点燃式发动机燃烧过程模拟分析及临界爆震预测

建立了火花点火式发动机的双区燃烧模型，其中包括化学动力学模型和湍流火焰燃烧模型．改进的双区燃烧模型中，区别于以往的绝热模型，考虑了已燃区向未燃区的传热．该模型通过模拟火花点火式发动机的燃烧过程，尝试性地进行了临界爆震预测和爆震分析工作．模型的计算结果与实验结果吻合得较好，验证了该模型分析的可行性．     

火花点火式发动机燃烧过程综述

本文总结火花点火式发动机燃烧过程研究的发展，着重讨论了火花点火式发动机分层，稀薄燃烧技术的特点，分析其相对传统燃烧方式的优点和应用中存在的问题，展望今后的发展趋势。     

汽车发动机电子控制半实物实时仿真的实现

研究利用Simulink建立发动机电子控制中进气系、供油系和点火系等系统的仿真模型。运行纯仿真，以修正发动机仿真控制逻辑、控制算法以及系统参数。利用Simulink的I／O模块把发动机仿真模型与数据采集卡连接，再连接真实发动机，实现半实物的仿真。同时利用实时工具RTW模块和Windows Target模块把仿真模型转化为可执行程序，建立仿真模型与仿真程序的连接，从而实现完整的半实物实时仿真系统。利用半实物实时仿真，可在线修改发动机系统参数和控制参数，仿真的结果可以同时体现在真实发动机与计算机上，用来开发、调试及检测汽车发动机电子控制系统。     

美国环保局提出新的排放限制条例

新标准适用于火花点火式发动机和船用柴油机，包括雪地机动车、越野摩托车和全地形车用发动机，2006年为第1个年型。 最近，美国环保局(EPA)提出了新的排放限制法规的建议，新法规适用于某些游览船用柴油机和功率在25马力（19kW）以上的工业用火花点火式发动机，也适用于游车用火花点火式发动机。该建议为制订法规过程的第一步。2001年10月EPA召开了两次意见听取会。书面意见可在12月19日前提交给EPA。 新法规的具体排放限值和实施日期见表1、2、3。根据EPA的研究分析，在移动式碳氢化合物(HC)、一氧化碳(CO)和氮氧化物(NOx)…     

火花点火式发动机未燃碳氢形成机理及影响因素的研究

详细阐述了火花点火苣了缸内未燃碳氢排放的主要生成源和形成机理，并测量了不同运转参数火花点火式发动机的碳氢排放。     

火花点火发动机准维湍流卷吸燃烧模型的适用性研究（二）

本文利用作者提出的火花点火发动机准维湍流卷吸燃烧模型，对压缩比为１０和１２的火球形燃烧室以及压缩比为１０的碗形燃烧室变工况进行了计算，将计算得到的示功图、质量燃烧率等与实验值进行了对比对分析。结果表明，合理选取与燃烧室结构相对应的四个经验常数，准维湍流卷吸燃烧模型完全适用于火花点火发动机变工况及不同燃烧室结构工作过程的计算，能够正确反映火花点火发动机结构参数和运转参数对燃烧过程的影响。     

火花点火发动机着火延迟期,燃烧持续期及NOx排放的数值模拟预测

本文介绍了火花点火发动机着火延迟期、燃烧持续期及ＮＯｘ排放的数值计算方法，并结全准维湍流卷吸模型进行了数值计算。文中给出了准维模型的计算与试验结果，并分析计算了若干发动机运行参数对着火延迟期、燃烧持续期及ＮＯｘ排放和平均指示压力的影响。结果表明，根据准维模型建立的着火延迟期、燃烧持续期及ＮＯｘ排放计算式有较清晰的物理意义，对分析、理解火花点火发动机燃烧与排放形成有一定的参考价值。     

火花点火式发动机燃烧过程综述

本文总结火花点火式发动机燃烧过程研究的发展,着重讨论火花点火式发动机分层、稀薄燃烧技术的特点,分析其相对传统燃烧方式的优点和应用中存在的问题,展望今后的发展趋势.     

