• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1754-1759
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• 2003

Two-dimensional flow over a pair of circular cylinders in side-by-side arrangements at low Reynolds numbers has been numerically investigated in this study. Numerical simulations are performed, using the immersed boundary method, in the ranges of $40{\leq}Re{\leq}160$ and $g^{\ast}<5$, where Re and $g^{\ast}$ are, respectively, the Reynolds number and the spacing between the two cylinder surfaces divided by the cylinder diameter. Results show that total six kinds of wake patterns are observed over the ranges: antiphase-synchronized, inphase-synchronized, flip-flopping, single bluff-body, deflected, and steady wake patterns. It is found that the characteristics of the flow significantly depends both on the Reynolds number and gap spacing, with the latter much stronger than the former. Instantaneous flow fields, time traces, flow statistics and so on are presented to identify the wake patterns and then to understand the underlying mechanism. It is remarkable that, for the deflected wake pattern, the gap flow is deflected invariably to the cylinder of higher drag coefficient and the deflection way does not change at all. Moreover, the bifurcation phenomena where either of two wake patterns can occur are found at certain flow conditions.

• 대한기계학회논문집B
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• 제27권7호
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• pp.909-919
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• 2003

Two-dimensional flow over a pair of circular cylinders in a side-by-side arrangement at low Reynolds numbers has been numerically investigated in this study Numerical simulations are performed, using the immersed boundary method, for the ranges of 40$\leq$Re$\leq$160 and $g^{*}$＜5, where Re and $g^{*}$ are, respectively, the Reynolds number and the spacing between the two cylinder surfaces divided by the cylinder diameter. Results show that a total of six kinds of wake patterns are observed over the ranges: antiphase-synchronized, inphase-synchronized, flip-flopping, single bluff-body, deflected, and steady wake patterns. It is found that the characteristics of the flow significantly depends both on the Reynolds number and gap spacing, with the latter much stronger than the former. Instantaneous flow fields, time traces, flow statistics and so on are presented to identify the wake patterns and then to understand the underlying mechanism. Moreover, the bifurcation phenomenon where either of two wake patterns can occur is found at certain flow conditions.ons.

• 전기의세계
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• 제13권1호
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• pp.20-23
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• 1964

본 변환기는 교번자계의 원리에 의한 보통 변환기가 아니고 회전자계의 원리를 이용한 변환기로서 상변환, 주파수변화, A.C.에서 D.C. 전원변환, D.C.에서 A.C. 전원변환, 속도제어, 진상기 등을 얻을 수 있는 경제적이고 능률적인 변환기를 얻을 수 있다. 임의의 다상을 얻을 수 있는 이 변환기는 다상 전원을 필요로 하는 수은정류기 등에 응용할 수 있고 A.C.전원에서 D.C.전원의 대용량전원을 얻어 D.C.전원이 필요로 하는 직류전철의 전원, 직류송전의 전원등에 이용할 수 있고, D.C.전원에서 A.C.전원을 얻어 교류전력기를 운전할 수 있으며 D.C.송전선에서 A.C.로 변환하여 종전의 A.C.배전선에 공급하면 D.C.송전을 이용한 송전손실을 경감시킬수 있고 주파수를 변환하여 속도제어를 하는 등 광범위하게 그 응용이 가능한 것이다.