Combustion engines have been around since the end of the 18e century, although they did not gain popularity until more than 50 years later. Now they’re pretty much ubiquitous, powering everything from cars and planes to turbines.
The part of the combustion engine in which fuel is burned (in the presence of oxygen) is called the combustion chamber. The life of a combustion chamber can be limited by a phenomenon called “thermoacoustic combustion oscillations”. When the thermoacoustic oscillations become too great or out of control, it causes fatal damage to the combustion chambers, which can have enormous financial and human consequences.
Detecting combustion oscillations and preventing damage is a key endeavor in thermal engineering. Recently, a team of Japanese scientists, including Hiroshi Gotoda, Yuhei Shinichi, and Naohiro Takeda from Tokyo University of Science, as well as Seiji Yoshida and Takeshi Shoji from the Japan Aerospace Exploration Agency (JAXA), developed a tool promising for the detection of a precursor of thermoacoustic oscillations. The study was posted online on May 10, 2021 and published in Volume 59 of the American Institute of Aeronautics and Astronautics Journal on October 1, 2021.
“In our study, we showed that the methodology combining dynamical systems theory and machine learning can be useful in detecting predictive combustion oscillations in multisectoral combustion chambers, such as those in aircraft engines,” explains Professor Gotoda, who led the study.
The team conducted combustion experiments with variable fuel flow rates in a multi-sector staged combustion chamber developed by JAXA.
Scientists used the data from these experiments to train a machine learning algorithm called a “Support Vector Machine (SVM)”. The SVM allowed them to classify combustion into three states: stable, transient and combustion oscillations. Pressure fluctuations in the transition state are essential for predicting future combustion oscillations. In the transition state, the pressure fluctuations change from low amplitude and aperiodic to high amplitude and periodic. Amplitude represents the “width” of the fluctuation, while periodicity describes the repetition of the fluctuation.
“The results of this study will greatly contribute to the development of a method for detecting combustion oscillations in aircraft engines in advance,” reveals Professor Gotoda.
These findings could have far-reaching consequences, paving the way for safe and timely predictions of combustion swings, with the potential to save billions of dollars and human lives.
About Tokyo University of Science
Tokyo University of Science (TUS) is a well-known and respected university, and the largest private science research university in Japan, with four campuses in central Tokyo and its suburbs and in Hokkaido. Founded in 1881, the university has continuously contributed to the scientific development of Japan by instilling a love of science in researchers, technicians and educators.
With the mission of “To create science and technology for the harmonious development of nature, humans and society”, TUS has undertaken a wide range of research ranging from basic science to applied science. TUS has taken a multidisciplinary approach to research and has undertaken intensive studies in some of today’s most vital areas. TUS is a meritocracy where the best of science is recognized and nurtured. It is the only private university in Japan that has produced a Nobel Laureate and the only private university in Asia to produce Nobel Laureates in the natural sciences.
About Professor Hiroshi Gotoda of Tokyo University of Science
Professor Hiroshi Gotoda is a prominent authority in thermal engineering, affiliated with the Department of Mechanical Engineering, Tokyo University of Sciences. He received his PhD from Keio University in 2003. His research interests include combustion engineering, nonlinear dynamics, and thermofluid mechanics. Professor Gotoda’s historic career includes teaching and research positions at Ritsumeikan University, Japan, the National Institute of Standards and Technology, Japan, and the Lawrence Berkley National Laboratory, United States. . He has received numerous awards, including the Yagami Prize from Keio University and the Young Scientist Prize from the Ministry of Education, Culture, Sports, Science and Technology.