Abstract High compression-ratio and ultra-lean burn are the two most effective measures to enhance economy of spark-ignition engines. The investigations were performed on a high compression-ratio stratified-charge direct-injection spark-ignition methanol engine with an injector of non-uniform spray-line distribution. The effect of timings of injection and spark on the concentration field of the stratified-charge mixture, combustion and emissions behaviors of methanol engine under ultra-lean burn conditions was studied by simulation. Simulation results demonstrated that an ideal stratified-charge mixture was the guarantee to obtain the best performance of a high compression-ratio spark-ignition methanol engine under ultra-lean burn. The timings of injection and spark had a remarkable effects on mixture formation, combustion and emission of a methanol engine under ultra-lean burn. There existed an optimal timings of injection and spark to obtain the peak in-cylinder pressure, peak heat release rate and peak in-cylinder temperature of methanol engine under ultra-lean burn, as well as the shortest ignition delay and combustion duration. Lower CO (carbon monoxide), unburned methanol and soot emissions, and higher NO (nitric oxide) emission were acquired at optimal timings of injection and spark under high compression-ratio and ultra-lean burn. Hence, realizing an ideal stratified-charge combustion was the key to obtain the best performance of a spark-ignition methanol engine under high compression-ratio and ultra-lean burn.

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超稀薄燃烧下高压缩比分层充量甲醇发动机喷油正时和点火正时优化

摘要 高压缩比和超稀薄燃烧是提高火花点火发动机经济性最有效的两种措施。研究是在高压缩比分层充气直喷火花点火甲醇发动机上进行的，该发动机具有非均匀喷雾线分布的喷射器。通过仿真研究了喷射和点火正时对甲醇发动机分层混合气浓度场、燃烧和排放行为的影响。仿真结果表明，理想的分层混合气是高压缩比火花点火甲醇发动机在超稀薄燃烧下获得最佳性能的保证。喷射和火花的时间对混合气的形成有显着的影响，超稀薄燃烧下甲醇发动机的燃烧与排放[J]. 超稀薄燃烧下甲醇发动机的缸内压力峰值、放热率峰值和缸内温度峰值，以及最短的点火延迟和燃烧持续时间，存在最佳的喷射和点火正时。在高压缩比和超稀薄燃烧下，在最佳喷射和火花正时获得较低的 CO（一氧化碳）、未燃烧的甲醇和烟尘排放以及较高的 NO（一氧化氮）排放。因此，实现理想的分层充气燃烧是获得火花点火甲醇发动机在高压缩比和超稀薄燃烧下最佳性能的关键。甲醇发动机在超稀薄燃烧下的峰值放热率和峰值缸内温度，以及最短的点火延迟和燃烧持续时间。在高压缩比和超稀薄燃烧下，在最佳喷射和火花正时获得较低的 CO（一氧化碳）、未燃烧的甲醇和烟尘排放以及较高的 NO（一氧化氮）排放。因此，实现理想的分层充气燃烧是获得火花点火甲醇发动机在高压缩比和超稀薄燃烧下最佳性能的关键。甲醇发动机在超稀薄燃烧下的峰值放热率和峰值缸内温度，以及最短的点火延迟和燃烧持续时间。在高压缩比和超稀薄燃烧下，在最佳喷射和火花正时获得较低的 CO（一氧化碳）、未燃烧的甲醇和烟尘排放以及较高的 NO（一氧化氮）排放。因此，实现理想的分层充气燃烧是获得火花点火甲醇发动机在高压缩比和超稀薄燃烧下最佳性能的关键。在高压缩比和超稀薄燃烧的最佳喷射和火花正时获得更高的 NO（一氧化氮）排放。因此，实现理想的分层充气燃烧是获得火花点火甲醇发动机在高压缩比和超稀薄燃烧下最佳性能的关键。在高压缩比和超稀薄燃烧的最佳喷射和火花正时获得更高的 NO（一氧化氮）排放。因此，实现理想的分层充气燃烧是获得火花点火甲醇发动机在高压缩比和超稀薄燃烧下最佳性能的关键。