Simultaneous measurement of outlet temperature and species concentrations in a dual-swirl combustor via multi-diagnostic integration

To provide advanced diagnostic techniques for diagnosing the outlet temperature distribution and species concentrations of future advanced combustors, this study focuses on a dual-swirl single-dome rectangular combustor. Through the integration of multiple diagnostics, simultaneous measurement of outlet temperature distribution and species concentrations was achieved. The study validates the engineering applicability of these simultaneous measurements using tungsten-rhenium (W-Re) thermocouples and Coherent Anti-Stokes Raman Scattering (CARS), CARS and Tunable Diode Laser Absorption Spectroscopy (TDLAS), as well as Gas Analysis (GA) and Mass Spectrometry (MS). The results demonstrate that measurements by thermocouples and CARS exhibit good consistency and repeatability, with a relative deviation of less than 4%, fully meeting the requirements of engineering experiments. The spatial distribution reconstruction results of TDLAS can reflect the temperature distribution characteristics at the combustor outlet. Temperature comparison between TDLAS and CARS at single-point positions shows consistent results, with a relative deviation of less than 11% and 7% under both conditions, respectively. Simultaneous measurements by integrating GA and MS show high engineering applicability for the first time, meeting the requirements for measuring both inorganic species and free radicals at the combustor outlet. Under C1 condition, the relative deviations of four key species (Unburned Hydrocarbon (UHC), NO, O₂, and CO₂) remain within 2%, while that of NO₂ is slightly higher at approximately 8%. Under C2 condition, the overall deviations increase for most species, with only O₂ and CO₂ maintaining relatively low deviations. The primary species of UHCs at the combustor outlet under both conditions are small molecular hydrocarbons (C₃-C₈) and RO₂ radicals, accounting for over 90% of total UHC. Specifically, RO₂ species (R is C₁-C₂ alkyl groups) are the predominant species, accounting for 74.3% and 82.1% of total RO₂ under both conditions, respectively. These integrated diagnostic methods for temperature and species concentrations at the combustor outlet serve as a crucial reference for its engineering applications.