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Obayashi, Hironari; Tasaka, Yuji*; Kon, Seiji*; Takeda, Yasushi*
Flow Measurement and Instrumentation, 19(3-4), p.189 - 195, 2008/06
Times Cited Count：13 Percentile：52.64(Engineering, Mechanical)This paper proposes a new technique that enables the measurement of the velocity vector in multi-dimensions on a line of the flow field. A system to achieve this goal was developed based on ultrasonic velocity profiling by using multiple transducers. A two-dimensional system was constructed and successfully applied to an actual flow field for two-dimensional velocity vector measurements. To estimate the influence of existence of a wall, acoustic field under the developed system was calculated by solving two-dimensional wave equation and then the focal point of an ultrasonic beam was determined to optimize the system. The system was applied to measure two directional velocity components of a periodic velocity fluctuation in a wake of a cylinder as an example of unsteady flow. Temporal variation of velocity vector profiles well represent the velocity fluctuation, and vorticity distribution, which is obtained from the spatial distribution of velocity vector, well represents vertical motion in the wake.
Obayashi, Hironari; Yamaguchi, Kohei*; Kon, Seiji*; Takeda, Yasushi*
Nihon Ryutai Rikigakkai Nenkai 2006 Koen Rombunshu (CD-ROM), 4 Pages, 2006/09
The velocity vector of fluid is expressed with the function of the velocity components of three directions, and the function of time. Therefore, in order to understand the flow structure, it becomes very important to measure these components. We propose the new equipment that enables three-dimensional velocity vector measurement of the flow field of the name of Vector-UVP. It consists of a central emitter, symmetrically surrounded by three receivers. If the plane transducer is used for the emitter, the ultrasonic beam will spread in the practical range, consequently measurement volume will become too large. Thus, the characteristic of the ultrasonic beam from the emitter has great influence on the performance of Vector-UVP. For the solution of this problem, and in order to simplify our equipment, we use commercial focused transducer for the emitter. We developed 2D Vecotor-UVP system. And this system successfully applied to an actual flow field for two-dimensional velocity vector measurements.
