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dc.contributor.authorWisda, David Martinen_US
dc.date.accessioned2015-06-22T08:00:51Z
dc.date.available2015-06-22T08:00:51Z
dc.date.issued2015-06-21en_US
dc.identifier.othervt_gsexam:5468en_US
dc.identifier.urihttp://hdl.handle.net/10919/52986
dc.description.abstractOn-blade hot wire anemometry measurements as well as far field sound measurements at several receiving angles have been previously made for a rotor partially embedded in a boundary layer. The inflow distortion effect on the rotor angle of attack distribution was determined directly from the on-blade measurements, and was found to minimally affect the angle of attack at the blade tips and lower the angle attack in the rotor disk plane as the radial location moves towards the hub. A narrow, sharp increase in angle of attack as the rotor blades approached the wall was also observed, indicating blade interaction with flow reversal. The haystacking pattern, or spectral humps that appear at multiples of the blade passage frequency, was studied for a wide range of advance ratios. At high advance ratios, evidence of vortex shedding from the blade trailing edges was observed. For low advance ratios, the haystacks narrowed, became more symmetric and increased in number. A method of determining the average acoustic signature of an eddy passage through a rotor was developed from time delay aligning multiple microphone signals and eddy passages detected using the continuous wavelet transform. It was found that the eddy passage signatures were similar to a cosine wave with a Gaussian window. It was also found that normalized timescales obtained directly from the eddy passage signatures remained somewhat constant with advance ratio, but increases slightly for fixed free stream velocities with increasing rotor RPM. For advance ratios less than 0.6, the eddy passage signatures were dominated by a tonal component due to rotor ingestion of misaligned flow caused by a boundary layer separation at the wall. This indicates that flow reversal known as the Pirouette Effect is interacting with the rotor blades.en_US
dc.format.mediumETDen_US
dc.publisherVirginia Techen_US
dc.rightsThis Item is protected by copyright and/or related rights. Some uses of this Item may be deemed fair and permitted by law even without permission from the rights holder(s), or the rights holder(s) may have licensed the work for use under certain conditions. For other uses you need to obtain permission from the rights holder(s).en_US
dc.subjectRotoren_US
dc.subjectAcousticsen_US
dc.subjectBoundary Layeren_US
dc.subjectIngestion Noiseen_US
dc.subjectExperimentalen_US
dc.subjectMicrophoneen_US
dc.subjectHot Wire Anemometryen_US
dc.subjectAnechoicen_US
dc.subjectWind Tunnelen_US
dc.subjectVirginia Techen_US
dc.titleNoise from a Rotor Ingesting Inhomogeneous Turbulenceen_US
dc.typeThesisen_US
dc.contributor.departmentAerospace and Ocean Engineeringen_US
dc.description.degreeMaster of Scienceen_US
thesis.degree.nameMaster of Scienceen_US
thesis.degree.levelmastersen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
thesis.degree.disciplineAerospace Engineeringen_US
dc.contributor.committeechairDevenport, William J.en_US
dc.contributor.committeememberLowe, Kevin T.en_US
dc.contributor.committeememberAlexander, William Nathanen_US


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