Showing papers on "Ignition system published in 1995"

Design and modeling of ignition targets for the National Ignition Facility

Abstract: Several targets are described that in simulations give yields of 1–30 MJ when indirectly driven by 0.9–2 MJ of 0.35 μm laser light. The article describes the targets, the modeling that was used to design them, and the modeling done to set specifications for the laser system in the proposed National Ignition Facility. Capsules with beryllium or polystyrene ablators are enclosed in gold hohlraums. All the designs utilize a cryogenic fuel layer; it is very difficult to achieve ignition at this scale with a noncryogenic capsule. It is necessary to use multiple bands of illumination in the hohlraum to achieve sufficiently uniform x‐ray irradiation, and to use a low‐Z gas fill in the hohlraum to reduce filling of the hohlraum with gold plasma. Critical issues are hohlraum design and optimization, Rayleigh–Taylor instability modeling, and laser–plasma interactions.

Internal combustion engines

Abstract: Review of basic principles air-standard cycles and their analysis fuel-air cycles and their analysis actual cycles and their analysis fuels carburetion injection ignition combustion and combustion chambers engine friction and lubrication heat rejection and cooling measurements and testing performance parameters and characteristics two-stroke engines.

Ignition and early soot formation in a DI diesel engine using multiple 2-D imaging diagnostics

Abstract: Combined optical imaging diagnostics in the fuel jet of a direct-injection diesel engine to study the ignition and early soot formation processes. A diesel engine of the ``heavy-duty`` size class was operated at a representative medium speed (1200 rpm) operating condition. Two fuels were used, a 42.5 cetane number mixture of the diesel reference fuels and a new low-sooting fuel. Combustion and soot formation are almost identical for both fuels. Ignition and early combustion were studied by imaging the natural chemiluminescence using a calibrated intensified video camera. Early soot development was investigated via luminosity imaging and simultaneous planar imaging of laser-induced incandescence (LII) and elastic scattering. The latter provide relative soot concentrations and particle size distributions. Data show that ignition occurs at multiple points across the downstream region of all the fuel jets prior to first apparent heat release well before any soot luminosity occurs. Quantitative vapor-fuel/air mixture images in the leading portion of the jet are also presented and discussed with respect to the early combustion data. The first soot occurs at random locations, and shortly thereafter, small soot particles develop throughout the cross section of the leading portion of the jet. Data indicate that this soot arises frommore » the fuel-rich premixed burn. Then, significantly larger soot particles appear around the periphery of the jet, presumably from the initial diffusion combustion. By the end of the premixed burn, the soot has developed a distribution pattern of a higher concentration toward the front of the jet and a lower concentration upstream, with the larger-sized soot particles being generally confined to the periphery of the jet.« less

Modeling Ignition and Burning Rate of Large Woody Natural Fuels

Abstract: As part of the development of a model for predicting fuel loading reductions by and intensity histories of fires burning in large woody natural fuels, it was necessary to develop separate models for the processes of ignition and rate of burning of individual fuel elements. This paper describes the derivation of predictive equations for ignition delay time and burning rate (from diameter reduction rate) of large woody natural fuels in a fire environment. The method consists of deriving approximate functional forms using fuel component properties and a measurable ''fire environment temperature'' and then fitting these forms to data taken in laboratory fires using a large propane burner. The equations describe the calibration data with precision adequate for the purpose for which they were designed.

Experimental Investigation of Kerosene Fuel Combustion in Supersonic Flow

Abstract: An experimental investigation of kerosene fuel ignition and combustion stabilization in a two-dimensional scramjet combustor duct was conducted. The purpose of the study was to demonstrate scramjet operational parameters (flameholder design, ignitor technique, and area ratio) with kerosene fuel. The model was tested at the freejet Mach number Mx of 6. Hydrogen piloting was used for ignition and stabilization of kerosene combustion. Conditions were found where the kerosene combustion was sustained after the hydrogen pilot was no longer being injected. Distributions of gas-thermodyn amic parameters along the duct, stability, and joint inlet-combustor operation are discussed. Nomenclature ER = equivalence fuel-air ratio hc = inlet entry height, 0.2 m M = Mach number p = pressure, Pa T = temperature, K x = xlhc = relative distance along the x axis T = time, s

Ignition and Combustion Performance of Scramjet Combustors with Fuel Injection Struts

Abstract: Ignition and combustion performance of a scramjet combustor with a fuel injection strut was experimentally investigated with Mach 2.5 vitiated air. Five strut models with different leading-edge geometry were tested without fuel injection to select the less flow-disturbing configuration. The nonreacting flowfields were also investigated by computation with a two-dimensional Navier—Stokes code. Using the selected strut, combustion and ignition tests were conducted. A pitot pressure and gas composition survey was carried out to deduce mixing and combustion efficiencies. It was found that mixing and combustion with a less flow-disturbing strut was considerably worse than those with a more flow-disturbing strut. Autoignition and forced ignition with plasma torches were tested for hydrogen. Ignition characteristics of parallel and perpendicular injection were quite different. The plasma igniters could successfully ignite both parallel and perpendicular fuel jets without a noticeable time delay between both sides of the strut.

