P. Bulat, I. Esakov, L. Grachev, M. Renev, K. Volkov, I. Volobuev
{"title":"IMPROVEMENT OF IGNITION SYSTEM OF DETONATION ENGINES WITH AN INITIATED MICROWAVE SUBCRITICAL STREAMER DISCHARGE","authors":"P. Bulat, I. Esakov, L. Grachev, M. Renev, K. Volkov, I. Volobuev","doi":"10.30826/icpcd13a05","DOIUrl":null,"url":null,"abstract":"Pulsed detonation engines are considered to be the promising e¨ective propulsion systems for future space missions. The ignition system has always posed problems in commercial applications. Many experimental, theoretical, and numerical studies have been performed for the past years and various ignition systems (e. g., electric discharge, microwave discharge, laser radiation) have been tested. The propulsive performance of air-breathing pulsed detonation engines (PDEs) has been theoretically and numerically studied over a wide range of system con¦gurations, operating parameters, and §ight conditions. It has been suggested that discharges which create the quickest expanding high-temperature region or discharges which occupy a large volume are optimal for ignition because they can most rapidly and reliably bring the radius of the ignition kernel to its critical value for transition into a self-propagating §ame. Signi¦cant e¨orts are being spent on acceleration of fuel combustion and rising its e©ciency. Existing studies have mainly focused on optimizing fuel injection and mixing, repetitive initiation of detonation, and integration of detonation tubes with fuel inlets. Understanding of streamer propagation mechanism is of essential importance for the studies of electrical breakdown phenomena and their related applications. In this study, a subcritical microwave streamer discharge is used to initiate ignition of air fuel mixtures. The study focuses on investigation of possibilities of the use of microwave radiation to initiate combustion and detonation of air fuel mixtures. The results of experimental and computational studies related combustion and detonation of air propane mixture are presented. To initiate the combustion and detonation, the deep subcritical streamer discharge is used. The discharge is formed by a ¦eld with the intensity smaller than the minimum pulse intensity leading to the gas breakdown. An acceleration of combustion and a uniform temperature front are obtained and the possibility of combustion of fuel-lean mixture is con¦rmed. An increase in combustion e©ciency is also observed. Streamer discharge ignition of particularly lean air fuel mixture with air-to-fuel ratio greater than the §ammability limit has been demonstrated under normal conditions. The indirect evidence suggests that the ignition by the microwave discharge is of the nonthermal nature. The advantages of igniting the fuel mixture by streamer discharge is attributed to the ultraviolet radiation emitted by oxygen atoms subjected to the discharge. The ultraviolet radiation generation causes formation of the nonequilibrium cold plasma with avalanche increase in the number of free electrons. The microwave streamer ignition can be considered for the application in internal combustion engines to replace the conventional spark ignition.","PeriodicalId":326374,"journal":{"name":"ADVANCES IN DETONATION RESEARCH","volume":"64 1","pages":"0"},"PeriodicalIF":0.0000,"publicationDate":"2022-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"ADVANCES IN DETONATION RESEARCH","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.30826/icpcd13a05","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
微波亚临界流点火对爆震发动机点火系统的改进
脉冲爆震发动机被认为是未来空间任务中最有前途的有效推进系统。点火系统在商业应用中一直存在问题。许多实验、理论和数值研究已经在过去的几年中进行了,各种点火系统(例如,放电、微波放电、激光辐射)已经进行了测试。吸气式脉冲爆震发动机(PDEs)的推进性能在理论和数值上进行了广泛的系统配置、工作参数和光照条件下的研究。有研究表明,产生高温扩展最快的放电或占据较大体积的放电是最适合点火的,因为它们能最迅速、最可靠地使点火核半径达到过渡到自传播过程的临界值。在加速燃料燃烧和提高其能效方面,人们正投入大量精力。现有的研究主要集中在优化燃油喷射和混合、重复起爆以及爆震管与燃油入口的集成等方面。了解流的传播机制对研究电击穿现象及其相关应用具有重要意义。在本研究中,使用亚临界微波流放电来引发空气燃料混合物的点火。这项研究的重点是调查利用微波辐射引发空气燃料混合物燃烧和爆轰的可能性。介绍了空气丙烷混合气燃烧爆轰的实验和计算结果。为了启动燃烧和爆震,采用了深亚临界流放电。放电由强度小于最小脉冲强度的电场形成,导致气体击穿。得到了燃烧加速和均匀温度锋,证实了贫油混合气燃烧的可能性。燃烧效率的提高也被观察到。在正常条件下,证明了空气-燃料比大于§ammability极限的特别稀薄的空气燃料混合物的拖流放电点火。间接证据表明,微波放电的点火是非热性质的。流光放电点燃混合燃料的优点是由于受到流光放电的氧原子所发出的紫外线辐射。紫外辐射的产生导致非平衡冷等离子体的形成,自由电子数量雪崩式增加。可以考虑在内燃机上应用微波流点火技术来代替传统的火花点火。
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