Auto Oscillations of Flow Inhomogeneities


Dr. Andrey Semenov
N.N. Andreev Acoustics Institute, Russia

Series: Physics Research and Technology
BISAC: SCI055000

The book provides the analysis and researches results related to flow inhomogeneities auto oscillations observed in free subsonic and supersonic jet flow as well as during jet flow interaction with adjacent bodies, acoustic resonators, ejectors and valves. It demonstrates the laws, relationships and experimental evidences for various auto oscillations phenomena directly related to incident flow regimes based on conditions of flow boundary instability and feed back mechanism realized by corresponding sound field radiated due to periodic hydrodynamic disturbances reflection propagating in opposite to flow direction in the form of sound impulses exciting flow origin. Book results allow devoting particular attention to auto oscillations condition prediction and in a sense to their control. Book is addressed to physicists, acousticians and hydrodynamics engineers developing low noise and vibration aircrafts, ships and space vehicles with aid of adjacent flow and jet flow auto oscillations cancellation as well as to specialists involved in flow induced auto oscillations sound sources efficiency increase research, say, related to musical instruments or to biological research of man and animal voice properties. Book will be useful as well to undergraduate and graduate students of these specialties.



Table of Contents




Chapter 1. Flow as Oscillations Amplifier

Chapter 2. Linear Approach to Supersonic Flow Auto Oscillations

Chapter 3. Flow Induced Auto Oscillation as Sound Source

Chapter 4. “Vortex Sound”

Chapter 5. “Voice of Sea”





“This new book, Auto Oscillations of Flow Inhomogeneities, written by Dr. Semenov will draw attention of various specialists interested in detection, prediction and suppression of moving inhomogeneities auto oscillations generated by stationary subsonic and supersonic flows in the presence of solid bodies producing narrow band sound and vibrations. Book provides experimental and theoretical background for prediction of corresponding additional hydrodynamic and sound fields in atmosphere and ocean. From our point of view one of most important results presented in the book is related to theoretical explanation of unexplained before type of ultra-low frequency atmospheric sound field observed near seas and oceans. In particular, specific auto oscillations phenomena, so called, ‘voice of sea’ related to interaction of heavy gale wind with chopped sea surface. Recently our institute was involved in development of its experimental measurement means necessary to control ‘voice of sea’ in environment. One of the next pioneer steps in the book is experimental proof of vortex role in flow inhomogeneities auto oscillation excitation and sound generation. It is shown that vortexes observed in body – flow interaction are mainly specific sources of flow energy losses; they can hardly contribute substantially to sound field generated due to auto oscillations. The text is rich in physical details and experimental data explaining conditions of known auto oscillations phenomena observation and providing their prediction methods as well as endorsing validity and reality of achieved results. The book is essential for any scientist, acoustics engineer and developer of sound production instruments taking a serious interest in auto oscillations application as well in its consequences suppression progress.” -Prof. Sergey N. Kulichkov, Deputy Director, Institute of Atmospheric Physics, Russian Academy of Sciences, Laureate of Russian Government Prize in the Field of Physical Sciences

“This book is written by an experienced specialist in acoustics of moving media and underwater hydroacoustics, Dr. Andrew (Andrey) Semenov from Acoustics Institute in Moscow, Russia. It shows insufficiency of current state-of-the art in moving media acoustics related to auto oscillations of flow inhomogeneities observed in wide range of science and technology phenomena from musical instruments to powerful rockets and airplanes. Proper understanding of auto oscillations physical mechanism is necessary to develop efficient sound sources, say, musical instruments based on flow auto oscillations as well as to suppress noise produced by airplane and missile engine jets during flight, take off and landing. Main chapters of the book are related to the detailed description of various auto oscillations phenomena observed at flow subsonic and supersonic velocities including conditions of stationary flow power transform to flow inhomogeneities oscillation, amplification and detection. This approach developed by the author together with his coauthors A.V. Rimsky-Korsakov and L.A. Bazhenova allowed better understanding physical background of so called ‘vortex sound’ phenomenon including nature of sound source and sound power dependence on Reynolds number. These results presented from the very beginning of 2000’s in Acoustical Physics Journal has attracted attention of many acousticians and engineers. One more interesting book item is related to auto oscillations of powerful rocket provided with engine of a lot of jets situated on its first stage bottom along circle. This phenomenon observed experimentally was predicted by author. Another impressive and informative chapter of the book is related to ‘voice of sea’ phenomenon generated in interaction of heavy gale wind with chopped sea surface. In general, book will be useful for acousticians and technology engineers developing acoustic systems based on flow inhomogeneities auto oscillations or interested in narrow band sound radiation reduction in airplanes development and shipbuilding.” -Prof. Igor B. Esipov, Full Professor of Physics Department in I.M. Gubkin’s Oil and Gas University, Moscow, Russia, Vice Editor-in-Chief of Acoustical Physics Journal, Russian Acoustical Society Executive Board Member, Acoustical Society of America Member

“This book provides noticeable contribution to solution of actual hydrodynamics and aeroacoustics problems related to control of airplane and ships structures noise and vibrations related to ambient flow inhomogeneities auto oscillations. It also provides description of various corresponding sound generation phenomena. Chapters of the book are related to description of physical mechanism of various natural and artificial sources of sound field provided by auto oscillations from musical instrument and various whistles to atmospheric acoustic phenomenon observed in interaction of heavy gale wind flow with chopped ocean surface and powerful rockets. Important portion of the book is devoted to model experiments related to acoustic resonators positioned in subsonic fluid flow. It allows finding out the role of vortexes in auto oscillation excitation and sound generation. Next portions of the book are devoted to linear approach to auto oscillations of supersonic jets and review of contemporary approach to flow – body interaction auto oscillations analysis. To conclude it is worth to note that wide enough range of presented results applications is demonstrated allowing recommending the book for acousticians and engineers developing various auto oscillations acoustic systems as well as for specialists interested in suppression of auto oscillations noise in ships and various flight vehicles.” -Prof. Victor D. Svet, Leading Research Scientist, Academician N.N. Andreev’s Acoustics Institute, Russian Academy of Sciences

“This book demonstrates new approach to actual hydrodynamics and aeroacoustics problems related to noise and vibrations generated by flow inhomogeneities auto oscillations based on instability of flow boundaries. Feed – back mechanism of auto oscillations is based on stationary flow energy transform into flow oscillation energy in conditions of negative acoustic resistance of ‘body – flow’ oscillation system. Main basis of problem statement is evident from book Introduction already. First chapters are devoted to various subsonic and supersonic auto oscillation problems where instability conditions are derived with aid of powerful mechanism of flow boundary stability dispersion equation solution (mainly in Chapter 2). Taking into account complexity of problems stated for supersonic flows, this method allows restricting their solutions by linear approach for infinite jets, while feed-back mechanism is explained with aid of Wiener-Hopf techniques. Phenomenon of noise spectrum discrete component generation for cold supersonic jets is investigated and explained as well. Classical problem of so called ‘vortex sound’ or Aeolian tone observed in ‘cylinder – flow’ interaction is discussed in chapters 3 and 4, while in Chapter 5 original explanation of ‘voice of sea’ phenomenon is proposed. This book is recommended for acousticians and engineers working in the field of aeroacoustics and hydrodynamics developing various auto oscillations acoustic systems as well as for specialists interested in suppression of auto oscillations noise in flight vehicles.” -Dr. Michael A. Mironov, Head of Department, Academician N.N. Andreev’s Acoustics Institute, Russian Academy of Sciences, Russian Acoustical Society Executive Board Member, Acoustical Society of America Member

Additional information