{"id":{"repo_id":"soton","oai_identifier":"oai:eprints.soton.ac.uk:162395"},"canonical_url":"https://search.dev.ndltd.org/etd/soton/oai:eprints.soton.ac.uk:162395","repository":{"repo_id":"soton","name":"University of Southampton","base_url":"https://eprints.soton.ac.uk/cgi/oai2"},"display":{"title":"Acoustic optimisation and prediction of sound propagation in turbofan engine ducts","abstract":"The research presented in this thesis explores the prediction of noise propagation and
radiation in turbofan engine intakes and bypass ducts, and the optimisation of noise attenuation
by using acoustic liners. A commercial FE/IE code ACTRAN/TM is used
within two shell programs; B-induct for bypass ducts and ANPRORAD for intake ducts.
An automated liner impedance capability has been demonstrated by exploiting an optimisation
suite, SOFT.
Automated liner impedance optimisations to maximise the liner insertion loss have
been performed for a uniform bypass duct with a multimodal noise source, by using
B-induct within SOFT. Results show that, multi-segment liners are effective at low frequencies
when few acoustic duct modes are present and less so at high frequencies when
many modes are present. Other results show that, at high frequencies, having different
liner impedances on the inner and outer walls could be more effective than axially segment
liners. An automated liner impedance optimisation has also been performed for a realistic
bypass duct, and an A-weighting has been considered.
Far field noise levels predicted by using ANPRORAD analysis have been validated
against measured data from rig and engine tests. The predicted results are in good agreement
with the measured data when the noise source is calibrated using in-duct measured
values. This demonstrates that ANPRORAD is a viable methodology for intake noise
predictions in industry. ANPRORAD has also been applied to investigate the effect of
the intake geometry on low-frequency acoustic reflections in the intake, and integrated
within SOFT to perform automated liner impedance optimisations to minimise acoustic
reflections to the fan.","abstract_html":"The research presented in this thesis explores the prediction of noise propagation and<br/>radiation in turbofan engine intakes and bypass ducts, and the optimisation of noise attenuation<br/>by using acoustic liners. A commercial FE/IE code ACTRAN/TM is used<br/>within two shell programs; B-induct for bypass ducts and ANPRORAD for intake ducts.<br/><br/>An automated liner impedance capability has been demonstrated by exploiting an optimisation<br/>suite, SOFT.<br/>Automated liner impedance optimisations to maximise the liner insertion loss have<br/>been performed for a uniform bypass duct with a multimodal noise source, by using<br/>B-induct within SOFT. Results show that, multi-segment liners are effective at low frequencies<br/>when few acoustic duct modes are present and less so at high frequencies when<br/>many modes are present. Other results show that, at high frequencies, having different<br/>liner impedances on the inner and outer walls could be more effective than axially segment<br/>liners. An automated liner impedance optimisation has also been performed for a realistic<br/>bypass duct, and an A-weighting has been considered.<br/><br/>Far field noise levels predicted by using ANPRORAD analysis have been validated<br/>against measured data from rig and engine tests. The predicted results are in good agreement<br/>with the measured data when the noise source is calibrated using in-duct measured<br/>values. This demonstrates that ANPRORAD is a viable methodology for intake noise<br/>predictions in industry. ANPRORAD has also been applied to investigate the effect of<br/>the intake geometry on low-frequency acoustic reflections in the intake, and integrated<br/>within SOFT to perform automated liner impedance optimisations to minimise acoustic<br/>reflections to the fan.","abstract_has_math":false,"creators":["Achunche, Iansteel Mukum"],"institution":"University of Southampton","degree_name":"Ph.D.","degree_level":"doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Astley, R.J.","Kempton, A.J."],"committee_chairs":[],"committee_members":[],"year":2010,"date_issued":"2010-01","date_published":"2010-01","updated_at":"2026-07-24T04:36:17Z","subjects":[],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":null,"outbound_label":null,"outbound_source":null},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Astley, R.J.","Kempton, A.J."]},{"key":"dc:creator","label":"Author","values":["Achunche, Iansteel Mukum"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2010-01"]},{"key":"dc:date.issued","label":"Date","values":["2010-01"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Fluid Dynamics & Acoustics Group (pre 2011 reorg)","Institute of Sound and Vibration Research"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["University of Southampton"]},{"key":"dc:relation.isreferencedby","label":"Dc Relation Isreferencedby","values":["https://eprints.soton.ac.uk/162395/"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["doctoral"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["Ph.D."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://eprints.soton.ac.uk/162395/1/P2645.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The research presented in this thesis explores the prediction of noise propagation and
radiation in turbofan engine intakes and bypass ducts, and the optimisation of noise attenuation
by using acoustic liners. A commercial FE/IE code ACTRAN/TM is used
within two shell programs; B-induct for bypass ducts and ANPRORAD for intake ducts.
