Showing papers on "Propellant published in 1981"

Apparatus for dispensing a carbonated beverage

Abstract: Apparatus for dispensing a carbonated beverage including a source of propellant gas, a reservoir for beverage to be dispensed, one or more dispensing valves connected to the reservoir, a propellant gas conduit for applying a first gaseous propellant pressure upon beverage supply vessels and for applying a second and lesser gaseous propellant pressure upon beverage in the reservoir, a beverage supply conduit for transferring beverage from a supply vessel to the reservoir and normally closed valves in the beverage supply and gas conduits, which valves are controllable by a level sensor in the reservoir; the apparatus also features structure for automatically switching from one supply vessel to another as vessels become emptied; a method of dispensing includes the steps of providing a supply of carbonated beverage, applying a first propellant pressure upon the supply, selectively transferring beverage from the supply to a reservoir, applying a second and lesser propellant pressure upon the reservoir and dispensing from the reservoir; there is also a step of automatically switching supply vessels as they become empty.

A model for solid propellant combustion

Abstract: A model has been developed to describe the combustion characteristics of composite solid propellants. The model is based on several new concepts. First, the oxidizer and binder have different surface temperatures rather than a single averaged temperature that has previously been assumed. Second, the overall burn rate is calculated from a time averaged approach rather than the conventional space averaging used in most propellant combustion models. A key contribution in the time averaging approach is use of an ignition delay time for the oxidizer. Third, a generalized flame standoff distance has been developed based on a modified Burke-Schumann diffusion flame analysis. The analysis accounts for variable oxidizer/fuel (O/F) ratio that differing oxidizer size fractions can experience. The analysis shows that the primary diffusion flame can extend over either the oxidizer or the fuel depending on the local O/F ratio. Calculated results for a series of HMX composite propellants show several key trends and excellent agreement when compared to experimental data. The propellants vary in oxidizer particle size and concentration over a range of pressures and temperatures. The model indicates that the fuel binder has a more significant influence than previously thought.

High-velocity jet and propellant fracture device for gas and oil well production

Abstract: An integrated jet perforation and controlled propellant fracture device and method for enhancing production in oil or gas wells, wherein the device is inserted in a well bore to the level of a geological production structure; the fracturing device being constructed with a cylindrical housing of variable cross-section and wall-thickness with the housing filled with combustible propellant gas generating materials surrounding specially oriented and spaced shaped charges, having an abrasive material distributed within the propellant filled volume along the device length to produce enhanced perforations with attendant pressure-controlled gas and fluid injection into the perforations to produce controlled frac entry at point or points desired in the producing zones of the well bore, wherein a high velocity jet penetrates the production zone of the well bore initiating fractures, and is simultaneously followed by a high pressure propellant material which amplifies and propagates the jet initiated fractures.

Characterization of Participates in the Exhaust Plume of Large Solid-Propellant Rockets

Abstract: Because of the very large size of the solid-propellant booster rockets employed by the Space Shuttle Launch System, and because of the projected high frequency of Space Shuttle launches, it has been necessary to estimate the effect of this launch activity on the environment. Two major combustion products of the rocket propellant employed in the Space Shuttle boosters are aluminum oxide (AI2O3) particles and hydrogen chloride (HC1) gas. This report is concerned with the characterization of these A12O3 particles in the atmosphere. Size distribution and number density results obtained by flying aerosol collecting and analyzing instruments through the *'ground clouds' and the high-altitude "exhaust plumes" generated by several Titan III launch vehicles, and by subsequent reduction of these data, are presented. The very-high-number densities of submicron-size particles detected in both the "ground cloud" and the high-altitude ''exhaust plume" constitute the principal and, to some extent, unanticipated results of this investigation. Preliminary results regarding the physical appearance, chemical composition, and crystallography of the particles were obtained through examination of collected particulates by scanning electron microscopy.

