Some observations in the vortex-turning behaviour of noncircular inclined jets

• Main Authors: Shi, Shengxian., New, T. H.
• Other Authors: School of Mechanical and Aerospace Engineering
• Format: Article
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Aeronautical engineering::Jet propulsion
• Online Access: https://hdl.handle.net/10356/85685; http://hdl.handle.net/10220/18346
• Institution: Nanyang Technological University

An experimental comparison was conducted for Re = 2,500, free elliptic and rectangular jets inclined at 30° and 60° along major or minor planes. Regardless of the jet base geometry, minor-plane inclined jets produced vortex roll-ups that remain inclined. In contrast, major-plane inclined jets produce significantly stronger vortex-roll-up turning behaviour. Interestingly, major-plane inclined rectangular jets exhibit strong vortex-overturning behaviour, where the vortex-roll-up inclination exceeds the 0° incline angle considerably. Vortex-turning extents and rates are compared between major-plane inclined elliptic and rectangular jets here and support present qualitative observations. Closer inspections reveal that the lack of axis-switching phenomenon in major-plane inclined rectangular jets allows vortex-overturning behaviour. In addition, jet centreline deflection is most sensitive in minor-plane inclined jets, where increasing the incline angle leads to a decrease and an increase in the elliptic and rectangular jet deflection, respectively.