Ignition system power converter and controller

Abstract: A high efficiency high power DC to DC power converter and controller system for a CD ignition system with a simple converter controller (8) for controlling a power switch (2) of a transformer (1) operated as a flyback which includes a lossless snubber (6) and simple current sensor (8a) for sensing and controlling the power converter current, and further including ignition trigger conditioner (9) and phase conditioner (10) for operating a trigger output circuit (11) based on an octal counter (67) for triggering ignition coil circuits of a preferred distributorless ignition circuit of the hybrid ignition system type.

Air-fuel ratio control in spark-ignition engines using estimation theory

Abstract: Increasingly strict emission standards require very accurate and fast air-fuel (A/F) ratio control. Theory, implementation, and experiments for a model-based A/F ratio control system using state-space control and estimation methods are presented. An excellent match of the in-cylinder A/F ratio with the desired A/F ratio can be achieved in spite of the time delay in the system. This is accomplished by compensating the air dynamics with a drive-by-wire throttle supported feedforward control, and the fuel dynamics with an observer-based feedback control. For fast correction of steady-state system errors, the control law is extended by learning control. The proposed method is applicable to multicylinder production engines. Experimental validation is made on a single-cylinder research engine, with A/F ratio feedback from either a linear or a nonlinear exhaust gas oxygen sensor. >

An Experimental Study of Ignition in Nonpremixed Counterflowing Hydrogen versus Heated Air

Abstract: A variable pressure, counterflow combustion chamber has been built for the experimental investigation of ignition in a convective-diffusive system. In this paper we present our results on ignition of nonpremixed, counterflowing jets of 20% H2 in N2 versus heated air, within a wide range of pressures and flow strain rates. The system was brought to ignition by increasing gradually the temperature of the air stream. Each steady-state situation just prior to ignition was characterized by measuring detailed centerline axial flow velocity and temperature distributions, for ambient pressures between 0.1-6.0 atm and pressure-weighted strain rates between 50-400 s−1. The ignition temperature, defined as the maximum temperature of the air jet just prior to ignition, was found to increase with increasing flow strain rate at all pressures. Furthermore, its sensitivity to strain-rate variations was found to be much higher at elevated and reduced pressures (above ∼ 2 atm and below ∼ 0.5 atm) than it was at at...

Combustion Chamber Deposits in Spark-Ignition Engines: A Literature Review

Abstract: Deposits, derived primarily from the fuel but with some contribution from the oil are formed inside the combustion chamber of a spark-ignition engine with use. The growth of combustion chamber deposits (CCD) is a dynamic and, to an extent, reversible process which at any given time reflects the balance between the formation and removal processes. Engine surface temperature is the most important parameter that affects their formation and changes in engine operation which tend to increase surface temperature, reduce deposit growth. At a fixed temperature, less volatile fuels tend to form more deposits than more volatile fuels. Some detergent additive packages tend to increase CCD levels. CCD reduce the heat lost to the coolant and increase charge temperature thereby increasing flame propagation rates but reducing volumetric efficiency; they might also affect the final phase of combustion by as yet undefined chemical means. This is reflected as an increase in octane requirement and NOx and a reduction in maximum power but an improvement in fuel economy and a reduction in CO2 emissions. They might also lead to higher HC emissions but not necessarily always since there might be competing mechanisms which come into play. CCD effect on CO emissions is not clearly established. They can also cause other interference problems like carbon rap. It is not known to what extent engine performance is affected by small changes in CCD levels. There is a large variation in deposit growth and its response to changes in fuel, additives and engine operating conditions across the combustion chamber and between different engines. Similarly, the performance of different engines will be affected to different extents by the deposits. While assessing the effects of different fuels or additives on engine performance and emissions through their effects on CCD, the simultaneous effects on other aspects such as inlet valve deposits which might have their own effects on engine operation, should also be considered. The paper reviews the literature on these topics.

Combustion chamber with premixing burner and jet propellent exhaust gas recirculation

Abstract: In the combustion chamber of a gas turbine, at least one premixing burner (110) is arranged in a dome (51) communicating with a plenum (50). Said premixing burner (110) is fastened on the outlet side to a front plate (52) limiting the combustion space (58) of the combustion chamber. The premixing burner procures the combustion air from the dome. The fuel injected via nozzles is intensively intermixed with the combustion air within a premixing space of the burner prior to ignition. There is provided a jet injector (53) which opens into the dome (51) and of which the central nozzle (54) is connected to the combustion space (58) via an orifice (55) in the front plate (52) and of which the annular space (56) surrounding the central nozzle is loaded with a propellant.

