{"495231":{"#nid":"495231","#data":{"type":"event","title":"PhD Proposal by Luke Humphrey","body":[{"value":"\u003Cp\u003ECommittee:\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;Dr. Tim Lieuwen (Advisor)\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;Dr. Jerry Seitzman\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;Dr. Devesh Ranjan\u003C\/p\u003E\u003Cp\u003ETitle: Ensemble-Averaged Dynamics of Harmonically Excited Turbulent Premixed Flames\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\u003Cp\u003EAbstract:\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\u003Cp\u003ECombustion instability is a significant problem for modern, lean, premixed combustors. This instability arises through a feedback loop between heat release and harmonic acoustic and\/or hydrodynamic oscillations. Although there is a substantial body of research which examines this problem for laminar flames, virtually all practical, high power, combustion systems operate in a turbulent environment. Prior studies of turbulent flames have utilized a \u201cquasi-laminar\u201d approach, which utilizes the time-averaged flame position, and ensemble-averaged disturbance field, as inputs to a problem which is essentially identical to the laminar problem. Although this approach shows promise, it does not capture any dynamical effects. In this work, I analyze an ensemble-averaged turbulent burning velocity closure proposed by Shin and Lieuwen (2013), who showed that the ensemble-averaged turbulent burning velocity for a harmonically forced flame is proportional to the ensemble-averaged flame curvature. The strength of this dependence is characterized by the turbulent Markstein length, which relates ensemble-averaged flame curvature to the turbulent, ensemble-averaged burning velocity.\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\u003Cp\u003EThe research I propose expands upon the results of Shin and Lieuwen (2013) by showing that their flame speed closure and definition for the ensemble-averaged turbulent burning velocity can provide a governing equation for the ensemble-averaged flame position, and allows development of reduced-order models for flame position and heat release dynamics. Because the turbulent displacement and consumption Markstein lengths are a critical component of the flame speed closure, I propose to characterize their dependence on harmonic forcing amplitude, turbulence intensity, and turbulence length scale, through analysis of a numerically simulated turbulent flame. In addition to this analytical modeling, I propose to develop a new experimental facility designed to allow investigation of a turbulent, premixed, V-flame attached to a harmonically oscillating flame holder. This facility will be used to examine the ensemble-averaged flame position and heat release and characterize the turbulent flame speed dependence on ensemble-averaged flame curvature.\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":"","field_summary_sentence":[{"value":"Ensemble-Averaged Dynamics of Harmonically Excited Turbulent Premixed Flames"}],"uid":"27690","created_gmt":"2016-02-04 10:19:41","changed_gmt":"2016-10-08 02:16:16","author":"Jacquelyn Strickland","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2016-02-15T13:00:00-05:00","event_time_end":"2016-02-15T15:00:00-05:00","event_time_end_last":"2016-02-15T15:00:00-05:00","gmt_time_start":"2016-02-15 18:00:00","gmt_time_end":"2016-02-15 20:00:00","gmt_time_end_last":"2016-02-15 20:00:00","rrule":null,"timezone":"America\/New_York"},"extras":[],"groups":[{"id":"221981","name":"Graduate Studies"}],"categories":[],"keywords":[{"id":"168324","name":"PhD proposal defense"}],"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":""}}}