期刊
AEROSPACE SCIENCE AND TECHNOLOGY
卷 99, 期 -, 页码 -出版社
ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER
DOI: 10.1016/j.ast.2020.105767
关键词
Scramjet cavity; Aerodynamic drag; Cavity upstream-wall; Shock tunnel; Schlieren imaging
资金
- Advance Queensland Research Fellowship [AQRF03416-17RD2]
- Australian Government
The cavity flameholder has been widely used in scramjets to improve mixing and combustion rates. While many have investigated modifications to the cavity downstream-wall, few have investigated modifying the upstream-wall - a rear-facing step. The rapid expansion produces a low pressure region and base drag force, while only the larger of the induced twin vortices contributes substantially to mixing. In this paper, the upstream-wall of a scramjet combustor cavity was inclined, aiming to reduce cavity base drag and remove superfluous cavity vortex structures. Upstream-wall angles of 90 degrees, 45 degrees and 22.5 degrees were examined, at cavity length-to-depth (L/D) ratios from 4 to 7. Cavity downstream-wall angles of 90 degrees and 22.5 degrees were examined for each configuration. Reflected shock tunnel experiments were conducted at Mach 7 enthalpy, scramjet combustor conditions. Experimental Schlieren imaging showed that reducing the upstream-wall angle did not significantly affect shear layer separation for L/D ratios of 4 and 5. At L/D ratios 6 and 7, however, reducing the upstream-wall angle saw the shear layer penetrating deeper into the cavity. Reynolds-averaged Navier-Stokes computations examined the internal flow structure and it was shown that reducing the upstream-wall angle to 45 degrees retained the dominant mixing vortex in the cavity, with base drag reduced by 21% compared to the standard 90 degrees upstream-wall case. (C) 2020 Elsevier Masson SAS. All rights reserved.
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