Showing papers on "Propellant published in 1979"

Effect of Transition Metal Oxides on Decomposition and Deflagration of Composite Solid Propellant Systems: A Survey

Abstract: Introduction T metal oxides (TMO) like Fe2O3, CuO, MnO2, CuCr2O4, etc., form a very popular group of catalysts for burning rate modification of composite solid propellants. Although it is well known that these oxides affect the decomposition characteristics of polymers and oxidizers like ammonium perchlorate (AP)' and potassium perchlorate, (KP) the exact mechanism of the effect on solid propellants is by no means clear even today. Much fragmentary literature is available on the effect of these oxides on propellant burning and decomposition, oxidizer burning and decomposition, and sandwich and condensed mixture combustion. It is the purpose of this review to bring the material together so that a comprehensive picture can be drawn of the mechanism of the action of these catalysts. It may be mentioned here that these oxides also catalyze hydrocarbon oxidation reactions by inducing free radical decomposition of hydroperoxides (formed by the contact of oxidizer and hydrocarbon).

Erosive Burning Study of Composite Solid Propellants by Turbulent Boundary-Layer Approach

Abstract: Erosive burning of composite solid propellants is investigated by analyzing a steady, two-dimensional, chemically reacting, turbulent boundary layer over a propellant surface. Predicted erosive burning rates agree closely with experimental data. The erosive burning rate augmentation is found to be caused by the increase in heat feedback introduced by the increase in transport coefficients, and the turbulence enhanced mixing and reaction of the oxidizer and fuel gases. The increase in freestream gas velocity brings the location of the peak turbulence intensity and the heat release zone closer to the propellant surface, thereby increasing the burning rate of a propellant.

Oxidizer Size Distribution Effects on Propellant Combustion

Abstract: The effect of the oxidizer size and size distribution on the pressure and temperature sensitivity for a nonaluminized composite solid propellant was investigated using a new mathematical model called the Petite Ensemble Model. Calculations were made using the new model, taking into account the oxidizer size and size distribution in determining the burning rates, rate exponents, and temperature sensitivities. Results were obtained for both unimodal and bimodal propellants with oxidizer particle sizes ranging from ultrafine (0.7 /*) to coarse (400 /*). For unimodal propellants, it was determined that the burning rate was higher for the smaller oxidizer sizes, as would be expected. Moreover, the rate exponent was larger for the small and large oxidizer particles with a minimum exponent obtained for some intermediate oxidizer diameter. Temperature sensitivity was found to be higher for propellants with larger oxidizer particles. However, it was found that the temperature sensitivity was constant for small particles. It was shown that for large particles, the temperature sensitivity and rate exponent decreased as the oxidizer distribution was widened.

THEORETICAL Computations of Equilibrium Compositions, Thermodynamic Properties, and Performance Characteristics of Propellant Systems

Abstract: : This report summarized the methods and equations used in a Naval Weapons Center computer program called the NWC thermochemical program or the propellant evaluation program (PEP) The program is used to calculate high- temperature thermodynamic properties and performance characteristics of propellant systems, and it will handle a maximum of 12 chemical elements and 200 combustion products Some of the parameters that can be computed with this program are flame temperature, chemical composition, enthalpy, entropy, specific heat ratio and molecular weight of both the combustion chamber and exhaust, frozen and shifting equilibrium, specific impulse, boost velocities, thrust coefficient, characteristic velocity, and exhaust gas velocity The assumptions made, the limitations imposed, and the input data required for the solution of a specific problem by use of this program are discussed in detail The appendices provide a working guide for those using the program and give examples of computer inputs (Author)

Pneumatic hydrogen pellet injection system for the ISX tokamak.

Abstract: We describe the design and operation of the solid hydrogen pellet injection system used in plasma refueling experiments on the ISX tokamak. The gun‐type injector operates on the principle of gas dynamic acceleration of cold pellets confined laterally in a tube. The device is cooled by flowing liquid helium refrigerant, and pellets are formed in situ. Room temperature helium gas at moderate pressure is used as the propellant. The prototype device injected single hydrogen pellets into the tokamak discharge at a nominal 330 m/s. The tokamak plasma fuel content was observed to increase by (0.5–1.2) ×1019 particles subsequent to pellet injection. A simple modification to the existing design has extended the performance to 1000 m/s. At higher propellant operating pressures (28 bars), the muzzle velocity is 20% less than predicted by an idealized constant area expansion process.

