Showing papers on "Burn rate (chemistry) published in 1987"

Smoking article with dual burn rate fuel element

Abstract: The present invention preferably relates to a smoking article which is capable of producing substantial quantities of aerosol, both initially and over the useful life of the product, without significant thermal degradation of the aerosol former and without the presence of substantial pyrolysis or incomplete combustion products or sidestream aerosol. The article employes a dual burn rate fuel element, which utilizes a fast burning segment (10B) and a slow burning segment (10A). The use of such a dual burn rate fuel element has several advantages over conventional homogeneous fuels. For example, the fast burning component assists in the ease of lighting the fuel element, and provides rapid heat transfer to the aerosol generating means (14). This in turn, provides early aerosol delivery. The slow burning component provides for even heat distribution throughout the burn period. The slow burning material ensures steady aerosol delivery in terms of amount and provides adequate fuel for simulating the number of puffs obtained from a conventional cigarette, i.e., about nine or ten, when smoked under standard FTC conditions.

Tool and process for stimulating a subterranean formation

Abstract: A high energy gas fracturing tool for radially fracturing a rock formation in a well bore consisting of a cylindrical canister that is holed to pass gas and is for housing a stack of propellant modules that are selected to provide a desired burn rate when ignited. Each propellant module mating face is angled from the horizontal between forty-five (45) to seventy-five (75) degrees, and the modules are bonded together with an epoxy resin wherein propellant or explosive particles are mixed, the resin to exhibit burn characteristics similar to those of the propellant stack. The tool, additional to the propellant containing canister, an ignitor rod and explosive device for igniting the propellant stack, mounts a bull head end over a lower end and a reverse thruster assembly that is connected to the canister upper end. The reverse thruster assembly includes a housing with nozzles formed therein that are angled from the vertical to pass gas on propellant deflagration, creating thereby a force against the tool lifting during propellant burning. Above the reverse thruster assembly is arranged a pressure pulse monitor that is battery powered to operate a pressure transducer for sensing pressure pulses at the tool. The monitor to turn on when a sufficient strength of pressure pulse is received, to store pressure pulses sensed over time, with the stored pressure data retrieved when the tool is removed from the well bore. The recorded pressure pulse data is used for determining the dynamic window of the formation, whereat, at a certain pressure over time the formation will be optimally radially fractured. The tool is suspended from the surface on a wire line and includes a collar locator for locating it at a certain level within the well bore.

Solid fuel rocket thrust control

Abstract: A solid fuel rocket burn rate control employing electrical energy preheating of the fuel grain at a plurality of locations dispersed over the grain burn face cross-section as a thrust control arrangement. The electrical energy of the preheating is generated by electrical battery cells which are dispersed across the grain cross-section and are triggered from an inert state into energy generation by burn face heat. The preheating situs moves continually in response to movement of the grain burn face; this is achieved through the use of high temperature electrical battery cell materials responding to the approach of the grain burn face by increased chemical activity and decreased electrical resistance. Preferably, the preheating is directly accomplished by the heat from electrical and other losses in the battery cells.

Studies on Some Aspects of Propellants for Improving the Performance of Tank Guns

Abstract: The main criterion, in the design of propellant charge for a tank gun, is to achieve the highest possible muzzle velocity for fin stabilized armour piercing dicarding sabot (FSAPDS) projectiles. This ensures penetration through the toughest armour plates by the kinetic energy of the projectile. One of the solutions, is to increase the force constant of the propellant. Higher force constant from conventional double and triple base propellant compositions lead to prohibitive linear rates of burning coefficients. ERDL has developed a high energy propellant based on RDX, with very high force constant and low linear rate of burning coefficient. The objective of the present paper is to discuss various aspects of the interior ballistics of the three types of propellants in question in 105 mm tank gun with FSAPDS ammunition. The study shows that only the solution with RDX base propellant is feasible for an increase of three per cent in muzzle velocity.

Combustible coatings as protective delay barriers

Abstract: A combustible coating for providing a delay barrier to intrusion into an object. The coating contains a source of fuel as a metal and/or a polymer and a source of oxygen such as an oxidizer. The coating is ignitable at a temperature in excess of about 300° C., during combustion is resistant to the effects of common fire extinguishing materials, and is capable of sustaining combustion for at least five minutes with a burn rate of no more than about six inches per minute.

Method for making solid rocket propellant

Abstract: A method of making solid rocket propellant that facilitates tailoring of a variable burn rate. The method comprises molding binder and fuel and/or oxidizer to produce, for example, a molded strip of solid rocket propellant material. The molded solid rocket propellant material is formed into a desired shape by, for example, filament winding. In a preferred aspect, the solid rocket propellant is cured prior to being encased in a rocket motor casing. This improves rocket propellant to rocket engine casing bonding. Yet another aspect of this invention is a method of making solid rocket propellant comprising forming binder and oxidizer into separate strips and combining the binder and oxidizer strips to form solid rocket propellant material.

