Showing papers on "Ignition system published in 1971"

On the shock-induced ignition of explosive gases

Abstract: The paper elucidates the distinction between two regimes of ignition, one strong and the other weak, that characterize the onset of combustion in homogeneous gaseous mixtures whose reaction mechanism is controlled by a chain-branching step, such as that associated with the H+O2 collision in the hydrogen-oxygen system. On the basis of experimental observations, made primarily by the use of a stroboscopic laser-schlieren system yielding a sequence of photographic records of the entire flow field behind a reflected shock near the closed end of the tube at a repetition rate of 2 microseconds between frames, it has been revealed that strong ignition is manifested by a practically instantaneous appearance of a relatively plane pressure front associated with the generation of a flow field across the whole cross section of the tube, while mild ignition starts in the form of distinct flame kernels whose growth is comparatively slow and essentially devoid of any gasdynamic effects. The demarcation line between the two regimes of ignition is then shown to be associated with a critical value of the gradient of the induction time with respect to temperature at constant initial pressure. Specifically, for a stoichiometric hydrogen-oxygen mixture, this turns out to be −2 microseconds/°K. Although basically controlled by the same elementary processes as those that establish the second explosion limit, this so-called strong ignition limit differs from the locus of states obtained by direct extrapolation of the second limit. Moreover, it does not intersect with any of the explosion limits, encompassing a region that is fully contained within the classical explosion regime.

Theory of Ignition of a Reactive Solid by Constant Energy Flux

Abstract: A formula for the ignition time, that Bradley obtained empirically, is derived analytically by a rigorous asymptotic analysis of the limit of large activation energy. Two terms in the expansion must be retained. The second term reveals the existence—just prior to ignition—of a reactive-diffusive zone at the surface of the solid and a transient-diffusive zone in the interior. The analysis also exhibits a universal correction factor for Bradley's formula, of order unity.

A preliminary investigation of the use of focused laser beams for minimum ignition energy studies

Abstract: The plasma produced by focusing a passively Q-switched 30 J ruby laser beam is studied as regards its suitability for minimum ignition energy measurement. By comparison with electric spark discharges, it would appear to offer shorter times and smaller volumes of the initiating plasma, as well as freedom from energy losses to electrodes and elsewhere within the circuit. The growth of the initiating plasma as well as that of the flame kernel are studied as a function of pressure and composition, the former using an optical delay line with a schlieren system and the latter by high-speed schlieren streak photography. It is found that the difficulties of the method are associated with the finite duration of the laser pulse. In the time between the onset of breakdown and the end of the pulse the plasma front facing the incident beam absorbs the incoming energy, leading to the production of an extended and unsymmetrical initiating source, an absorption threshold which may already be in excess of the minimum ignition energy, and the formation of a blast wave which may be powerful enough to initiate a detonation rather than a deflagration. For a pulse of approx. 20 nano second half width these effects become serious above about half an atmosphere for stoichiometric methane-air mixtures. For lower pressures, or near limit mixtures, the promise of the method is borne out and both ignition energies and quenching distances fall below those determined by the electric spark method. For higher pressures and faster reacting mixtures it will be necessary to decrease the duration of the laser pulse and the size of the plasma.

Electronic ignition spark advance system

Abstract: An electronic ignition spark advance system for use with internal combustion engine transistor ignition systems having an ignition coil primary winding switching transistor. A reference pulse, produced a selected number of degrees before the top dead center position of each engine piston, enables an ignition spark advance gate to gate a series of crankshaft position pulses, each indicating one degree of crankshaft rotation, to a counter circuit. When the counter circuit has counted the number of crankshaft position pulses equal to the number of selected degrees before top dead center the reference pulses are produced, an ignition signal is produced which extinguishes the ignition coil primary winding switching transistor and operates circuitry which produces a signal which may disenable the ignition spark advance gate. To provide speed ignition spark advance, however, delay circuitry responsive to each ignition signal provides two consecutive delay periods during which the disenabling of the ignition spark advance gate is delayed. Consequently, the counter circuit continues to count crankshaft position pulses during the delay periods, thereby providing a speed ignition spark advance in degrees equal to the number of crankshaft position pulses counted during the delay periods at any engine speed. To provide two speed ignition spark advance limits, the first delay period is terminated with a first selected crankshaft position pulse count if it occurs before the end thereof and the second delay period is terminated with a second greater selected crankshaft position pulse count if it occurs before the end thereof. To provide vacuum ignition spark advance, a vacuum spark advance signal is provided at the conclusion of the delay periods for the number of crankshaft position pulses equal to the degrees of vacuum ignition spark advance required which enables the ignition spark advance gate to gate the crankshaft position pulses to the counter circuit after the delay periods.

