Presentations

従来のTLCDの制振性能を改善するため, 定常磁場を印加することで固有振動数を制御可能としたセミアクティブ型液柱管ダンパーを製作し, 磁場による液柱固有振動数の変化について実験的解析を行った。

We measured the velocity distribution of a rectangular duct flow of a magnetic fluid using UVP. The experiments were carried out with changing external magnetic field intensity and Reynolds number of the magnetic fluid flow. On the basis of the results of these experiments, the influence of magnetic field on the velocity distribution of rectangular duct flow of magnetic fluid was discussed.

We proposed qualitative analysis to investigate resistance force of MR fluid when subjected to a shock loading. The MR fluid was subjected to a shock loading through a piston rod which placed in the one side of the U-pipe. Experiments have been conducted by measuring displacement of piston rod and a resistance force. Based on the experimental result, the effect of orifice inner diameter on the resistance force of MR fluid was discussed.

矩形管内を流れる磁性流体の速度分布を超音波を利用して計測し，速度分布および伝熱特性におよぼす磁場の影響を調べた。

矩形流路内を流れる磁性流体の強制対流熱伝達特性について，乱流と層流の場合での検討を行った。

Dynamic pressure response in an oscillating rectangular container filled with a magnetic fluid under a horizontal magnetic field was discussed. An investigation was made experimental approach based on the measurement of pressure at several points by pressure transducers and the real-time computation of a discrete Fourier transform.

We designed a novel semi-active damper using a magnetic fluid as a working fluid of the tuned liquid column damper (MF-TLCD). Experiments were performed to analyze the effect of a magnetic field on natural frequencies of the MF-TLCD. Based on the experimental results, relations among setting positions of an electromagnet, strength of magnetic field, and changes of a natural frequency were discussed.

We carried out experiments by applying different magnetic field (M/F) sweep rates to MR fluid. The ultrasonic propagation velocity was measured and the change of ultrasonic propagation velocity was calculated for various M/F sweep rate. The relation between the change of ultrasonic propagation velocity and M/F sweep rate was discussed.

Effect of magnetic field on forced convective heat transfer in rectangular duct flow of a magnetic fluid was investigated experimentally. When the magnetic field is applied to the magnetic fluid laminar flow, heat transfer coefficient locally increased in the region where the magnetic field exists. The flow velocity at the center of the rectangular duct decreases and the velocity gradient in the near-wall region increased with increasing magnetic field intensity.

This paper presents experimental analysis of cluster growth in Magneto-rheological (MR) fluid. The experiments were conducted by applying magnetic field to MR fluid in different sweep rates. Magnetic field was swept from 0 to 400 mT at different time. Ultrasonic propagation velocity was measured and the change of ultrasonic propagation velocity was calculated. Based on the experiment result, the relation between the change of ultrasonic propagation velocity and M/F sweep rate is discussed. Furthermore, the relation between the maximum change of ultrasonic propagation velocity and various M/F sweep rate is presented.

同調液柱管ダンパー(TLCD)の作動流体として磁性流体を用い，電磁石によって外部から定常磁場を印加することで制振のセミアクティブ化を試みた。実験では液柱のみの1自由度強制振動実験と，液柱と構造物からなる2自由度強制振動実験を行い，磁場印加によって構造物振幅や圧力変動の周波数応答がどのように変化するかを調べた。

MR流体に衝撃力が加わった時の減衰特性が磁場によってどのように変化するかを調べた。

磁性流体を作動流体に用いることで磁場制御を可能にした液柱管ダンパーの提案とその振動特性におよぼす磁場の影響を調べた。

Experiments were performed to measure how the ultrasonic propagation attenuation in an MR fluid under an external magnetic field was affected by temperature, elapsed time, magnetic field intensity, magnetic field angle, removal of the magnetic field, and hysteresis. The influence of the clustering structures on change of ultrasonic propagation attenuation in MR fluids is discussed.

Dynamic pressure change of a magnetic fluid in a lateral oscillating container was investigated. An experimental approach based on the measurement of pressure at several points by small disc-type pressure transducers was used. Several frequency response spectra are received. These results indicated that the free surface disturbance caused by the sloshing was suppressed by the applied magnetic field.

Effect of cluster formations on two-dimensional channel flow of a magnetic fluid flow was investigated. Pressure drop was measured by changing the application times of the magnetic field, Reynolds numbers and magnetic field intensities.

We propose a qualitative analysis to investigate the damping characteristic of the MR fluid under a shock loading. The experimental apparatus consists of a drop-test tower, U-pipe and sensor tower. MR fluid is placed in U-pipe which was subjected to the shock loading through a piston. The experiment was carried out by measuring the displacement, velocity and acceleration of piston. The effect of the orifice inner-diameter on damping characteristic of an MR fluid was discussed.

Experiments have been performed with a closed-circuit loop with the rectangular duct having square cross-section for the test section. In case of laminar flow, when the magnetic field is applied to magnetic fluid, heat transfer was drastically enhanced locally in the region where the magnetic field exists. This heat transfer becomes large with increasing magnetic field and is saturated with applying more than 400 mT of magnetic field. In addition, velocity distribution of magnetic fluid flow also changed under magnetic field. On the contrary, in the case of turbulent flow, local heat transfer coefficient ratio does not increase but slightly decreases. This is because turbulent diffusion is largely suppressed by the magnetic field.

MR流体中を伝播する超音波の減衰特性を実験的に調べ，温度・磁場強度のおよぼす影響の検討を行った。

Heat transfer characteristics in rectangular duct flow of a magnetic fluid under magnetic field were investigated experimentally. As a result of this experiment, in laminar flow, when the magnetic field is applied to magnetic fluid, heat transfer coefficient drastically increases locally in the region where the magnetic field exists. On the contrary, in the turbulent flow, heat transfer is not enhanced but slightly decreases.