facilities in the immediate vicinity of the rocket launch pad.

Caimi, Raoul E.↗
NASA NTRS2001

Rocket Launch-Induced Vibration and Ignition Overpressure Response

Rocket-induced vibration and ignition overpressure response environments are predicted in the low-frequency (5 to 200 hertz) range. The predictions are necessary to evaluate their impact on critical components, structures, and facilities in the immediate vicinity of the rocket launch pad.

Caimi, Raoul↗
NASA NTRS2010

Propellant Readiness Level: A Methodological Approach to Propellant Characterization

A methodological approach to defining propellant characterization is presented. The method is based on the well-established Technology Readiness Level nomenclature. This approach establishes the Propellant Readiness Level as a metric for ascertaining the readiness of a propellant or a propellant combination by evaluating the following set of propellant characteristics: thermodynamic data, toxicity, applications, combustion data, heat transfer data, material compatibility, analytical prediction modeling, injector/chamber geometry, pressurization, ignition, combustion stability, system storability, qualification testing, and flight capability. The methodology is meant to be applicable to all propellants or propellant combinations; liquid, solid, and gaseous propellants as well as monopropellants and propellant combinations are equally served. The functionality of the proposed approach is tested through the evaluation and comparison of an example set of hydrocarbon fuels.

Bossard, John A.↗
NASA NTRS1992

Analytical flow/thermal modeling of combustion gas flows in Redesigned Solid Rocket Motor test joints

A one-dimensional analytical tool, TOPAZ (Transient One-dimensional Pipe flow AnalyZer), was used to model the flow characteristics of hot combustion gases through Redesigned Solid Rocket Motor (RSRM) joints and to compute the resultant material surface temperatures and o-ring seal erosion of the joints. The capabilities of the analytical tool were validated with test data during the Seventy Pound Charge (SPC) motor test program. The predicted RSRM joint thermal response to ignition transients was compared with test data for full-scale motor tests. The one-dimensional analyzer is found to be an effective tool for simulating combustion gas flows in RSRM joints and for predicting flow and thermal properties.

Woods, G. H.↗
NASA NTRS2000

Annual Research Briefs - 2000: Center for Turbulence Research

This report contains the 2000 annual progress reports of the postdoctoral Fellows and visiting scholars of the Center for Turbulence Research (CTR). It summarizes the research efforts undertaken under the core CTR program. Last year, CTR sponsored sixteen resident Postdoctoral Fellows, nine Research Associates, and two Senior Research Fellows, hosted seven short term visitors, and supported four doctoral students. The Research Associates are supported by the Departments of Defense and Energy. The reports in this volume are divided into five groups. The first group largely consists of the new areas of interest at CTR. It includes efficient algorithms for molecular dynamics, stability in protoplanetary disks, and experimental and numerical applications of evolutionary optimization algorithms for jet flow control. The next group of reports is in experimental, theoretical, and numerical modeling efforts in turbulent combustion. As more challenging computations are attempted, the need for additional theoretical and experimental studies in combustion has emerged. A pacing item for computation of nonpremixed combustion is the prediction of extinction and re-ignition phenomena, which is currently being addressed at CTR. The third group of reports is in the development of accurate and efficient numerical methods, which has always been an important part of CTR's work. This is the tool development part of the program which supports our high fidelity numerical simulations in such areas as turbulence in complex geometries, hypersonics, and acoustics. The final two groups of reports are concerned with LES and RANS prediction methods. There has been significant progress in wall modeling for LES of high Reynolds number turbulence and in validation of the v(exp 2) - f model for industrial applications.

Source record↗
NASA NTRS1996

Ignition, Burning, and Extinction of a Strained Fuel Strip

Flame structure and ignition and extinction processes associated with a strained fuel strip are explored numerically using detailed transport and complex kinetics for a propane-air reaction. Ignition modes are identified that are similar to those predicted by one-step activation energy asymptotics, i.e., modes in which diffusion flames can ignite as independent or dependent interfaces, and modes in which single premixed or partially premixed flames ignite. These ignition modes are found to be dependent on critical combinations of strain rate, fuel strip thickness, and initial reactant temperatures. Extinction in this configuration is seen to occur due to fuel consumption by adjacent flames, although viscosity is seen to have the effect of delaying extinction by reducing the effective strain rate and velocity field experienced by the flames.