Combustion and ignition of particles of finely dispersed aluminum

Abstract: 1. It has been established that the burning time of individual aluminum particles in a high-temperature gas flow is almost independent of the pressure (P>20 atm) and temperature (T>2000° K) of the medium, but is a very strong function of the oxidizing properties of the flow relative to the concentration of active oxygen-containing products (H2O, CO2, etc). The formula τb0==0.67(d1.5/(akr)0.9) is suggested for calculation of the particle burning time. This gives satisfactory agreement with experiment. 2. The ignition time for aluminum particles is insensitive to the composition of the oxidizing medium and pressure, but depends strongly on the temperature of the gas flow. The increase in ignition time as the particle diameter increases is proportional to d2.

Shock Tube Investigation of Ignition in Propane-Oxygen-Argon Mixtures.

Abstract: A detailed shock-tube study of ignition-delay times in propane-oxygen-argon mixtures is presented. Ignition delays were determined from pressure and heat-flux measurements in the reflected shock region. The induction times measured ranged from 12 to 600 μsec and the temperature range covered was 1250°–1600°K. The pressures varied from 2 to 10 atm, and the equivalence ratios of the various mixtures ranged from 0.125 to 2.0 The influence of each parameter on ignition-delay times was separately determined. The dependence upon the concentrations close to stoichiometric composition, derived from more than 150 shocks is the following: τ = 4.4 × 10 − 14 exp ⁡ [ ( 42.2 × 10 3 ) / RT ] [ Ar ] 0 [ C 3 H 8 ] 0.57 [ O 2 ] − 1.22 sec ⁡ , where the concentrations are in moles/cc. Additional experiments were carried out in order to determine the product distribution before and after ignition. Considerable decomposition of propane takes place before ignition. The rate of decomposition is close to that of pure propane, and is very little affected by the presence of oxygen.

Electronic ignition timing system for internal combustion engines

Abstract: An electronic ignition timing system for internal combustion engines is disclosed which utilizes electronic circuitry to vary the timing of ignition pulses in response to engine speed and vacuum to provide optimum or improved performance by the engine. Preferably the electrical circuitry utilizes digital signals for high accuracy.

Combustion of boron particles at elevated pressures

Abstract: Combustion of single boron particles, about 75 microns in diameter, from a crystalline powder sample has been studied. Particles were, ignited by being dropped through a focused laser beam in several oxidizing gases over a range of pressures In pure oxygen, in air, and in O2/Ar (20/80), particles were merely preheated to a temperature about 2000°K; ignition took place spontaneously after a measurable induction period. Quantitative values of both the induction period and the subsequent self-sustained combustion period are listed. In air and in the O2/Ar mixture, the burning times decrease from about 45 msec to about 20 msec as the pressure is increased from 1 to 35 atm. In pure O2 at atmospheric pressure, the total burning time is only 6.8 msec. In pure CO2 and in O2/N2 (7/93), there is no induction period, no selfignition, and no steady-state combustion; particles must be brought to a burning regime by an external energy flux, and they are able to maintain that regime for only a limited time before extinguishment. It is shown that the classical theory of ignition and combustion can account for all three observed burning modes: metastable surface reaction during the pre-ignition period rapid self-sustained diffusion combustion, and decaying combustion. Previously reported reaction-rate and ignition-limit data are used for quantitative estimates of parameters pertaining to the three regimes.

Supersonic combustion of hydrogen in a vitiated air stream using stepped wall injection

Abstract: Combustion physics and ignition of hydrogen in supersonic stream of vitiated air or inert gases using stepped-wall injection procedure

Sampled-data theory applied to the modelling and control analysis of compression ignition engines—Part I†

Abstract: Proposals for the use of electronic speed governing of diesel engines used for driving alternators has led to a re-examination of the dynamic behaviour of the engine for control purposes. If maximum advantage to the plant performance is to be achieved from using more complex and expensive governing devices, then better models of individual components in the power system for simulation and control studies may be necessary. This paper describes an investigation performed to model the engine in terms of a discrete system. The frequency domain properties of the model (for various numbers of cylinders) are examined and compared with the model usually assumed, as well as with the frequency response of an actual engine. A companion paper will extend this work using 2-transform techniques.

Electronic control for the air-fuel mixture and for the ignition of an internal combustion engine

Abstract: A function generator is fed input signals corresponding to at least two different engine operating parameters, such as the position of the accelerator pedal and the engine rpm, the function generator, in dependence on these input signals, controlling the amount of fuel supplied to the cylinder so as to maintain a desired excess air coefficient lambda for each operating condition of the engine. In one form of the invention, the function generator controls the fuel and air supplied, as well as the ignition timing.

