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1.
The inline and lift forces on bipiles in parallel array induced by both irregular waves and currents were investigated experimentally in this paper. The characteristics in both time and frequency domains of inline, lift and resultant forces as well were analyzed. The grouping effect coefficients of inline and resultant forces on two piles related to KC number and relative spacing parameters are given. A comparison of the magnitude and direction of resultant forces on two piles in parallel array with the corresponding values for single cylinder is also made. 相似文献
2.
《中国海洋工程》1990,(1)
Based on the linear wave theory, the lift force on the cylinder under the action of both regular waves and currents related to inline force and the resultant force has been investigated. The relationship between the hydrodynamic coefficients of resultant force Cf, of drag force Cd, of inertia force Cm and of lift force CL and the redefined KC number is reported. It is indicated that in a certain region of KC number, the influence of lift force on the resultant force can not be ignored. 相似文献
3.
Li Yucheng Wang Fenglong Professor Dalian University of Technology Dalian Senior Engineer Dalian University of Technology Dalian 《中国海洋工程》1993,(1)
- The wave-current forces on vertical piles in side-by-side arrangement induced by irregular waves with opposing current are investigated experimentally in this paper. The characteristics in both time and frequency domain of in-line, lift and resultant forces are analyzed. The grouping effect coefficients of inline, lift and resultant forces on piles related to KC number and relative spacing parameters are given. These results are compared with those in the case of irregular waves combined with following currents. It is found that the results in these two cases are quite different. The range of KC number tested is 10- 60, the range of Reynolds number is (0.55-3.43) ×104. 相似文献
4.
《中国海洋工程》1990,(1)
The total transverse forces on each of the two piles in the side-by-side arrangement and tandem arrangement are experimentally investigated in irregular waves and the total in-line wave forces are measured simultaneously. The statistical and spectral characteristics of the transverse forces are analyzed. The ratio of the transverse force on each pile in group to that on a single pile is defined as the transverse groupling-pile factor, KGL. Both the transverse coefficients CLG and KGL for each pile in array are varied with the relative pile distance and KC number and their relationships are presented in this paper. Also the ratio of the resultant wave froce of in-line force and transverse force to the in-line force and the vriation of the resultant coefficient are investigated. 相似文献
5.
Based on model tests, the lift and resultant forces on small square cylinders caused by waves (regular and irregular) and currents are analyzed in this paper. The lift and resultant force coefficients CL and Cf related to KC number and the effect of direction of wave propagation are also given, which may be useful for practical engineering application. 相似文献
6.
-The hydrodynamic coefficients for each of two piles and three piles in both side-by-side arrangement and tandem arrangement under the action of irregular waves are experimentally investigated. These coefficients vary with the KC number, the relative pile spacing, the number of piles and the pile location, and their relationships are presented in this paper. They can be used in Morison Equation and other equations to calculate directly the in-line wave forces and the transverse forces on each pile in array. 相似文献
7.
Li Yucheng Zhang Ningchuan
Professor Dalian University of Technology Dalian . Lecturere Delian University of Technology Dalian 《中国海洋工程》1994,(1)
- A composite pipeline is defined as a main big pipe composed of one or several small pipes. The flow behaviour around a submarine composite pipeline is more complicated than that around a single submarine pipeline. A series model test of composite pipelines in a wave-current coexisting field was conducted by the authors. Both in-line and lift forces were measured, and the resultant forces were also analyzed. The results of lift forces and resultant forces are reported in this paper. It is found that the lift force coefficients for composite pipelines are well related to the KC number. The lift force coefficients for an irregular wave-current coexisting field are smaller than those for a regular wave-current coexisting field. The frequency of lift force is usually twice the wave frequency or higher. The authors test indicates that the resultant forces are about 10 to 20 percent larger than in-line forces (horizontal forces). The effect of water depth is analyzed. Finally, the relationship between lift f 相似文献
8.
《中国海洋工程》1989,(1)
The magnitude and the fluctuating frequency of the total transverse wave forces, particularly those by irregular waves on an isolated pile are investigated experimentally. The results indicate that the transverse force FL is usually not negligible and the resultant force FR of the transverse force and the inline force may be 40% (in regular waves) or 18% (in irregular waves) larger than the inline force F. The plots of FL/F, FR/F and several kinds of lift coefficient CL versus KC number are given for both regular waves and irregular waves. The methods for estimating the total transverse forces and resultant wave forces are suggested. 相似文献
9.
