Showing papers on "Ignition system published in 1982"

Ignition Mechanisms of Explosives during Mechanical Deformation

Abstract: In earlier papers we have described the development of photographic and pressure-measuring techniques to study the detailed behaviour of thin layers of explosive when impacted. Ignition, when it occurs, invariably does so at local sites where 'hot spots' have been generated. The present paper gives the evidence for ignition by a variety of mechanisms including adiabatic shear of the explosive, adiabatic heating of trapped gas spaces, viscous flow, friction, fracture or shear of added particles, and triboluminescent discharge. Some of these mechanisms have been suggested earlier though others have resulted from our recent work. The value of the new photographic evidence is that it allows us to assess the viability of each mechanism for different explosives and impact conditions.

Turbulent flame structure and speed in spark-ignition engines

Abstract: Recent exprimental, observations of flame structure and speed in spark-ignition enginesare discussed. Schlieren photographs, shadowgraphs and laser scattering measurements strongly suggest a highly wrinkled structure for the turbulent flame in such engines. Simultaneous pressure measurements and high-speed motion picture records are used to derive two closely related sets of empirical equations for calculating burning rates. One set suggests an eddy entrainment and laminar burn-out model and the other, a laminar flame stretching and wrinkling model. Tentative correlations relating the parameters in the burning equations to engine geometry and operating variables are derived. Statistical variations in the parameters produce cycle-to-cycle dispersions in the pressure, but correlations for predicting the magnitude of the dispersions have not yet been obtained.

Plasma ignition system for an internal combustion engine

Abstract: An N cylinder internal combustion engine plasma ignition system comprises a DC-DC converter for boosting low DC voltage to high DC voltage. Each of N ignition energy charging circuits includes a first capacitor connected between the DC-DC converter and ground via first and second diodes. The capacitor is charged by the DC-DC converter. Each of N reverse blocked thyristors connected to a junction of the first diode and first capacitor selectively grounds an electrode of the corresponding first capacitor to discharge ignition energy stored in the first capacitor. For each cylinder a transformer connected between the first capacitor and a spark plug boosts and feeds the discharged energy to the plug. One end of the transformer primary winding is grounded via a second capacitor to generate a damped oscillation when the corresponding thyristor grounds the first capacitor. An ignition trigger signal generator sequentially triggers the corresponding thyristor in a predetermined ignition order whenever the engine revolves through a predetermined angle and supplies a pulse to the DC-DC converter in synchronization with the ignition trigger signal. Derivation of the high DC voltage is halted for a period of time according to the pulsewidth. Each of N core-less inductors connected in series with the secondary winding of a transformer restricts an abrupt large current flow from the corresponding spark plug, to extend the discharge duration of each spark plug and ignite the air-fuel fixture stably without misfire.

Experimental Evaluation of Flammability Parameters of Polymeric Materials

Abstract: An evaluation of the fire behavior of polymers and liquids over a wide range of experimental conditions is made using a laboratory scale flammability apparatus developed by the author. Results are presented for the following fuel parameters: (1) minimum heat flux (surface temperature), energy, and critical mass loss rate required for the piloted ignition of fuel vapor-air mixture and kinetic parameter for fuel vapors; (2) “effective” heat of gasification of the fuel; (3) flame-convective and flame-radiative heat flux to the fuel surface; (4) mass generation rates of CO, CO2, gaseous hydrocarbons, and “pyrolyzate”,† expressed as fractional theoretical stoichiometric yields (or fractions of carbon in the fuel converted to the products); (5) chemical formula of the fuels based on measured elemental compositions; (6) heat release rates (actual, convective, and radiative) expressed as combustion efficiency of the fuel vapors and convective and radiative fractions of the theoretical stoichiometric heat release rate for the complete combustion of the fuel vapors; (7) net heat of complete combustion and actual heat of combustion of the fuels; and (8) the ratio of optical density per unit path length to mass concentration of the fuel vapors defined as “modified mass absorbency index.”

Laser ignition apparatus for an internal combustion engine

Abstract: A laser ignition apparatus includes a laser oscillator which generates at least two successive pulse-shaped laser beams during each compression stroke of the engine. A first pulse-shaped laser beam is generated by a Q switching action of the laser oscillator and thus has a high peak output and a second pulse-shaped laser beam is generated without the Q switching action and has a low peak output but a larger pulse duration than the first laser beam. The first and second pulse-shaped laser beams are guided and directed into the combustion chamber of the engine and the first laser beam of a high energy density causes the breakdown of the air-fuel mixture in the combustion chamber to develop a plasma and the second laser beam further increases the energy of the plasma thereby to ensure the setting fire of the air-fuel mixture.

