Enhancing mixing and combustion using Chevron riblets in near-wall jet injection into supersonic flows

Le résumé fourni par la source

Chevron riblets leverage their unique geometric configuration to induce abundant vortical structures, enhancing turbulent characteristics of the flow field and effectively enhancing fuel−oxidizer mixing and combustion. This study integrates Chevron riblets into the Burrows−Kurkov supersonic near-wall jet combustion. A large-eddy simulation approach is employed, coupled with tabulated dynamic adaptive chemistry technology to accelerate computational processes. The research focuses on the influence of Chevron riblets on supersonic near-wall turbulent dynamics, including turbulent fluctuations, turbulent kinetic energy (TKE), and velocity distributions. Results demonstrate that Chevron riblets induce large-scale vortex, significantly amplifying velocity fluctuations and enhancing downstream TKE. These vortices effectively entrain fuel jets and high-enthalpy air, achieving efficient mixing. Analysis of reacting flow fields reveals that Chevron riblets advance the starting point for autoignition and increase flame zone thickness. Specifically, compared to the starting point of ignition x = 0.16 m in Burrow−Kurkov experiment, the starting point for autoignition in Chevron riblet configuration shifts upstream to x = 0.1 m. To investigate the mechanism of riblet geometry on supersonic near-wall jets, parametric variations in riblet spacing (s), height (h), and number (n) are analyzed alongside boundary-layer combustion characteristics. Key findings include that increasing riblet height (h = 1.25 mm) and spacing (s = 6 mm) slightly advances starting point for autoignitions. Expanding the number of riblets (n = 12) markedly shifts the starting point of ignition upstream to x = 0.05 m, increases flame thickness, and elevates combustion intensity. Comparative analysis of wall heat flux and skin friction coefficient distributions shows that Chevron riblets reduce film-cooling effectiveness but exhibit minimal impact on near-wall frictional resistance.

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