Search

In order to develop a burner with uniform temperature field, the combustion characteristics and thermal performance of partially premixed methane/air jet flames were experimentally studied by using micro jet array burners. The circular tubes of 1.0-mm inner diameter and 1.5-mm outer diameter were used as nozzles. The effects of nozzle spacing and equivalence ratio on flame phenomenology, temperature distribution and pollutant emissions were respectively investigated by camera photography, thermocouple measurement and sampling analysis. Results show that there are two clean flame patterns: clean merged-flame and clean non-merging flames. The flame patterns depend on the strength of flame interaction, the equivalence ratio of the mixture and the quantity of air entrainment through the gap between nozzles. The burners with small nozzle spacing such as 2 mm and 2.5 mm tend to produce fully merged flame with low equivalence ratio limit and the corresponding temperature fields are very uniform with fluctuations less than 0.3%, but a small increase in equivalence ratio will lead to rapid deterioration of combustion property. The burner with a medium spacing of 3 mm can produce partially merged flame in a wide equivalence ratio range with low emissions, and the temperature fluctuation can be less than 0.5% (

This paper explores the characteristics of absorption and fluorescence spectra of p-xylene within the temperature range that is frequently encountered during the mixture formation in internal combustion engines. At 266 nm wavelength, the p-xylene absorption cross section shows a mean value of (3.4 ± 0.2) × 10−19 cm2/molecule within the temperature range from 423 to 623 K in N2. As expected, fluorescence peak intensity decreases by a factor of 3 when the temperature increases by 100 K, due to a increasing non-radiative decay rate of excited state at increasing temperatures. In addition, the suitability of p-xylene for temperature measurements in the gas phase via the single-wavelength excitation (at 266 nm) two-color detection laser-induced fluorescence imaging is explored. Combinations of spectral detection bands were compared and the combination of 320/289 nm provides the best temperature performance with a relative error of 2.6% within the investigated temperature range. It is also shown that the temperature field measurement has not been strongly affected by the laser attenuation.