Title:
Helicopter Blade Tip Vortex Modifications in Hover Using Piezoelectrically Modulated Blowing

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dc.contributor.advisor Dancila, D. Stefan
dc.contributor.author Vasilescu, Roxana en_US
dc.contributor.committeeMember Ruzzene, Massimo
dc.contributor.committeeMember Sankar, Lakshmi N.
dc.contributor.committeeMember Smith, Marilyn J.
dc.contributor.committeeMember Yu, Yung
dc.contributor.department Aerospace Engineering en_US
dc.date.accessioned 2005-03-01T19:40:12Z
dc.date.available 2005-03-01T19:40:12Z
dc.date.issued 2004-12-01 en_US
dc.description.abstract Aeroacoustic investigations regarding different types of helicopter noise have indicated that the most annoying noise is caused by impulsive blade surface pressure changes in descent or forward flight conditions. Blade Vortex Interaction (BVI) is one of the main phenomena producing significant impulsive noise by the unsteady fluctuation in blade loading due to the rapid change of induced velocity field during interaction with vortices shed from previous blades. The tip vortex core structure and the blade vortex miss distance were identified as having a primary influence on BVI. In this thesis, piezoelectrically modulated and/or vectored blowing at the rotor blade tip is theoretically investigated as an active technique for modifying the structure of the tip vortex core as well as for increasing blade vortex miss distance. The mechanisms of formation and convection of rotor blade tip vortices up to and beyond 360 degrees wake age are described based on the CFD results for the baseline cases of a hovering rotor with rounded and square tips. A methodology combining electromechanical and CFD modeling is developed and applied to the study of a piezoelectrically modulated and vectored blowing two-dimensional wing section. The thesis is focused on the CFD analysis of rotor flow with modulated tangential blowing over a rounded blade tip, and with steady mid-plane blade tip blowing, respectively. Computational results characterizing the far-wake flow indicate that for steady tangential blowing the miss distance can be doubled compared to the baseline case, which may lead to a significant reduction in BVI noise level if this trend shown in hover can be replicated in low speed forward flight. Moreover, near-wake flow analysis show that through modulated blowing a higher dissipation of vorticity can be obtained. en_US
dc.description.degree Ph.D. en_US
dc.format.extent 8403178 bytes
dc.format.mimetype application/pdf
dc.identifier.uri http://hdl.handle.net/1853/4896
dc.language.iso en_US
dc.publisher Georgia Institute of Technology en_US
dc.subject Piezoelectric actuation en_US
dc.subject Active flow control
dc.subject CFD rotor wake
dc.subject Rotor blade tip vortices
dc.subject Unsteady modulated blowing
dc.subject.lcsh Flutter (Aerodynamics) en_US
dc.subject.lcsh Rotors (Helicopters) Aerodynamics en_US
dc.title Helicopter Blade Tip Vortex Modifications in Hover Using Piezoelectrically Modulated Blowing en_US
dc.type Text
dc.type.genre Dissertation
dspace.entity.type Publication
local.contributor.corporatename College of Engineering
local.contributor.corporatename Daniel Guggenheim School of Aerospace Engineering
local.relation.ispartofseries Doctor of Philosophy with a Major in Aerospace Engineering
relation.isOrgUnitOfPublication 7c022d60-21d5-497c-b552-95e489a06569
relation.isOrgUnitOfPublication a348b767-ea7e-4789-af1f-1f1d5925fb65
relation.isSeriesOfPublication f6a932db-1cde-43b5-bcab-bf573da55ed6
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