针对先进发动机燃烧组织与优化的飞秒激光技术开发与应用

Development of advanced engines relies on fine organization and control of combustion, where combustion laser diagnostics play a key role. The behavior of femtosecond (fs) laser interaction with matter differs significantly from that of traditional nanosecond laser. Hence, development of advanced fs laser techniques provides new opportunities for R & D of engines. This project intends to perform systematic study, both experimentally and theoretically, of fs laser-induced chemiluminescence, multi-photon fs laser-induced fluorescence and fs laser filamentation. We would like to discover the discipline and mechanism of the interaction between the fs laser and the flow/combustion fields, and to build the relationship between the fs laser-induced spectral signal and the key parameters that could characterize the flow/combustion fields. The target is to develop new fs laser techniques for diagnosing flow/combustion fields in terms of velocimetry, shock wave structure, key intermediates, temperature, flame structure and mixture fraction. Meanwhile, this project intends to reveal the physical mechanism governing the long-range filamentous discharge by using fs laser-induced filamentation, and to realize the space-time regulation of the discharge, and to ultimately develop a new technique concerning engine ignition and combustion stabilization. Finally, the fs laser techniques developed in this project will be used in a scramjet to verify their applicability. This project is expected to enhance the independent innovation ability of our country in the area of flow/combustion laser diagnostics, and it will also benefit the general national interest in 'development of original scientific research equipment'.

先进发动机研发基于对燃烧的精细组织与控制，燃烧激光诊断技术在此起到关键作用。飞秒激光与物质相互作用的特性与传统纳秒激光区别显著，开发先进的飞秒激光技术将为发动机研发提供新契机。本项目拟通过系统开展飞秒激光光致化学发光、多光子飞秒激光诱导荧光和飞秒激光成丝的实验及理论研究，获取飞秒激光与流场/燃烧场相互作用规律及机理，建立飞秒激光产生的光谱信号与表征流场/燃烧场关键参量之间的关联，从而开发出流场速度、激波结构、关键组分、温度、火焰结构和混合分数等流场/燃烧场飞秒激光诊断新技术。同时，本项目还希望阐明飞秒激光引导电极长程丝状放电现象的物理机制，实现对放电的时空调控，从而开发出基于该原理的发动机点火与稳燃新技术。最后，本项目拟将新开发的一系列飞秒激光技术应用于超燃冲压发动机台架实验，验证技术的适用性。本研究将提升我国在流场/燃烧场激光诊断领域的自主创新能力，对推动国内开发原创科研仪器有重要意义。

先进发动机研发基于对燃烧的精细组织与控制，燃烧激光诊断技术在此起到关键作用。飞秒激光与物质相互作用的特性与传统纳秒激光区别显著，开发先进的飞秒激光技术将为发动机研发提供新契机。本项目拟通过系统开展飞秒激光光致化学发光、多光子飞秒激光诱导荧光和飞秒激光成丝的实验及理论研究，获取飞秒激光与流场/燃烧场相互作用规律及机理，开发出基于飞秒激光的流场/燃烧场的诊断新技术；同时，本项目还希望阐明飞秒激光引导电极长程丝状放电现象的物理机制，并开发基于该机制的发动机点火技术。最后，将新开发的一系列飞秒激光技术应用于超燃冲压发动机台架实验，验证技术的适用性。.在本项目的研究中，取得了以下主要进展。首先，通过实验和理论研究，建立了飞秒激光产生的光谱信号与表征流场/燃烧场关键参量之间的关联，并开发出流场速度、激波结构、关键组分、温度、火焰结构和混合分数等流场/燃烧场飞秒激光诊断新技术，为进一步研究燃烧机理从而实现燃烧控制提供了支撑。其次，阐明了飞秒激光引导电极长程丝状放电现象的物理机制，实现了对电极放电的精确时空调控，并开发出基于该机理的发动机点火与稳燃新技术。最后，将新开发的一系列飞秒激光技术应用于超燃冲压发动机台架实验，国内首次实现了超燃冲压发动机内火焰结构二维成像，并通过放电等离子体实现了超声速燃烧的点火与稳燃，验证了技术的适用性。本研究对提升我国在流场/燃烧场激光诊断领域的自主创新能力，推动国内开发原创科研仪器有重要意义。