Selerland, T.↗
NASA NTRS1998

Ignition, Burning and Extinction of a Strained Fuel Strip with Complex Kinetics

Flame structure and ignition and extinction processes associated with a strained fuel strip are explored numerically using detailed transport and complex kinetics for a propane-air reaction. Ignition modes are identified that are similar to those predicted by one-step activation energy asymptotics, i.e., modes in which diffusion flames can ignite as independent or dependent interfaces and modes in which single premixed or partially premixed flames ignite and burn. These ignition modes have been found to be dependent on critical combinations of strain rate, fuel strip thickness and initial reactant temperatures. The formation of NO/NO2 is found to be strongly dependent on strain rate and the local molecular mixing of reactants which occurs as a consequence of strain. Extinction in this configuration is seen to occur due to fuel consumption by adjacent flames, although viscosity is seen to have the effect of delaying extinction by reducing the effective strain rate experienced by the flames. Response of the flames to oscillatory strain rates is seen to be strongly dependent on the amplitude and frequency of the oscillation.

Selerland, T.↗
NASA NTRS2004

Single Droplet Combustion of Decane in Microgravity: Experiments and Numerical Modeling

This paper presents experimental data on single droplet combustion of decane in microgravity and compares the results to a numerical model. The primary independent experiment variables are the ambient pressure and oxygen mole fraction, pressure, droplet size (over a relatively small range) and ignition energy. The droplet history (D(sup 2) history) is non-linear with the burning rate constant increasing throughout the test. The average burning rate constant, consistent with classical theory, increased with increasing ambient oxygen mole fraction and was nearly independent of pressure, initial droplet size and ignition energy. The flame typically increased in size initially, and then decreased in size, in response to the shrinking droplet. The flame standoff increased linearly for the majority of the droplet lifetime. The flame surrounding the droplet extinguished at a finite droplet size at lower ambient pressures and an oxygen mole fraction of 0.15. The extinction droplet size increased with decreasing pressure. The model is transient and assumes spherical symmetry, constant thermo-physical properties (specific heat, thermal conductivity and species Lewis number) and single step chemistry. The model includes gas-phase radiative loss and a spherically symmetric, transient liquid phase. The model accurately predicts the droplet and flame histories of the experiments. Good agreement requires that the ignition in the experiment be reasonably approximated in the model and that the model accurately predict the pre-ignition vaporization of the droplet. The model does not accurately predict the dependence of extinction droplet diameter on pressure, a result of the simplified chemistry in the model. The transient flame behavior suggests the potential importance of fuel vapor accumulation. The model results, however, show that the fractional mass consumption rate of fuel in the flame relative to fuel vaporized is close to 1.0 for all but the lowest ambient oxygen mole fractions.

Dietrich, D. L.↗
NASA NTRS1976

Shock wave ignition of metal powders

The interaction between isolated metal particles and shock-induced flowfields is analyzed to characterize physical events and determine experimental feasibility for shock wave ignition studies. Emphasis is placed on incident shock wave phenomenon as opposed to reflected shock wave. A pre-ignition particle-flow interaction is hypothesized which presumes a vapor phase ignition reaction and an absence of significant vaporization prior to particle melting and erosion. Rapid vaporization of eroded mass is expected, with ignition reaction in the particle wakes. Experimental observation of the 6438-A Cd line and the 3721-A MgO band support the ignition mechanism hypothesized. Scattered cloud data are believed to substantiate the hypothesis that ignition delays could be correlated with predicted melting times.

Fox, T. W.↗
NASA NTRS1986

On the Theory of Type 1 X-Ray Bursts: The Energetics of Bursts and the Nuclear Fuel Reservoir in the Envelope

The observed properties of type 1 X-ray bursts from 4U/MXB 1636-53 and those of models of thermonuclear flashes on accreting neutron stars are compared. Ways to explain variations in the burst recurrence properties without an apparent correlation with the accretion rate, including the rapid succession of bursts at intervals 10 min are discussed. The strongest X-ray bursts, which occur after a very long interval, are well described by thermonuclear flash models with simple accumulation of accreted fuel, and a spherically symmetric structure in the burning shell. The majority of observed bursts, however, occur after much shorter intervals, and radiate much smaller amounts of energy, by a factor of up to 10 times that predicted by the spherical models. An ignition mechanism of the bursts is proposed in terms of elemental mixing and dissipative heating associated with hydrodynamical instabilities in the neutron star envelope caused by angular momentum carried inward by accreted gas.

Fujimoto, Masayuki Y.↗
NASA NTRS1986

Comparisons between thermodynamic and one-dimensional combustion models of spark-ignition engines

Results from a one-dimensional combustion model employing a constant eddy diffusivity and a one-step chemical reaction are compared with those of one-zone and two-zone thermodynamic models to study the flame propagation in a spark-ignition engine. One-dimensional model predictions are found to be very sensitive to the eddy diffusivity and reaction rate data. The average mixing temperature found using the one-zone thermodynamic model is higher than those of the two-zone and one-dimensional models during the compression stroke, and that of the one-dimensional model is higher than those predicted by both thermodynamic models during the expansion stroke. The one-dimensional model is shown to predict an accelerating flame even when the front approaches the cold cylinder wall.