Ignition apparatus for internal combustion engine

Abstract: An ignition apparatus for an internal combustion engine comprises an intake path supplying a mixture of air and fuel into the combustion chamber of the engine, a particle supplying unit having an ejection port opening into the combustion chamber for supplying minute particles of a material which is not the fuel and has a high light absorption factor, and a light source radiating a laser beam through a light focusing unit toward a suitably selected position in the internal space of the combustion chamber, so that the laser beam can strike the minute particles of high light absorption factor supplied from the particle supplying unit thereby producing a torch for igniting the air-fuel mixture

Method and apparatus for producing electrical energy from a cyclic combustion process utilizing coupled pistons which reciprocate in unison

Abstract: Method of and device for producing electric energy from a cyclic combustion process. The device includes two oppositely disposed aligned spark ignited internal combustion engine cylinders axially spaced from each other, means rigidly connecting the pistons so that they reciprocate in unison in their respective cylinders, and a reciprocable electrical linear generator-motor unit driven by said reciprocatory piston system. The generator-motor unit includes a very light coreless (ironless) coil rigidly attached to and reciprocatory with the piston system, the said coil reciprocating through a constant strength magnetic field. The beginning of the combustion process (or cycle) in each combustion chamber takes place at the lowest possible compression ratio sufficient for the initial ignition of the fuel-air mixture, the combustion process proceeding at a diminishing volume under the pressure from the compression- and combustion-forces of the opposite combustion chamber-piston system. The combustion process terminates after some extreme point at an expanding volume, whereby the resulting forces are used for compression in the opposite combustion chamber and there the cycle being repeated, which processes (cycles) are taking place under a positive feed-back relation. Because said feed-back relation is very pronounced, this results in a height velocity and a reciprocating rate of the connected piston system whereby there is induced an electromotive voltage in the coil.

Measurement of Material Flame Spread Properties

Abstract: A concept was examined for measuring flame spread parameters suitable for predicting the performance of a material in fires The study examines a radiant panel test apparatus used to measure downward and lateral flame spread, and ignition An analysis of data from tests of Douglas fir particle board is presented A procedure has been identified for measuring specific parameters useful in the general prediction of ignition and flame spread for complex materials

Ignition system for an internal combustion engine

Abstract: An ignition system for a multi-cylinder internal combustion engine eliminates high-voltage cables and a mechanical distributor in order to reduce electrical power losses due to joule effect caused mainly by the high voltage circuit, comprises a plurality of ignition coils and plugs, one provided for each cylinder, a distribution unit for distributing advance-angle control signals into the respective cylinders, and a booster for boosting the supply voltage in order to reduce the size of the ignition coil, in addition to the conventional ignition system. Furthermore, the ignition coil can be built integrally with the ignition plug for eliminating high-voltage cables connected between coil and plug.

The ignition and combustion of propane/air mixtures in a fluidised bed

Abstract: Mixtures of propane and air have been used to fluidise a bed of silica sand at atmospheric pressure. Both the ignition and combustion of these gas mixtures have been studied in this situation. It is noteworthy that high temperatures (ca. 800°C) have to be reached before bubbles of propane and air ignite within the bed. The indications are that combustion occurs only in the bubble phase and not to any significant extent in the particulate phase. Moreover, it appears that a bubble of fuel and air has to reach a critical size (about 30 mm, depending on bed conditions) before it ignites. This is because ignition is controlled by a balance between near-isothermal chain branching and rapid removal of radicals from a bubble by gas circulating to the surrounding sand particles where radical recombination occurs. Analysis of the size of bubbles igniting at various temperatures indicates an activation energy for the chain branching step of around 254 kJ/mol. In addition, a correlation due to Darton appears preferable to an alternative one for predicting the sizes of gas bubbles in hot fluidised beds.

Compression wave former

Abstract: Compression waves are formed by detonating a mixture of fuel and air confined within a chamber that has a constricted output opening. The mixture is ignited instantaneously throughout a peripheral region of the chamber opposite the output opening, and this region is shaped relative to the dimensions of the chamber and the output opening so that the burning of the mixture accelerates toward the output opening and inward from the peripheral region. This dynamically compresses and detonates the mixture to form a high pressure compression wave and direct it out of the output opening. The instantaneous ignition can be by plasma jets or flames injected into the ignition region from an ignition chamber adjacent to the detonation chamber. The device can directly transform the chemical energy of a fuel into a high pressure thrust directed against a relatively movable resistance to serve as a prime mover suitable for many tasks. It can drive a piston, plunger, or rotor vane; provide propulsive thrust; or direct a compression wave through open air.