火花点火式发动机点火过程数值模拟

本文以着火的热理论为基础,提出了一个火花点火式发动机点火过程的一维数学模型。应用这个数学模型对点火过程进行数值计算,可以得到临界着火半径、最小点火能量和各工况时的着火延迟期,并可研究发动机转速、点火提前角和当量燃空此等参数对着火延迟期的影响。文中对两台汽油机的点火过程进行了实例计算。     

关于火花点火发动机预混燃烧若干问题的研究进展

围绕降低火花点火发动机的有害排放和提高其经济性，内燃机工作者对火花点发动机的燃烧进行了大量的基础研究工作。本文对其中若干问题的研究现状与动态进行了综述，以期对火花点火发动机预混燃烧的基础研究有一个最基本的了解。     

火花点火对CAI燃烧过程的影响

CAI燃烧具有高效节能和低NOx的优点,但CAI燃烧也存在燃烧始点和放热率难以控制的难点。通过添加火花点火的方法,在缸内制造热点,产生有助于CAI燃烧的着火条件,从而达到了控制CAI燃烧始点的目的。试验表明,在添加火花点火后,着火滞燃期明显缩短,CAI着火及燃烧更稳定,并对经济性有一定改善。火化辅助点火也有利于CAI运行范围向更低负荷方向拓展。因此,火花点火可以作为控制CAI燃烧的一种辅助手段。     

Evaluation of a spark ignition engine cycle using first and second law analysis techniques

In the present work, a simulation model of the actual processes occurring during the thermodynamic cycle of a real spark ignition engine is developed. The model incorporates such important features as heat exchange of the cylinder gases with the chamber walls (during all phases), real spark ignition timings, real valve opening and closing timings, accurate simulation of the spherical flame front movement issuing from the spark plug and calculation of eight chemical species concentration during combustion, at every engine degree crank angle. The results from this first law analysis of the real cycle (for example pressure indicator diagrams, efficiencies) are compared favourably with the relevant experimental results obtained from a flexible, variable compression ratio, Ricardo E-6 spark ignition engine, located at the author's laboratory, forming thus a sound basis for moving towards a second law evaluation of this cycle. The thermodynamic state points, determined from the first law analysis, are used to determine the availability (second law analysis) at each engine crank angle and so lead to the effectiveness computation, as well as to the revelation of the magnitude of the work-potential lost during the various processes in a much more realistic way than the first law analysis can. The second law analysis results, for the actual engine in hand, are compared with the up-to-now existing ideal cycle Otto engine results. Also, a second law parametric investigation is performed over a wide range of design and operation conditions (compression ratio, fuel-air ratio, ignition advance), providing useful information for the cycle processes performance assessment by bringing state degradations and thermodynamic losses into perspective.     

点火方式对汽油机燃烧过程的影响

通过基本结构的微小变动,将单火花塞点火(single spark ignition,SSI)改造成双火花塞点火(dual spark ignition,DSI),运用三维仿真软件AVL FIRE模拟仿真,并通过试验验证。再对单火花塞点火、双火花塞同步点火(dual synchronous spark ignition,DSSI)、异步点火(dual asynchronous spark ignition,DASI)3种不同的点火方式进行对比。结果表明:在6500 r/min转速全负荷状态下,空气过量系数为1.00而其他参数调整为最佳时,单火花塞的最佳点火提前角为29°,在空气过量系数为1.15的最佳参数下,双火花塞同步点火的最佳点火提前角为22°,双火花塞异步点火的最佳点火提前角为22°和24°。其中,发动机综合性能在双火花塞异步点火条件下表现最好:相对于单火花塞点火指示功提升8.49%;相对于同步点火,可将最高燃烧压力和压缩负功减小,指示功提升3.60%;同时改善了排放性。上述研究中发动机均控制在未发生爆震情况下。     

