The development of next-generation high-speed aerospace systems—including reusable space vehicles and supersonic/hypersonic aircrafts—relies on propulsion systems capable of operating at extremely high speeds. A major barrier to innovation in this domain is the complex and poorly understood behavior of turbulent combustion under high Mach number conditions. These flows involve intricate interactions between turbulence, shock waves, and chemically reacting gases, which make predictive modeling difficult. This project addresses this critical gap by developing advanced simulation tools and experimental data that will improve the accuracy and reliability of combustion models used in aerospace design. By integrating well-resolved simulations with physical experiments, the research promises to transform how engineers understand and predict combustion in extreme conditions. The broader impacts of this project include training graduate and undergraduate students, developing new educational content, and engaging the public through STEM outreach and hands-on learning opportunities. The goal of this project is to build a comprehensive framework for modeling turbulent combustion in high-speed flows relevant to scramjets and ramjets. This will be achieved through a three-pronged effort: (i) conducting direct numerical simulations of reactive shear layers to capture key phenomena such as chemical non-equilibrium, multi-component diffusion, and real-gas effects; (ii) initiating an experi