《中国海洋工程》1988,(3)
The irregular wave forces on the piles of small diameters are experimentally investigated. The total in-line forces on single vertical pile and on each pile in array in irregular waves are measured. For single pile, the relationships between Cd, Cm and K-C number are determined with the best least-square method in time domain. In the case of two piles in the side-by-side arrangement and the tandem arrangement, a grouping-pile factor, KG, is used to consider the interference between two piles. Based on the experiments, the plots of KG versus K-C number and the relative distance, l/D, are given. 相似文献
10.
The total inline wave forces, the irregular wave forces in particular, on an isolated pile are investigated by experiment. The relationships between force coefficients Cd and CM including in Morison's Eq. . and KC number or Reynolds number Re, and the variation of Cd and Cm in frequency domain are analysed with the method of least-squares in time domain and that of cross-spectral analysis. The plots of C4and Cmversus KCare given for both regular and irregular waves and those for irregular waves are used for numerical simulation of the irregular wave forces on the vertical pile and the results are in fairly good agreement with the test data. Based on the experimental results , the applicability of the spectral analysis method for calculating irregular wave forces on an isolated pile is investigated with the coherency γ between wave and wave forces and with KC number. 相似文献
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冰激振动及冰荷载动力特性的试验研究 总被引：2，自引：0，他引：2
回顾了解决海冰引起结构振动分析方法的要求，通过室内冰力模型试验得出了冰激振动的重要参数－冰力频率，幅值的特性。研究表明，在低冰速时，冰力频率与冰速对冰厚之比呈线性关系；高冰速时，冰力步与冰速对冰厚之比呈现恒定性，文章还根据试验数据以及统计分析，推荐了冰力幅值计算公式和取值范围。 相似文献
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The shielding effect of the front pile-row on the ice force acting on the hack pile-row is studied by ice force model tests. In the tests, the front pile-row is designed to model jacket legs and the hack pile-row to model the water resisting pipe-phalanx within the jacket. The shielding factor for ice force corresponding to different conditions are given in this paper. The research indicates that there are many factors, including the longitudinal and lateral spacing between the front and hack pile-row, ice attacking angle and the ratio of pile diameter to ice thickness, that influence the shielding effect on ice force. 相似文献
15.
This paper presents the results of an experimental investigation on the variation in the tension and the distribution of drag force coefficients along flexible risers under vortex-induced vibration (VIV) in a uniform flow for Reynolds numbers (Re) up to 2.2×105. The results show that the mean tension is proportional to the square of the incoming current speed, and the tension coefficient of a flexible riser undergoing VIV can be up to 12. The mean drag force is uniformly and symmetrically distributed along the axes of the risers undergoing VIV. The corresponding drag coefficient can vary between 1.6 and 2.4 but is not a constant value of 1.2, as it is for a fixed cylinder in the absence of VIV. These experimental results are used to develop a new empirical prediction model to estimate the drag force coefficient for flexible risers undergoing VIV for Reynolds number on the order of 105, which accounts for the effects of the incoming current speed, the VIV dominant modal number and the frequency. 相似文献
16.
C.H.K. Williamson 《Applied Ocean Research》1985,7(3):124-127
The present brief paper is intended to show that the fluid forces on a small cylinder can be considerably magnified when it is in the flow field of a larger cylinder. Two cylinders of unequal diameter are oscillated in a tank of fluid, and the lift and in-line forces on the smaller cylinder are measured when the pair of cylinders is placed at various orientations and spacings. 相似文献
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岙山成品油码头海底边坡稳定性分析 总被引：1，自引：0，他引：1
根据岙山成品油码头工程地质勘察所得的资料,选择边坡较陡的地段,采用折线法、圆弧条分法和总应力极限平衡法,对在自重、地震力和波浪力等因素作用下的边坡稳定性进行验算分析。结果表明,海底边坡较陡地段浅层土体的稳定性较差,土体滑动面可能发生在海底下９～１２．５ｍ处。对地层的作用波浪力较地震力要小,但两者均可能成为边坡土体滑动的诱因。 相似文献
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高雷诺数下均匀振荡流中倾斜桩柱上的水动力特征研究 总被引：1，自引：0，他引：1
本文介绍了均匀振荡流中光滑倾斜桩柱上（α＝４５°）水动力特征的试验研究及其与水平桩柱（α＝９０°）研究结果的对比。 相似文献