Abstract
In the present work, dynamic detonation stabilization in expanding channels is numerically investigated by injecting a hot jet into a hydrogen-oxygen combustible mixture flowing at supersonic speed. The two-dimensional reactive Navier-Stokes equations and one-step two-species reaction model are solved using a hybrid sixth-order Weighted Essentially-Centered Difference scheme based on the Structured Adaptive Mesh Refinement framework. The results show that the highly unstable shear layer interactions with the unburned jet resulting from the Prandtl-Meyer expansion fan result in numerous large-scale vortices, which contribute significantly to rapid turbulent mixing and diffusion effects. This can further facilitate the consumption of the unburned jet and its subsequent heat release to support the dynamically stationary propagation of detonation. Meanwhile, detonation attenuation in the supersonic flow can be also effectively suppressed because of the formation of a hydrodynamic channel associated with a corresponding hydrodynamic throat. It is indicated that the shear layer interactions with the unburned jet and the generation of hydrodynamic channel can both play important roles in dynamically stationary propagation of detonation in supersonic expanding channels after the shutdown of the hot jet. With the increase of the expansion angle, the enlarged unburned jet is gradually extended out of the sonic line, and the deficit of heat release cannot contribute to stationary propagation of detonation, thus eventually leading to detonation failure. It is indicated that there might exist a critical angle . Dynamic stabilization of detonation can be realized in expanding channels when the angle is smaller than the , while the detonation propagates below the CJ velocity and finally fails when the angle is larger than the . Through the control of the moving boundary by dynamically changing the expansion angle, the continuous detonation attenuation can be effectively suppressed and finally turned to forward propagation successfully, indicating that dynamically stationary propagation of detonation can be realized through the dynamic control of the moving boundary.
- Received 7 October 2018
DOI:https://doi.org/10.1103/PhysRevFluids.4.083201
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