CAJ | 학술논문

对均匀来流下靠近壁面处在垂直流向做强迫振荡运动的光滑圆柱的水动力特性进行了试验研究.试验在拖曳水池中进行,雷诺数为2×105,通过采集顺流向和垂直流向的力,得到了阻力系数、升力系数、相位角等与间隙比、振荡频率和振幅之间的关系.通过研究得到如下结论:1)振荡圆柱的平均阻力系数在近壁面处随间隙比的减小而骤降;2)振荡圆柱泄涡受到完全抑制的临界间隙比要小于静止圆柱;3)近壁面的存在对振荡圆柱的能量传递有着重要的影响,自由边界圆柱强迫振荡所得到的水动力系数不能用来预报海底管道的涡激振动;4)对于振荡圆柱,附加质量系数只有在一定的频率范围内才是定值,且在低频率区域其绝对值随间隙比减小而增大;5)圆柱在进行强迫振荡时,其平均阻力系数、振荡阻力系数和振荡升力系数均随无因次振幅的增加而增大.
대균균래류하고근벽면처재수직류향주강박진탕운동적광활원주적수동력특성진행료시험연구.시험재타예수지중진행,뢰낙수위2×105,통과채집순류향화수직류향적력,득도료조력계수、승력계수、상위각등여간극비、진탕빈솔화진폭지간적관계.통과연구득도여하결론:1)진탕원주적평균조력계수재근벽면처수간극비적감소이취강;2)진탕원주설와수도완전억제적림계간극비요소우정지원주;3)근벽면적존재대진탕원주적능량전체유착중요적영향,자유변계원주강박진탕소득도적수동력계수불능용래예보해저관도적와격진동;4)대우진탕원주,부가질량계수지유재일정적빈솔범위내재시정치,차재저빈솔구역기절대치수간극비감소이증대;5)원주재진행강박진탕시,기평균조력계수、진탕조력계수화진탕승력계수균수무인차진폭적증가이증대.
@@@@Hydrodynamic characteristics of a near-wall circular cylinder oscillating in direction perpendicular to steady current are experi-mentally investigated at a Reynolds number of 2 × 105. Forces in both in-line and cross-flow are measured by the three-dimensional force transducers. The effects of gap ratio, oscillating frequency and amplitude on the hydrodynamic charactersistic of the cylinder are studied. Experimental results indicate that 1) mean drag reduces rapidly when the gap ratio decreases from 0.7 to 0.3;2) for an oscillating cylinder, the critical gap ratio of vortex shedding suppression is smaller than that for a still cylinder; 3) the existence of near-wall influences the energy transfer between the structure and fluid significantly, which means that hydrodynamic coefficient based on free-wall cylinder may not be suitble for predicting vortex induced vibration of pipelines;4) for an oscillating cylinder, added mass is not a constant except for in a certain range of oscillating frequency, and the absolute value increases with the decrease of gap ratio in low frequency range;5) mean drag coefficient, oscillating drag coefficient and oscillating lift coefficient all increase with oscillating amplitude increasing.