{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/70630"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/70630","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Rotor Blade Flap-Lag Stability and Response in Forward Flight in Turbulent Flows","abstract":"The effect of random air turbulence on the coupled flap-lag motion of a helicopter rotor blade in forward flight is investigated. By assuming white noise turbulence and applying a special case of the stochastic averaging procedure, equations are developed which describe the stochastic first and second moments of the perturbations in flap and lead-lag angles due to turbulence.","abstract_html":"The effect of random air turbulence on the coupled flap-lag motion of a helicopter rotor blade in forward flight is investigated. By assuming white noise turbulence and applying a special case of the stochastic averaging procedure, equations are developed which describe the stochastic first and second moments of the perturbations in flap and lead-lag angles due to turbulence.","abstract_has_math":false,"creators":["Shiau, Ting-Nung Bernard"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Aeronautical and Astronautical Engineering","degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2014,"date_issued":"2014-12-15T23:55:54Z","date_published":"2014-12-15T23:55:54Z","updated_at":"2026-07-22T22:26:03Z","subjects":["Engineering, Aerospace"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["(UMI)AAI8502297"],"render_values":[{"text":"(UMI)AAI8502297","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/70630","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Shiau, Ting-Nung Bernard"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2014-12-15T23:55:54Z","10000-01-01","1984"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Aeronautical and Astronautical Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Engineering, Aerospace"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/70630","(UMI)AAI8502297"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The effect of random air turbulence on the coupled flap-lag motion of a helicopter rotor blade in forward flight is investigated. By assuming white noise turbulence and applying a special case of the stochastic averaging procedure, equations are developed which describe the stochastic first and second moments of the perturbations in flap and lead-lag angles due to turbulence.","Numerical results for stability in forward flight illustrate that turbulence exhibits a stabilizing effect, compared to the deterministic (no turbulence) case. Results for the steady-state responses of the perturbations in forward flight indicate that the average responses of the perturbations in forward flight indicate that the average response of the blade is not significantly affected by turbulence. In contrast, the random fluctuations away from the average response exhibit significantly large values due to the effects of turbulence. The effects of various blade parameters on the steady-state response are also investigated.","The stability of multibladed rotors in the presence of turbulence is investigated using the example of a three-bladed rotor. The constant coefficient approximation using multiblade coordinates is shown to be accurate for moderate advance ratio in the case of a trimmed rotor. For an untrimmed rotor the approximation is less accurate and provides very conservative stability boundaries.","Made available in DSpace on 2014-12-15T23:55:54Z (GMT). No. of bitstreams: 1 8502297.pdf: 4160002 bytes, checksum: ff764afc3f91ae64df75768f39a174ed (MD5) Previous issue date: 1984","Embargo set by: Seth Robbins for item 70796 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","U of I Only","178 p.","Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1984."]},{"key":"dc:title","label":"Title","values":["Rotor Blade Flap-Lag Stability and Response in Forward Flight in Turbulent Flows"]}]}],"canonical_facts":{"dc:creator":["Shiau, Ting-Nung Bernard"],"dc:date":["2014-12-15T23:55:54Z","10000-01-01","1984"],"dc:description":["The effect of random air turbulence on the coupled flap-lag motion of a helicopter rotor blade in forward flight is investigated. By assuming white noise turbulence and applying a special case of the stochastic averaging procedure, equations are developed which describe the stochastic first and second moments of the perturbations in flap and lead-lag angles due to turbulence.","Numerical results for stability in forward flight illustrate that turbulence exhibits a stabilizing effect, compared to the deterministic (no turbulence) case. Results for the steady-state responses of the perturbations in forward flight indicate that the average responses of the perturbations in forward flight indicate that the average response of the blade is not significantly affected by turbulence. In contrast, the random fluctuations away from the average response exhibit significantly large values due to the effects of turbulence. The effects of various blade parameters on the steady-state response are also investigated.","The stability of multibladed rotors in the presence of turbulence is investigated using the example of a three-bladed rotor. The constant coefficient approximation using multiblade coordinates is shown to be accurate for moderate advance ratio in the case of a trimmed rotor. For an untrimmed rotor the approximation is less accurate and provides very conservative stability boundaries.","Made available in DSpace on 2014-12-15T23:55:54Z (GMT). No. of bitstreams: 1 8502297.pdf: 4160002 bytes, checksum: ff764afc3f91ae64df75768f39a174ed (MD5) Previous issue date: 1984","Embargo set by: Seth Robbins for item 70796 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","U of I Only","178 p.","Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1984."],"dc:identifier":["http://hdl.handle.net/2142/70630","(UMI)AAI8502297"],"dc:subject":["Engineering, Aerospace"],"dc:title":["Rotor Blade Flap-Lag Stability and Response in Forward Flight in Turbulent Flows"],"dc:type":["text"],"thesis:degree_discipline":["Aeronautical and Astronautical Engineering"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:26:03Z"}