{"46120":{"#nid":"46120","#data":{"type":"news","title":"Rocket Mystery Explained With New Imaging Technique","body":[{"value":"\u003Cp\u003EThere\u0027s a strange wave phenomenon that\u0027s plagued rocket scientists for years, a lurking threat with the power to destroy an engine at almost any time. For decades, scientists have had a limited understanding of how or why it happens because they could not replicate or investigate the problem under controlled laboratory conditions.\u003C\/p\u003E\u003Cp\u003EScientists generally believe that these powerful and unstable sound waves, created by energy supplied by the combustion process, were the cause of rocket failures in several U.S. and Russian rockets. Scientists have also observed these mysterious oscillations in other propulsion and power-generating systems such as missiles and gas turbines.\u003C\/p\u003E\u003Cp\u003ENow, researchers at the Georgia Institute of Technology have developed a liquid rocket engine simulator and imaging techniques that can help demystify the cause of these explosive sound waves and bring scientists a little closer to being able to understand and prevent them. The Georgia Tech research team was able to clearly demonstrate that the phenomenon manifests itself in the form of spinning acoustic waves that gain destructive power as they rotate around the rocket\u0027s combustion chamber.\u003C\/p\u003E\u003Cp\u003E\u0022This is a very troublesome phenomenon in rockets,\u0022 said Ben Zinn, the David S. Lewis Jr. Chair and Regents\u0027 Professor in the Guggenheim School of Aerospace Engineering at Georgia Tech. \u0022These spinning acoustic oscillations destroy engines without anyone fully understanding how these waves are formed. Visualizing this phenomenon brings us a step closer to understanding it.\u0022\u003C\/p\u003E\u003Cp\u003EThe research was presented at the 2008 American Institute of Aeronautics and Astronautics (AIAA) Aerospace Sciences Meeting in Reno, Nevada, and funded by the Air Force Office of Scientific Research.\u003C\/p\u003E\u003Cp\u003EDuring past investigations into this damaging instability, scientists were able to observe initial stages of the problem but were forced to shut down engines before the waves could fully develop and cause serious damage to the engine. Researchers were also hindered by their inability to clearly observe the complex processes inside the investigated rocket engines.\u003C\/p\u003E\u003Cp\u003EBut with a great deal of help from Dr. Oleksandr Bibik, a visiting physicist and research scientist from Ukraine, the Georgia Tech research team developed an experimental setup and imaging technique that provides detailed information on how these waves form and behave - without blowing up an engine or endangering lives.\u003C\/p\u003E\u003Cp\u003EFirst, the researchers developed a low-pressure combustor that serves as a true simulator of larger rocket engines. Bibik then used a very-high-speed camera in combination with series of fiber optic probes that together allowed researchers to clearly observe the formation and behavior of excited spinning sound waves within the engine. Additionally, Bibik\u0027s new imaging method enabled researchers to determine the conditions under which these waves are excited and how they can be controlled.\u003C\/p\u003E\u003Cp\u003EBibik\u0027s method uses a high-speed camera to view the reaction zone via a system of filters that allow only specific light radiation generated in the combustion zone to reach the camera\u0027s lens. This strategy eliminates all background light interference and provides clear images of combustion (and sound) waves spinning around the engine\u0027s periphery. Simultaneously, strategically placed fiber optic probes collect information on the reaction process oscillations in various locations in the combustor.\u003C\/p\u003E\u003Cp\u003EUsing these new techniques, the research team discovered that the destructive waves gained energy as they spun around the engine\u0027s periphery at a rate of 5,000 revolutions per second.\u003C\/p\u003E\u003Cp\u003EThe capability to simulate and observe these destructive oscillations in a controlled laboratory environment could help researchers develop techniques to prevent their occurrence in real engines.\u003C\/p\u003E\u003Cp\u003E\u0022Better understanding this phenomenon could very likely lead to safer tactical and space missions and save billions of dollars for technologies that use combustors,\u0022 Zinn said.\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003EResearchers at Georgia Tech have discovered why rocket engines are occasionally destroyed by mysterious waves of sound. The new imaging techniques allow scientists to observe and understand the destructive waves.\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"Images reveal destructive waves that destroy rocket engines"}],"uid":"27281","created_gmt":"2008-04-09 00:00:00","changed_gmt":"2016-10-08 03:01:10","author":"Lisa Grovenstein","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2008-04-09T00:00:00-04:00","iso_date":"2008-04-09T00:00:00-04:00","tz":"America\/New_York"},"extras":[],"related_links":[{"url":"http:\/\/www.ae.gatech.edu\/labs\/comblab5\/","title":"Zinn Combustion Lab"},{"url":"http:\/\/www.ae.gatech.edu\/","title":"Daniel Guggenheim School of Aerospace Engineering"}],"groups":[{"id":"1183","name":"Home"}],"categories":[{"id":"136","name":"Aerospace"},{"id":"145","name":"Engineering"},{"id":"147","name":"Military Technology"},{"id":"135","name":"Research"}],"keywords":[{"id":"2136","name":"accoustic waves"},{"id":"1325","name":"aerospace"},{"id":"2082","name":"aerospace engineering"},{"id":"2135","name":"Ben Zinn"},{"id":"2134","name":"combustor"},{"id":"2133","name":"rockets"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003E\u003Cstrong\u003ELisa Grovenstein\u003C\/strong\u003E\u003Cbr \/\u003ECommunications \u0026amp; Marketing\u003Cbr \/\u003E\u003Ca href=\u0022http:\/\/www.gatech.edu\/contact\/index.html?id=lgrovenste3\u0022\u003EContact Lisa Grovenstein\u003C\/a\u003E\u003Cbr \/\u003E\u003Cstrong\u003E404-894-8835\u003C\/strong\u003E\u003C\/p\u003E","format":"limited_html"}],"email":["lisa.grovenstein@comm.gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}