Abstract
Experiments were carried out to study the effect of rectangular tabs of aspect ratio 4, with and without corrugation, on controlling the mixing of subsonic and sonic free jets. The corrugations used in the present investigation were rectangular. The blockage of the tabs without and with corrugation is 4.2% and 3.6%, respectively. The centerline pitot pressure decay for the jets, without control, with plain rectangular tabs, and with corrugated rectangular tabs, revealed that the core length reduction caused by the plain tabs is larger than that by the corrugated tabs, at all the Mach numbers studied. Up to an axial distance of about 22D, the uncontrolled and controlled jets retain their signatures. For the sonic jet, a maximum core length reduction of 32.3% was achieved with the plain tabs, whereas with the corrugated tabs the corresponding reduction was 17.63%.
Highlights
Control of high-speed jets, with passive control in the form of tabs of various shapes has been reported by large number of researchers in open literature
To understand the effectiveness of corrugated rectangular tabs, and their relative performance compared to identical plain rectangular tabs, jets from Mach 0.3 to Mach 1 axisymmetric convergent nozzle without control, controlled with corrugated tabs and plain tabs have been investigated in the present study
The present study aims at quantifying the mixing effectiveness of plain and corrugated tabs over a range of subsonic Mach numbers and correctly expanded sonic Mach number
Summary
Control of high-speed jets, with passive control in the form of tabs of various shapes has been reported by large number of researchers in open literature. To exploit the advantage of smaller vortices, rectangular tabs with corrugated edges have been studied in the present investigation. To understand the effectiveness of corrugated rectangular tabs, and their relative performance compared to identical plain rectangular tabs, jets from Mach 0.3 to Mach 1 axisymmetric convergent nozzle without control, controlled with corrugated tabs and plain tabs have been investigated in the present study. Zaman [2] proposed that, the distortion introduced to a jet controlled by a mechanical tab is due to a pair of streamwise vortices shed by the tab. This distortion might result in significant increase of entrainment of the surround fluid into the jet. Subsequent researchers have clearly determined that, the tab produces a pair of counter-rotating streamwise vortices
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