Stability of liquid-fuel-rocket engine operation ustoychivost' raboty zhidkostnogo raketnogo dvigatelya
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Artamanov, K. I.↗
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Results for “liquid fuel”
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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Addition of solid oxidizer increases liquid fuel specific impulse
Adding soluble solid oxidizers to hydrazine and similar fuels makes them useful in low temperature bipropellant systems. These oxidizers improve the low specific impulse, high freezing point, low boiling point, and low density of the fuels.
Hendel, F. J.↗
Secondary nondestructive instability in medium size liquid fuel rocket engines
Linearized mathematical models of feed-system-coupled combustion instability are summarized and discussed. Following the derivation of sufficient conditions for stability from the simplest bipropellant model, the complications that are imposed on the model by compressible fluids in the feed system, nonrigid feed system structures, and time-varying combustion processes are considered. A specific case of an instability associated with a nonrigid injector is described; it is shown that the instability was eliminated by the method predicted by the model to be most effective for control. A bibliography lists papers dealing with these kinds of stabilities.
R J Fontaine↗
Catalytic hydrosolvation process converts coal to low-sulfur liquid fuel
Development of the catalytic hydrosolvation process for converting coal to low-sulfur fuel oil is described in this paper. Coal impregnated with catalyst was slurried with oil, and the mixture was hydrogenated at a temperature of 475 C, and 30 min residence time under 3600 psi pressure. A ton of coal yielded 3.5 bbl of fuel oil containing 0.2% sulfur, with naphtha and C1-C4 hydrocarbon gases as byproducts. A preliminary economic evaluation of the process indicated potential for further development.
Qader, S. A.↗
Calculation of CO concentration for liquid fueled gas turbine combustor
The extensive computation time required for the numerical integration of the differential equations obtained in studies of the concentrations of pollutants emitted by gas turbine combustors, can be reduced significantly by assuming the heat releasing hydrocarbon reactions to be in local equilibrium. In determining the CO and NO concentrations produced in spray combustion, it is, therefore, tempting to use the same local equilibrium assumption in order to simplify the kinetic calculations. An investigation of the validity of the local equilibrium assumption is conducted by using a simple analytical model, and then by actually carrying out the kinetic and local equilibrium calculations for typical case.
Patil, P. B.↗
A study of the conversion of coal to hydrogen, methane and liquid fuels for aircraft
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Tsaros, C. L.↗
Analysis of combustion instability in liquid fuel rocket motors
The development of an analytical technique used in the solution of nonlinear velocity-sensitive combustion instability problems is presented. The Galerkin method was used and proved successful. The pressure wave forms exhibit a strong second harmonic distortion and a variety of behaviors are possible depending on the nature of the combustion process and the parametric values involved. A one dimensional model provides insight into the problem by allowing a comparison of Galerkin solutions with more exact finite difference computations.
Wong, K. W.↗
Analysis of Combustion Instability in Liquid Fuel Rocket Motors
The development of a technique to be used in the solution of nonlinear velocity-sensitive combustion instability problems is described. The orthogonal collocation method was investigated. It found that the results are heavily dependent on the location of the collocation points and characteristics of the equations, so the method was rejected as unreliabile. The Galerkin method, which has proved to be very successful in analysis of the pressure sensitive combustion instability was found to work very well. It was found that the pressure wave forms exhibit a strong second harmonic distortion and a variety of behaviors are possible depending on the nature of the combustion process and the parametric values involved. A one-dimensional model provides further insight into the problem by allowing a comparison of Galerkin solutions with more exact finite-difference computations.
Wong, K. W.↗
A laser tomographic investigation of liquid fuel sprays
A light scattering technique is combined with a tomographic transformation to convert line of sight integrated data, measured in sprays, to measurements of droplet size and concentration in volume elements within the spray. The technique is developed and assessed by systematic experiments in axisymmetric sprays generated by twin-fluid atomisers. The good agreement found shows that, provided certain conditions are satisfied by the local spray structure, the technique provides information on spray structure, similar in detail and extent to that derived by photography, but with reduced experimental time. The technique is applied to an investigation of a kerosene spray vaporizing in a hot gas stream.
Yule, A. J.↗
Deposit formation in liquid fuels. II - The effect of selected compounds on the storage stability of Jet A turbine fuel
The influence of substituted pyridines, pyrroles, indoles, and quinolines on the storage stability of conventional Jet A turbine fuel is evaluated. Significant increases in the amount of deposit formed in accelerated storage tests are found upon addition of these compounds at levels as low as one ppm nitrogen. While the effect is correlated with basicity of the nitrogen compound within a given compound class, the correlation does not hold between classes (pyridines, quinolines, etc.). Steric hindrance at the nitrogen atom greatly inhibits deposit promotion. The characteristics, but not the elemental composition, of deposits vary with the identity of the added nitrogen compound and with deposition temperature.
Worstell, J. H.↗
Deposit formation in liquid fuels. III - The effect of selected nitrogen compounds on diesel fuel
The influence of substituted quinolines, pyrroles, indoles, and pyridines on deposit formation in a diesel fuel is evaluated. Significant increases in deposition rate are found which are dependent upon the basicity of the nitrogen compound within a given compound class. These effects correspond closely with those produced in a Jet A fuel. Removal of highly polar fuel components renders the nitrogen compound influence inoperative. These components are therefore participants in deposit-forming reactions.