无节气门负荷控制策略对汽油机性能影响的研究

在汽油机上取消节气门,采用可变气门升程和气门定时控制进气量,继而控制发动机负荷,实现汽油机的无节气门负荷控制.针对一台4缸汽油机采用可变气门驱动负荷控制方式建立了无节气门汽油机仿真模型,并得到试验验证.在此基础上研究了不同负倚控制方式对汽油机性能的影响.结果表明,采用可变气门开启持续期(VET)负荷控制方式可以有效降低汽油机部分负荷泵气损失,最大降低幅度达到57%,同时比油耗降低了5.63%.VET同样可以使伞负荷时低速转矩和高速功率得到提高,其中低速转矩提升达到了27.8%.但VET实现汽油机怠速控制较为困难,需要同时采用降低气门升程的(VVL)控制方式,该控制方式下泵气损失有所提高,但是气门升程降低造成进气流通特性的改变使燃油雾化及燃烧得到改善.     

Modelling cycle to cycle variations in an SI engine with detailed chemical kinetics

This paper presents experimental results and a new computational model that investigate cycle to cycle variations (CCV) in a spark ignition (SI) engine. An established stochastic reactor model (SRM) previously used to examine homogeneous charge compression ignition (HCCI) combustion has been extended by spark initiation, flame propagation and flame termination sub-models in order to simulate combustion in SI engines. The model contains a detailed chemical mechanism but relatively short computation times are achieved. The flame front is assumed to be spherical and centred at the spark location, and a pent roof and piston bowl geometry are accounted for. The model is validated by simulating the pressure profile and emissions from an iso-octane fuelled single cylinder research engine that showed low CCV. The effects of key parameters are investigated. Experimental results that show cycle to cycle fluctuations in a four-cylinder naturally aspirated gasoline fuelled SI engine are presented. The model is then coupled with GT-Power, a one-dimensional engine simulation tool, which is used to simulate the breathing events during a multi-cycle simulation. This allows an investigation of the cyclic fluctuations in peak pressure. The source and magnitude of nitric oxide (NO) emissions produced by different cycles are then investigated. It was found that faster burning cycles result in increased NO emissions compared with cycles that have a slower rate of combustion and that more is produced in the early stages of combustion compared with later in the cycle. The majority of NO was produced via the thermal mechanism just after combustion begins.     

火花点火发动机准维湍流卷吸燃烧模型的适用性研究（1）

本文在分析火花点火发动机湍流涡结构及缸内湍流特性参数的基础上，提出了适用于火花点火发动机燃烧计算的准维湍流卷吸模型，通过建立相应的子模型及求解方程，实现了燃烧过程的计算；对压缩比为１０的紧凑型燃烧室，在改变发动机转速、负荷、空燃比以及点火正时的情况下，计算得到的压力示功图、质量燃烧率等与实测值一致，从而证实了该模型的合理性。     

采用离子电流分析法实现发动机爆震信号的正确检测

本描述了了种直接利用火花塞电极作为传感器检测发动机爆震的方法。作在章中详细分析及讨论了离子电流的产生机理及影响其测量的因素，并利用这一方法在发动机做了大量的试验研究，获得了宝贵的第一手资料。为了获得正确的信号检测，作在火花塞电极上加一定的直汉电压、使其能灵敏的感受燃气密度的变化。     

Effects of ignition advance on a dual sequential ignition engine at lean mixture for hydrogen enriched butane usage

In this study, the effects of ignition advance on dual sequential ignition engine characteristics and exhaust gas emissions for hydrogen enriched butane usage and lean mixture were investigated numerically and experimentally. The main purpose of this study is to reveal the effects of h-butane application in a commercial spark ignition gasoline engine. One cylinder of the commercially dual sequential spark ignition engine was modeled in the Star-CD software, taking into account all the components of the combustion chamber (intake-exhaust manifold connections, intake-exhaust valves, cylinder, cylinder head, piston, spark plugs). Angelberger wall approximation, k-ε RNG turbulence model and G-equation combustion model were used for analysis. In the dual sequential spark ignition, the difference between the spark plugs was defined as 5° CAD. At the numerical analysis; 10.8:1 compression ratio, 1.3 air-fuel ratio, 2800 rpm engine speed, 0.0010 m the flame radius and 0.0001 m the flame thickness were kept constant. The hydrogen-butane mixture was defined as 4%–96% by mass. In the analysis, the optimal ignition advance was determined by the working conditions. In addition, the effects of changes in ignition advance were examined in detail at lean mixture. For engine operating conditions under investigation, it has been determined that the 50° CAD ignition advance from the top dead center is the optimal ignition advance in terms of engine performance and emission balance. It has also been found that the NO_x formation rises up as the ignition advance increases. The BTE values were approximately 12.01% higher than butane experimental results. The experimental BTE values for h-butane were overall 3.01% lower than h-butane numerical results.     

