Compressible Dynamics of Fast Turbulent Flames*

h $-abstract-$\backslash $f1The research characterizes the dynamics of compressible flame-turbulence interactions for propagating fast flames. A Turbulent Shock Tube with a series of turbulence inducing plates has a large viewing area to capture the flame dynamics with various optical diagnostics, including high-speed PIV and schlieren. The experimental results show that the turbulent Mach number, $M_{T}$, within the flame increases non-linearly relative to the flame propagation Mach number, $M_{f}$, and grows quickly for flames propagating faster than Chapman-Jouguet deflagrations ($M_{f}$\textgreater 1). This relationship shows that turbulence is self-generated by fast turbulent flames. Furthermore, the flames with $M_{f}$\textgreater 1 are intrinsically unsteady. They tend to accelerate and generate shocks. This acceleration is accompanied by the fast increase of $M_{T}$ and continues until shocks become strong enough to ignite a detonation. Slower flames with $M_{f}$ \textless 1 show, little or no self-generated turbulence, and do not produce shocks. The results are highly relevant for hypersonic scramjet propulsion engines and compressible shock-laden turbulent reacting flows in rotating detonation engines.$\backslash $f2-/abstract-$\backslash $\tex