Development Of Pressure-Dependence Laminar Premixed Flame Facility

In this dissertation, we developed a pressure-dependence laminar premixed flame facility (abbreviated to "premixed flame facility" or "the facility" in the following) for experimental studies of various fuels. Firstly, the design concept is proposed, and the fundamental concepts and theories of each part of the facility are described in detail. The details also include the assembly and test process of the facility. Finally, the three premixed ethylene/oxygen flames with the pressures of30,150and760Torr are carried out with the facility. The instrument consists of a flame chamber, an ionization chamber, an ion guide system and a reflectron time-of-flight mass spectrometer coupled with synchrotron vacuum ultraviolet single-photon ionization. This setup can be used to probe the chemical composition of various fuels including hydrocarbons, biomass, nitrogenous hydrocarbons, et al. With this instrument, reactive species such as radicals can be detected qualitatively, isomers can be distinguished easily, and polycyclic aromatic hydrocarbons can be detected sensitively. The most important is that mole fractions of the reactions, intermediates and products can be measured quantitatively.This dissertation contains five chapters. In the first chapter, the development of the experimental diagnostic of combustion is reviewed. The current studies on combustion are briefly summarized and evaluated. The fundamental idea in designing the pressure-dependence flame facility is raised. Compared with other combustion diagnostic technologies, the molecular beam mass spectrometry combined to vacuum ultraviolet single-photon ionization has incomparable advantages, which are soft ionization, energy tunability, et al. Moreover, the importance and necessity of pressure-dependence premixed flame studies are described. Finally, the basic concept for designing the pressure-dependence premixed flame facility is proposed.In Chapter2, the fundamental principles of each part of the facility are described. Firstly, the history of is briefly reviewed. Secondly, several critical techniques of designing time-of-flight mass spectrometry, which include double-field acceleration, ion mirror, orthogonal acceleration and time-lag focusing, are introduced and analyzed in detail. Finally, the theoretical principle of the ion transfer system is introduced briefly. In Chapter3, the designs of each part of the facility are descripted in detail, which include the design of the global structure, the vacuum system, the sampling system, the power supply system and the data acquisition system.In Chapter4, the assembly process of the premixed flame facility is described in detail. The test results of the facility are also shown in this chapter.In the last chapter, three pressure-dependence (30Torr,150Torr,760Torr) ethylene premixed flames (φ=1.7) are experimentally studied using the newly developed facility coupled with synchrotron vacuum ultraviolet single-photon ionization. Briefly, on the one hand, various mass spectra at different photon energies are obtained for distinguishing stable species and unstable radicals. Radicals detected in the ethylene flames include CH3, C2H3, C2H5, C3H3and C3H5, et al. On the other hand, the spatial distributions of every species in the flame are measured with proper photon energies and the mole fractions are calculated based on the mass spectra with different photon energies.