{"id":{"repo_id":"ohiolink","oai_identifier":"oai:etd.ohiolink.edu:osu1366213652"},"canonical_url":"https://search.dev.ndltd.org/etd/ohiolink/oai:etd.ohiolink.edu:osu1366213652","repository":{"repo_id":"ohiolink","name":"OhioLINK","base_url":"https://etd.ohiolink.edu/acprod/odb_etd/ws/oai/oai"},"display":{"title":"An Investigation of the Irrotational Near Field of an Excited High Speed Jet.","abstract":"The near-field pressure of a Mach 0.9 jet with Reynolds number of 6.2x10^5 has been investigated to examine the response of the jet to low-frequency forcing with localized arc filament plasma actuators (LAFPAs). The well-defined actuation phase allows for the phase averaging of the near-field pressure in order to separate the relevant features of the response from the background turbulence. The resulting phase-averaged signal illustrates a compact wave with a positive pressure excursion preceding a negative one. This is indicative of a large-scale structure (a vortex ring) that is generated by each impulsively seeded perturbation. The signature of these large-scale structures is shown to rapidly decay with radial distance from the jet. Simultaneous measurements of acoustic far field were also performed along with the near field, allowing the relationship between the two fields to be examined. Although the region near the jet shear-layer is largely hydrodynamic in nature, there is still significant correlation between the near-field pressure and the far-field acoustic around 30° polar angle, particularly as the jet evolves downstream past the potential core. This region is shown to shift upstream when the jet is forced.","abstract_html":"The near-field pressure of a Mach 0.9 jet with Reynolds number of 6.2x10^5 has been investigated to examine the response of the jet to low-frequency forcing with localized arc filament plasma actuators (LAFPAs). The well-defined actuation phase allows for the phase averaging of the near-field pressure in order to separate the relevant features of the response from the background turbulence. The resulting phase-averaged signal illustrates a compact wave with a positive pressure excursion preceding a negative one. This is indicative of a large-scale structure (a vortex ring) that is generated by each impulsively seeded perturbation. The signature of these large-scale structures is shown to rapidly decay with radial distance from the jet. Simultaneous measurements of acoustic far field were also performed along with the near field, allowing the relationship between the two fields to be examined. Although the region near the jet shear-layer is largely hydrodynamic in nature, there is still significant correlation between the near-field pressure and the far-field acoustic around 30° polar angle, particularly as the jet evolves downstream past the potential core. This region is shown to shift upstream when the jet is forced.","abstract_has_math":false,"creators":["Alkandry, Hind"],"institution":"The Ohio State University","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Mechanical Engineering","degree_department":null,"school":null,"contributors":["Samimy , Mo"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2013,"date_issued":"2013-08-08","date_published":"2013-08-08","updated_at":"2026-07-24T03:37:46Z","subjects":["Aerospace Engineering","Mechanical Engineering"],"languages":["English"],"rights":["unrestricted","This thesis or dissertation is protected by copyright: all rights reserved. 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This is indicative of a large-scale structure (a vortex ring) that is generated by each impulsively seeded perturbation. The signature of these large-scale structures is shown to rapidly decay with radial distance from the jet. Simultaneous measurements of acoustic far field were also performed along with the near field, allowing the relationship between the two fields to be examined. Although the region near the jet shear-layer is largely hydrodynamic in nature, there is still significant correlation between the near-field pressure and the far-field acoustic around 30° polar angle, particularly as the jet evolves downstream past the potential core. This region is shown to shift upstream when the jet is forced."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf","p.89","18. 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The signature of these large-scale structures is shown to rapidly decay with radial distance from the jet. Simultaneous measurements of acoustic far field were also performed along with the near field, allowing the relationship between the two fields to be examined. Although the region near the jet shear-layer is largely hydrodynamic in nature, there is still significant correlation between the near-field pressure and the far-field acoustic around 30° polar angle, particularly as the jet evolves downstream past the potential core. This region is shown to shift upstream when the jet is forced."],"dc:format":["application/pdf","p.89","18. MB"],"dc:identifier":["http://rave.ohiolink.edu/etdc/view?acc_num=osu1366213652"],"dc:language":["English"],"dc:publisher":["The Ohio State University / OhioLINK"],"dc:rights":["unrestricted","This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws."],"dc:subject":["Aerospace Engineering","Mechanical Engineering"],"dc:title":["An Investigation of the Irrotational Near Field of an Excited High Speed Jet."],"dc:type":["Electronic Thesis or Dissertation"],"thesis:degree_discipline":["Mechanical Engineering"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["The Ohio State University"]},"updated_at":"2026-07-24T03:37:46Z"}