PARAMETERS GOVERNING SEPARATION CONTROL WITH SWEEPING JET ACTUATORS

Persistent Link:
http://hdl.handle.net/10150/203475
Title:
PARAMETERS GOVERNING SEPARATION CONTROL WITH SWEEPING JET ACTUATORS
Author:
Woszidlo, Rene
Issue Date:
2011
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Parameters governing separation control with sweeping jet actuators over a deflected flap are investigated experimentally on a generic "Multiple Flap Airfoil" (MFA). The model enables an extensive variation of geometric and aerodynamic parameters to aid the scaling of this novel flow control method to full-size applications.Sweeping jets exit from discrete, millimeter-scale nozzles distributed along the span and oscillate from side-to-side. The sweeping frequency is almost linearly dependent on the supplied flowrate per actuator. The measured thrust exerted by a row of actuators agrees well with vectored momentum calculations. Frequency and thrust measurements suggest that the jet velocity is limited to subsonic speeds and that any additional increase in flowrate causes internal choking of the flow.Neither the flowrate nor the momentum input is found to be a sole parameter governing the lift for varying distance between adjacent actuators. However, the product of the mass flow coefficient and the square root of the momentum coefficient collapses the lift onto a single curve regardless of the actuator spacing. Contrary to other actuation methods, separation control with sweeping jets does not exhibit any hysteresis with either momentum input or flap deflection. A comparison between sweeping and non-sweeping jets illustrates the superior control authority provided by sweeping jets. Surface flow visualization on the flap suggests the formation of counter-rotating pairs of streamwise vortices caused by the interaction of neighboring jets.The actuation intensity required to attach the flow increases with increasing downstream distance from the main element's trailing edge and increasing flap deflection. No obvious dependence of the ideal actuation location on actuator spacing, flap deflection, angle of attack, or actuation intensity is found within the tested range. Comparisons between experimental and numerical results reveal that the inviscid flow solution appears to be a suitable predictor for the effectively and efficiently obtainable lift of a given airfoil configuration. The flap size affects the achievable lift, the accompanying drag, and the required flap deflection and actuation intensity. By controlling separation, the range of achievable lift coefficients is doubled without significant penalty in drag even when considering a safety margin for the maximum applicable incidence.
Type:
text; Electronic Dissertation
Keywords:
fluidic oscillators; separation control; streamwise vortices; sweeping jets; Aerospace Engineering; active flow control; aerodynamics
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Aerospace Engineering
Degree Grantor:
University of Arizona
Advisor:
Wygnanski, Israel J.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titlePARAMETERS GOVERNING SEPARATION CONTROL WITH SWEEPING JET ACTUATORSen_US
dc.creatorWoszidlo, Reneen_US
dc.contributor.authorWoszidlo, Reneen_US
dc.date.issued2011-
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractParameters governing separation control with sweeping jet actuators over a deflected flap are investigated experimentally on a generic "Multiple Flap Airfoil" (MFA). The model enables an extensive variation of geometric and aerodynamic parameters to aid the scaling of this novel flow control method to full-size applications.Sweeping jets exit from discrete, millimeter-scale nozzles distributed along the span and oscillate from side-to-side. The sweeping frequency is almost linearly dependent on the supplied flowrate per actuator. The measured thrust exerted by a row of actuators agrees well with vectored momentum calculations. Frequency and thrust measurements suggest that the jet velocity is limited to subsonic speeds and that any additional increase in flowrate causes internal choking of the flow.Neither the flowrate nor the momentum input is found to be a sole parameter governing the lift for varying distance between adjacent actuators. However, the product of the mass flow coefficient and the square root of the momentum coefficient collapses the lift onto a single curve regardless of the actuator spacing. Contrary to other actuation methods, separation control with sweeping jets does not exhibit any hysteresis with either momentum input or flap deflection. A comparison between sweeping and non-sweeping jets illustrates the superior control authority provided by sweeping jets. Surface flow visualization on the flap suggests the formation of counter-rotating pairs of streamwise vortices caused by the interaction of neighboring jets.The actuation intensity required to attach the flow increases with increasing downstream distance from the main element's trailing edge and increasing flap deflection. No obvious dependence of the ideal actuation location on actuator spacing, flap deflection, angle of attack, or actuation intensity is found within the tested range. Comparisons between experimental and numerical results reveal that the inviscid flow solution appears to be a suitable predictor for the effectively and efficiently obtainable lift of a given airfoil configuration. The flap size affects the achievable lift, the accompanying drag, and the required flap deflection and actuation intensity. By controlling separation, the range of achievable lift coefficients is doubled without significant penalty in drag even when considering a safety margin for the maximum applicable incidence.en_US
dc.description.notePage 5 revised, Feb. 14, 2014.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectfluidic oscillatorsen_US
dc.subjectseparation controlen_US
dc.subjectstreamwise vorticesen_US
dc.subjectsweeping jetsen_US
dc.subjectAerospace Engineeringen_US
dc.subjectactive flow controlen_US
dc.subjectaerodynamicsen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineAerospace Engineeringen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorWygnanski, Israel J.en_US
dc.contributor.committeememberTumin, Anatolien_US
dc.contributor.committeememberLittle, Jesse C.en_US
dc.contributor.committeememberWygnanski, Israel J.en_US
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