Applying in combustion research, Raman scattering technique can provide high accuracy and high precision measurements of temperature and major species concentrations. However detailed knowledge of the temperature dependent Raman spectra of the probed species is a precondition to realise the potential of high precision and accuracy of the technique. As a carbon free novel fuel, the knowledge of high temperature Raman spectra of ammonia is rarely reported. We measured the Raman spectra of ammonia ranging from 299 K to 760 K. The high resolution Raman spectra are excited with a continuous wave 532 nm laser and detected with an low aberration Schmidt-Czerny-Turner spectrometer. The temperature of probe volume was determined by the fitting of N2 Raman spectra. The Raman spectra of ammonia under different temperatures were quantitatively normalized to the same number density to research the temperature behavior of spectra. Within the Raman shift region from 3150 cm−1 to 3810 cm−1, the Raman intensity and the polarization anisotropy of vibrational modes ν1, ν3, and 2ν4 were reported. The relative intensity between ν1, ν3, and 2ν4 modes were also analyzed under different temperatures.
Metal fuel is one of the attractive alternative fuels for its high energy density and zero carbon emission. In the past, they were often used as additives in fireworks and propellants. More attentions have been paid to metal fuels as the environmental issue and energy dilemma become increasingly severe. Ongoing efforts have been devoted to both modelling and experimental studies of metal fuel combustion. This review mainly focuses on the experimental progress on the combustion of micron-scale metal fuels during the past three decades. The experimental setups and the combustion diagnostics techniques used for single particle combustion and metal dust flames have significant distinctions, so they have been summarized separately. Those setups to produce single particle flames or metal dust flames are discussed in terms of their structure, scope of application, advantages and disadvantages. The diagnostics techniques are classified according to the physical parameters that are commonly adopted to characterize the metal particle combustion including burn time, temperature, particle size, dust concentration and burning velocity. Both online and offline measurement techniques are investigated in detail focusing on the measurement principle, system configuration and uncertainty analysis. Finally, the review is concluded with some unresolved problems in the field of metal particles combustion diagnostics, and provides insights into promising future research directions.
In this Letter, we introduce a novel fiber-bundle-based 2D Raman and Rayleigh imaging system for 2D measurements of major species mole fractions and temperature in flames. A cascade of dichroic mirrors and bandpass filters separate the Raman signal associated with each major species and direct it to a custom-built four-inputs/one-output fiber bundle. The single output of the fiber bundle allows simultaneous detection of four species by using a single back-illuminated CCD camera. The novel imaging system combined with a pulse-burst laser operated at 10 kHz and a 10 kHz optical shutter is characterized from measurements in a Mckenna burner and then applied to a flame stabilized over a Santoro burner. The work is, to the best of our knowledge, the first demonstration of 2D measurements of temperature and major species (i.e., N2, O2, H2, and H2O) in H2–air diffusion flames at atmospheric pressure.
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