Multiple-stage rocket motor nozzle throat

Abstract: The invention is concerned with reducing the effect of a progressive surface area versus web thickness relationship in a rocket motor and is particularly useful with center perforate propellant grains where the chamber pressure versus time history is generally progressive. In a very short action time rocket motor, it is desirable to keep the chamber pressure as close as practical to the peak during the entire burn to increase the propellant burn rate. The multiple-stage throat makes this possible in a motor that uses the cost effective center perforate propellant grain design and operates by allowing a first stage throat to erode at a predictable rate while the area of the propellant burning surface is increasing. The motor initial Kn (propellant surface area divided by nozzle area) is raised by using a relatively small initial size for the first stage throat and as a result the rocket motor reaches peak chamber pressure quickly. With the erosion of the first stage matching the increasing propellant surface area the chamber pressure remains nearly constant. Near the end of the burn the first stage throat erodes out to the diameter of a non-eroding second stage throat which then becomes the controlling throat.

Gas generation with high pressure sensitivity exponent propellant

Abstract: Gas generator apparatus usable with a ducted rocket propellant having a high exponent burn rate, a burn rate that is burn chamber pressure sensitive to a greater degree than are normally used propellants. The gas generator includes elementary pressure regulating elements and apparatus for damping movement of the pressure regulating elements to remove oscillatory components of motion therefrom. Burn rate operating point determination and the stability characteristics thereof are described along with the effects of variations in propellant burn rate exponent and regulating element parameters.

Rocket propellant charge with negative pressure exponent

Abstract: A solid propellant charge for a rocket motor or gas generator, the charge having a selected bulk propellant (2) with longitudinal cores of control material (3). The control cores have a burning rate, greater than that of the bulk propellant, which decreases as pressure increases, so that the solid propellant charge has a burning rate which also decreases as pressure increases.

Process for assessing the effect of propellant strain on propellant burn rate

Abstract: The present invention describes a process for relating burn rate in a sample propellant to a strain field imposed therein by bending the sample propellant by a determined amount. The propellant is cast upon an initially flat plate having a single pair of fixed parallel walls. The plate is bent parallel to the walls before the test burn. Measurements of the thickness of the propellant before the burn and after the burn are related to the strain placed in the propellant by the bending. All measurements occur when the plate is flat.

Validation of turbulent entrainment model in a spark-ignition engine

Abstract: A turbulent entrainment burning model is considered to be a reasonable one for the combustion in a spark-ignition engine. The concept is based on the Blizard and Tabaczynski model. It is important to estimate the turbulence characteristics, turbulent burning velocity, flame surface area and several experimental constants. Nevertheless, the examination of these values are insufficient, regardless of using many assumptions in previous studies. In this study, turbulence characteristics, the initial stage of burn duration and turbulent burning velocity were discussed in detail. This model was examined under various conditions of engine speed (600-1200 rpm), compression ratio (3.2-4.8) and ignition timing. The calculation results of mass fraction burned, burn rate and burn duration were in good agreement with the experimental ones. It was found that this model was valid for predicting the combustion in a spark-ignition engine.

Solid propellant burn rate control device

Abstract: In a power unit for a vehicle using a solid propellant fuel material which is burned within a combustion chamber (1), the chamber is provided with an outlet port (3) including an adjustable valve (4) arranged for controlling the rate of gas flow through said port, in which the valve (4) is a fluid flow valve capable of effecting control of the gas flow in the abscence of a mechanically movable valve member. The valve (4) may be a fluidic vortex valve the flow through which is adjustable by controlling flow of a control fluid into the valve. This arrangement permits a build-up of gas pressure within the chamber (1) in order to increase the fuel burn rate at times when a high power output is demanded.

Smoking article equipped with fuel element having two combustion speeds

Abstract: The present invention preferably relates to a smoking article which is capable of producing substantial quantities of aerosol, both initially and over the useful life of the product, without significant thermal degradation of the aerosol former and without the presence of substantial pyrolysis or incomplete combustion products or sidestream aerosol. The article employes a dual burn rate fuel element, which utilizes a fast burning segment (10B) and a slow burning segment (10A). The use of such a dual burn rate fuel element has several advantages over conventional homogeneous fuels. For example, the fast burning component assists in the ease of lighting the fuel element, and provides rapid heat transfer to the aerosol generating means (14). This in turn, provides early aerosol delivery. The slow burning component provides for even heat distribution throughout the burn period. The slow burning material ensures steady aerosol delivery in terms of amount and provides adequate fuel for simulating the number of puffs obtained from a conventional cigarette, i.e., about nine or ten, when smoked under standard FTC conditions.