On the vortical structures and behaviour of inclined elliptic jets
A study has been carried out to clarify vortical structures and behaviour resultant from imposing inclined exits along either the major or minor plane of an elliptic nozzle. Laser-induced fluorescence (LIF) flow visualizations show production of inclined vortex roll-ups along the inclined planes, wi...
| Main Authors: | , |
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| Format: | Journal Article |
| Language: | English |
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2013
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| Online Access: | https://hdl.handle.net/10356/85692 http://hdl.handle.net/10220/16696 |
| _version_ | 1826121597780492288 |
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| author | New, T. H. Tsovolos, D. |
| author2 | School of Mechanical and Aerospace Engineering |
| author_facet | School of Mechanical and Aerospace Engineering New, T. H. Tsovolos, D. |
| author_sort | New, T. H. |
| collection | NTU |
| description | A study has been carried out to clarify vortical structures and behaviour resultant from imposing inclined exits along either the major or minor plane of an elliptic nozzle. Laser-induced fluorescence (LIF) flow visualizations show production of inclined vortex roll-ups along the inclined planes, with corresponding narrowing of jet columns along the non-inclined planes. Minor-plane inclined nozzles result in significant growths in the jet spread along the inclined plane, while major-plane inclined nozzles produce little variations. Formation of rib structures is observed to be suppressed in minor-plane inclined nozzles and linked to braid vortices inducing the formation of streamwise vortices along the minor plane. Particle-image velocimetry measurements show that increasing the incline angle in major-plane inclined nozzles reduce the strengths of the discrete vortex roll-ups, while the opposite occurs in minor-plane inclined nozzles. Although Reynolds shear stress variations correspond well with changes in incline angle and vortex roll-up strength in major-plane inclined nozzles, they demonstrate a non-monotonic relationship in minor-plane inclined nozzles. LIF visualizations further clarify how strong asymmetric interactions between the inclined vortex roll-ups and braid vortices lead to suppression of axis-switching in major-plane inclined nozzles but not in minor-plane inclined nozzles. The more complex flow behaviour in the latter is responsible for the non-linear relationship in Reynolds shear stress levels observed earlier. Comparisons of the half-jet width profiles confirm the suppression of axis-switching in major-plane inclined nozzles only, while momentum thickness profiles show significant variations in the mixing layer characteristics between major- and minor-plane inclined nozzles. |
| first_indexed | 2024-10-01T05:34:49Z |
| format | Journal Article |
| id | ntu-10356/85692 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T05:34:49Z |
| publishDate | 2013 |
| record_format | dspace |
| spelling | ntu-10356/856922023-03-04T17:15:45Z On the vortical structures and behaviour of inclined elliptic jets New, T. H. Tsovolos, D. School of Mechanical and Aerospace Engineering DRNTU::Engineering::Aeronautical engineering A study has been carried out to clarify vortical structures and behaviour resultant from imposing inclined exits along either the major or minor plane of an elliptic nozzle. Laser-induced fluorescence (LIF) flow visualizations show production of inclined vortex roll-ups along the inclined planes, with corresponding narrowing of jet columns along the non-inclined planes. Minor-plane inclined nozzles result in significant growths in the jet spread along the inclined plane, while major-plane inclined nozzles produce little variations. Formation of rib structures is observed to be suppressed in minor-plane inclined nozzles and linked to braid vortices inducing the formation of streamwise vortices along the minor plane. Particle-image velocimetry measurements show that increasing the incline angle in major-plane inclined nozzles reduce the strengths of the discrete vortex roll-ups, while the opposite occurs in minor-plane inclined nozzles. Although Reynolds shear stress variations correspond well with changes in incline angle and vortex roll-up strength in major-plane inclined nozzles, they demonstrate a non-monotonic relationship in minor-plane inclined nozzles. LIF visualizations further clarify how strong asymmetric interactions between the inclined vortex roll-ups and braid vortices lead to suppression of axis-switching in major-plane inclined nozzles but not in minor-plane inclined nozzles. The more complex flow behaviour in the latter is responsible for the non-linear relationship in Reynolds shear stress levels observed earlier. Comparisons of the half-jet width profiles confirm the suppression of axis-switching in major-plane inclined nozzles only, while momentum thickness profiles show significant variations in the mixing layer characteristics between major- and minor-plane inclined nozzles. Accepted version 2013-10-23T05:04:02Z 2019-12-06T16:08:23Z 2013-10-23T05:04:02Z 2019-12-06T16:08:23Z 2011 2011 Journal Article New, T. H., & Tsovolos, D. (2011). On the vortical structures and behaviour of inclined elliptic jets. European Journal of Mechanics - B/Fluids, 30(4), 437-450. 0997-7546 https://hdl.handle.net/10356/85692 http://hdl.handle.net/10220/16696 10.1016/j.euromechflu.2011.04.006 159297 en European Journal of Mechanics - B/Fluids © 2011 Elsevier Masson SAS.This is the author created version of a work that has been peer reviewed and accepted for publication by European Journal of Mechanics - B/Fluids, Elsevier. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at DOI: [http://dx.doi.org/10.1016/j.euromechflu.2011.04.006]. application/pdf |
| spellingShingle | DRNTU::Engineering::Aeronautical engineering New, T. H. Tsovolos, D. On the vortical structures and behaviour of inclined elliptic jets |
| title | On the vortical structures and behaviour of inclined elliptic jets |
| title_full | On the vortical structures and behaviour of inclined elliptic jets |
| title_fullStr | On the vortical structures and behaviour of inclined elliptic jets |
| title_full_unstemmed | On the vortical structures and behaviour of inclined elliptic jets |
| title_short | On the vortical structures and behaviour of inclined elliptic jets |
| title_sort | on the vortical structures and behaviour of inclined elliptic jets |
| topic | DRNTU::Engineering::Aeronautical engineering |
| url | https://hdl.handle.net/10356/85692 http://hdl.handle.net/10220/16696 |
| work_keys_str_mv | AT newth onthevorticalstructuresandbehaviourofinclinedellipticjets AT tsovolosd onthevorticalstructuresandbehaviourofinclinedellipticjets |