HTPB Propellant Aging

Abstract: Three HTPB propellants, varying in solids loading from 88% to 91%, were selected and developed for evaluation studies including aging. The 88%-solids propellant was verified to fit a previously developed aging model. The aging model has been further successfully applied to the measured mechanical-property aging data for the higher-solids propellants with excellent definition of behavior as well as HTPB propellants from other programs. The model has been used to predict long-time mechanical-property behavior from thermally accelerated tests and the results agree with 6 yr of measured aging data. The predicted failure properties can be used with motor requirements to determine service life for the grain of the motor system for a preselected margin of safety. Data are shown comparing the aging rate for the various composite propellants. Analysis of the aging results has provided a mathematical expression for the broad-spectrum aging behavior.

Aerosol spray device

Abstract: An aerosol spray device having a spray container charged with an agent to be sprayed, and an assembly including a bomb charged with a propellant compressed gas and a pressure regulator attached to the outlet side of the bomb. The assembly is mounted and fixed to the inside of the spray container through a packing interposed therebetween. The pressure regulator includes a piston adapted to control the flow of the gas from the bomb into the spray container through the pressure regulator. Means are provided for holding the piston in inoperative position until the aerosol spray device is actually used by the user after fabrication.

Combustion mechanisms of nitramine composite propellants

Abstract: The combustion mechanisms of nitramine composite propellants were investigated to determine the parameters that control the burning rate in combustion waves. The nitramines studied were RDX (cyclotrimethylene trinitramine) and HMX (cyclotetramethylene tetranitramine), which have similar chemical compositions, but different reaction schemes. Since RDX and HMX composite propellants consist of crystalline nitramines and a polymeric binder, the physical structure of these propellants is heterogeneous. From experiments, it was found that the combustion waves of these propellants are homogeneous. In addition, the combustion waves exhibited a two-stage flame structure. The luminous flame produced above the burning surface approached the burning surface when the pressure was increased. However, the burning rates of both RDX and HMX propellants were not affected by the luminous flame reaction. In the preparation zone separating the luminous flame and the burning surface, the gas phase reaction primarily consist of the exothermic reduction reaction of NO to N 2 which is similar to the reaction in the dark zone of double-base propellants. From quenched burning tests, it was found that the nitramines and the binder melted at the burning surface and formed an energetic mixture. Thus, the decomposed gases ejected from the burning surface consisted of a homogeneous mixture of oxidizer and fuel species. The temperature profile measurements in the combustion waves revealed that there is a large heat release at the burning surface. This exothermic decomposition reaction at the surface plays a major role in controlling the burning rate of RDX and HMX composite propellants. The higher burning rate of RDX propellants, as compared to HMX propellants, is due to the larger heat release at their burning surface.

Gas generating charge and a process for producing the same

Abstract: A gas generating propellant charge which is made by piling explosive powder sheets having a plurality of projections on at least one surface thereof so as to make contact them with each other is excellent in firing characteristics, and the explosive powders in the gas generating propellant charge can be burnt in a short time, thereby generating a large amount of gas.

Thermoplastic composite rocket propellant

Abstract: A process is disclosed by which thermoplastic elastomers may be utilized torepare melt-formable composite rocket propellants. The thermoplastic elastomer is dissolved in a volatile organic solvent, the other propellant ingredients are mixed in, and the volatile organic solvent is evaporated. The dried propellant is melt-formed to final shape by molding or extruding above the melting point of the elastomer. An example of a usable thermoplastic elastomer is a block copolymer comprised of about 5 to about 20 weight percent styrene and of about 80 to 95 weight percent diene. The formed grain can be reclaimed by melting or dissolution in an organic solvent for reuse of the propellant ingredients.

Pulsed laser propulsion

Abstract: : A fluid mechanical model is developed to assess the performance in both finite background pressure and vacuum environments of a rocket that is propelled by the absorption of radiant energy from a remotely stationed, repetitively pulsed laser. The model describes the gaseous propellant flow within a conical nozzle that is subjected to a series of point energy depositions at the apex of the cone. An equivalence between conical and parabolic nozzles is discussed for finite background pressure operation. The model predicts laser parameters necessary to achieve high specific impulses, i. e., 600 to 1000 sec. Scaling laws for high thrust - high specific impulse rocket systems are discussed.

