Ducted Fan Aerodynamics and Modeling, with Applications of Steady and Synthetic Jet Flow Control

dc.contributor.authorOhanian, Osgar Johnen
dc.contributor.committeechairInman, Daniel J.en
dc.contributor.committeememberKochersberger, Kevin B.en
dc.contributor.committeememberKurdila, Andrew J.en
dc.contributor.committeememberMason, William H.en
dc.contributor.committeememberWilson, Sam B.en
dc.contributor.departmentMechanical Engineeringen
dc.date.accessioned2014-03-14T20:11:59Zen
dc.date.adate2011-05-17en
dc.date.available2014-03-14T20:11:59Zen
dc.date.issued2011-05-04en
dc.date.rdate2011-05-17en
dc.date.sdate2011-05-12en
dc.description.abstractDucted fan vehicles possess a superior ability to maximize payload capacity while minimizing vehicle size. Their ability to both hover and fly at high speed is a key advantage for information-gathering missions, particularly when close proximity to a target is essential. However, the ducted fan's aerodynamic characteristics pose difficulties for stable vehicle flight and therefore require complex control algorithms. In particular, they exhibit a large nose-up pitching moment during wind gusts and when transitioning from hover to forward flight. Understanding ducted fan aerodynamic behavior and how it can be altered through flow control techniques are the two prime objectives of this work. This dissertation provides a new paradigm for modeling the ducted fan's nonlinear behavior and new methods for changing the duct aerodynamics using active flow control. Steady and piezoelectric synthetic jet blowing are employed in the flow control concepts and are compared. The new aerodynamic model captures the nonlinear characteristics of the force, moment, and power data for a ducted fan, while representing these terms in a set of simple equations. The model attains excellent agreement with current and legacy experimental data using twelve non-dimensional constants. Synthetic jet actuators (SJA) have potential for use in flow control applications in UAVs with limited size, weight, and power budgets. Piezoelectric SJAs for a ducted fan vehicle were developed through two rounds of experimental designs. The final SJA design attained peak jet velocities in the range of 225 ft/sec (69 m/s) for a 0.03â x 0.80â rectangular slot. To reduce the magnitude of the nose-up pitching moment in cross-winds, two flow control concepts were explored: flow separation control at the duct lip, and flow turning at the duct trailing edge using a CoandÄ surface. Both concepts were experimentally proven to be successful. Synthetic jets and steady jets were capable of modifying the ducted fan flow to reduce pitching moment, but some cases required high values of steady blowing to create significant responses. Triggering leading edge separation on the duct lip was one application where synthetic jets showed comparable performance to steady jets operating at a blowing coefficient an order of magnitude higher.en
dc.description.degreePh. D.en
dc.identifier.otheretd-05122011-155823en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-05122011-155823/en
dc.identifier.urihttp://hdl.handle.net/10919/27687en
dc.publisherVirginia Techen
dc.relation.haspartOhanian_OJ_D_2011_Copyright.pdfen
dc.relation.haspartOhanian_OJ_D_2011.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectnon-dimensionalen
dc.subjectmicro air vehicleen
dc.subjectDrone aircraften
dc.subjectMAVen
dc.subjectunmanned aerial vehicleen
dc.subjectaerodynamic modelingen
dc.subjectflow controlen
dc.subjectsynthetic jetsen
dc.subjectrotoren
dc.subjectshrouded propelleren
dc.subjectducted fanen
dc.titleDucted Fan Aerodynamics and Modeling, with Applications of Steady and Synthetic Jet Flow Controlen
dc.typeDissertationen
thesis.degree.disciplineMechanical Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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