In this study, a strategy was developed for in situ, non-intrusive, and quantitative measurement of the oxides of nitrogen (NO and NO₂) to describe emission characteristics in gas turbines. The linear calibration-free wavelength modulation spectroscopy (LCF-WMS) approach combined with the temperature profile-fitting strategy was utilized for trace NO and NO₂ concentration detection with broad spectral interference from gaseous water (H₂O). Transition lines near 1308 nm, 5238 nm, and 6250 nm were selected to investigate the H₂O, NO, and NO₂ generated from combustion. Experiments were performed under different equivalence ratios in a combustion exhaust tube, which was heated at 450–700 K, with an effective optical length of 1.57 m. Ultra-low NO_x emissions were captured by optical measurements under different equivalence ratios. The mole fractions of H₂O were in agreement with the theoretical values calculated using Chemkin. Herein, the uncertainty of the TDLAS measurements and the limitation of improving the relative precision are discussed in detail. The proposed strategy proved to be a promising combustion diagnostic technique for the quantitative measurement of low-absorbance trace NO and NO₂ with strong H₂O interference in real combustion gases.

Cyanide often forms as a byproduct during the fermentation process of distilled spirits, and excessive amounts can cause damage to health. Cyanide poisoning is also common in alcoholic beverages and water. Therefore, the cyanide content measurement in water and distilled spirits is essential. Here, a Raman integrating sphere technique for the in situ detection of cyanide has been established, and a lower limit of detection of 1.56 mg L⁻¹ in water and ethanol was achieved, owing to the efficient collection of Raman signals and the efficient use of laser power. The Raman peak of cyanide is located at 2080 cm⁻¹. The detection range was from 1.56 to 25 mg L⁻¹ cyanide in water, ethanol, and liquor with high linearity (R² = 0.9986, 0.9986, and 0.9908) and precision (%RSD = 5.53%, 6.92%, and 14.12%). This instrument provides an alternative method for detecting cyanide, which can not only be used for accurate qualitative and quantitative detection of cyanide but also for food safety detection and physical evidence analysis of cyanide in beverage poisoning. Key to our method is that it offers advantages such as no need for sample pretreatment, simplicity and speed of operation, non-destructive analysis, minimal sample consumption (only 3 milliliters are required for a single measurement), and the ability to preserve the analyzed sample as evidence.

Double-wall cooling has been extensively investigated due to its exceptional cooling performance. However, most previous studies on the cooling characteristics of double-wall geometry have been conducted under non-reacting conditions, neglecting the influence of high-temperature flue gas...

Swirling flow is widely used in gas turbine burners to promote fuel/air mixing uniformity and to stabilize lean premixed flames. In this study, numerical and experimental methods are utilized to investigate the effects of burner geometry on fuel/air mixing and combustion performance and to optimize the burner geometry. The premixed burner geometry parameters including air swirling