Effect of deformation on flame spreading and combustion in propellant cracks

Abstract: A comprehensive theoretical model was formulated to study the development of convective burning in a solid propellant crack which continually deforms due to burning and pressure loading The effect of interrelated structural deformation and combustion processes was included in the theoretical model The set of coupled, nonlinear, governing partial-differential equations was solved numerically Several regions of partial crack closures were observed experimentally in narrow cracks (gap width -450 /on) Predicted results indicate that the partial closures may generate substantial local pressure peaks along the crack, implying a strong coupling between chamber pressurization, crack combustion, and propellant deformation, especially when cracks are narrow and chamber pressurization rates are high Predicted results for ignition-front propagation and pressure distribution are in good agreement with experimental data Both theoretical and experimental results indicate that the maximum pressure in the crack cavity is generally higher than that in the chamber Under the conditions studied, it was found that the initial flame-spreading process is not affected substantially by propellant deformation

Spray head apparatus

Abstract: An elongated member is provided in the discharge orifice of a spray head nozzle so that the fluid being sprayed is discharged as a hollow stream resulting inter alia in a better and more complete atomization of the fluid in coaction with a low pressure propellant.

Device for dispensing a single-component or multi-component substance

Abstract: A device for dispensing measured amounts of a single-component or multi-component substance, such as an adhesive material, a sealing material or a filler material, includes a container holding the substance. A cartridge of propellant gas is positioned within the container and is arranged to supply the propellant gas into contact with a piston which is displaceable in the container for dispensing the substance.

Extrusion apparatus for the production of foamed synthetic material

Abstract: In the production of foamed thermoplastic synthetic material, synthetic material is melted in a screw extruder and fluid propellant is injected into the molten sythetic material. The residence time of the molten mixture has a determining effect in regard to uniform distribution of the propellant and thus also in regard to the uniformity of the cell structure. In order to provide for homogeneous mixing of the propellant and uniform cooling of the molten mixture, without using an excessively long screw extruder, the screw extruder is provided, downstream of a melting region thereof and of an injection opening thereof through which propellant is introduced, with flow obstruction structure which is by-passed by static mixing structure disposed outside the screw extruder. The molten synthetic material is simultaneously mixed with the propellant and cooled in the static mixing structure.

Linear analysis of forced longitudinal waves in rocket motor chambers

Abstract: A methodology centered around the forced longitudinal wave (FLW) motor is being developed to investigate dynamic responses of rocket motors. The FLW motor establishes periodic longitudinal pressure and velocity oscillations in solid propellant rocket chambers. A linear analysis was developed to study propellant pressureand velocity-coupled responses using dynamic pressure measurements at several locations in a motor. The analysis uses pressure amplitude and phase measurements. Variations in the propellant reponses are shown to produce measurable changes in the calculated oscillating pressures with velocity-coupled responses showing the greatest promise for determination from experimental data. Experimentally deduced velocity-coupled response functions are examined over a frequency range centered around the chamber fundamental mode for a range of interior flowfields and chamber pressures for 86%AP-14%HTPB propellants.

Experimental and theoretical study of the effects of pressure and crossflow velocity on composite propellant burning rate

Abstract: A model for prediction of burning rates of composite (ammonium perchlorate oxidizer) propellants has been developed. In addition, an experimental device for measuring effects of crossflow on burning rate has been used to characterize eight propellants with systematicall, varied formulation parameters. Model predictions of no-crossflow burning rate-pressure behavior agree very well with data, while agreement between erosive burning predictions and data is generally good. The dominant factor influencing composite propellant burning rate sensitivity to crossflow is the base (no-crossflow) burning rate (lower base rate leading to increased sensitivity) with other factors having at most second order effects outside their influence on base rate. Three formulations with widely variant compositional and ingredient particle size parameters, but nearly identical base burning characteristics, exhibited very similar crossflow behavior.

