{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/44399"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/44399","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Fan noise reduction from a supersonic inlet","abstract":"A series of experiments was conducted to investigate the radiation of fan noise through a supersonic inlet. A scaled-down model of an axisymmetric, mixed-compression, supersonic inlet (P-inlet) was used in conjunction with a 10.4 cm (4.1 in) diameter turbofan engine simulator as the noise source. The tests were conducted at an outdoor facility under static conditions. An attempt is made to reduce the fan noise radiated in the forward sector by modifying the auxiliary inlet doors. The modified doors are designed to reduce the inlet distortion to the fan face. In addition, the new design also uses a converging flow passage in the auxiliary doors in order to take advantage of the noise attenuation due to the choking effect. Both aerodynamic and acoustic measurements are taken in the experiments. The results show that when compared to the original design, the modified auxiliary inlet doors are successful in reducing distortion to the fan face, and that the blade passing frequency tone has been decreased by an average of 6 dB in the forward sector. Results from the closed auxiliary inlet door case are also presented to provide additional comparisons.","abstract_html":"A series of experiments was conducted to investigate the radiation of fan noise through a supersonic inlet. A scaled-down model of an axisymmetric, mixed-compression, supersonic inlet (P-inlet) was used in conjunction with a 10.4 cm (4.1 in) diameter turbofan engine simulator as the noise source. The tests were conducted at an outdoor facility under static conditions. An attempt is made to reduce the fan noise radiated in the forward sector by modifying the auxiliary inlet doors. The modified doors are designed to reduce the inlet distortion to the fan face. In addition, the new design also uses a converging flow passage in the auxiliary doors in order to take advantage of the noise attenuation due to the choking effect. Both aerodynamic and acoustic measurements are taken in the experiments. The results show that when compared to the original design, the modified auxiliary inlet doors are successful in reducing distortion to the fan face, and that the blade passing frequency tone has been decreased by an average of 6 dB in the forward sector. Results from the closed auxiliary inlet door case are also presented to provide additional comparisons.","abstract_has_math":false,"creators":["Nuckolls, William E."],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Mechanical Engineering","degree_department":"Mechanical Engineering","school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1992,"date_issued":"1992","date_published":"1992","updated_at":"2026-07-22T22:19:38Z","subjects":[],"languages":["en"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-08222009-040447"],"render_values":[{"text":"etd-08222009-040447","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/44399","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.department","label":"Department","values":["Mechanical Engineering"]},{"key":"dc:creator","label":"Author","values":["Nuckolls, William E."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2014-03-14T21:43:31Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2014-03-14T21:43:31Z","2009-08-22"]},{"key":"dc:date.issued","label":"Date","values":["1992"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.dcmitype","label":"Dc Type Dcmitype","values":["Text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Mechanical Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-08222009-040447"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/44399"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["A series of experiments was conducted to investigate the radiation of fan noise through a supersonic inlet. A scaled-down model of an axisymmetric, mixed-compression, supersonic inlet (P-inlet) was used in conjunction with a 10.4 cm (4.1 in) diameter turbofan engine simulator as the noise source. The tests were conducted at an outdoor facility under static conditions. An attempt is made to reduce the fan noise radiated in the forward sector by modifying the auxiliary inlet doors. The modified doors are designed to reduce the inlet distortion to the fan face. In addition, the new design also uses a converging flow passage in the auxiliary doors in order to take advantage of the noise attenuation due to the choking effect. Both aerodynamic and acoustic measurements are taken in the experiments. The results show that when compared to the original design, the modified auxiliary inlet doors are successful in reducing distortion to the fan face, and that the blade passing frequency tone has been decreased by an average of 6 dB in the forward sector. Results from the closed auxiliary inlet door case are also presented to provide additional comparisons."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["BTD"]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Fan noise reduction from a supersonic inlet"]}]}],"canonical_facts":{"dc:contributor.department":["Mechanical Engineering"],"dc:creator":["Nuckolls, William E."],"dc:date.accessioned":["2014-03-14T21:43:31Z"],"dc:date.available":["2014-03-14T21:43:31Z","2009-08-22"],"dc:date.issued":["1992"],"dc:description.abstract":["A series of experiments was conducted to investigate the radiation of fan noise through a supersonic inlet. 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