| Project/Area Number |
17500411
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Sports science
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| Research Institution | Akita University |
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Principal Investigator |
HASEGAWA Hiroaki Akita University, Mechanical Engineering, Lecturer (90344770)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUUCHI Kazuo University of Tsukuba, Graduate School of Systems & Information Engineering, Professor (70111367)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,610,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥210,000)
Fiscal Year 2007: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2006: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2005: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | Dynamic Lift / Unsteady Fluid Force / Pitchine Motion / Lift / Drag / Three-Dimensional Airfoil / Swimming / 非定序流体力 / 動的失速 |
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| Research Abstract |
For experiments in circulating water channel by a human swimmer
The PIV (Particle Image Velocimetry) technique can visualize the unsteady flow field and can detect the vortex behavior around a hand. Moreover, motion analysis has been widely used in the field of biomechanics of sport. A motion analysis can analyze the unsteady motion of swimmer quantitatively, and can also be expected to evaluate the swimmer's complicated motion. Two methods were combined to know the generating mechanism of swimming thrust. Measurements were made for two subjects; one is a female Olympic swimmer (subject 1) and the other is a male with no competitive career (subject 2). From the results of visualization of flow field, subject 1 generates strong vortices or vortex pair after the phase turned from in-sweep to out-sweep. In addition, the shed vortex pair follows a jet flow in the direction of the flume flow. In contrast, subject 2 did not shed any vortex pairs. It was confirmed that: the hand motion in swim
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ming was closely related to the vortex generation and also to the thrust.
For wind tunnel experiments
In order to investigate the effect of leading edge profile on unsteady fluid forces, several types of model (circular, triangular and square shapes) were installed. The delay of stall for the pitching models is observed and also the value of maximum lift coefficient is greater than the maximum lift coefficient under stationary condition. The unsteady fluid forces are affected by the differences of the leading edge vortex due to the different leading edge profile. Furthermore, to investigate the mechanism of propulsion in front crawl swimming, we measured the flow field around a discoid airfoil simulating a human hand by using hot-wire anemometry and PIV. The structure of flow around the pitching and heaving airfoil was also measured. At high reduced frequency, the leading edge vortex and tip vortex are formed in the wake of the airfoil and shed when the circumferential velocity of the airfoil reaches maximum. It was confirmed that the unsteady fluid forces are closely related to the generation of large vortices. The flow structures due to the behavior of vortices shedding from the airfoil edge during the pitching motion were strongly affected by the reduced frequency. At high reduced frequency, the significant vortices were formed close to the airfoil's treading edge, and large scale vortices were generated in the wake of the airfoil. Less
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