Semi-circular corrugated tabs to control subsonic and correctly expanded sonic jets

Purpose This paper aims to present the jet mixing effectiveness of triangular tabs with semi-circular corrugations to control the subsonic and sonic correctly expanded jets. Design/methodology/approach Three semi-circular corrugated triangular tabs (Tab A, Tab B and Tab C) of equal blockage 5.11% are used, in which the corrugation locations on the tabs are varied. The offset distance between the semi-circular corrugations at the leaned edges of the triangular tabs are 0.0, 0.75 and 1.5 mm for the Tabs A, B and C, respectively. Two identical semi-circular corrugated tabs has been placed exactly 180 degrees apart at the exit of the convergent nozzle. The pitot pressure measurements were taken to study the jet mixing characteristics of the tabs for the jet exit Mach numbers of 0.6, 0.8 and 1.0, and it is compared with the free jet. Findings The jet centerline pitot pressure decay reveals that, Tab A is very effective than Tab B and Tab C. For the jet exit Mach numbers of 0.6, 0.8 and 1.0, the potential core reduction for the Tab A is found to be 69.1%, 69.7% and 70.8%, respectively, when compared with the free jet. Practical implications The semi-circular corrugated triangular tabs were found to be more effective than the plain triangular tabs of equal blockage ratio for reducing the core length with minimum thrust loss. Originality/value The offset distance of the semi-circular corrugations are varied along the leaned sides of the triangular tabs, which is the novelty of this study.