Visualization of an Isolated Vortex Ring Generated from Step-Like Wind Variation and the Overshoot Phenomenon of Axial Velocity
The flow field of a free square jet generated from an unsteady wind tunnel with a step-like axial velocity variation was measured using an ultrasonic anemometer. Three-dimensional velocity vector fields were synthesized by computational modeling from the measured time-series velocity data. The vorti...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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The Japan Society of Mechanical Engineers
2011-06-01
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| Series: | Journal of Fluid Science and Technology |
| Subjects: | |
| Online Access: | https://www.jstage.jst.go.jp/article/jfst/6/4/6_4_685/_pdf/-char/en |
| _version_ | 1819364470765387776 |
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| author | Yutaka HARA Naoya HIRATA Tsutomu HAYASHI |
| author_facet | Yutaka HARA Naoya HIRATA Tsutomu HAYASHI |
| author_sort | Yutaka HARA |
| collection | DOAJ |
| description | The flow field of a free square jet generated from an unsteady wind tunnel with a step-like axial velocity variation was measured using an ultrasonic anemometer. Three-dimensional velocity vector fields were synthesized by computational modeling from the measured time-series velocity data. The vorticity vector field was calculated after appropriate interpolation and extrapolation. A three-dimensional geographical representation of the isosurface of the vorticity vector norm showed that an isolated vortex ring separated from the shear layer and changed its shape as it moved downstream. In order to elucidate the cause of the overshoot peak observed in time-dependent variations of the axial velocity for the step-like jet, the velocities induced at an observation point on the jet axis, first by the isolated vortex ring and then by the other unsteady portions, were calculated using Biot-Savart's Law. The contribution to the overshoot peak from the other portions, including the re-developing shear layer, was larger than that from the isolated vortex ring. |
| first_indexed | 2024-12-24T22:59:27Z |
| format | Article |
| id | doaj.art-e4aaaf477cd24e049b5895a45e2c3f89 |
| institution | Directory Open Access Journal |
| issn | 1880-5558 |
| language | English |
| last_indexed | 2024-12-24T22:59:27Z |
| publishDate | 2011-06-01 |
| publisher | The Japan Society of Mechanical Engineers |
| record_format | Article |
| series | Journal of Fluid Science and Technology |
| spelling | doaj.art-e4aaaf477cd24e049b5895a45e2c3f892022-12-21T16:35:11ZengThe Japan Society of Mechanical EngineersJournal of Fluid Science and Technology1880-55582011-06-016468569910.1299/jfst.6.685jfstVisualization of an Isolated Vortex Ring Generated from Step-Like Wind Variation and the Overshoot Phenomenon of Axial VelocityYutaka HARA0Naoya HIRATA1Tsutomu HAYASHI2Department of Mechanical and Aerospace Engineering, Graduate School of Engineering, Tottori UniversityDepartment of Mechanical and Aerospace Engineering, Graduate School of Engineering, Tottori UniversityNagoya Industrial Science Research InstituteThe flow field of a free square jet generated from an unsteady wind tunnel with a step-like axial velocity variation was measured using an ultrasonic anemometer. Three-dimensional velocity vector fields were synthesized by computational modeling from the measured time-series velocity data. The vorticity vector field was calculated after appropriate interpolation and extrapolation. A three-dimensional geographical representation of the isosurface of the vorticity vector norm showed that an isolated vortex ring separated from the shear layer and changed its shape as it moved downstream. In order to elucidate the cause of the overshoot peak observed in time-dependent variations of the axial velocity for the step-like jet, the velocities induced at an observation point on the jet axis, first by the isolated vortex ring and then by the other unsteady portions, were calculated using Biot-Savart's Law. The contribution to the overshoot peak from the other portions, including the re-developing shear layer, was larger than that from the isolated vortex ring.https://www.jstage.jst.go.jp/article/jfst/6/4/6_4_685/_pdf/-char/envortex ringovershootstep windunsteady wind tunnelfree square jetvorticityultrasonic anemometer |
| spellingShingle | Yutaka HARA Naoya HIRATA Tsutomu HAYASHI Visualization of an Isolated Vortex Ring Generated from Step-Like Wind Variation and the Overshoot Phenomenon of Axial Velocity Journal of Fluid Science and Technology vortex ring overshoot step wind unsteady wind tunnel free square jet vorticity ultrasonic anemometer |
| title | Visualization of an Isolated Vortex Ring Generated from Step-Like Wind Variation and the Overshoot Phenomenon of Axial Velocity |
| title_full | Visualization of an Isolated Vortex Ring Generated from Step-Like Wind Variation and the Overshoot Phenomenon of Axial Velocity |
| title_fullStr | Visualization of an Isolated Vortex Ring Generated from Step-Like Wind Variation and the Overshoot Phenomenon of Axial Velocity |
| title_full_unstemmed | Visualization of an Isolated Vortex Ring Generated from Step-Like Wind Variation and the Overshoot Phenomenon of Axial Velocity |
| title_short | Visualization of an Isolated Vortex Ring Generated from Step-Like Wind Variation and the Overshoot Phenomenon of Axial Velocity |
| title_sort | visualization of an isolated vortex ring generated from step like wind variation and the overshoot phenomenon of axial velocity |
| topic | vortex ring overshoot step wind unsteady wind tunnel free square jet vorticity ultrasonic anemometer |
| url | https://www.jstage.jst.go.jp/article/jfst/6/4/6_4_685/_pdf/-char/en |
| work_keys_str_mv | AT yutakahara visualizationofanisolatedvortexringgeneratedfromsteplikewindvariationandtheovershootphenomenonofaxialvelocity AT naoyahirata visualizationofanisolatedvortexringgeneratedfromsteplikewindvariationandtheovershootphenomenonofaxialvelocity AT tsutomuhayashi visualizationofanisolatedvortexringgeneratedfromsteplikewindvariationandtheovershootphenomenonofaxialvelocity |