Worstell, J. H.↗
A laser tomographic investigation of liquid fuel sprays
(Previously announced in STAR as N80-17399)
Yule, A. J.↗
High-pressure flame visualization of autoignition and flashback phenomena with liquid-fuel spray
A study was undertaken to determine the effect of boundary layers on autoignition and flashback for premixed Jet-A fuel in a unique high-pressure windowed test facility. A plate was placed in the center of the fuel-air stream to establish a boundary layer. Four experimental configurations were tested: a 24.5-cm-long plate with either a pointed leading edge, a rounded edge or an edge with a 0.317-cm step, or the duct without the plate. Experiments at an equivalence ratio ranging from 0.4 to 0.9 were performed at pressures to 2500 kPa (25 atm.) at temperatures of 600, 645, and 700 K and velocities to 115 meters per second. Flame shapes were observed during flashback and autoignition using high speed cinematography. Flashback and autoignition limits were determined.
Marek, C. J.↗
A study of mesospheric rocket contrails and clouds produced by liquid-fueled rockets
Changes in the atmospheric composition, particularly through the condensation of rocket vehicle exhaust, caused by the flights of 400 heavy lift launch vehicles (HLLV) to carry crews and materials into space to build a satellite solar power system (SPS) were examined. Attention was given to the formation of mesospheric contrails and clouds. A one-dimensional model was used to formulate the photochemistry and vertical transport of water vapor, its nucleation into an ice cloud, and the microphysical development of the cloud. Considering one HLLV launch per day for a decade, it is projected that the upper atmosphere water vapor concentration would be increased by 10-20%, thereby augmenting the size and opacity of natural noctilucent clouds by 50%. No climatological consequences are foreseen from the clouds, although spectacular noctiluminescent cloud displays are thought to be possible.
Turco, R. P.↗
Combustion characteristics in the transition region of liquid fuel sprays
A number of important effects were observed in the droplet size transition region in spray combustion systems. In this region, where the mechanism of flame propagation is transformed from diffusive to premixed dominated combustion, the following effects have been observed: (1) maxima in burning velocity; (2) extension of flammability limits; (3) minima in ignition energy; and (4) minima in NO(x) formation. Unfortunately, because of differences in experimental facilities and limitations in the ranges of experimental data, a unified description of these transition region effects is not available at this time. Consequently, a fundamental experimental investigation was initiated to study the effect of droplet size, size distribution, and operating parameters on these transition region phenomena in a single well controlled spray combustion facility.
Cernansky, N. P.↗
Automatic holographic droplet analysis for liquid fuel sprays
The basic scheme for automated holographic analysis involves an optical system for reconstruction of the three dimensional real image of the droplet field, a spatial scanning system to transport a digitizing X-y image sensor through the real image, and processing algorithms for droplet recognition which establish the droplet sizes and positions. The hardware for system demonstrated includes the expanded and collimated beam from a 5 mW helium-neon laser for hologram reconstruction, an imaging lens for magnification of the real image field, and a video camera and digitizer providing 512-by-512 pixel resolution with 8-bit digitization. A mechanical stage is used to scan the hologram in three dimensional space, maintaining constant image magnification. A test droplet hologram is used for development and testing of the image processing algorithms.
Stanton, A. C.↗
Combustion characteristics in the transition region of liquid fuel sprays
A monodisperse aerosol generator was modified to study ignition requirements, flammability limits, and flame speeds in the transition region. An ignition system was developed and tested. The fabrication of an optical drop sizing system is nearly complete. Preliminary measurements of droplet size effects on the minimum ignition energy for n-heptane sprays performed. Parameteric studies of droplet size effects on minimum ignition energies of various fuels including alcohols are in progress.
Cernansky, N. P.↗
Oxides of Nitrogen Emissions from the Combustion of Monodisperse Liquid Fuel Sprays
A study of NO sub x formation in a one dimensional monodisperse spray combustion system, which allowed independent droplet size variation, was conducted. Temperature, NO and NO sub x concentrations were measured in the transition region, encompassing a 26 to 74 micron droplet size range. Emission measurements of hydrocarbons, carbon monoxide, carbon dioxide and oxygen were also made. The equivalence ratio was varied between 0.8 and 1.2 for the fuels used, including methanol, isopropanaol, n-heptane and n-octane. Pyridine and pyrrole were added to n-heptane as nitrogen-containing additives in order to simulate synthetic fuels. Results obtained from the postflame regions using the pure fuels indicate an optimum droplet size in the range of 43 to 58 microns for minimizing NO sub x production. For the fuels examined, the maximum NO sub x reductions relative to the small droplet size limit were about 10 to 20% for lean and 20 to 30% for stoichiometric and rich mixtures. This behavior is attributed to droplet interactions and the transition from diffusive to premixed type of burning. Preflame vaporization controls the gas phase stoichiometry which has a significant effect on the volume of the hot gases surrounding a fuel droplet, where NO sub x is formed.
Sarv, H.↗