Showing papers on "Spark (mathematics) published in 1971"

Numerical Simulation of Spark Discharges in Air

Abstract: A numerical model is presented which describes the evolution with time of a short segment of a spark channel in air and its associated acoustic wave. The model assumes a straight, cylindrical conducting column in which local thermodynamic equilibrium exists at every point. The electrical energy input to the column is determined by a prescribed electrical current waveform, coupled with a computation of the plasma conductivity. The evolution with time of the conducting column and its surrounding flow field is then found by numerical integration of the equations of gas dynamics. The model employs a realistic equation of state for air at high temperatures, and incorporates kinetic and radiative energy transport processes. It is shown that a satisfactory description of the properties of a spark channel cannot be achieved when radiative transport processes are neglected. The model agrees well with experimental measurements of spark channel radii, temperatures, pressures, and electron densities, and predicts the resultant shock wave strengths closely. The voltage gradients along the spark channel predicted by the model, and the total energy input to the channel, are not as uniformly in agreement with experiment. Possible reasons for these discrepancies are discussed.

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.

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.

Discrete modelling of spark-ignition engines for control purposes†

Abstract: A sampled-data model of a spark-ignition engine, when used in essentially constant-speed situations, is developed. This has resulted in the discussion of an unusual type of control element termed an ‘integrate, sample and cancel circuit’. Some properties of this type of element are demonstrated. A comparison is made between this model and the model for diesel-engine control studies previously developed by the authors.

Rotary combustion engine ignition

Abstract: In a preferred embodiment, a rotary combustion engine of the eccentric rotor type includes a housing mounted spark plug which coacts with a plurality of rotor mounted electrodes to provide improved spark ignition for the various combustion chambers of the engine. The rotor mounted electrodes are suitably profiled to optimize the initial spark gap for best spark forming characteristics under various operating conditions.

Apparatus for continuous spectral analysis of molten substances

Abstract: Apparatus for direct and continuous spectrometric analysis of molten metals has a riser which draws a continuous stream of molten metal from a furnace in response to actuation of an electromagnetic pump. The stream flows through a spark chamber which contains a sill or barrier over which the metal must flow to rise to a predetermined level at a desired distance from a first electrode which is connected with one pole of a spark generator. The other pole of the spark generator is connected with a second electrode which dips into the stream of molten metal in the chamber with attendant generation of a spark between the exposed surface of the stream and the first electrode. The light or radiation which is generated by the spark is directed into a spectrometer by way of a horizontal or vertical tube. Such tube further serves to admit into the spark chamber a stream of inert gas which evacuates metallic vapors developing in the chamber in response to generation of the spark.

Portable automotive spark voltage tester

Abstract: A circuit for testing spark voltages in internal combustion engines or similar devices wherein the circuit capacitively samples the voltage of an in situs spark plug of an internal combustion engine by shunt-rectifying, filtering, and applying it to a direct current meter for visual indication.

Internal combustion engine ignition spark vacuum advance system

Abstract: A system for enabling the ignition spark vacuum advance mechanism of an internal combustion engine until the engine has reached operating temperature for use with ignition spark vacuum advance systems which disenable the vacuum spark advance mechanism with vehicle speeds less than a predetermined magnitude of the type having a speed sensitive switch, closed below a selected vehicle speed, connected in series in the energizing circuit of the operating coil of a two-way valve which, when energized, operates the valve to the condition which vents the associated spark advance vacuum unit to atmosphere. The parallel combination of a normally open temperature sensitive in-vehicle temperature switch and a normally open temperature sensitive engine temperature switch is connected in series with the speed sensitive switch to prevent the operation of the valve to the condition which vents the spark advance vacuum unit vacuum port to atmosphere until the engine has reached operating temperature.

Wire spark chambers for clinical imaging of gamma-rays.

Abstract: Spark chambers with digitized read-outs offer distinct advantages in spatial resolution and coverage over other gamma -ray imaging devices. While these chambers usually require external logic signals for triggering, in this paper a method is described that provides self-triggering spark chambers. Initial tests of a 45*45 cm externally triggered spark chamber with 60Co and 198Au samples are also described and future developments are mentioned.

Igniting system for diesel engine starting

Abstract: AN IGNITING SYSTEM IS PROVIDED IN A DIESEL ENGINE WHEREIN A SPARK IGNITION CIRCUIT INCLUDING A SPARK PLUG MOUNTED IN ONE OF THE ENGINE COMBUSTION CHAMBERS ASSISTS STARTING BY SPARK IGNITION. AFTER NORMAL COMPRESSION IGNITION IS ESTABLISHED, THE IGNITION CIRCUIT IS DEACTIVATED BY A SEMICONDUCTOR SWITCH. THE SEMICONDUCTOR SWITCH IS CONTROLLED IN RESPONSE TO IONIZATION OF COMBUSTION CHAMBER GASES WHICH NORMALLY OCCURS AS THE ENGINE IS RUNNING.

Pressure responsive switch

Abstract: This invention relates to a normally open pressure responsive electrical switch. Such a switch can be used in an automobile transmission as part of the transmission control spark advance systems presently found on automobiles.

The spark chamber as a detector for positron angular correlation measurements

Abstract: Describes a new kind of apparatus for making positron annihilation, angular correlation measurements. The use of a spark chamber as a two-dimensional gamma -ray detector enables two components of the momentum of photon pairs to be determined instead of the normal one. The development and construction of the special narrow gap spark chambers needed for this work are described and a discussion of the spark mechanism of narrow gap chambers is given. The use of television cameras to read out the spark chamber information is then considered and the logic of the complete recording system is briefly described. This apparatus was used to study a copper single crystal and the effect of the 'necks' of the copper Fermi surface was visible in the data. Various possible ways to improve the performance of the apparatus are then discussed.

Time-resolved spark-source mass spectrometry: the effect of spark duration on ion intensity and precision of analysis.

Abstract: A radio-frequency probe and a synchronized electronic ion-beam chapper have been used to determine ion-intensity variation with spark duration. Large peaks in multiply charged ion intensities are detected in the early stages of the radio-frequency spark, while later in the spark period the singly charged species predominate. The effects of these variations on the precision of analysis have been determined. A gate was selected in the spark pulse, and a factor of two increase in precision was obtained.

Electrochemical spark detection system

Abstract: A spark detection system for an electrochemical machining apparatus has an adjustable threshold for electrical disturbances typically caused by sparking in the gap between the electrode and the workpiece The threshold level is directly readable in volts

Spark erosion device

Abstract: The electro-erosion device gives a smoother surface and is coupled to a trigger circuit spark generator that is connected to a workpiece electrode and a tool electrode. The electrical connections are made by conductors consisting in each case of a bundle of strands having a cross-section 0.2 mm.

The Sequential Spark Technique: A Tool for Wake Velocity Studies in Ballistic Ranges

Abstract: : For more than six years, the Defence Research Establishment Valcartier (DREV) has been carrying out a program of investigation of turbulent wakes in its ballistic range facilities. One of the experimental techniques used in the program has been the sequential spark technique which makes use of electrical discharges (sparks) in sequence to measure velocity profiles in the wake of projecticles in free flight. This experimental technique is based on the formation of an ionized luminous path in the wake by a first spark and on the periodic reillumination of the displaced ionized path by successive sparks. Open-shutter photography yields a profile of the displacement of the path which can be used to calculate the velocity. The report presents a comprehensive review of the sequential spark technique.