Comprehensive view of the combustion models of composite solid propellants

Abstract: Introduction C solid propellants contain an inorganic oxidizer (generally ammonium perchlorate, AP) and a fuel binder (organic polymers) as the major ingredients. In order to understand the combustion phenomena of the propellant in its totality, it is worthwhile to examine the combustion of the ingredients, i.e., AP and the polymer, as a prelude to the propellant combustion. Some attempts have been made in the past to understand the combustion of AP, which also happens to be a monopropellant, and some similarities have been shown to exist between the combustion of AP and the combustion of the propellant. The binder combustion, from the viewpoint of propellant combustion, has not received adequate attention, which may perhaps be due to the belief that the binder occupies a smaller proportion in the propellant. However, combustion and physicochemical characteristics of a propellant do depend on the nature of the binder. Thus, there is a need to understand the combustion of AP and the polymer separately. Since the information available in the literature on the various aspects of combustion of the binder, AP, and the propellants is fragmentary, it is the purpose of the present review to bring together the information and examine it critically.

Aerosol can, having a super-fine atomization valve, with a filling which contains a propellant, process for its manufacture, and its use

Abstract: An aerosol can having a super-fine atomization valve, a process for its manufacture, and a process for introducing a filling which contains a propellant into the can. The can imparts a suitable fine division of droplets to the propellant medium which is to be sprayed. The can is suitable for the spraying of homogeneous mediums which do not contain chlorofluorinated hydrocarbons or hydrocarbon propellant gases.

Double ramp discarding sabot

Abstract: A segmented sabot utilizes a double ramp configuration and a centrally poioned obturating band in alignment with the center of gravity of an in-bore projectile to improve the uniformity of the shear traction forces at the interface between the sabot segments and a subcaliber projectile, to reduce propellant gas blow-by and to enhance projectile in-bore and trajectory stability. The increased uniformity of shear traction forces between sabot and projectile interfaces and propellant gas self-sealing design permits a reduction in sabot weight of sufficient magnitude to increase the velocity of the projectile at the muzzle exit.

Pneumatic conveyor of adjustable conveyance capacity for powdered to granular bulk material

Abstract: A pneumatic conveyor for powdered to granular bulk material, having adjustable conveyance capacity, is disclosed, the capacity being adjusted by electromagnetic adjustment of a pressure regulator disposed in a conduit used to supply a propellant for drawing the bulk material from a storage container thereof and for conveying it. A supplemental supply of gas, which may be but need not be different from the propellant gas, may be provided to control the flow of propellant gas independently of the first pressure regulator. In this case, the flow of the supplemental gas may itself be controlled by a second pressure regulator. The pressure regulators operate according to the diffuser or Venturi principle. The device may be particularly advantageously applied to the spray-coating of articles with a bulk material.

Erosive Burning of Composite Solid Propellants: Experimental and Modeling Studies

Abstract: : An experimental apparatus designed for measurement of erosive burning rates at crossflow velocities up to Mach 1 has been used to determine the erosive burning characteristics of seven propellant formulations with systematically varied properties. A composite propellant erosive burning model based on the bending of columnar diffusion flames gives reasonably good agreement with the measured erosive burning data over a wide range of conditions, breaking down only in regions where the fuel-oxidizer gas stream mixing does not control burning rate. Propellant base (no-crossflow) burning rate is found to have a predominant effect on sensitivity to crossflow (higher- burning-rate formulations being considerably less sensitive) whether the base burning rate differences are produced by oxidizer particle size variation, oxidizer/fuel ratio variation, or use of catalysts. Comparison of erosive burning predictions using the erosive burning model described herein with flow profiles expected to prevail in the test apparatus to predictions using profiles believed to exist in cylindrically-perforated motor grains indicate that erosive burning may be considerably less for a given mainstream crossflow velocity in such a motor than in the typical erosive burning test apparatus, a result quite important to extrapolation of test apparatus erosive burning data to actual motor conditions.

Probability of Solid-Propellant Motor Failure Due to Environmental Temperatures

Abstract: Solid-propellant rocket motors are frequently stored in the field without environmental protection; hence they are subjected to variable thermal stresses and material degradation due to aging and fatigue. Temperature variations are modeled as narrow-band random processes; thermal stresses in the motor will exhibit similar characteristics. Because material properties are statistically distributed, the probability that the thermal stress exceeds the strength of the propellant is synonymous with the probability of failure. A simplified solidpropellant rocket motor is analyzed as a long hollow elastic cylinder in a thin case (plane strain). The daily probabilities of failure are determined from a stress-strength interference-t ype analysis as functions of time and are summed up to produce the probability of failure at the end of the service life. The additional complexities of viscoelasticity, aging, and loads other than thermal will be introduced in subsequent analyses.

Propellant charge igniter

Abstract: A propellant charge igniter includes a casing that contains a central contact member, an igniter element, a sealing element associated with the igniter element, and a powder charge. The sealing element has on a side facing the powder charge, an annular collar in sealing contact with an inner wall of the casing.