Ignition key device having chargeable storage cell supplying selectively attachable remote unit

Abstract: An ignition key device including an ignition key for use with a motor vehicle and a remote unit which is capable of remotely locking and unlocking a door of the motor vehicle and displaying information concerning and the status of the motor vehicle. A secondary cell is accommodated in the ignition key. When the ignition key is inserted into an ignition switch lock in the motor vehicle, the secondary cell is charged by a storage battery of the motor vehicle. When the ignition key is attached to the remote unit, the stored electric energy is supplied from the secondary cell to the remote unit to energize the remote unit for transmitting and receiving signals to perform the functions of remotely locking and unlocking a door of the motor vehicle and displaying information and the status of the motor vehicle. The ignition key can be detached from the remote unit. The ignition key device achieves a suitable weight balance between the ignition key and the remote unit, and allows the ignition key to be easily inserted into and removed from the ignition switch lock.

In situ combustion using ammonium nitrate as oxygene source

Abstract: A method is disclosed for recovering crude oil from a subterranean formation. The invention utilizes the introduction of water containing ammonium nitrate, which is capable of decomposing to generate an oxidant, into the formation. Decomposition conditions and ignition conditions are established within the formation to cause ignition within the formation. The in-situ combustion which results assists in the recovery of crude oil from the formation.

Initiator for an air bag inflator

Abstract: An electrically actuatable initiator (10) for an air bag inflator (20) includes an electrically sensitive ignition charge (280) disposed in an electrically conductive ignition cup (290). A plastic insulation cup (320) overlies the ignition cup (290). The insulation cup (320) electrically insulates the ignition cup (290) to block the flow of electric current into the ignition cup to prevent unintended actuation of the ignition charge (280). A locking ring member (380) is made from a shape-memory alloy which shrinks in diameter when heated above a predetermined temperature. The locking ring member (380) secures an output cup (360) to a retainer (150) and hermetically seals between the output cup and the retainer. A second locking ring member (310) secures the ignition cup (290) to a header (150) and seals between the ignition cup and the header.

Two Stage Ignition of n-Heptane Isolated Droplets

Abstract: Experimental and theoretical studies on the spontaneous ignition process of isolated fuel droplets were carried out. Time dependent temperature fields around the igniting droplets were observed by interferometry so that two step temperature rise can be detected. Some experiments are performed under microgravity to obtain reference data. Induction times are examined as a function of ambient temperature. As a result, a zero temperature coefficient region is found, which is equivalent to the NTC (negative temperature coefficient) region for the ignition of premixed gas. A numerical model is developed applying a simplified chemical reaction model that includes the low and the high temperature reactions. The model is able to reproduce the two step temperature rise and the roles of the two kinds of reactions on the ignition process up to the establishment of a diffusion flame around the droplet are examined.

Precombustion chamber device

Abstract: A precombustion chamber ignition device for preferably lean fuel-air mixtures and having a precombustion chamber. This precombustion chamber contains a electrode carrier extending into the precombustion chamber and on it at least one ignition electrode is attached, which has at least one ignition portion, which cooperates with a internal wall surface of the precombustion chamber in defining at least one spark gap extending substantially athwart the longitudinal axis of the precombustion chamber. In this respect the internal wall surface acts as a ground electrode. The ignition portion of the at least one ignition electrode is offset in relation to the longitudinal axis of the precombustion chamber and is arranged essentially parallel to the wall surface, which is substantially cylindrical in the spark gap portion, of the precombustion chamber close to the wall surface. In consequence it is possible for the ignition potential to be reduced and in the case of long term operation for the working life of the precombustion chamber ignition device to be increased. More particularly however the reliability of flaming is a substantially improved in the case of diluted fuel-air mixtures (lean mixtures, recycled exhaust gas ).

Fuels, for spark-ignition engines, containing polyether amines

Abstract: A fuel contains small amts. of polyetheramines of formula R1-(OBu)n-NR2R3 (I), R1 = 2-30C alkyl, R2 and R3 = H, 1-8C alkyl, aminoalkylene of formula -R4-NR5 (II) or polyaminoalkylene of formula -(R4-NR5)m-R6 (III). R4 = 2-10C alkylene, R5 and R6 = H or 1-8C alkyl, Bu - butylene residue derived from butylene oxide, and n = 12-28.

Method and arrangement for controlling a vehicle

Abstract: A method and an arrangement for controlling the drive power of a vehicle are suggested wherein, on the basis of a desired value for the torque to be outputted by the drive unit, the following are influenced in the sense of preparing the desired value: the ratio of the air supplied to the drive unit and of the fuel supplied as well as the ignition angle and/or the metering of fuel to the individual cylinders. The interventions into the air/fuel ratio as well as the ignition angle and/or the metering of fuel are synchronized with each other so that the torque-changing effects of the individual interventions occur essentially at the same time point especially at the same inducting cylinder.