Experimental investigation of the influence of natural convection and end-effects on Rayleigh streaming in a thermoacoustic engine

The influence of both the natural convection and end-effects on Rayleigh streaming pattern in a simple standing-wave thermoacoustic engine is investigated experimentally at different acoustic levels. The axial mean velocity inside the engine is measured using both Laser Doppler Velocimetry and Parti...

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Bibliographic Details
Published in:The Journal of the Acoustical Society of America 2018-01, Vol.143 (1), p.361-372
Main Authors: Ramadan, Islam A., Bailliet, Hélène, Valière, Jean-Christophe
Format: Article
Language:English
Subjects:
Acoustics
Automatic
Biomechanics
Chemical Sciences
Electric power
Electromagnetism
Engineering Sciences
Fluid mechanics
Material chemistry
Materials and structures in mechanics
Mathematical Physics
Mechanics
Physics
Polymers
Quantum Physics
Reactive fluid environment
Thermics
Vibrations
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Summary:The influence of both the natural convection and end-effects on Rayleigh streaming pattern in a simple standing-wave thermoacoustic engine is investigated experimentally at different acoustic levels. The axial mean velocity inside the engine is measured using both Laser Doppler Velocimetry and Particle Image Velocimetry. The mean flow patterns are categorized in three different regions referred to as “cold streaming” region, “hot streaming” region, and “end-effects” region. In the cold streaming region, the dominant phenomenon is Rayleigh streaming and the mean velocity measurements correspond well with the theoretical expectations of Rayleigh streaming at low acoustic levels. At higher acoustic levels, the measurements deviate from the theoretical expectations which complies with the literature. In the hot streaming region, temperature measurements reveal that the non-uniformity of the resonator wall temperature is the origin of natural convection flow. Velocity measurements show that natural convection flow superimposes on the Rayleigh streaming flow so that the measured mean velocity deviates from the theoretical expectations of Rayleigh streaming. In the last region, the measured mean velocity is very different from Rayleigh streaming due to the combined effects of both the flow disturbances generated near the extremity of the stack and the natural convection flow.
ISSN:0001-4966
1520-8524
DOI:10.1121/1.5021331