{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/129794"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/129794","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"An extension to Hanson’s theory of harmonic noise of rotors","abstract":"Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2027-05-01","abstract_html":"Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2027-05-01","abstract_has_math":false,"creators":["Nanjappa, Niranjan"],"institution":"University of Illinois Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Aerospace Engineering","degree_department":null,"school":null,"contributors":["Clarke, Matthew"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2025,"date_issued":"2025-05-09","date_published":"2025-05-09","updated_at":"2026-07-22T22:25:05Z","subjects":["Aeroacoustics","Aerodynamics"],"languages":["en","eng"],"rights":["Copyright, 2025 Niranjan Nanjappa"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2142/129794","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Clarke, Matthew"]},{"key":"dc:creator","label":"Author","values":["Nanjappa, Niranjan"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2025-05-09","2025-05"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Aerospace Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Aeroacoustics","Aerodynamics"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en","eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright, 2025 Niranjan Nanjappa"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/2142/129794"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2027-05-01","The student, Niranjan Nanjappa, accepted the attached license on 2025-05-09 at 16:41.","The student, Niranjan Nanjappa, submitted this Thesis for approval on 2025-05-09 at 16:57.","This Thesis was approved for publication on 2025-05-09 at 17:02.","DSpace SAF Submission Ingestion Package generated from Vireo submission #22294 on 2025-10-19 at 19:56:08","The rapid emergence of electric-vertical-take-off-and-landing (eVTOL) aircraft has renewed interest in rotor-generated noise. Because eVTOL configurations rely on many simultaneously operating propellers, accurate prediction demands higher-fidelity aeroacoustic tools than those used for conventional single-rotor systems. This study extends Hanson’s frequency-domain harmonic-noise formulation by coupling it with advanced aerodynamic models that resolve the blade-loading distribution more realistically. Point and line load compactness are addressed with an extended QPROP model for axial inflow propellers and using prescribed vortex wake and free vortex wake methods for non-axial inflow propellers, which furnishes the unsteady sectional forces for propellers at arbitrary pitch angles. Planar (chord-wise) loading is captured using an airfoil panel method. A novel viscous vortex panel method is developed that does not rely on a global Newton solver to obtain a flow solution around an airfoil. This method has the drawback of not being able to obtain self-consistent solutions, but the convergence issues at high angles of attack for airfoils experienced in other viscous vortex panel methods like XFOIL are avoided. The resulting time histories are transformed via discrete Fourier analysis to supply the modal loading inputs required by Hanson’s equations. Predictions obtained with these refined load models are benchmarked against (i) experimental data for both axial and non-axial inflow rotors and (ii) time domain numerical solutions for axial inflow propellers. The comparison demonstrates a significant improvement in noise-level accuracy across harmonic orders."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["An extension to Hanson’s theory of harmonic noise of rotors"]}]}],"canonical_facts":{"dc:contributor":["Clarke, Matthew"],"dc:creator":["Nanjappa, Niranjan"],"dc:date":["2025-05-09","2025-05"],"dc:description":["Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2027-05-01","The student, Niranjan Nanjappa, accepted the attached license on 2025-05-09 at 16:41.","The student, Niranjan Nanjappa, submitted this Thesis for approval on 2025-05-09 at 16:57.","This Thesis was approved for publication on 2025-05-09 at 17:02.","DSpace SAF Submission Ingestion Package generated from Vireo submission #22294 on 2025-10-19 at 19:56:08","The rapid emergence of electric-vertical-take-off-and-landing (eVTOL) aircraft has renewed interest in rotor-generated noise. Because eVTOL configurations rely on many simultaneously operating propellers, accurate prediction demands higher-fidelity aeroacoustic tools than those used for conventional single-rotor systems. This study extends Hanson’s frequency-domain harmonic-noise formulation by coupling it with advanced aerodynamic models that resolve the blade-loading distribution more realistically. Point and line load compactness are addressed with an extended QPROP model for axial inflow propellers and using prescribed vortex wake and free vortex wake methods for non-axial inflow propellers, which furnishes the unsteady sectional forces for propellers at arbitrary pitch angles. Planar (chord-wise) loading is captured using an airfoil panel method. A novel viscous vortex panel method is developed that does not rely on a global Newton solver to obtain a flow solution around an airfoil. This method has the drawback of not being able to obtain self-consistent solutions, but the convergence issues at high angles of attack for airfoils experienced in other viscous vortex panel methods like XFOIL are avoided. The resulting time histories are transformed via discrete Fourier analysis to supply the modal loading inputs required by Hanson’s equations. Predictions obtained with these refined load models are benchmarked against (i) experimental data for both axial and non-axial inflow rotors and (ii) time domain numerical solutions for axial inflow propellers. The comparison demonstrates a significant improvement in noise-level accuracy across harmonic orders."],"dc:format":["application/pdf"],"dc:identifier":["https://hdl.handle.net/2142/129794"],"dc:language":["en","eng"],"dc:rights":["Copyright, 2025 Niranjan Nanjappa"],"dc:subject":["Aeroacoustics","Aerodynamics"],"dc:title":["An extension to Hanson’s theory of harmonic noise of rotors"],"dc:type":["text"],"thesis:degree_discipline":["Aerospace Engineering"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["M.S."],"thesis:institution_name":["University of Illinois Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:05Z"}