An automated liner impedance capability has been demonstrated by exploiting an optimisation
suite, SOFT.
Automated liner impedance optimisations to maximise the liner insertion loss have
been performed for a uniform bypass duct with a multimodal noise source, by using
B-induct within SOFT. Results show that, multi-segment liners are effective at low frequencies
when few acoustic duct modes are present and less so at high frequencies when
many modes are present. Other results show that, at high frequencies, having different
liner impedances on the inner and outer walls could be more effective than axially segment
liners. An automated liner impedance optimisation has also been performed for a realistic
bypass duct, and an A-weighting has been considered.
Far field noise levels predicted by using ANPRORAD analysis have been validated
against measured data from rig and engine tests. The predicted results are in good agreement
with the measured data when the noise source is calibrated using in-duct measured
values. This demonstrates that ANPRORAD is a viable methodology for intake noise
predictions in industry. ANPRORAD has also been applied to investigate the effect of
the intake geometry on low-frequency acoustic reflections in the intake, and integrated
within SOFT to perform automated liner impedance optimisations to minimise acoustic
reflections to the fan."]},{"key":"dc:format","label":"Dc Format","values":["text"]},{"key":"dc:title","label":"Title","values":["Acoustic optimisation and prediction of sound propagation in turbofan engine ducts"]}]}],"canonical_facts":{"dc:contributor.advisor":["Astley, R.J.","Kempton, A.J."],"dc:creator":["Achunche, Iansteel Mukum"],"dc:date":["2010-01"],"dc:date.issued":["2010-01"],"dc:description.abstract":["The research presented in this thesis explores the prediction of noise propagation and
radiation in turbofan engine intakes and bypass ducts, and the optimisation of noise attenuation
by using acoustic liners. A commercial FE/IE code ACTRAN/TM is used
within two shell programs; B-induct for bypass ducts and ANPRORAD for intake ducts.
An automated liner impedance capability has been demonstrated by exploiting an optimisation
suite, SOFT.
Automated liner impedance optimisations to maximise the liner insertion loss have
been performed for a uniform bypass duct with a multimodal noise source, by using
B-induct within SOFT. Results show that, multi-segment liners are effective at low frequencies
when few acoustic duct modes are present and less so at high frequencies when
many modes are present. Other results show that, at high frequencies, having different
liner impedances on the inner and outer walls could be more effective than axially segment
liners. An automated liner impedance optimisation has also been performed for a realistic
bypass duct, and an A-weighting has been considered.
Far field noise levels predicted by using ANPRORAD analysis have been validated
against measured data from rig and engine tests. The predicted results are in good agreement
with the measured data when the noise source is calibrated using in-duct measured
values. This demonstrates that ANPRORAD is a viable methodology for intake noise
predictions in industry. ANPRORAD has also been applied to investigate the effect of
the intake geometry on low-frequency acoustic reflections in the intake, and integrated
within SOFT to perform automated liner impedance optimisations to minimise acoustic
reflections to the fan."],"dc:format":["text"],"dc:identifier.uri":["https://eprints.soton.ac.uk/162395/1/P2645.pdf"],"dc:publisher.department":["Fluid Dynamics & Acoustics Group (pre 2011 reorg)","Institute of Sound and Vibration Research"],"dc:publisher.institution":["University of Southampton"],"dc:relation.isreferencedby":["https://eprints.soton.ac.uk/162395/"],"dc:title":["Acoustic optimisation and prediction of sound propagation in turbofan engine ducts"],"dc:type":["Thesis"],"dc:type.qualificationlevel":["doctoral"],"dc:type.qualificationname":["Ph.D."]},"updated_at":"2026-07-24T04:36:17Z"}