Radiative ignition of polymeric materials in oxygen/nitrogen mixtures

Abstract: The radiative ignition behavior of two polymeric fuels—polystyrene and an epoxy—in oxygen/nitrogen mixtures has been determined experimentally. A CO2 laser was adapted for use as the radiation source to simplify interpretation of the results. Ignition delay (as determined by first light emission) was measured as a function of oxygen percentage, pressure, radiant flux, and fuel absorptivity. The observed ignition delays, and the variations with pressure, oxygen fraction, and radiation intensity, conform to the predictions of a theoretical model based on the need to heat the surface to a critical ignition temperature. The most important finding is that ignition of a solid fuel by radiation is much slower than ignition by an identical heat flux applied by a hot gas source. Two main reasons for the retardation can be deduced from the experimental results: (1) the radiative transparency of the fuel, even for seemingly opaque substances, results in slower surface heating, and (2) the cool gas environment in the usual radiation ignition test suppresses the incipient ignition.

Shock-tube studies of the ignition and combustion of ethane and slightly rich methane mixtures with oxygen

Abstract: Studies have been made of the ignition of ethane-oxygen-argon mixtures over the range 1400° T 2 T 2 A model of the combustion mechanism has been devised which approximately reproduces the main features of ignition. With ethane-oxygen mixtures, considerable fuel degradation occurs before ignition, first producing ethylene in the pre-ignition zone, and then acetylene during ignition. In contrast, in slightly rich-methane mixtures, little fuel degradation occurs and only moderate concentrations of ethylene and acetylene are produced during ignition.

Ignition arrangement for a discharge tube

Abstract: The invention relates to an arrangement for igniting a discharge tube provided with an external ignition electrode.

Automatic electronic regulator of spark advance in otto engines

Abstract: An automatic electronic regulator of spark advance in Otto Engines which compares the phase between explosion and crankshaft angle during each cycle, in order to provide an electric negative feed-back signal should an error result through such comparison with respect to a predetermined crankshaft angle as initially regulated. This electric negative feed-back signal will correct the spark advance for the next cycle. In this manner, a very careful regulation of the ignition moment can be obtained, since the same conditions may be assumed between one cycle and the next.

Ignition Temperatures of Metals in Oxygen Atmospheres

Abstract: The ignition temperature of ten common non-toxic metals has been determined experimentally in an oxygen environment. In this investigation a induction furnace facility that emphasized the preignition surface.oxidation effects upon the ignition temperature was used. The bulk ignition temperatures of barium, bismuth, calcium, iron, lead, magnesium, molybdenum, strontium, tin, and zinc were found and compared to the previous results of Grosse and Conway. The differences in the results are attributed to how the heating cycle is carried out and how the cycle affects the surface oxide coat.

Surging prevention device for use in vehicle having multicylinder spark-ignition internal combustion engine

Abstract: A device for preventing fluctuations in the output torque of a spark-ignition internal combustion engine which result from irregular combustion of air-fuel mixture. According to the present invention, instead of the conventional idling device of which the idling jet is situated on the engine side of the edge of the throttle valve, a communication passage communicating at the downstream side of the throttle valves between a pair of intake passages each connecting the carburetor to the respective combustion chambers, an additionally fuel supplying means interposed in the communication passage and means for supplying a primary air from an air source to one of said pair of the intake passages are provided in the intake system of the internal combustion engine.

Fuel spray ignition atomizer nozzle

Abstract: A liquid fuel spray atomizer nozzle for use with a gas turbine during combustion chamber fuel ignition, comprising a member having a high pressure air blast passageway for directing a stream of air, angularly in relation to the direction of fuel spray from a nozzle into the combustion chamber, so as to atomize and forcibly blow at least a part of the fuel toward an ignition device into ignition proximity therewith. The air blast can be blown directly across the fuel spray pattern or may be directed toward a side of the spray pattern. In all cases, the air must be under sufficient pressure to deflect and atomize the fuel spray sufficiently to provide for its ignition by the spark gap or other igniter.

Resonance tube ignition of hydrogen-oxygen mixtures

Abstract: Resonance tube ignition system for hydrogen oxygen engines including ignition limits and pressure and temperature effects

Auxiliary battery for motor vehicles

Abstract: An electric storage battery for motor vehicles is composed of two subunits which are a main storage battery and an auxiliary storage battery. both subunits are interconnected by a switch which, in one operation position, disconnects the auxiliary battery from the main battery and connects it directly to ignition terminal of the ignition system of a motor vehicle. Thus, the spark plugs of the engine receive the full voltage of the electric storage battery undiminished by voltage drops such as caused by operating the electric starting motor of the system. Thereby, the disadvantage of starting difficulties experienced with motor vehicles having normal electric storage batteries in cold weather is successfully avoided. The main unit has U-shaped plates, and these define a recess in which the auxiliary unit is received.

Ammunition high voltage electrical ignition system

Abstract: An electrical ignition system for ammunition that utilizes two fixed electrical contacts in the bolt face; and a primer having an electrically conductive priming mix, and a consumable dielectric disc having two annular consumable conductors therethrough, the gap between the two conductors being significantly greater than twice any gap between the bolt face and the disc, the ignition system being completed and energized by a high voltage power source of sufficient voltage to overcome any air gap between the cartridge and the bolt face.