共查询到17条相似文献，搜索用时 156 毫秒
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双消浪室局部开孔沉箱防波堤具有低反射、结构受力小、适宜较大水深和工程造价低等优点。为明确双消浪室局部开孔沉箱水动力特性的主要影响因素,采用理论分析和物理模型试验相结合的方法,对规则波和不规则波作用下双消浪室局部开孔沉箱防波堤的反射特性进行研究。基于势流理论,建立规则波和不规则波对局部开孔沉箱防波堤作用的三维解析解,采用二次压力损失边界条件考虑沉箱开孔墙对波浪运动的影响,利用周期性边界条件考虑防波堤结构沿长度方向的周期性变化。开展相应规则波和不规则波物理模型试验,验证理论模型的合理性。通过算例分析,研究不同波浪要素和结构参数对防波堤反射特性的影响。研究表明:双消浪室局部开孔沉箱相对消浪室宽度取值为0.08~0.20,沉箱前墙开孔率大于后墙开孔率时,防波堤在较大波浪频率范围内消波效果显著;当前后墙的开孔率相等时,防波堤反射系数的最小值随着开孔率增大而减小。 相似文献
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开孔率是开孔沉箱波浪反射系数的重要影响因素,迄今为止关于开孔沉箱的物模试验研究成果(包括《防波堤设计与施工规范》)中,开孔率μ通常以线性关系反映在开孔沉箱波浪反射系数的计算关系式中,适用范围为0.2~0.4。但当μ0.2或μ0.4时,开孔率μ对波浪反射系数Kr的影响规律尚需进一步的研究探讨。现借助二维数值波浪水槽,在扩大了的开孔率取值范围内,模拟不规则波与可渗明基床上开孔沉箱的相互作用。结果表明:在0.2≤μ≤0.4的范围内,用线性关系描述开孔率μ对波浪反射系数Kr的影响是合适的;在μ0.4时,数模值和物模试验拟合的经验关系式的趋势是一致的;在μ0.2时,开孔沉箱反射系数K_r随开孔率μ的减小而增大,用物模试验拟合的经验关系式及《防波堤设计与施工规范》中计算公式的线性关系来描述开孔率μ对反射系数K_r的影响是不恰当的。研究成果对开孔沉箱消浪机理的深入认识和开孔沉箱结构的优化设计具有重要意义。 相似文献
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本文基于雷诺平均的Navier-Stokes方程和k-ε模型求解湍流流动,采用流体体积法(Volume of Fluid,VOF)追踪自由表面运动,建立无反射波浪数值水槽,对多消浪室开孔沉箱的消浪特性进行数值模拟研究。将单消浪室和多消浪室开孔沉箱反射系数和结构前波面分布的数值分析结果与物理模型试验结果进行对比验证,两者符合良好。利用数值算例,研究多消浪室开孔沉箱的反射特性以及开孔结构附近的速度场和湍流强度分布。分析结果表明:波浪与开孔沉箱相互作用时,涡旋和湍动主要分布在开孔墙和消浪室内部自由表面附近;与单消浪室开孔沉箱相比,多消浪室开孔沉箱可以更有效的耗散波浪能量,降低结构的反射系数。本文分析结果可为开孔沉箱结构的工程设计提供参考依据。 相似文献
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由于开孔前墙和消浪室具有强扰动作用,所以开孔沉箱结构具有很好的消浪效果。本文通过日照港岚山港区码头开孔沉箱结构的物理模型试验,研究了沉箱不同开孔位置的消浪效果和水动力特征,分析了不同方案的反射系数和越浪量。结果表明：水位对反射系数的影响较大,开孔位置较高的方案,其消浪性能较好,且越浪量较小。选择反射系数和越浪量均较小的设计方案进行了水动力试验,结果表明：水平力最大时对应的浮托力约为最大浮托力的60%;浮托力最大时对应的水平力约为最大水平力的75%;波浪对开孔沉箱的作用主要集中于外壁迎浪侧,内部结构受到的波浪力很小;第二消浪室波浪力小于第一消浪室。 相似文献
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多消浪室局部开孔沉箱防波堤反射特性的迭代解析研究 总被引：1，自引：0，他引：1
基于势流理论，对多消浪室局部开孔沉箱防波堤的反射特性进行解析研究。研究中采用开孔墙处的二次压力损失边界条件，可以直接考虑波高对于开孔墙处能量损失的影响。利用匹配特征函数展开法和迭代方法得到当前问题的解析解。收敛性验证表明，迭代计算和级数解均具有良好的收敛性。该解析解的计算结果与分区边界元的数值计算结果一致，并且与已有的试验结果符合良好。通过算例分析，研究开孔沉箱防波堤反射系数的主要影响因素。结果表明：与单消浪室开孔沉箱防波堤相比，多消浪室开孔沉箱防波堤可以在更宽的波浪频率范围内保持低反射；增大开孔墙的开孔率，有利于降低多消浪室开孔沉箱防波堤的反射系数；当开孔墙的开孔率沿着入射波方向依次递减时，多消浪室开孔沉箱防波堤的反射系数较小。本文所建立的解析模型简单可靠，可用于工程初步设计中分析开孔沉箱防波堤的水动力性能。 相似文献
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Wang Jianyi Senior Engineer River Harbour Department Nanjing Hydraulic Research Institute Nanjing 《中国海洋工程》1992,(1)
This paper describes the design of a perforated caisson breakwater and presents the results of model test. Tests with regular and irregular waves have demonstrated that the perforated caisson breakwater has the advantages of low reflection coefficient, good wave-absorbing performance, relatively small wave height in front of the breakwater, and small amount of overtopping. Analyses have been made of the coefficient of reflection, wave height in front of the breakwater, and wave overtopping. Relevant figures and tables are presented for reference. 相似文献
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《Coastal Engineering》2001,44(2):141-151
An analytical model has been developed that predicts the reflection of irregular waves normally incident upon a perforated-wall caisson breakwater. To examine the predictability of the developed model, laboratory experiments have been conducted for the reflection of irregular waves of various significant wave heights and periods impinging upon breakwaters having various wave chamber widths. For frequency-averaged reflection coefficients, though the overall agreement is fairly good between measurement and calculation, the model somewhat over-predicts the reflection coefficients at larger values, and under-predicts at smaller values. The model also underestimates the energy loss coefficients as wave reflection becomes larger. These differences occur because the model neglects the evanescent waves near the breakwater, which increase the energy loss at the perforated wall. The frequency-averaged reflection coefficient shows a minimum when the wave chamber width is approximately 0.2 times the significant wavelength, and it decreases with increasing wave steepness. Finally, it is shown that the reflection of irregular waves from a perforated-wall caisson breakwater depends on the wave frequency, so that the reflected wave spectrum shows a frequency dependent oscillatory behavior. 相似文献
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由于在前壁上设置了尺寸较小的孔,开孔沉箱受流体黏性力作用显著,依照弗劳德数相似准则设计模型存在比尺效应。为揭示比尺效应,建立了模拟波浪与开孔沉箱相互作用的光滑粒子流体动力学(SPH)模型。其中流体运动由连续性方程和Navier-Stokes方程控制,固壁边界由改进的动力边界粒子施加。模型收敛性通过分析不同粒子分辨率下的波浪反射系数得到,模型精度通过比较计算与理论波浪反射系数证明。使用经过验证的SPH模型,计算并比较了不同几何比尺和开孔率下开孔沉箱附近的涡量场、箱体外侧的波面时程曲线和波浪反射系数。结果表明,随着模型几何比尺的减小,开孔沉箱受到偏大的流体黏性力,致使更多波能在湍流运动中耗散,进而减小了波浪反射系数并降低了箱体外侧的波面高度。 相似文献
