The alternating wedge strut, serving as both an injector and a vortex generator, has great potential for application in the scramjet combustor. The expansive trailing edge structure can further enhance the mixing performance of the alternating wedge strut. To enhance the performance of scramjet engines, it is essential to investigate the fuel/air mixing characteristics and mechanism downstream of alternating wedge struts with expansive trailing edges. The research focused on the impact of two different fuel injection schemes on the air/fuel mixing process and plume morphology. The optical diagnostic technique, particle laser-induced fluorescence, was employed to measure fuel plume morphology at various downstream locations under ambient temperature conditions. The results show that the expansive trailing edge significantly enhances the vertical diffusion of the fuel, leading to distinct plume characteristics. Compared to the strut injecting fuel into the edge of the streamwise vortex, the strut injecting fuel into the core of the streamwise vortex results in a larger fuel plume area with a more uniform distribution. Additionally, a streamwise vortex model was established to investigate the vortex dynamics and mixing mechanisms behind the strut from a mechanistic perspective. The simulation results indicate that the model demonstrates good performance in forecasting the dynamics of streamwise vortices and the evolution of fuel plume morphology.

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.

Acetone Planar Lase-Induced Fluorescence (PLIF) and OH-PLIF were employed to capture the fuel distribution and OH distribution downstream for the supersonic combustor based on the alternating-wedge strut. The combustion establishment process and combustion mode in the combustor under different fuel injection methods and different equivalence ratios were analyzed. Combined with the kerosene-PLIF and OH-PLIF results in the cavity combustor, a comparative analysis was conducted to understand the combustion characteristics and combustion modes between the alternating-wedge strut-based combustor and the cavity-based combustor. The results show that the combustor is in weak combustion mode in the case of low equivalence ratio, and the combustor is in intensive combustion mode in the case of high equivalence ratio. The lower limit of the equivalence ratio of the combustor to maintain the intensive combustion mode varies based on different fuel injection methods. The OH distribution under reacting condition has a strong correlation with the fuel distribution under non-reacting condition. The OH fluorescence signal near the injector is weaker when the fuel distribution is more concentrated. The injector position located at the base of the strut rear has better mixing performance, enabling the combustor to be in intensive combustion mode at a lower equivalence ratio. The combustion reaction in the alternating-wedge strut-based combustor is not necessarily dominated by mass transfer due to the mixing enhancement and premixed zone downstream of strut, while the combustion reaction process in the cavity-based combustor is mainly influenced by mass transfer.