Flame Propagation and Combustion Processes in Solid Propellant Cracks

Abstract: The effects of pressurizatio n rate, crack-gap width, crack length, and propellant type on the ignition and flame-spreading processes in isolated AP-based solid propellant cracks have been studied experimentally. Ignition front propagation rates were measured using a high-speed (up to 44,000 pictures/s) camera. Cracks up to 200 mm in length with gap widths as low as 450 j*m were studied. It was observed that the hot gases precede the ignition front. The ignition-front propagation speed increases near the crack entrance, reaches a maximum, and then decreases near the crack tip. The results of parametric study indicate that the time required for the ignition front to reach the crack tip decreases, and that the maximum velocity of the ignition front increases as the pressurization rate or burning rate of the propellant is increased. The maximum pressure in the crack increases with an increase in burning rate or crack length, but decreases with an increase in gap width. Nomenclature a = pre-exponential factor in Saint Robert's burning rate relationship aPn, (mm/s)/(atm)/I An = Andr eev number ,rbdh/a dh = hydraulic diameter of crack, mm L = length of crack, mm n = pressure exponent in Saint Robert's burning rate relationship P = pressure, atm Pmax = maximum pressure in the crack cavity, atm rb = burning rate of solid propellant, mm/s T = temperature, K t =time, s Tf = adiabatic flame temperature of solid propellant, K Tpi = initial propellant temperature, 295 K vfp = convective ignition front propagation velocity, m/s x = axial location, measured from entrance of crack, mm a. = thermal dif fusivity d = gap width of crack p = density, kg/m3

Catalysts for nitramine propellants

Abstract: : Small amounts of metal tetrahydridoborohydrides, e.g. as low 1% by weight of the nitramine, are effective for increasing the burning rate of nitramine propellants. Excellent results can be obtained by employing the metal tetrahydridoborohydrides in an amount of about 10% by weight of the nitramine component, whereby burning rates several times higher than that obtained with the unmodified propellant are obtained. Amounts of such metal tetrahydridoborohydrides up to 20% or more by weight of the nitramine are also effective to increase the burning rate of nitramine propellants; however, the use of such larger amounts is less desirable since it reduces the proportion of nitramine and hence the enrgy output of the propellant.

Hybrid gun system

Abstract: A hybrid gun system provides the benefits of both solid and liquid propelts by utilizing a shortened conventional cased ammunition which utilizes the propellant gas generated by the solid propellant contained within the cartridge case to operate a concentric fluid injection system to result in a compact firearm which offers possibilities of retrofitting conversions for certain applications.

Projectile carrier for liquid propellant gun

Abstract: This invention concerns an improved round for use in liquid propellant gu The improved round comprises a projectile attached to a carrier which is shaped like an abbreviated cartridge case. The carrier has a plurality of injection ports that communicate to an expandable volume. Sealing means prevent the escape of liquid propellant from the expandable volume which upon injection causes the projectile to be pumped to a forcing cone leaving the carrier behind. Several ignition means are used employing Boxer, Berdan or electric primers.

Direct measurements of acoustic admittance using laser Doppler velocimetry

Abstract: Research was directed at making measurements of oscillatory velocities in propane/air and solid propellant flames using laser Doppler velocimetry (LDV) instrumentation. Combustors were developed to impose controlled periodic pressure disturbances on burning solid propellants and to excite a propane/air flame. A tracking system was developed to maintain the LDV control volume at a fixed position above the regressing propellant surface so that a large number (over 10,000) of velocity realizations could be recorded. The research demonstrated that unsteady velocities (up to 1000 Hz) could be measured for propane/air flames seeded with micronsized particles and for solid propellant flames. The simultaneous velocity and pressure measurements were used to obtain acoustic admittances over a range of excitation frequencies, amplitudes, and pressures.

Liquid propellant weapon system

Abstract: A feature of this invention is the provision of an ignition mechanism for a main combustion chamber including an ignition antechamber having a first cross-sectional area, an electrode, and an inlet port for liquid propellant; a conduit having a length over diameter ratio greater than one, a second cross-sectional area which is less than said first area, and an inlet which opens into said ignition antechamber and an outlet which opens through an orifice into said main combustion chamber.