Fluid supply systems

Abstract: The invention relates to a fluid supply system and seeks to provide a simpler, safer but reliable system than at present known. The fluid supply system comprises a multi-charge solid propellant gas generator and a fluid explusion unit integrated into a single unit, the gas generator being provided in a cap (8) for a chamber (1) having a gas portion (3) and a fluid portion (2) and a movable partition (4) between these two portions operable to expel fluid from the chamber when the gas generator is rendered operative. The system also comprises ignition control means (22) operable to control the ignition of the solid propellant charges (13) when required to give a fully controllable system output. The system can be designed for supplying under pressure fluids such as hydraulic oil, fuels, oxidents and water and is particularly useful in aerospace applications.

A Model of the Effects of Pressure and Crossflow Velocity on Composite Propellant Burning Rate

Abstract: : Several variations of a model for prediction of burning rate versus pressure behavior of unimodal oxidizer composite propellants in the absence of crossflow were developed and evaluated against a set of data for a series of four formulations. Three variants, including one in which an average oxidizer- burning-surface intersectional area concept is employed and two in which allowance is made for geometry and stoichiometry changes as the propellant recedes past an oxidizer crystal, were found to give excellent agreement with data. The former variant was extended to treat multimodal oxidizer formulations, yielding predictions in excellent agreement with data for two additional formulations containing bimodal oxidizer. In the initial development of the erosive burning aspect of the model, columnar diffusion flame bending was assumed to the sole mechanism leading to burning rate augmentation by crossflow. This assumption led to severe underprediction of erosive burning effects. Accordingly, the model was revised through addition of a flow profile analysis for prediction of cross-flow-induced turbulence augmentation of transport properties governing heat feedback from gas flames as well as flame-bending. This revised model was found to yield good agreement with erosive burning data for five of the six formulations tested, but gave higher predicted rates than observed values for the sixth propellant.

Propellant charge igniter

Abstract: The invention relates to a propellant charge igniter mountable in a propellant charge carrier or in a cartridge. Propellant charge igniter is provided with an expulsion charge to avoid breech flash, said charge being suitable for driving an ignition guide tube completely out of an annular chamber formed between a bottom part and a flame guide tube of the propellant charge igniter.

Turbo-electric power plant and process

Abstract: A turbo-electric power plant comprising a drag turbine with a hollow rotor in which are mounted the elements of an electric generator. The drag turbine is operated with a low-temperature propellant and the spent propellant is led out of the drag turbine in heat exchange with the elements of the generator. The drag turbine is propelled by a plurality of jets which are supplied from a manifold encircling the turbine which continuously diminishes in cross-section throughout 360 degrees.

Determination of plateau burning effect of catalyzed double-base propellant

Abstract: Combustion wave structures of noncatalyzed and catalyzed double-base propellants were studied to clearly identify and explain the plateau burning mechanism with photographic observations and temperature profile measurements. The propellants used in this study were specially formulated to obtain a wide range plateau burning region that would occur at the lowest possible pressure and burning rate. The reaction processes in the dark zone were unchanged by the addition of the catalyst. While the burning rate remained constant in the plateau region, the luminous flame of the catalyzed propellant approached the burning surface more rapidly than the luminous flame of the noncatalyzed propellant, when the pressure was increased. The temperature gradient in the fizz zone was significantly different for the noncatalyzed and catalyzed propellants. The temperature gradient in the fizz zone of the noncatalyzed propellant increased monotonously with pressure, whenreas the temperature gradient in the fizz zone of the catalyzed propellant increased in the super-rate region and was constant in the plateau region. It was found that the change of the temperature gradient in the fizz zone with pressure is similar to the change of the burning rate with pressure for each propellant. The temperature gradient in the fizz zone of the catalyzed propellant remains unchanged in the plateau region, which indicates that the reaction rate is constant. Therefore, the conductive heat feedback from the fizz zone to the burning surface remains unchanged throughout the plateau pressure region. However, no special trends, in the burning surface temperature and the heat release in the subsurface reaction zone were observed in the plateau burning region, when compared with the normal burning of the noncatalyzed propellant. Thus, the pressure insensitive reaction in the fizz zone is considered to be directly responsible for plateau burning.

Integral rocket-ramjet closed loop fuel control system

Abstract: In an integral rocket-ramjet having a combustor which initially serves as a rocket combustion chamber for booster propellant, and after the booster propellant is expended serves as a ramjet combustor where fuel and air are burned, a fuel control system is described for the ramjet stage by which ram burner light-off is automatically initiated upon transition from rocket to ramjet propulsion. The fuel control regulates fuel flow to the combustor over the entire flight regime and responds to operating conditions to provide a light-off schedule, to stabilize the shock wave at the air inlet, to provide a maximum fuel-to-air ratio limit, to limit the maximum vehicle Mach number, and to prevent lean burner blowout by providing a minimum fuel-to-air ratio limit. Mach number limiting and air inlet margin limiting are performed in closed loop fashion, while the other functions are scheduled or open loop controls. The closed loop functions are performed by scheduling a ratio of combustion chamber pressure to a reference pressure, and comparing this ratio to the ratio of the pressures as measured, any error therebetween being used to produce a desired fuel flow to combustion chamber pressure ratio. By measuring the actual combustion chamber pressure, the desired fuel flow is obtained.