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The wave force on a seawater intake structure consisting of a perforated square caisson of 400 mm×400 mm size encircling a vertical suction pipe of 160-mm diameter is investigated using physical model studies. The porosity of caisson was varied from 1.6 to 16.9%. Regular and random waves of wide range of heights and periods were used. It is found that the force ratio (ratio of the force on perforated caisson to the force on caisson with zero percent porosity) reduces to an extent of up to 60% with increase in porosity of the caisson from 1.6 to 16.9%. The force ratio was found to increase with increase in relative wave height and reduces with increase in relative width. Multiple regression analysis of the measured data points was carried out and predictive equations for wave force ratios are obtained both for regular and random waves. The results of this investigation can be used in the hydrodynamic design of perforated caissons, which are widely used as seawater intake structures. 相似文献
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波浪在Jarlan型开孔潜堤上的运动 总被引：2，自引：0，他引：2
The wave motion over a submerged Jarlan-type breakwater consisting of a perforated front wall and a solid rear wall was investigated analytically and experimentally. An analytical solution was developed using matched eigenfunction expansions. The analytical solution was confirmed by previously known solutions for single and double submerged solid vertical plates, a multidomain boundary element method solution, and experimental data. The calculated results by the analytical solution showed that compared with double submerged vertical plates, the submerged Jarlan-type perforated breakwater had better wave-absorbing performance and lower wave forces. For engineering designs, the optimum values of the front wall porosity, relative submerged depth of the breakwater, and relative chamber width between front and rear walls were 0.1–0.2, 0.1–0.2, and 0.3–0.4, respectively. Interchanging the perforated front wall and solid rear wall may have no effect on the transmission coefficient. However, the present breakwater with a seaside perforated wall had a lower reflection coefficient. 相似文献
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The reflection coefficient and the total horizontal forces of regular waves acting on theperforated caisson are experimentally investigated. The empirical relationship between reflection coefficient and the ratio of the total horizontal forces acting on the perforated caisson to those on solid vertical walls with the relative chamber width, relative water depth and porosity of perforated wall, etc. are given. Moreover, the results of the ratio of the total horizontal forces are also compared with formulas given by Chinese Harbour Design Criteria and Takahashi, which may be useful for the practical engineering application. 相似文献
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Simplified analytical solutions are presented to model the interaction of linear waves with absorbing-type caisson breakwaters, which possess one, or two, perforated or slotted front faces which result in one, or two, interior fluid regions (chambers). The perforated/slotted surfaces are idealized as thin porous plates. Energy dissipation in the interior fluid region(s) inside the breakwater is modelled through a damping function. Under the assumption of potential flow and linear wave theory a boundary-value problem may then be formulated to describe wave interaction with the idealized structure. A solution to this simplified problem may be obtained by an eigenfunction expansion technique and an explicit analytical expression may be obtained for the reflected wave height. Using the experimental work of previous authors, damping coefficients are determined for both single and double chamber absorbing-type caisson breakwaters. Based on the damping for a single perforated-wall breakwater, a methodology is proposed to enable the estimation of the damping coefficients for a breakwater with two chambers. The theoretical predictions of the reflection coefficients for the two-chamber structures using the present model are compared with those obtained from laboratory experiments by other authors. It is found that the inclusion of the damping in the interior fluid region gives rise to improved agreement between theory and experiment. 相似文献