{"682477":{"#nid":"682477","#data":{"type":"event","title":"PhD Proposal by Jackson Larisch","body":[{"value":"\u003Cp\u003EJackson Larisch\u003Cbr\u003E(Advisor: Prof. Krish Ahuja)\u003Cbr\u003Ewill propose a doctoral thesis entitled,\u003Cbr\u003ENoise Reduction Mechanisms and Sources of Noise in Jets Issuing from Lobed\u003Cbr\u003EMixer Nozzles\u003Cbr\u003EOn\u003Cbr\u003EFriday, May 23 at 12:00 p.m.\u003Cbr\u003EMontgomery Knight Building 317\u003Cbr\u003EAbstract\u003C\/p\u003E\u003Cp\u003EWith the return of SST on the horizon, future supersonic civilian airliners will need to meet\u0026nbsp;\u003Cbr\u003Estringent noise criteria for certification. As a result of this, such aircraft are likely to employ\u0026nbsp;\u003Cbr\u003Einternally mixed exhaust systems with forced mixers which demonstrate the ability to improve thrust\u0026nbsp;\u003Cbr\u003Eand reduce jet noise during LTO regimes. In such a configuration, the core and bypass exhaust gases\u0026nbsp;\u003Cbr\u003Eare mixed within the engine before being expelled through a final exhaust nozzle. Improved mixing\u0026nbsp;\u003Cbr\u003Eof these streams reduces the average velocity and temperature of exhaust gasses, helping to combat\u0026nbsp;\u003Cbr\u003Eincreased levels of thrust-specific jet noise introduced through the use of low-to- moderate bypass\u0026nbsp;\u003Cbr\u003Ejet engines more efficient at higher cruise speeds.\u003Cbr\u003EOne popular jet mixing enhancement device is the so-called lobed mixer or lobed suppressor nozzle.\u0026nbsp;\u003Cbr\u003EThese forced mixer nozzles have petal-shaped corrugations on the nozzle trailing edge which greatly\u0026nbsp;\u003Cbr\u003Eincrease the contact perimeter between the jet and ambient (or core stream and bypass stream if\u0026nbsp;\u003Cbr\u003Eused internally) and introduce streamwise vorticity to rapidly inject quiescent gas into the jet.\u0026nbsp;\u003Cbr\u003EHowever, these two mechanisms paint an incomplete picture and are insufficient in describing the\u0026nbsp;\u003Cbr\u003Ecomplex processes by which lobed nozzles enhance mixing and reduce jet noise. As with most jet\u0026nbsp;\u003Cbr\u003Emixing-enhancement devices, lobed nozzles typically result in decreased levels of jet noise at low\u0026nbsp;\u003Cbr\u003Efrequencies - especially at observation angles close to the jet axis - and substantially increased\u0026nbsp;\u003Cbr\u003Elevels of jet noise at higher frequencies. The former is typically ascribed to the inhibited\u0026nbsp;\u003Cbr\u003Eformation of large-scale turbulent structures within the jet, while the latter is chalked up as\u0026nbsp;\u003Cbr\u003Emixing noise due to increased levels of fine-scale turbulence. This too fails to provide a\u0026nbsp;\u003Cbr\u003Ecomprehensive explanation of the effects of lobed nozzles on jet aeroacoustics.\u003Cbr\u003EThe proposed thesis seeks to provide a detailed explanation of the precise mechanisms by which\u0026nbsp;\u003Cbr\u003Elobed nozzles combat jet noise through complementary acoustic and flow analyses. This is achieved\u0026nbsp;\u003Cbr\u003Ethrough various experimental tests involving two novel lobed mixer nozzles of equivalent exit area\u0026nbsp;\u003Cbr\u003Eand a circular, axisymmetric baseline nozzle. The findings of this work are expected to inform the\u0026nbsp;\u003Cbr\u003Edesign of future noise suppression devices including nozzles and acoustic liners, as well as\u0026nbsp;\u003Cbr\u003Eprovide models to predict jet noise reduction and mixing noise levels.\u003Cbr\u003ECommittee\u003Cbr\u003E\u2022 \u0026nbsp;Prof. Krishan K. Ahuja \u2013 School of Aerospace Engineering (advisor)\u003Cbr\u003E\u2022 \u0026nbsp;Prof. Lakshmi Sankar \u2013 School of Aerospace Engineering\u003Cbr\u003E\u2022 \u0026nbsp;Assistant Prof. Beckett Zhou \u2013 School of Aerospace Engineering\u003Cbr\u003E\u2022 \u0026nbsp;Dr. Joseph Gavin \u2013 Preliminary Design, Gulfstream Aerospace Corporation\u003Cbr\u003E\u2022 \u0026nbsp;Dr. Donald Nance \u2013 Senior Scientist, Harris Miller Miller \u0026amp; Hanson Inc.\u003Cbr\u003E\u0026nbsp;\u003C\/p\u003E","summary":"","format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003ENoise Reduction Mechanisms and Sources of Noise in Jets Issuing from Lobed Mixer Nozzles\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"Noise Reduction Mechanisms and Sources of Noise in Jets Issuing from Lobed Mixer Nozzles"}],"uid":"27707","created_gmt":"2025-05-20 17:00:56","changed_gmt":"2025-05-20 17:01:28","author":"Tatianna Richardson","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2025-05-23T12:00:00-04:00","event_time_end":"2025-05-23T14:00:00-04:00","event_time_end_last":"2025-05-23T14:00:00-04:00","gmt_time_start":"2025-05-23 16:00:00","gmt_time_end":"2025-05-23 18:00:00","gmt_time_end_last":"2025-05-23 18:00:00","rrule":null,"timezone":"America\/New_York"},"location":"Montgomery Knight Building 317","extras":[],"groups":[{"id":"221981","name":"Graduate Studies"}],"categories":[],"keywords":[{"id":"102851","name":"Phd proposal"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[{"id":"1788","name":"Other\/Miscellaneous"}],"invited_audience":[{"id":"78771","name":"Public"}],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[],"email":[],"slides":[],"orientation":[],"userdata":""}}}