Simultaneous measurements of fuel concentration and temperature in gas jets by laser induced breakdown spectroscopy

Quantitative measurements of fuel concentrations in direct-injection methanol-n-hexane sprays by laser induced breakdown spectroscopy

“…Within 630-790 nm, the atomic lines of hydrogen at 656 nm, nitrogen at 742-746 nm and oxygen at 777 nm can be observed. All of the hydrogen, nitrogen and oxygen lines were employed to By using appropriate background and baseline subtraction method [13], the intensities of atomic lines can be accurately quantified. Then the correlations between line intensity ratios and atom concentration ratios were built up.…”

“…As a result, the equivalence ratio can be also estimated. The measurement uncertainties are estimated to be about 5%-10% by considering both the systematic errors including inaccuracies in calibrations and random errors including the pulse energy instability and the variations in laser-plasma interactions [13]. Figure 5(a) depicts the concentrations of methanol and n-hexane and the blending fraction in M15 spray at different radial distances from spray axis (r).…”

“…In addition, the fuel concentration information is necessary for understanding fuel-air mixing mechanism and calibration of spray model. To achieve the quantitative concentration measurements, laser-based techniques are commonly used, such as the planar laser induced fluorescence (PLIF) [9,10], the laser absorption and scattering (LAS) [11,12], the laser induced breakdown spectroscopy (LIBS) [13,14] etc. The PLIF technique is a most popular technique for concentration measurements.…”

Injection characteristics and fuel-air mixing process of ammonia jets in a constant volume vessel

“…The delay and width of the ICCD gate were optimized to be 0.4 and 0.5 s respectively, according to the signal-tobackground ratios (SBRs) of atomic lines and the stability of the PIR. The detailed information can be found in our previous study [32]. In the LIBS calibrations, the ammonia and the nitrogen as a substitute of the air from high-pressure gas bottles were sequentially transferred to the CVV to produce the homogeneous mixture of a certain equivalence ratio.…”

“…In addition, the PIRs show a deviation of 3-7% from the mean value, indicating a high measurement precision. The total measurement uncertainties of LIBS concentration measurements are estimated to be 5-10% by considering the inaccuracy in the equivalence ratio calibrations and the laser pulse instability [32].…”