Comparative study of some experimental methods to characterize the combustion process in a SI engine

Seven common methods based on in-cylinder data, usually applied to determine the combustion parameters (ignition delay and combustion duration), are compared using in-cylinder data provided from a natural gas spark ignition engine operating under lean conditions. The influence of three engine operating parameters: spark advance, throttle opening and fuel/air equivalence ratio, on combustion parameters are tested using every method and the results are compared. The application of these methods on average and individual cycles is also performed. The advantages and disadvantages of these methods are presented and discussed. Some methods can be used only for the ignition delay determination. A comparison with a motor-cycle, so a specific experimental device, is necessary for three methods. Others are very sensitive to noise, or can be used only in some restricted area of engine operating conditions. One method needs calculations based on several experimental assumptions.     

Understanding ignition processes in spray-guided gasoline engines using high-speed imaging and the extended spark-ignition model SparkCIMM: Part B: Importance of molecular fuel properties in early flame front propagation

Recent high-speed imaging of ignition processes in spray-guided gasoline engines has motivated the development of the physically-based spark channel ignition monitoring model SparkCIMM, which bridges the gap between a detailed spray/vaporization model and a model for fully developed turbulent flame front propagation. Previously, both SparkCIMM and high-speed optical imaging data have shown that, in spray-guided engines, the spark plasma channel is stretched and wrinkled by the local turbulence, excessive stretching results in spark re-strikes, large variations occur in turbulence intensity and local equivalence ratio along the spark channel, and ignition occurs in localized regions along the spark channel (based upon a Karlovitz-number criteria).In this paper, SparkCIMM is enhanced by: (1) an extended flamelet model to predict localized ignition spots along the spark plasma channel, (2) a detailed chemical mechanism for gasoline surrogate oxidation, and (3) a formulation of early flame kernel propagation based on the G-equation theory that includes detailed chemistry and a local enthalpy flamelet model to consider turbulent enthalpy fluctuations. In agreement with new experimental data from broadband spark and hot soot luminosity imaging, the model establishes that ignition prefers to occur in fuel-rich regions along the spark channel. In this highly-turbulent highly-stratified environment, these ignition spots burn as quasi-laminar flame kernels. In this paper, the laminar burning velocities and flame thicknesses of these kernels are calculated along the mean turbulent flame front, using tabulated detailed chemistry flamelets over a wide range of stoichiometry and exhaust gas dilution. The criteria for flame propagation include chemical (cross-over temperature based) and turbulence (Karlovitz-number based) effects. Numerical simulations using ignition models of different physical complexity demonstrate the significance of turbulent mixture fraction and enthalpy fluctuations in the prediction of early flame front propagation. A third paper on SparkCIMM (companion paper to this one) focuses on the importance of molecular fuel properties and flame curvature on early flame propagation and compares computed flame propagation with high speed combustion imaging and computed heat release rates with cylinder pressure analysis.The goals of SparkCIMM development are to (a) enhance our fundamental understanding of ignition and combustion processes in highly-turbulent highly-stratified engine conditions, (b) incorporate that understanding into a physically-based submodel for RANS engine calculations that can be reliably used without modification for a wide range of conditions (i.e., homogeneous or stratified, low or high turbulence, low or high dilution), and (c) provide a submodel that can be incorporated into a future LES model for physically-based modeling of cycle-to-cycle variability in engines.