Review of Solid-Propellant Ignition Studies

Abstract: AN extensive review of the literature on solid-propell ant ignition was made to establish the state-of-the-art. Various ignition theories, experimental measurements, and ignition criteria were critically examined. The review was summarized in easy-to-read tabular form to facilitate comparison between various studies. The effects of important parameters on ignition processes were also discussed. Major technological gaps were identified and areas for future studies recommended. Contents The study of the ignition processes of solid propellants is important for many combustion and propulsion applications. An extensive review of research work performed in this area was conducted 14 years ago by Price et al. * Because many ignition studies have been conducted in the interim, a detailed survey of literature subsequent to the review paper of Price et al.1 is presented by the authors in Ref. 2. This synoptic of Ref. 2 (in which over 100 publications are cited) brings together the developments to date and the difficulties encountered under a unified view in order to establish the stateof-the-art in solid-propellant ignition. In general, ignition of a solid propellant is a complex phenomenon which involves many physicochemical processes, as depicted in Fig. 1. The ignition consists of the following sequence of events: 1) energy transfer to the propellant by an external stimulus which can be thermal, chemical, or mechanical; 2) heating and subsequent decomposition of the solid phase; 3) diffusion of vaporized gases into the surrounding atmosphere; and 4) subsurface, heterogeneous, and/or gas-phase reactions. When the net heat evolved from chemical reactions overcomes heat losses, sustained ignition is achieved. It is generally understood that ignition is incomplete if steady-state combustion does not follow the ignition event after the removal of external energy stimulus. The time period from the start of external stimulus to the instant of sustained ignition is called ignition delay^. Generally, it is controlled by three characteristic time intervals, viz., inert heating time, mixing (diffusion plus convection) time, and reaction time. Ignition delay, however, is not simply the algebraic sum of these three characteristic time intervals since there is no clear demarcation between the mixing process and the chemical reactions; these processes may have some overlapping periods. Ignition delay is one of the most important parameters in the study of ignition. However, it is very difficult to identify precisely the instant of sustained ignition.

Electronic delay blasting circuit

Abstract: An electronic delay blasting cap (10) receives an input signal over leg wires (12, 14). The input signal is passed through a rectifier (16) to produce a D.C. signal on output lines (26, 28). The D.C. signal charges a storage capacitor (32). When the input signal is removed or the wires (12, 14) are opened or shorted, the charge storage capacitor (32) discharges through a resistor (36) to produce a voltage which charges a timing capacitor (38). When the voltage on capacitor (38) reaches the threshold voltage of a zener diode (48) the diode is rendered conductive which in turn activates an SCR (46). A resistive ignition element (44) is connected in series with the SCR (46) and the charge storage capacitor (32) and is ignited when the SCR (46) is turned on. The charge stored in capacitor (32) causes ignition of the ignition element (44).

Water addition to gasoline - effect on combustion, emissions, performance, and knock

Abstract: A single cylinder engine was used to determine basic combustion, emission and performance characteristics of water-gasoline mixtures, with water introduced to the intake manifold as a liquid or a vapor. Measurements on ignition delays, combustion intervals, power, exhaust temperature, knock and exhaust emissions were made over a range of operating conditions. Test conditions, which included several values of speed, engine air flow, spark timing, mixture ratio and water addition rate were chosen to isolate effects of individual parameters and as such are not typical of conditions used with practical engine systems. The results of this basic study were used to determine the effects of water and its state of matter on the measured parameters.

The group combustion of a spherical cloud of monodisperse fuel droplets

Abstract: The vaporization and combustion of a spherical, uniform monodisperse cloud of fuel drops in equilibrium with a quiescent atmosphere is considered. For typical fuel sprays in which the drops are separated by five to ten drop diameters only the droplets within a thin inwardly propagating vaporization wave at the edge of the cloud will vaporize. In analogy with single drop theory the cloud radius is found to decrease acording to a “d2 law,” although with a modified vaporization constant for both purely vaporizing and burning clouds. The cloud interior in all cases remains in saturated, non vaporizing equilibrium at a temperature determined by ambient conditions. Burning occurs at a spherical diffusion flame front outside the cloud. The flame radius to cloud radius ratio is found to be constant and independent of the cloud radius and the droplet radius and number density within the cloud. An external ignition temperature is determined by considering the bifurcation of steady state solutions for single step, irreversible Arrhenius kinetics. At ignition the cloud interior reaches a new equilibrium which is still too cool and rich for single drop ignition. Under conditions of the present analysis a fuel cloud, if it burns at all, will do so with an external diffusion flame.

Spark plug for internal combustion engines having an alloy layer between the electrodes and tip ends

Abstract: A spark plug for an internal combustion engine including a center electrode, an earth electrode, a metal tip joined by welding to an ignition section of at least one of the center electrode and the earth electrode, and an alloy layer located at a welding portion between the metal tip and the at least one electrode. The metal tip is formed of material highly resistant to heat and wear which is distinct in the coefficient of thermal expansion from the material of the electrodes. The alloy layer is formed to have a thickness of at least about 10μ, so as to avoid the rupture of the metal tip along the surface thereof adjacent to the welding portion.

An Experimental Study of ignition and Flame Development in a Spark Ignited Engine

Abstract: Etude experimentale de l'allumage et de la formation de la flamme dans un moteur a allumage par etincelle

Starter device for a multi-cylinder spark-ignition engine

Abstract: Multi-cylinder spark-ignition engines the combustion chambers of which are supplied with fuel by petrol injection have starter devices. Starter devices of this type are to be designed so that they have a low energy requirement, are of low weight, permit the use of accumulators with a low ampere-hour number and generate no unwanted starter noise. To this end it is proposed that a detector device should signal the respective piston state of the engine to a microprocessor which, when starting, causes a quantity of fuel necessary for combustion to be injected into and ignited in that cylinder of which the piston is in the working position, and thereafter fuel to be injected into that cylinder of which the piston will perform the next working stroke, followed by ignition as soon as the piston in question has reached the working position.