Abstract To achieve high efficiency and low pollutant emissions with large spark ignited gas engines, operation at high excess air ratios and high turbulence levels in the combustion chamber is necessary. Under these severe boundary conditions, it is a great challenge to reliably ignite the air-fuel mixture and keep cycle-to-cycle variation of the combustion process within reasonable limits. This paper investigates the influence of ignition system parameters on combustion behavior by analyzing the overall ignition and combustion process in detail: the ignition system, the electric arc, the early phase of combustion and finally the whole combustion process. Measurements were carried out on a large bore spark ignited single-cylinder research engine and on a specially designed arc test rig. In the research engine, ion current probes were applied around the spark plug in the spark plug sleeve so that a detailed analysis of the early phase of combustion was possible in order to assess the influence of ignition system parameters on combustion. In addition, crank-angle resolved in-cylinder pressure measurements provided information about the overall combustion process. The arc test rig enables the optical investigation of the influence of ignition system parameters on electric arc behavior under non-combustible atmospheres and at thermodynamic conditions and flow conditions similar to those in the research engine at spark timing. For consistency, the same modulated capacitive discharge ignition system and spark plug were installed on both test rigs. The combination of the two test setups facilitates in-depth understanding of the phenomena observed during ignition and combustion. Near the lean engine operating limit, increasing the nominal spark current duration to a certain level yielded faster combustion progress and lower cycle-to-cycle variation of the combustion process. The investigation of the early phase of combustion by means of the ion current measurements revealed the same trend: Increasing the nominal spark current duration leads to an increase in the flame front velocity during the early phase of combustion. The results from the arc test rig indicated that an increase in nominal spark current duration leads to an increase in the maximum of the cycle-averaged electric arc length. In total, the arc test rig results suggest that besides the increase in overall dissipated secondary energy, the increase in electric arc length is the second important factor in achieving the development of a stable flame kernel and a rapid combustion process in the engine when the nominal spark current duration is varied from 100 to 500 µs at very lean engine operation.

中文翻译：

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大型稀燃火花点火燃气发动机点火系统参数对燃烧行为影响的试验研究

摘要 为了实现大型火花点火燃气发动机的高效率和低污染物排放，必须在燃烧室中以高过量空气比和高湍流水平运行。在这些严酷的边界条件下，可靠地点燃空气-燃料混合物并将燃烧过程的循环变化保持在合理范围内是一个巨大的挑战。本文通过对点火系统、电弧、燃烧初期和最终整个燃烧过程的整体点火和燃烧过程的详细分析，研究了点火系统参数对燃烧行为的影响。测量是在大口径火花点火单缸研究发动机和专门设计的电弧试验台上进行的。在研究引擎中，在火花塞套筒中的火花塞周围应用离子电流探头，以便对燃烧的早期阶段进行详细分析，以评估点火系统参数对燃烧的影响。此外，曲轴转角解析的缸内压力测量提供了有关整个燃烧过程的信息。电弧试验台可以对点火系统参数对非可燃气氛下电弧行为的影响进行光学研究，热力学条件和流动条件类似于研究发动机在点火正时。为保持一致性，两个测试台上都安装了相同的调制电容放电点火系统和火花塞。两种测试设置的结合有助于深入了解点火和燃烧过程中观察到的现象。在接近稀燃发动机运行极限时，将标称火花电流持续时间增加到一定水平会产生更快的燃烧进程和更低的燃烧过程的循环变化。通过离子电流测量对燃烧早期阶段的研究揭示了相同的趋势：增加标称火花电流持续时间会导致燃烧早期阶段火焰前缘速度的增加。电弧试验台的结果表明，标称火花电流持续时间的增加导致循环平均电弧长度的最大值增加。总共，