Ramos, J. I.↗
NASA NTRS1956

Spark ignition of flowing gases

Research conducted at the NACA Lewis Laboratory on ignition of flowing gases by means of long-duration discharges is summarized and analyzed. Data showing the effect of a flowing combustible mixture on the physical and electrical characteristics of spark discharges and data showing the effects of variables on the spark energy required for ignition that has been developed to predict the effect of many of the gas-stream and spark variables is described and applied to a limited amount of experimental data.

Swett, Clyde C , Jr↗
NASA NTRS2000

RSRM Propellant Grain Geometry Modification

This document is composed of viewgraphs about the RSRM propellant grain geometry modification project, which hopes to improve personnel and system safety by modifying propellant grain geometry to improve structural factors of safety. Using techniques such as Finite Element Analysis to determine blend radii required to reduce localized stresses, and ballistic predictions to ensure that the ballistics, ignition transient and Block Model have not been adversely affected, the project hopes to build and test FSM-10 with a new design, and determine flight effectivity pending successful test evaluation.

Schorr, Andrew A.↗
NASA NTRS2016

CFD Based Design of a Filming Injector for N+3 Combustors

An effort was undertaken to perform CFD analysis of fluid flow in Lean-Direct Injection (LDI) combustors with axial swirl-venturi elements for next-generation LDI-3 combustor design. The National Combustion Code (NCC) was used to perform non-reacting and two-phase reacting flow computations for a newly-designed pre-filming type fuel injector LDI-3 injector, in a single-injector and a five-injector array configuration. All computations were performed with a consistent approach of mesh-optimization, spray-modeling, ignition and kinetics-modeling. Computational predictions of the aerodynamics of the single-injector were used to arrive at an optimized main-injector design that meets effective area and fuel-air mixing criteria. Emissions (EINOx) characteristics were predicted for a medium-power engine cycle condition, and will be compared with data when it is made available from experimental measurements. The use of a PDF-like turbulence-chemistry interaction model with NCC's Time-Filtered Navier-Stokes (TFNS) solver is shown to produce a significant impact on the CFD results, when compared with a laminar-chemistry TFNS approach for the five-injector computations.

combustion chambers↗
NASA NTRS1991

A computer program to perform flow and thermal analysis during pressurization of the Space Shuttle Solid Rocket Motor field joint

A computational technique for prediction of the flow and thermal environment in the SRM field joint cavities is described. The SRM field joint hardware was tested with a defect in the insulation, and due to this defect, the O-ring gland cavities are pressurized during the early part of the ignition. A computer model is developed to predict the thermal environment and flow through the simulated flaw, during the pressurization of the field joint. The transient mass, momentum, and energy conservation equations in the flow passage together with the thermodynamic equation of state are solved by a fully implicit iterative numerical procedure.

Clayton, J. Louie↗
NASA NTRS2014

Combustion Stability Characteristics of the Project Morpheus Liquid Oxygen / Liquid Methane Main Engine

The project Morpheus liquid oxygen (LOX) / liquid methane (LCH4) main engine is a Johnson Space Center (JSC) designed ~5,000 lbf-thrust, 4:1 throttling, pressure-fed cryogenic engine using an impinging element injector design. The engine met or exceeded all performance requirements without experiencing any in- ight failures, but the engine exhibited acoustic-coupled combustion instabilities during sea-level ground-based testing. First tangential (1T), rst radial (1R), 1T1R, and higher order modes were triggered by conditions during the Morpheus vehicle derived low chamber pressure startup sequence. The instability was never observed to initiate during mainstage, even at low power levels. Ground-interaction acoustics aggravated the instability in vehicle tests. Analysis of more than 200 hot re tests on the Morpheus vehicle and Stennis Space Center (SSC) test stand showed a relationship between ignition stability and injector/chamber pressure. The instability had the distinct characteristic of initiating at high relative injection pressure drop at low chamber pressure during the start sequence. Data analysis suggests that the two-phase density during engine start results in a high injection velocity, possibly triggering the instabilities predicted by the Hewitt stability curves. Engine ignition instability was successfully mitigated via a higher-chamber pressure start sequence (e.g., ~50% power level vs ~30%) and operational propellant start temperature limits that maintained \cold LOX" and \warm methane" at the engine inlet. The main engine successfully demonstrated 4:1 throttling without chugging during mainstage, but chug instabilities were observed during some engine shutdown sequences at low injector pressure drop, especially during vehicle landing.

Melcher, John C.↗