Numerical investigation on the flowfield of “swallowtail” cavity for supersonic mixing enhancement

Abstract

A "swallowtail" cavity for the supersonic combustor was proposed to serve as an efficient flame holder for scramjets by enhancing the mass exchange between the cavity and the main flow. A numerical study on the "swallowtail" cavity was conducted by solving the three-dimensional Reynolds-averaged Navier-Stokes equations implemented with a k-ε turbulence model in a multi-block mesh. Turbulence model and numerical algorithms were validated first, and then test cases were calculated to investigate into the mechanism of cavity flows. Numerical results demonstrated that the certain mass in the supersonic main flow was sucked into the cavity and moved spirally toward the combustor walls. After that, the flow went out of the cavity at its lateral end, and finally was efficiently mixed with the main flow. The comparison between the "swallowtail" cavity and the conventional one showed that the mass exchanged between the cavity and the main flow was enhanced by the lateral flow that was induced due to the pressure gradient inside the cavity and was driven by the three-dimensional vortex ring generated from the "swallowtail" cavity structure.

Steady-state Analysis of Supersonic Mixing Enhanced by a Three-dimensional Cavity Flow

“…A lot of techniques have been proposed for enhancing supersonic mixing; e.g., enhancement using a ramp injector 4) , lobed strut 5) , pylon 6) , elliptical injector 7) , diamond shaped orifice 8) , shallow-tail cavity 9) , wavy-wall 10) , fin-guided fuel injection 11) , wall mounted cavity 12)13)14) , a multi-sided wheel within the injector 15) , and so on.…”