| 王长通,张韧,李卫,等.掺混策略对聚甲氧基二甲醚/甲醇双燃料燃烧影响的可视化研究[J].内燃机工程,2024,45(3):21-29. |
| 掺混策略对聚甲氧基二甲醚/甲醇双燃料燃烧影响的可视化研究 |
| An Optical Investigation on the Effects of Blending Strategies on Polyoxymethylene Dimethyl Ethers/Methanol Dual-Fuel Combustion |
| DOI：10.13949/j.cnki.nrjgc.2024.03.003 |
| 关键词:光学发动机 掺混策略 聚甲氧基二甲醚 甲醇 火焰发展 燃烧稳定性 |
| Key Words:optical engine blending strategy polyoxymethylene dimethyl ethers（PODE） methanol flame development combustion stability |
| 基金项目:国家重点研发计划项目（2022YFE0100100）；国家自然科学基金优秀青年科学基金项目（52222604） |
|
| 摘要点击次数: 738 |
| 全文下载次数: 445 |
| 摘要:基于一台单缸光学发动机，采用高速摄影和瞬态压力同步测量方法，开展了不同掺混策略对聚甲氧基二甲醚（polyoxymethylene dimethyl ethers， PODE）/甲醇双燃料燃烧及火焰发展特性的影响研究，其中掺混策略包括P/M20（甲醇和PODE以2∶8的体积比掺混）燃料双喷射模式和缸内直喷PODE引燃预混甲醇混合气的反应活性控制压燃（reactivity-controlled compression ignition， RCCI）模式。结果表明，对于P/M20燃料双喷射模式，随着气道喷射比例增加，低温反应增强，滞燃期缩短，着火时刻显著提前，进而显著改善了燃烧稳定性；对于RCCI模式，随着气道喷射甲醇占比的增加，滞燃期延长，燃烧相位推迟，峰值压力和放热率均降低，并伴随着燃烧稳定性变差。燃烧可视化显示，两种掺混策略下，随着气道喷射比例的增加，蓝色预混火焰占比增大，最大火焰传播速度降低，由于末端未燃混合气浓度增加，火焰发展由明显的扩散燃烧逐渐转变为末端混合气不断出现新自燃点的顺序自燃模式。对比两种掺混策略可以发现，推迟缸内直喷时刻均能在一定程度上优化燃烧相位，显著改善指示热效率，然而其原因侧重点不同：对于P/M20燃料双喷射模式，提高气道喷射比例可以增强低温放热，促进着火，显著改善燃烧稳定性；对于RCCI模式，其燃烧过程主要位于上止点之后，燃烧相位更接近最佳燃烧相位，进一步减小了传热损失和循环负功，因此其具有更高的指示热效率，也更适合PODE/甲醇双燃料燃烧模式。 |
| Abstract:Based on a single-cylinder optical engine， synchronization measurement of in-cylinder pressure and high-speed photography was performed， and the influences of different blending strategies on combustion and flame development characteristics of polyoxymethylene dimethyl ethers（PODE）/methanol dual-fuel mode was investigated. The blending strategies include P/M20 （methanol and PODE mixed in a volume ratio of 2∶8） fuel dual-injection mode and reactivity-controlled compression ignition（RCCI） mode that direct-injected PODE pilot ignites premixed methanol/air mixture. The results show that for the P/M20 fuel dual-injection mode， as the proportion of port-injection increases， the low-temperature heat release （LTHR） is enhanced， the ignition delay time（IDT） is shortened and the ignition timing is significantly advanced， further improving the combustion instability. For RCCI mode， as the methanol fraction increases， IDT is prolonged， the combustion phasing is delayed， peak pressure and heat release rate are decreased. Combustion visualizations show that under the two blending strategies， as the proportion of port-injection increases， the proportion of blue premixed flame increases， and the maximum flame propagation speed decreases. Due to the increase of the equivalence ratio of unburned mixture， the flame development gradually changes from obvious diffusion combustion to a sequential auto-ignition mode where new auto-ignition points continuously occur in the unburned mixture. Comparing the two blending strategies， it is shown that as the direct-injection timing is retarded， the combustion phasing can be optimized in some extent and the thermal efficiency can be improved. However， the two blending strategies have different focuses on combustion improvement. For P/M20 fuel dual-injection mode， increasing the port-injection ratio can enhance low-temperature heat release and promote auto-ignition， and then improve combustion instability. For RCCI mode， under the same port-injection ratio， the main combustion process is after the top dead center（TDC）， and the combustion phasing is closer to the optimal combustion phasing， which further reduces the heat transfer loss and negative circulating work. Therefore， the RCCI mode has higher indicated thermal efficiency and is more suitable for PODE/methanol dual-fuel combustion mode. |
|
查看全文 HTML
查看/发表评论 下载PDF阅读器 |