Use of gas bubbles for ultrasound Doppler flow velocity profile measurement |
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| Affiliation: | 1. Sika Services AG, Zurich, Switzerland;2. BG Ingénieurs Conseils SA, Lausanne, Switzerland;3. EPFL-LCH, Station 18, CH-1015 Lausanne, Switzerland;4. ETH-FPE, CH-8092 Zurich, Switzerland;1. Department of Mathematics, Stockholm University, SE-106 91 Stockholm, Sweden;2. James Weir Fluids Laboratory, Department of Mechanical and Aerospace Engineering, University of Strathclyde, Glasgow G1 1XJ, United Kingdom;3. State Key Laboratory of High Temperature Gas Dynamics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China;1. Faculty of Engineering, Hokkaido University, N13W8, Sapporo 060-8628, Japan;2. Institute of Food, Nutrition and Health, ETH Zürich, 8092 Zürich, Switzerland;1. Chair of Measurement and Sensor System Techniques, Faculty of Electrical and Computer Engineering, Technische Universität Dresden, 01062 Dresden, Germany;2. SolarWorld Innovations GmbH, Berthelsdorfer Str. 111A, 09599 Freiberg, Germany;3. Institute for Nonferrous Metallurgy and Purest Materials, TU Bergakademie Freiberg, Leipziger Str. 34, 09599 Freiberg, Germany |
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| Abstract: | Ultrasonic velocimetry based on the Doppler shift effect accurately provides quasi-instantaneous flow fields for fluids with a sufficiently high acoustic scattering level. However, ultrasonic velocity instruments are known to perform poorly in clear water with low acoustic scattering level, which are frequent conditions in laboratory applications. This work confirms a technique to solve the problem by seeding the flow with micro hydrogen bubbles, generated by means of electrolysis.This paper investigates the influence of gas bubbles density on the quality of the ultrasound Doppler based velocity profiles in an open channel flow. The bubbles are generated by electrolysis of water using different magnitudes of electrical current. The estimation of the number of bubbles in the measurement volume confirms that the bubble diameter is similar to that of the wire used for electrolysis. This enables to determine the minimum density of gas bubbles needed to obtain a reasonably good echo and therefore an accurate velocity profile. |
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| Keywords: | Open channel flow Ultrasound Doppler method Velocity profile Gas bubble seeding Electrolysis |
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