摘要
基于功率诊断方法,研究了不同微波参数(脉冲波形和馈入延迟时间)下对微波辅助点火的增强效果,精确测量了点火过程中与火核耦合的微波能量,并分析了能量耦合的内在机制.结果表明:入射的部分微波能量以产生等离子体的形式耦合到点火火核中,耦合能量随微波脉冲功率的增大而提高,随延迟时间的增大而减小,最高耦合能量达到6.16 mJ;火核的增强效果与耦合能量的变化趋势一致,表明耦合的微波能量是点火增强的内在原因;能量耦合效率(耦合能量/入射能量)一般随脉宽和延迟时间增大而减小,最高耦合效率达到7.23%;并发现了微波能量耦合过程中存在从较低的效率转变到较高的稳定耦合效率的现象,将后者定义为饱和耦合模式;脉冲持续时间内到达饱和耦合模式的转变过程越短,能量耦合效率越高;饱和耦合模式下的能量耦合效率不受微波参数的影响,但高功率短脉宽的脉冲波形和低延迟时间能够更快达到饱和耦合模式,明显提高点火增强效果.
Based on the power diagnosis method,an enhancement effect of different microwave parameters(pulse waveform and feed delay time)on microwave assisted ignition was studied.The microwave energy coupling with the ignition kernel during ignition was precisely measured,and the mechanism of energy coupling was analyzed.The results show that a part of the incident microwave energy is coupled to the ignition kernel in the form of plasma generation.The coupling energy increases with the increase of the microwave pulse power and decreases with the increase of the delay time,and the highest coupling energy reaches 6.16 mJ.The enhancement effect of the ignition kernel is consistent with the variation trend of the coupling energy,which indicates that the coupling microwave energy is the essence of the enhancement of ignition.The energy coupling efficiency(coupling energy/incident energy)generally decreases with the increase of pulse width and delay time,and the highest coupling efficiency reaches 7.23%.It is also found that the efficiency of microwave energy coupling increases to a plateau,which is defined as the saturated coupling pattern.The shorter the transition to the saturated coupling pattern is,the higher the energy coupling efficiency is.The energy coupling efficiency of the saturated coupling pattern is not affected by the microwave parameters,but the transition can be facilitated by the pulse waveform with higher power,shorter pulse width and lower delay time,leading to a significant improvement of the ignition enhancement effect.
作者
王兆文
许景星
吴慧珉
刘超辉
成晓北
Wang Zhaowen;Xu Jingxing;Wu Huimin;Liu Chaohui;Cheng Xiaobei(Department of Energy and Power Engineering,Huazhong University of Science and Technology,Wuhan 430074,China)
出处
《内燃机学报》
EI
CAS
CSCD
北大核心
2024年第3期279-287,共9页
Transactions of Csice
基金
国家自然科学基金资助项目(52206144)
工信部高技术船舶资助项目([2022]296).
关键词
微波辅助点火
功率诊断
增强指数
能量沉积
耦合模式转换
microwave assisted ignition
power diagnostic
enhancement index
energy coupling
coupling mode transition
