火花点火发动机推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、质量率等与实测值一致，从而证实了该模型的合理性。     

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。     

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．     

点火位置对天然气转子发动机燃烧的影响

为了实现对火花点燃式转子发动机工作过程的动态模拟,建立了相应的湍流和燃烧模型。在此基础上,计算得到了转子发动机缸内的流场、温度场演变及火焰传播过程。并在相同点火条件下,分析了不同点火位置对缸内燃烧过程的影响。研究结果表明:点火位置位于湍流到单向流的过渡区域时,压力峰值增大,但同时缸内平均温度增大,NO排放量也相应增加。     

火花点火发动机燃烧循环变动的理论研究

本文改进了一个火花点火发动机的准维计算模型，并对燃烧的循环变动进行了理论计算研究。这个模型包括点火时刻火花塞附近气流平均速度、湍流强度、气缸内残余废气系数以及缸内总的混合气质量等的循环变动的影响。将计算结果和试验结果进行了比较，证实了用这个模型可以较精确地预测燃烧的循环变动。另外，运用这个模型分别讨论了湍流强度、火焰中心位置在缸内的移动，以及残余废气系数的循环变动对不同燃烧阶段循环变动的影响程度，从而得出了一些有益的结论。     

用新的相关火焰模型对火花点火发动机燃烧过程的多维模拟

本文在ＫＩＶＡ－Ⅱ程序中实现了由作者提出了一个新的相关火焰模型。该模型的火焰面积密度的毁灭项中，从分形几何的角度出发引入了湍流的作用。通过对工质为丙烷的火花点火发动机进行的变工况计算，对新模型与Ｂｏｕｄｉｅｒ的燃烧模型进行了对比。结果表明，新模型合理地考虑了湍流的作用，计算结果与实验值吻合更好。     

火花点火发动机实现稀薄燃烧的技术措施

本文介绍了火花点火发动机稀薄燃烧的特点及实现稀薄燃烧所采用的关键技术措施，文章指出：实现稀薄燃烧是提高车用火花点火发动机的经济性和改善排放性能的重要途径。     

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。     

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。     

用紊流卷吸燃烧模型计算研究点火时刻紊流参数对燃烧循环的影响

利用准维紊流卷吸燃烧模型计算研究了点火时刻气缸内紊流参数的变化对汽油机燃烧循环变动的影响。结果表明，点火时刻紊流强度u′及紊流长度积分标尺L的变动对汽油机燃烧循环变动均有很大影响，增大u′或L均有利于加快燃烧速度及火焰传播速度，缩短火焰发展期；u′或L的变动加大，燃烧循环变动也随之加大，其中，u′对燃烧循环变动的影响尤其大。     

汽油机燃烧过程模拟计算及爆震预测

将计算焰前反应的化学反应动力学模型与燃烧模型及湍流火焰传播模型相结合,建立了含有碳氢燃料焰前反应的简易化学动力学模型的汽油机双区燃烧模型。用该模型能较好地模拟汽油机燃烧过程,并能实现爆震预测,研究影响爆震发生的诸多因素。采用此模型对４９２ Ｑ Ａ 汽油机进行模拟计算的结果与试验结果能较好地吻合,证明了该模型的可行性。     

摩托车汽油机的爆燃预测研究

结合燃烧模型，湍流火焰传播模型以及化学动力学模型，建立了摩托车四冲程汽油机双区准维燃烧模型。运用该模型模拟燃烧过程，并进行爆燃预测。用此模型CUB100摩托车汽油机进行了计算，预测了CUB100提高压缩比后爆燃的发生。     

透过燃烧图像对汽油机湍流火焰分形特性的试验研究和模拟(英文)

汽油机湍流预混燃烧的火焰结构具有分形几何的自相似性.利用基于分形理论的燃烧模型对发动机的燃烧过程进行了模拟计算,并将计算结果与试验数据进行了对比.试验采用自行设计的以光学发动机和高速摄像机为核心的系统,通过对拍摄到的湍流火焰照片经过图像处理来获取火焰的分形维数、火焰面积、湍流火焰速度等特性参数.研究结果表明:试验结果和模型计算值吻合得较好,分形燃烧模型是一种有效的模拟发动机工作过程的手段,具有良好的预测精度.     

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.     

在定容燃烧弹中湍流特征参数对预混燃烧的影响

:给出在定容燃烧弹中火花点燃 CH4-空气充量进行湍流预混合燃烧的试验结果并进行了分析 ,得到一些有价值的结论 :如在火核起始发展期中存在一个最小火焰传播速度 ,此时的火核半径与湍流积分长度标尺大致相等 ,增加湍流强度 (u <1 .8m/s) ,瞬时燃烧率增加 ,燃烧持续期缩短 ,相对缓燃期增加 ,相对主燃期缩短 ,这是组织湍流可以提高火花点火发动机热效率的主要原因。此外本文还给出不同间隙的失火率并指出减少火核向电极传热是减少失火率的主要措施     

Study of the cycle-to-cycle variations of an internal combustion engine fuelled with natural gas/hydrogen blends from the diagnosis of combustion pressure

A methodology is presented for studying the influence of using alternative fuels on the cycle-to-cycle variations of a spark ignition engine which has been fuelled with mixtures of natural gas and hydrogen in different proportions (0–100%). The experimental facility consists of a single-cylindrical spark ignition engine coupled to an asynchronous machine with a constant engine rotation speed of 1500 rpm. A thermodynamic combustion diagnostic model based on genetic algorithms is used to evaluate the combustion chamber pressure data experimentally obtained in the mentioned engine. The model is used to make the pressure diagnosis of series of 830 consecutive engine cycles automatically, with a high grade of objectivity of the combustion analysis, since the relevant adjustment parameters (i.e. pressure offset, effective compression ratio, top dead center angular position, heat transfer coefficients) are calculated by the genetic algorithm. Results indicate that the combustion process is dominated by the turbulence inside the combustion chamber (generated during intake and compression), showing little dependency of combustion variation on the mixture composition. This becomes more evident when relevant combustion variables are plotted versus the Mass Fraction Burned of each mixture. The only exception is the case of 100% hydrogen, due to the inherent higher laminar speed of hydrogen that causes combustion acceleration and thus turbulence generation.     

Pre-chamber turbulent jet ignition of methane/air mixtures with multiple orifices in a large bore constant volume chamber: effect of air-fuel equivalence ratio and pre-mixed pressure

Liquefied natural gas (LNG), mainly composed of methane, is in progress to substitute diesel fuel in heavy-duty marine engine for practical, economic, and environmental considerations. However, natural gas is relatively difficult to be ignited in a large bore combustion chamber. A combustion enhancement technique called pre-chamber turbulent jet ignition (TJI) can permit combustion and flame propagation in a large-bore volume. To investigate the effect of air-fuel equivalence ratio and pre-mixed pressure on pre-chamber TJI of methane/air mixtures with multiple orifices in a large bore volume, experimental tests and computational simulations were implemented to study the discharge of hot turbulent jets from six orifices of the pre-chamber. Different initial pressures and air-fuel equivalence ratios were considered to analyze the characteristics of TJI. The asymmetry of the turbulent jet actuated from six different orifices were found due to the asymmetric orientation of the spark plug, resulting in the inhomogeneous distribution of combustion in the constant volume chamber, which should be considered seriously in the marine engine design. Besides, as the premixed pressure increases, it has more effect on the flame propagation and plays a more important role, as it further increases.