Control piston for liquid propellant gun injector

Abstract: The injection piston of a regenerative liquid propellant gun is attached to a second piston that has a programmed hydraulic resistance which controls its motion, thus the propellant injection rate from the injection piston and the burning rate of the injected propellants is controlled to provide better propellant pressure-time burning characteristics.

High-performance MHD solid gas generator

Abstract: A solid propellant gas generator based upon dialkali tetranitroethane salts which produces high electron densities for magnetohydrodynamic (MHD) applications.

Ignition of composite propellant at subatmospheric pressures by means of carbon dioxide laser

Abstract: Ignition behavior of solid propellant composed of 25 wt% polybutadiene and 75% ammonium perchlorate under subatmospheric conditions has been studied using a carbon dioxide laser whose radiant flux is uniformalized. Data of ignition time in Ar, N2 and He atmospheres, and critical radiant flux and pressures over which ignition might be achieved, were obtained. Moreover, the data were compared with theoretical values, taking account of variable heat conductivity for the ambient gases with a surface ignition hypothesis. It is concluded that these ambient gases participate in the pre- and post-ignition reactions and the ignition preventive behavior of He atmosphere is not predictable merely based on its high transport properties. The detailed observation of the ignition transient near the critical pressure revealed that the ignition in Ar atmosphere occurs in gas phase under less than 100 torr whereas in He atmosphere it occurs always at the condensed phase surface.

Effect of Storage Temperatures on the Mechanical Properties of the Composite Solid Propellants

Abstract: Accelerated ageing studies for three composite propellant formulations, namely polystyrene (PS)/ ammonium perchlorate (AP), polymethylmethacrylate (PMMA)/AP and poly phenol formaldehyde (PPF)/AP have been carried out in the temperature range of 55-125°C. Measurements of the ultimate compression strength (U c) and isothermal decomposition rate (TD rate) were monitored as a function of storage time and temperature. The change in U c was found to be linearly dependent on the change in TD rate irrespective of the propellant systems. Analysis of the results further revealed that the cause of ageing for both U c and burning rate (r) is the thermal decomposition of the propellant. The safe-life for the change in mechanical properties was found to be higher compared to the change in r for PS and PMMA based propellants.

Method of 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 appartus 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.

Rocket motor or gas generator having controlled thrust or mass flow output

Abstract: A solid propellant rocket motor of gas generator of the type having retractable filaments embedded in the propellant for the purpose of controlling the overall thrust or mass flow output is combined with a channeled separator located between the propellant and its casing with the channels open to the combustion chamber. This results in distribution of combustion chamber pressure and temperatures over the exterior of the propellant grain so that distortion of the grain will not occur sufficiently to cause binding or sticking of the filament in their holes in the propellant nor will the holes be enlarged to cause uncontrolled burning between the filament and the hole.

Turbine engine altitude chamber and flight testing with liquid hydrogen

Abstract: In the late fifties the Lewis Research Center evaluated experimentally the use of hydrogen using three different turbojet engines in altitude test chambers. One of these engines was later flown experimentally using liquid hydrogen fuel. This paper is a brief overview of the significant aspects of this exploratory research and gives a few implications of the results to modern turbine engines. A subsequent contract dealing with a positive displacement pump operating on liquid hydrogen is discussed and some aspects of liquid hydrogen propellant systems, reflected by rocket booster experience are treated briefly. Areas requiring further research and technology effort are delineated.

Device for spraying of a coolant on steel plates during continuous casting

Abstract: A device for spraying a mixture of coolant and propellant onto steel plate emerging from a continuous casting mold through guide rolls comprising a mixing chamber and means separately feeding coolant and propellant thereto, a nozzle housing having at least two nozzle outlets offset in side by side and oppositely directed relationship and adapted to discharge the coolant/propellant mixture in wide dispersion and at an acute angle onto the steel plate and feed means connecting the mixing chamber with the nozzle housing and including a replaceable insert pipe extending into the mixing chamber.

Microwave measurement of the solid propellant pressure-coupled response function

Abstract: The results of an investigation are presented on the applicability of a microwave Doppler shift technique for directly determining propellant response functions over the desired frequency range. The investigation consisted of three phases. In Phase 1 the validity of the technique was established by comparing measured pressure-coupled response function data to existing data from T-burners and rotating valve tests. In Phase 2 a new microwave burner-pressure modulation system capable of achieving frequencies and mean chamber pressures of at least 1500 Hz and 10.5 MPa (1500 psia), respectively, was developed. During Phase 3 test firings are being carried out to define the frequency limit, response function resolution, and precision of the new design.